title: Planned Parenthood v. Casey

text: The Court of Appeals for the Third Circuit affirmed in part and reversed in part, upholding all of the regulations except for the husband notification requirement. The Third Circuit concluded that the husband notification was unduly burdensome because it potentially exposed married women to spousal abuse, violence, and economic duress at the hands of their husbands. Then-Circuit Judge Samuel Alito sat on that three-judge appellate panel and dissented from the court's invalidation of that requirement. Thirty-one years later, as a Supreme Court Justice, Alito wrote the opinion in "Dobbs v. Jackson Women's Health Organization", which overturned "Roe" and "Casey".


title: Planned Parenthood v. Casey

text: At the conference of the Justices two days after oral argument, Souter defied expectations, joining Justices Stevens, Blackmun, and Sandra Day O'Connor, who had all dissented three years earlier in "Webster v. Reproductive Health Services" with regard to that plurality's suggested reconsideration and narrowing of "Roe". This resulted in a precarious five-Justice majority consisting of Chief Justice William Rehnquist, Byron White, Antonin Scalia, Anthony Kennedy, and Clarence Thomas that favored upholding all five contested abortion restrictions and overturning "Roe"; however, Kennedy changed his mind shortly thereafter, and joined with fellow Reagan-Bush justices O'Connor and Souter to write a plurality opinion that would reaffirm "Roe".


title: Planned Parenthood v. Casey

text: Except for the three opening sections of the O'Connor–Kennedy–Souter opinion, "Casey" was a divided judgment, as no other sections of any opinion were joined by a majority of justices. The plurality opinion jointly written by Justices Souter, O'Connor, and Kennedy was recognized as the principal opinion.


title: Planned Parenthood v. Casey

text: In the 1992 case of "Planned Parenthood v. Casey", the authors of the plurality opinion abandoned "Roe's" strict trimester framework but maintained its central holding that women have a right to have an abortion before viability. "Roe" had held that statutes regulating abortion must be subject to "strict scrutiny"—the traditional Supreme Court test for impositions upon fundamental Constitutional rights. "Casey" instead adopted the lower, undue burden standard for evaluating state abortion restrictions, but re-emphasized the right to abortion as grounded in the general sense of liberty and privacy protected under the constitution. The authors of the plurality opinion likewise noted the U.S. government's previous challenges to "Roe v. Wade" and expounded on the concept of "liberty."


title: Planned Parenthood v. Casey

text: The plurality opinion stated that it was upholding what it called the "essential holding" of "Roe". The essential holding consisted of three parts: (1) Women had the right to have an abortion prior to viability and to do so without undue interference from the State; (2) the State could restrict the abortion procedure post-viability, so long as the law contained exceptions for pregnancies which endangered the woman's life or health; and (3) the State had legitimate interests from the outset of the pregnancy in protecting the health of the woman and the life of the fetus that may become a child. The plurality asserted that the fundamental right to abortion was grounded in the Due Process Clause of the Fourteenth Amendment, and the plurality reiterated what the Court said in "Eisenstadt v. Baird": "If the right of privacy means anything, it is the right of the individual, married or single, to be free from unwarranted governmental intrusion into matters so fundamentally affecting a person as the decision whether to bear or beget a child."


title: Planned Parenthood v. Casey

text: The plurality's opinion included a thorough discussion on the doctrine of "stare decisis" (respect of precedent), and provided a clear explanation for why the doctrine had to be applied in "Casey" with regards to "Roe". The authors of the plurality opinion emphasized that "stare decisis" had to apply in "Casey" because the "Roe" rule had not been proven intolerable; the rule had become subject "to a kind of reliance that would lend a special hardship to the consequences of overruling and add inequity to the cost of repudiation"; the law had not developed in such a way around the rule that left the rule "no more than a remnant of abandoned doctrine"; and the facts had not changed, nor viewed differently, to "rob the old rule of significant application or justification." The plurality acknowledged that it was important for the Court to stand by prior decisions, even those decisions some found unpopular, unless there was a change in the fundamental reasoning underpinning the previous decision. The authors of the plurality opinion, making a special note of the precedential value of "Roe v. Wade", and specifically how women's lives were changed by that decision, stated,


title: Planned Parenthood v. Casey

text: The sum of the precedential enquiry to this point shows Roe's underpinnings unweakened in any way affecting its central holding. While it has engendered disapproval, it has not been unworkable. An entire generation has come of age free to assume Roe's concept of liberty in defining the capacity of women to act in society, and to make reproductive decisions; no erosion of principle going to liberty or personal autonomy has left Roe's central holding a doctrinal remnant.


title: Planned Parenthood v. Casey

text: The authors of the plurality opinion also acknowledged the need for predictability and consistency in judicial decision making. For example,Where, in the performance of its judicial duties, the Court decides a case in such a way as to resolve the sort of intensely divisive controversy reflected in Roe and those rare, comparable cases, its decision has a dimension that the resolution of the normal case does not carry. It is the dimension present whenever the Court's interpretation of the Constitution calls the contending sides of a national controversy to end their national division by accepting a common mandate rooted in the Constitution."


title: Planned Parenthood v. Casey

text: The plurality went on to analyze past judgments refusing to apply the doctrine of stare decisis, such as "Brown v. Board of Education". There, the authors of the plurality opinion explained, society's rejection of the "Separate but Equal" concept was a legitimate reason for the "Brown v. Board of Education" court's rejection of the "Plessy v. Ferguson" doctrine. Emphasizing the lack of need to overrule the essential holding of "Roe", and the Court's need to not be seen as overruling a prior decision merely because the individual members of the Court had changed, the authors of the plurality opinion stated,


title: Planned Parenthood v. Casey

text: Because neither the factual underpinnings of Roe's central holding nor our understanding of it has changed (and because no other indication of weakened precedent has been shown), the Court could not pretend to be reexamining the prior law with any justification beyond a present doctrinal disposition to come out differently from the Court of 1973.


title: Planned Parenthood v. Casey

text: The plurality further emphasized that the Court would lack legitimacy if it frequently changed its Constitutional decisions, stating,


title: Planned Parenthood v. Casey

text: The Court must take care to speak and act in ways that allow people to accept its decisions on the terms the Court claims for them, as grounded truly in principle, not as compromises with social and political pressures having, as such, no bearing on the principled choices that the Court is obliged to make.


title: Planned Parenthood v. Casey

text: Since the O'Connor-Kennedy-Souter plurality overruled some portions of "Roe v. Wade" despite its emphasis on "stare decisis", Chief Justice Rehnquist in dissent argued that this section was entirely "obiter dicta". All these opening sections were joined by Justices Blackmun and Stevens for the majority. The remainder of the decision did not command a majority, but at least two other Justices concurred in judgment on each of the remaining points.


title: Planned Parenthood v. Casey

text: Although it upheld the "essential holding" in "Roe", and recognized that women had some constitutional liberty to terminate their pregnancies, the O'Connor–Kennedy–Souter plurality overturned the "Roe" trimester framework in favor of a viability analysis. The "Roe" trimester framework completely forbade states from regulating abortion during the first trimester of pregnancy, permitted regulations designed to protect a woman's health in the second trimester, and permitted prohibitions on abortion during the third trimester (when the fetus becomes viable) under the justification of fetal protection, and so long as the life or health of the mother was not at risk. The plurality found that continuing advancements in medical technology had proven that a fetus could be considered viable at 23 or 24 weeks rather than at the 28 weeks previously understood by the Court in "Roe". The plurality thus redrew the line of increasing state interest at viability because of increasing medical accuracy about when fetus viability takes place. Likewise, the authors of the plurality opinion felt that fetus viability was "more workable" than the trimester framework.


title: Planned Parenthood v. Casey

text: Under this new fetus viability framework, the plurality held that at the point of viability and subsequent to viability, the state could promote its interest in the "potentiality of human life" by regulating, or possibly proscribing, abortion "except where it is necessary, in appropriate medical judgment, for the preservation of the life or health of the mother." Prior to fetus viability, the plurality held, the State can show concern for fetal development, but it cannot pose an undue burden on a woman's fundamental right to abortion. The plurality reasoned that the new pre- and post-viability line would still uphold the essential holding of "Roe", which recognized both the woman's constitutionally protected liberty, and the State's "important and legitimate interest in potential life."


title: Planned Parenthood v. Casey

text: In replacing the trimester framework with the viability framework, the plurality also replaced the strict scrutiny analysis under "Roe", with the "undue burden" standard previously developed by O'Connor in her dissent in "Akron v. Akron Center for Reproductive Health". A legal restriction posing an undue burden is one that has "the purpose or effect of placing a substantial obstacle in the path of a woman seeking an abortion of a nonviable fetus." An undue burden is found even where a statute purports to further the interest of potential life or another valid state interest, if it places a substantial obstacle in the path of access to abortion. The Supreme Court in the 2016 case "Whole Woman's Health v. Hellerstedt" clarified exactly what the 'undue burden' test requires: ""Casey" requires courts to consider the burdens a law imposes on abortion access together with the benefits those laws confer." The Supreme Court further clarified in the 2020 "June Medical Services, LLC v. Russo" opinion written by Justice Stephen Breyer with respect to the undue burden standard: "[T]his standard requires courts independently to review the legislative findings upon which an abortion-related statute rests and to weigh the law's "asserted benefits against the burdens" it imposes on abortion access. 579 U.S., at ___(slip op., at 21) (citing "Gonzales v. Carhart", 550 U. S. 124, 165 (2007))." In "Whole Woman's Health v. Hellerstedt" the court described the undue burden standard in its overall context with these words:


title: Planned Parenthood v. Casey

text: In applying the new undue burden standard, the plurality overruled "City of Akron v. Akron Center for Reproductive Health", 462 U.S. 416 (1983) and "Thornburgh v. American College of Obstetricians and Gynecologists", 476 U.S. 747 (1986), each of which applied "strict scrutiny" to abortion restrictions.


title: Planned Parenthood v. Casey

text: Applying this new standard to the challenged Pennsylvania Act, the plurality struck down the spousal notice requirement, finding that for many women, the statutory provision would impose a substantial obstacle in their path to receive an abortion. The plurality recognized that the provision gave too much power to husbands over their wives ("a spousal notice requirement enables the husband to wield an effective veto over his wife's decision"), and could worsen situations of spousal and child abuse. In finding the provision unconstitutional, the authors of the plurality opinion clarified that the focus of the undue burden test is on the group "for whom the law is a restriction, not the group for whom the law is irrelevant." Otherwise stated, courts should not focus on what portion of the population is affected by the legislation, but rather on the population the law would restrict. The plurality upheld the remaining contested regulations – the State's informed consent and 24-hour waiting period, parental consent requirements, reporting requirements, and the "medical emergencies" definition – holding that none constituted an undue burden.


title: Planned Parenthood v. Casey

text: Notably, when the authors of the plurality discuss the right to privacy in the joint opinion, it is all within the context of a quotation or paraphrase from "Roe" or other previous cases. The authors of the plurality opinion do not, however, explicitly or implicitly state that they do not believe in a right to privacy, or that they do not support the use of privacy in "Roe" to justify the fundamental right to abortion. Justice Blackmun would not agree with an implication asserting otherwise, stating "[t]he Court today reaffirms the long recognized rights of privacy and bodily integrity."


title: Planned Parenthood v. Casey

text: Chief Justice John Roberts's concurrence in the 2020 "June Medical Services, LLC v. Russo" case noted the key outcomes in "Casey": "The several restrictions that did not impose a substantial obstacle were constitutional, while the restriction that did impose a substantial obstacle was unconstitutional." Before an abortion regulation can be struck down as unconstitutional there must be a determination that this regulation imposes a substantial obstacle in light of the undue burden standard explained in the section above. In "Casey" "the justices imposed a new standard to determine the validity of laws restricting abortions. The new standard asks whether a state abortion regulation has the purpose or effect of imposing an "undue burden", which is defined as a "substantial obstacle in the path of a woman seeking an abortion before the fetus attains viability." The key judgment of "Casey" can be summed up as follows: "Under "Casey", abortion regulations are valid so long as they do not pose a substantial obstacle and meet the threshold requirement of being "reasonably related" to a "legitimate purpose." "Id.", at 878; "id.", at 882 (joint opinion)."


title: Planned Parenthood v. Casey

text: Justices Harry Blackmun and John Paul Stevens, who both joined the plurality in part, also each filed opinions concurring in the Court's judgment in part and dissenting in part. Chief Justice William Rehnquist filed an opinion concurring in the Court's judgment in part and dissenting in part, which was joined by Justices Byron White, Antonin Scalia, and Clarence Thomas, none of whom joined any part of the plurality. Justice Scalia also filed an opinion concurring in the judgment in part and dissenting in part, which was also joined by Rehnquist, White, and Thomas.


title: Planned Parenthood v. Casey

text: Rehnquist and Scalia each joined the plurality in upholding the parental consent, informed consent, and waiting period laws. However, they dissented from the plurality's decision to uphold "Roe v. Wade" and strike down the spousal notification law, contending that "Roe" was incorrectly decided. In his opinion, Chief Justice Rehnquist questioned the fundamental right to an abortion, the "right to privacy", and the strict scrutiny application in "Roe". He also questioned the new "undue burden" analysis under the plurality opinion, instead deciding that the proper analysis for the regulation of abortions was rational-basis.


title: Planned Parenthood v. Casey

text: In his opinion, Justice Scalia also argued for a rational-basis approach, finding that the Pennsylvania statute in its entirety was constitutional. He argued that abortion was not a "protected" liberty, and as such, the abortion liberty could be intruded upon by the State. To this end, Justice Scalia concluded this was so because an abortion right was not in the Constitution, and "longstanding traditions of American society" have allowed abortion to be legally proscribed. Rehnquist and Scalia joined each other's concurrence/dissents. White and Thomas, who did not write their own opinions, joined in both.


title: Planned Parenthood v. Casey

text: Justices Blackmun and Stevens wrote opinions in which they approved of the plurality's preservation of "Roe" and rejection of the spousal notification law. They did not agree with the plurality's decision to uphold the other three laws at issue.


title: Planned Parenthood v. Casey

text: Justice Stevens concurred in part and dissented in part. Justice Stevens joined the plurality's preservation of "Roe" and rejection of the spousal notification law, but under his interpretation of the undue burden standard ("[a] burden may be 'undue' either because the burden is too severe or because it lacks a legitimate rational justification"), he would have found the information requirements in §§ 3205(a)(2)(i)–(iii) and § 3205(a)(1)(ii), and the 24-hour waiting period in §§ 3205(a)(1)–(2) unconstitutional. Instead of applying an undue burden analysis, Justice Stevens would have preferred to apply the analyses in "Akron" and "Thornburgh," two cases that had applied a strict scrutiny analysis, to reach the same conclusions. Justice Stevens also placed great emphasis on the fact that women had a right to bodily integrity, and a constitutionally protected liberty interest to decide matters of the "highest privacy and the most personal nature." As such, Justice Stevens felt that a State should not be permitted to attempt to "persuade the woman to choose childbirth over abortion"; he felt this was too coercive and violated the woman's decisional autonomy.


title: Planned Parenthood v. Casey

text: Justice Blackmun concurred in part, concurred in the judgment in part, and dissented in part. He joined the plurality's preservation of "Roe" – of which he wrote the majority – and he, too, rejected the spousal notification law. Justice Blackmun, however, argued for a woman's right to privacy and insisted, as he did in "Roe", that all non-"de-minimis" abortion regulations were subject to strict scrutiny. Using such an analysis, Justice Blackmun argued that the content-based counseling, the 24-hour waiting period, informed parental consent, and the reporting regulations were unconstitutional. He also dissented from the plurality's undue burden test, and instead found his trimester framework "administrable" and "far less manipulable". Blackmun even went further in his opinion than Stevens, sharply attacking and criticizing the anti-"Roe" bloc of the Court.


title: Planned Parenthood v. Casey

text: In May 2022, "Politico" obtained a leaked initial draft majority opinion written by Justice Samuel Alito suggesting that the Supreme Court was poised to overturn "Casey" along with "Roe" in a pending final decision on "Dobbs v. Jackson Women's Health Organization." On June 24, 2022, the final opinion was issued, with the Court overturning the "essential opinion" in "Roe", criticizing the "Casey" Court's failure to address the deficiencies of the "Roe" decision and overturning the "key judgment" in "Casey".


title: Planned Parenthood v. Casey

text: The dissenting opinion disputed the majority's opinion that the "undue burden" standard was not workable, and criticized the majority for overturning precedent, holding that their reasoning was not sufficient to overrule "Roe" and "Casey", which they described as a precedent about precedent, and warned that by the same reasoning many other rights would be under threat.


title: Chat-Avenue

text: Chat Avenue is a web site that hosts chat rooms. A total of 20 chat rooms are available. Originally launched with DigiChat software based on Java, it was subsequently changed and built with 123 Flash Chat, an Adobe Flash-based software for in-browser chat rooms in October 2005. In 2018, new PHP software was added to the website due to browser restrictions and the upcoming end-of-life announcement by Flash. In 2021, new chat software was added enabling user support of a webcam. The chat rooms are administered by volunteer moderators and administrators.


title: Chat-Avenue

text: Some chat rooms within the site, which target younger audiences, are known to be used by law enforcement to catch online predators.


title: Chat-Avenue

text: On September 18, 2018, New Jersey Attorney General Gurbir Grewal announced the arrests of 24 alleged child predators in “Operation Open House,” a multi-agency undercover operation targeting men who allegedly were using social media in an attempt to lure underage girls and boys for sexual activity. Chat Avenue was among the social media and messaging apps named to have allegedly been used by the child predators.


title: Chat-Avenue

text: In February 2021, Channel 4 released a television series documenting a specialist covert police unit tracking sexual predators online. Chat Avenue was one of the platforms used by the police officers and was featured abundantly in the first episode of the series.


title: Scapula

text: The scapula (plural scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on either side of the body being roughly a mirror image of the other. The name derives from the Classical Latin word for trowel or small shovel, which it was thought to resemble.


title: Scapula

text: In compound terms, the prefix omo- is used for the shoulder blade in medical terminology. This prefix is derived from ὦμος (ōmos), the Ancient Greek word for shoulder, and is cognate with the Latin , which in Latin signifies either the shoulder or the upper arm bone.


title: Scapula

text: The scapula forms the back of the shoulder girdle. In humans, it is a flat bone, roughly triangular in shape, placed on a posterolateral aspect of the thoracic cage.


title: Scapula

text: The scapula is a thick, flat bone lying on the thoracic wall that provides an attachment for three groups of muscles: intrinsic, extrinsic, and stabilizing and rotating muscles. The intrinsic muscles of the scapula include the muscles of the rotator cuff—the subscapularis, teres minor, supraspinatus, and infraspinatus. These muscles attach to the surface of the scapula and are responsible for the internal and external rotation of the shoulder joint, along with humeral abduction.


title: Scapula

text: The extrinsic muscles include the biceps, triceps, and deltoid muscles and attach to the coracoid process and supraglenoid tubercle of the scapula, infraglenoid tubercle of the scapula, and spine of the scapula. These muscles are responsible for several actions of the glenohumeral joint.


title: Scapula

text: The third group, which is mainly responsible for stabilization and rotation of the scapula, consists of the trapezius, serratus anterior, levator scapulae, and rhomboid muscles. These attach to the medial, superior, and inferior borders of the scapula.


title: Scapula

text: The head, processes, and the thickened parts of the bone contain cancellous tissue; the rest consists of a thin layer of compact tissue.


title: Scapula

text: The central part of the supraspinatus fossa and the upper part of the infraspinatous fossa, but especially the former, are usually so thin in humans as to be semitransparent; occasionally the bone is found wanting in this situation, and the adjacent muscles are separated only by fibrous tissue. The scapula has two surfaces, three borders, three angles, and three processes.


title: Scapula

text: The front of the scapula (also known as the costal or ventral surface) has a broad concavity called the subscapular fossa, to which the subscapularis muscle attaches. The medial two-thirds of the fossa have 3 longitudinal oblique ridges, and another thick ridge adjoins the lateral border; they run outward and upward. The ridges give attachment to the tendinous insertions, and the surfaces between them to the fleshy fibers, of the subscapularis muscle. The lateral third of the fossa is smooth and covered by the fibers of this muscle.


title: Scapula

text: The back of the scapula (also called the dorsal or posterior surface) is arched from above downward, and is subdivided into two unequal parts by the spine of the scapula. The portion above the spine is called the supraspinous fossa, and that below it the infraspinous fossa. The two fossae are connected by the spinoglenoid notch, situated lateral to the root of the spine.


title: Scapula

text: There is a ridge on the outer part of the back of the scapula. This runs from the lower part of the glenoid cavity, downward and backward to the vertebral border, about 2.5 cm above the inferior angle. Attached to the ridge is a fibrous septum, which separates the infraspinatus muscle from the Teres major and Teres minor muscles. The upper two-thirds of the surface between the ridge and the axillary border is narrow, and is crossed near its center by a groove for the scapular circumflex vessels; the Teres minor attaches here.


title: Scapula

text: The broad and narrow portions above alluded to are separated by an oblique line, which runs from the axillary border, downward and backward, to meet the elevated ridge: to it is attached a fibrous septum which separates the Teres muscles from each other.


title: Scapula

text: Its lower third presents a broader, somewhat triangular surface, the inferior angle of the scapula, which gives origin to the Teres major, and over which the Latissimus dorsi glides; frequently the latter muscle takes origin by a few fibers from this part.


title: Scapula

text: The acromion forms the summit of the shoulder, and is a large, somewhat triangular or oblong process, flattened from behind forward, projecting at first laterally, and then curving forward and upward, so as to overhang the glenoid cavity.


title: Scapula

text: The superior angle of the scapula or medial angle, is covered by the trapezius muscle. This angle is formed by the junction of the superior and medial borders of the scapula. The superior angle is located at the approximate level of the second thoracic vertebra. The superior angle of the scapula is thin, smooth, rounded, and inclined somewhat lateralward, and gives attachment to a few fibers of the levator scapulae muscle.


title: Scapula

text: The inferior angle of the scapula is the lowest part of the scapula and is covered by the latissimus dorsi muscle. It moves forwards round the chest when the arm is abducted. The inferior angle is formed by the union of the medial and lateral borders of the scapula. It is thick and rough and its posterior or back surface affords attachment to the teres major and often to a few fibers of the latissimus dorsi. The anatomical plane that passes vertically through the inferior angle is named the scapular line.


title: Scapula

text: The lateral angle of the scapula or glenoid angle also known as the head of the scapula is the thickest part of the scapula. It is broad and bears the glenoid fossa on its articular surface which is directed forward, laterally and slightly upwards, and articulates with the head of the humerus. The inferior angle is broader below than above and its vertical diameter is the longest. The surface is covered with cartilage in the fresh state; and its margins, slightly raised, give attachment to a fibrocartilaginous structure, the glenoidal labrum, which deepens the cavity. At its apex is a slight elevation, the supraglenoid tuberosity, to which the long head of the biceps brachii is attached.


title: Scapula

text: The anatomic neck of the scapula is the slightly constricted portion which surrounds the head and is more distinct below and behind than above and in front. The surgical neck of the scapula passes directly medial to the base of the coracoid process.


title: Scapula

text: The scapula is ossified from 7 or more centers: one for the body, two for the coracoid process, two for the acromion, one for the vertebral border, and one for the inferior angle. Ossification of the body begins about the second month of fetal life, by an irregular quadrilateral plate of bone forming, immediately behind the glenoid cavity. This plate extends to form the chief part of the bone, the scapular spine growing up from its dorsal surface about the third month. Ossification starts as membranous ossification before birth. After birth, the cartilaginous components would undergo endochondral ossification. The larger part of the scapula undergoes membranous ossification. Some of the outer parts of the scapula are cartilaginous at birth, and would therefore undergo endochondral ossification.


title: Scapula

text: At birth, a large part of the scapula is osseous, but the glenoid cavity, the coracoid process, the acromion, the vertebral border and the inferior angle are cartilaginous. From the 15th to the 18th month after birth, ossification takes place in the middle of the coracoid process, which as a rule becomes joined with the rest of the bone about the 15th year.


title: Scapula

text: Between the 14th and 20th years, the remaining parts ossify in quick succession, and usually in the following order: first, in the root of the coracoid process, in the form of a broad scale; secondly, near the base of the acromion; thirdly, in the inferior angle and contiguous part of the vertebral border; fourthly, near the outer end of the acromion; fifthly, in the vertebral border.


title: Scapula

text: The base of the acromion is formed by an extension from the spine; the two nuclei of the acromion unite, and then join with the extension from the spine. The upper third of the glenoid cavity is ossified from a separate center (sub coracoid), which appears between the 10th and 11th years and joins between the 16th and the 18th years. Further, an epiphysial plate appears for the lower part of the glenoid cavity, and the tip of the coracoid process frequently has a separate nucleus. These various epiphyses are joined to the bone by the 25th year.


title: Scapula

text: Failure of bony union between the acromion and spine sometimes occurs (see os acromiale), the junction being effected by fibrous tissue, or by an imperfect articulation; in some cases of supposed fracture of the acromion with ligamentous union, it is probable that the detached segment was never united to the rest of the bone.


title: Scapula

text: Movements of the scapula are brought about by the scapular muscles. The scapula can perform six actions:


title: Scapula

text: Because of its sturdy structure and protected location, fractures of the scapula are uncommon. When they do occur, they are an indication that severe chest trauma has occurred.


title: Scapula

text: Scapular fractures involving the neck of the scapula have two patterns. One (rare) type of fracture is through the anatomical neck of the scapula. The other more common type of fracture is through the surgical neck of the scapula. The surgical neck exits medial to the coracoid process.


title: Scapula

text: An abnormally protruding inferior angle of the scapula is known as a winged scapula and can be caused by paralysis of the serratus anterior muscle. In this condition the sides of the scapula nearest the spine are positioned outward and backward. The appearance of the upper back is said to be wing-like. In addition, any condition causing weakness of the serratus anterior muscle may cause scapular "winging".


title: Scapula

text: Abnormal scapular function is called scapular dyskinesis. One action the scapula performs during a throwing or serving motion is elevation of the acromion process in order to avoid impingement of the rotator cuff tendons. If the scapula fails to properly elevate the acromion, impingement may occur during the cocking and acceleration phase of an overhead activity. The two muscles most commonly inhibited during this first part of an overhead motion are the serratus anterior and the lower trapezius. These two muscles act as a force couple within the glenohumeral joint to properly elevate the acromion process, and if a muscle imbalance exists, shoulder impingement may develop.


title: Scapula

text: Other conditions associated with scapular dyskenesis include thoracic outlet syndrome and the related pectoralis minor syndrome.


title: Scapula

text: The name "scapula" as synonym of "shoulder blade" is of Latin origin. It is commonly used in medical English and is part of the current official Latin nomenclature, "Terminologia Anatomica". Shoulder blade is the colloquial name for this bone.


title: Scapula

text: In fish, the scapular blade is a structure attached to the upper surface of the articulation of the pectoral fin, and is accompanied by a similar coracoid plate on the lower surface. Although sturdy in cartilagenous fish, both plates are generally small in most other fish, and may be partially cartilagenous, or consist of multiple bony elements.


title: Scapula

text: In the early tetrapods, these two structures respectively became the scapula and a bone referred to as the procoracoid (commonly called simply the "coracoid", but not homologous with the mammalian structure of that name). In amphibians and reptiles (birds included), these two bones are distinct, but together form a single structure bearing many of the muscle attachments for the forelimb. In such animals, the scapula is usually a relatively simple plate, lacking the projections and spine that it possesses in mammals. However, the detailed structure of these bones varies considerably in living groups. For example, in frogs, the procoracoid bones may be braced together at the animal's underside to absorb the shock of landing, while in turtles, the combined structure forms a Y-shape in order to allow the scapula to retain a connection to the clavicle (which is part of the shell). In birds, the procoracoids help to brace the wing against the top of the sternum.


title: Scapula

text: In the fossil therapsids, a third bone, the true coracoid, formed just behind the procoracoid. The resulting three-boned structure is still seen in modern monotremes, but in all other living mammals, the procoracoid has disappeared, and the coracoid bone has fused with the scapula, to become the coracoid process. These changes are associated with the upright gait of mammals, compared with the more sprawling limb arrangement of reptiles and amphibians; the muscles formerly attached to the procoracoid are no longer required. The altered musculature is also responsible for the alteration in the shape of the rest of the scapula; the forward margin of the original bone became the spine and acromion, from which the main shelf of the shoulder blade arises as a new structure.


title: Scapula

text: In dinosaurs the main bones of the pectoral girdle were the scapula (shoulder blade) and the coracoid, both of which directly articulated with the clavicle. The clavicle was present in saurischian dinosaurs but largely absent in ornithischian dinosaurs. The place on the scapula where it articulated with the humerus (upper bone of the forelimb) is called the glenoid. The scapula serves as the attachment site for a dinosaur's back and forelimb muscles.


title: Usury

text: Usury () is the practice of making unethical or immoral monetary loans that unfairly enrich the lender. The term may be used in a moral sense—condemning taking advantage of others' misfortunes—or in a legal sense, where an interest rate is charged in excess of the maximum rate that is allowed by law. A loan may be considered usurious because of excessive or abusive interest rates or other factors defined by the laws of a state. Someone who practices usury can be called a "usurer", but in modern colloquial English may be called a "loan shark".


title: Usury

text: In many historical societies including ancient Christian, Jewish, and Islamic societies, usury meant the charging of interest of any kind, and was considered wrong, or was made illegal. During the Sutra period in India (7th to 2nd centuries BC) there were laws prohibiting the highest castes from practicing usury. Similar condemnations are found in religious texts from Buddhism, Judaism ("ribbit" in Hebrew), Christianity, and Islam ("riba" in Arabic). At times, many states from ancient Greece to ancient Rome have outlawed loans with any interest. Though the Roman Empire eventually allowed loans with carefully restricted interest rates, the Catholic Church in medieval Europe, as well as the Reformed Churches, regarded the charging of interest at any rate as sinful (as well as charging a fee for the use of money, such as at a bureau de change). Religious prohibitions on usury are predicated upon the belief that charging interest on a loan is a sin.


title: Usury

text: Usury (in the original sense of any interest) was denounced by religious leaders and philosophers in the ancient world, including Moses, Plato, Aristotle, Cato, Cicero, Seneca, Aquinas, Gautama Buddha and Muhammad.


title: Usury

text: Certain negative historical renditions of usury carry with them social connotations of perceived "unjust" or "discriminatory" lending practices. The historian Paul Johnson, comments:


title: Usury

text: Theological historian John Noonan argues that "the doctrine [of usury] was enunciated by popes, expressed by three ecumenical councils, proclaimed by bishops, and taught unanimously by theologians."


title: Usury

text: Banking during the Roman Empire was different from modern banking. During the Principate period, most banking activities were conducted by private individuals who operated as large banking firms do today. Anybody that had any available liquid assets and wished to lend it out could easily do so.


title: Usury

text: The annual rates of interest on loans varied in the range of 4–12 percent, but when the interest rate was higher, it typically was not 15–16 percent but either 24 percent or 48 percent. They quoted them on a monthly basis, and the most common rates were multiples of twelve. Monthly rates tended to range from simple fractions to 3–4 percent, perhaps because lenders used Roman numerals.


title: Usury

text: Moneylending during this period was largely a matter of private loans advanced to persons persistently in debt or temporarily so until harvest time. Mostly, it was undertaken by exceedingly rich men prepared to take on a high risk if the profit looked good; interest rates were fixed privately and were almost entirely unrestricted by law. Investment was always regarded as a matter of seeking personal profit, often on a large scale. Banking was of the small, back-street variety, run by the urban lower-middle class of petty shopkeepers. By the 3rd century, acute currency problems in the Empire drove such banking into decline. The rich who were in a position to take advantage of the situation became the moneylenders when the increasing tax demands in the last declining days of the Empire crippled and eventually destroyed the peasant class by reducing tenant-farmers to serfs. It was evident that usury meant exploitation of the poor.


title: Usury

text: Cicero, in the second book of his treatise "De Officiis", relates the following conversation between an unnamed questioner and Cato:


title: Usury

text: Jews are forbidden from usury in dealing with fellow Jews, although not exclusively. Lending is to be considered tzedakah. However, there are permissions to charge interest on loans to non-Jews, restricted to cases when there is no other means of subsistence "If we nowadays allow interest to be taken from non-Jews, it is because there is no end to the yoke and the burden king and ministers impose on us, and everything we take is the minimum for our subsistence, and anyhow we are condemned to live in the midst of the nations and cannot earn our living in any other manner except by money dealings with them; therefore the taking of interest is not to be prohibited" (Tos. to BM 70b S.V. tashikh).


title: Usury

text: Johnson contends that the Torah treats lending as philanthropy in a poor community whose aim was collective survival, but which is not obliged to be charitable towards outsiders.


title: Usury

text: As Jewish people were ostracized from most professions by local rulers during the Middle Ages, the Western churches and the guilds, they were pushed into marginal occupations considered socially inferior, such as tax and rent collecting and moneylending. Natural tensions between creditors and debtors were added to social, political, religious, and economic strains.


title: Usury

text: Several historical rulings in Jewish law have mitigated the allowances for usury toward non-Jews. For instance, the 15th-century commentator Rabbi Isaac Abarbanel specified that the rubric for allowing interest does not apply to Christians or Muslims, because their faith systems have a common ethical basis originating from Judaism. The medieval commentator Rabbi David Kimhi extended this principle to non-Jews who show consideration for Jews, saying they should be treated with the same consideration when they borrow.


title: Usury

text: In England, the departing Crusaders were joined by crowds of debtors in the massacres of Jews at London and York in 1189–1190. In 1275, Edward I of England passed the Statute of the Jewry which made usury illegal and linked it to blasphemy, in order to seize the assets of the violators. Scores of English Jews were arrested, 300 were hanged and their property went to the Crown. In 1290, all Jews were to be expelled from England, allowed to take only what they could carry; the rest of their property became the Crown's. Usury was cited as the official reason for the Edict of Expulsion; however, not all Jews were expelled: it was easy to avoid expulsion by converting to Christianity. Many other crowned heads of Europe expelled Jewish people, although again converts to Christianity were no longer considered Jewish. Many of these forced converts still secretly practiced their faith.


title: Usury

text: The growth of the Lombard bankers and pawnbrokers, who moved from city to city, was along the pilgrim routes.


title: Usury

text: In the 16th century, short-term interest rates dropped dramatically (from around 20–30% p.a. to around 9–10% p.a.). This was caused by refined commercial techniques, increased capital availability, the Reformation, and other reasons. The lower rates weakened religious scruples about lending at interest, although the debate did not cease altogether.


title: Usury

text: The 18th century papal prohibition on usury meant that it was a sin to charge interest on a money loan. As set forth by Thomas Aquinas in the 13th century, because money was invented to be an intermediary in exchange for goods, it is unjust to charge a fee to someone after giving them money. This is because transferring ownership of property implies the right to use that property for its purpose: "Accordingly if a man wanted to sell wine separately from the use of the wine, he would be selling the same thing twice, or he would be selling what does not exist, wherefore he would evidently commit a sin of injustice."


title: Usury

text: Charles Eisenstein has argued that pivotal change in the English-speaking world came with lawful rights to charge interest on lent money, particularly the 1545 Act, "An Act Against Usurie" (37 Hen. VIII, c. 9) of King Henry VIII of England.


title: Usury

text: The Old Testament "condemns the practice of charging interest on a poor person because a loan should be an act of compassion and taking care of one’s neighbor"; it teaches that "making a profit off a loan from a poor person is exploiting that person (Exodus 22:25–27)." Similarly, charging of interest () or the taking of clothing as pledges is condemned in Ezekiel 18 (early 6th century BC), and Deuteronomy 23:19 prohibits the taking of interest in the form of money or food when lending to a "brother"; it is not clear if this refers to an actual brother, a fellow Israelite or any human being.


title: Usury

text: "And if you lend to those from whom you expect repayment, what credit is that to you? Even sinners lend to sinners, expecting to be repaid in full. But love your enemies, do good to them, and lend to them, expecting nothing in return. Then your reward will be great, and you will be sons of the Most High; for He is kind to the ungrateful and wicked. Be merciful, just as your Father is merciful. - Luke 6:34-36 NIV


title: Usury

text: At the time, usury was interest of any kind, and the canon forbade the clergy to lend money at interest rates even as low as 1 percent per year. Later ecumenical councils applied this regulation to the laity.


title: Usury

text: Lateran III decreed that persons who accepted interest on loans could receive neither the sacraments nor Christian burial.


title: Usury

text: The Council of Vienne made the belief in the right to usury a heresy in 1311, and condemned all secular legislation that allowed it.


title: Usury

text: Up to the 16th century, usury was condemned by the Catholic Church, but not really defined. During the Fifth Lateran Council, in the 10th session (in the year 1515), the Council for the first time gave a definition of usury:


title: Usury

text: The Fifth Lateran Council, in the same declaration, gave explicit approval of charging a fee for services "so long as no profit was made" in the case of Mounts of Piety:


title: Usury

text: Pope Sixtus V condemned the practice of charging interest as "detestable to God and man, damned by the sacred canons, and contrary to Christian charity.


title: Usury

text: The first of the scholastic Christian theologians, Saint Anselm of Canterbury, led the shift in thought that labelled charging interest the same as theft. Previously usury had been seen as a lack of charity.


title: Usury

text: St. Thomas Aquinas, the leading scholastic theologian of the Catholic Church, argued charging of interest is wrong because it amounts to "double charging", charging for both the thing and the use of the thing. Aquinas said this would be morally wrong in the same way as if one sold a bottle of wine, charged for the bottle of wine, and then charged for the person using the wine to actually drink it. Similarly, one cannot charge for a piece of cake and for the eating of the piece of cake. Yet this, said Aquinas, is what usury does. Money is a medium of exchange, and is used up when it is spent. To charge for the money and for its use (by spending) is therefore to charge for the money twice. It is also to sell time since the usurer charges, in effect, for the time that the money is in the hands of the borrower. Time, however, is not a commodity for which anyone can charge. In condemning usury Aquinas was much influenced by the recently rediscovered philosophical writings of Aristotle and his desire to assimilate Greek philosophy with Christian theology. Aquinas argued that in the case of usury, as in other aspects of Christian revelation, Christian doctrine is reinforced by Aristotelian natural law rationalism. Aristotle's argument is that interest is unnatural, since money, as a sterile element, cannot naturally reproduce itself. Thus, usury conflicts with natural law just as it offends Christian revelation: see Thought of Thomas Aquinas. As such, Aquinas taught "that interest is inherently unjust and one who charges interest sins."


title: Usury

text: Outlawing usury did not prevent investment, but stipulated that in order for the investor to share in the profit he must share the risk. In short he must be a joint-venturer. Simply to invest the money and expect it to be returned regardless of the success of the venture was to make money simply by having money and not by taking any risk or by doing any work or by any effort or sacrifice at all, which is usury. St Thomas quotes Aristotle as saying that "to live by usury is exceedingly unnatural". Islam likewise condemns usury but allowed commerce (Al-Baqarah 2:275) – an alternative that suggests investment and sharing of profit and loss instead of sharing only profit through interests. Judaism condemns usury towards Jews, but allows it towards non-Jews (Deut 23:19–20). St Thomas allows, however, charges for actual services provided. Thus a banker or credit-lender could charge for such actual work or effort as he did carry out e.g. any fair administrative charges. The Catholic Church, in a decree of the Fifth Council of the Lateran, expressly allowed such charges in respect of credit-unions run for the benefit of the poor known as "montes pietatis".


title: Usury

text: In the 13th century Cardinal Hostiensis enumerated thirteen situations in which charging interest was not immoral. The most important of these was "lucrum cessans" (profits given up) which allowed for the lender to charge interest "to compensate him for profit foregone in investing the money himself." This idea is very similar to opportunity cost. Many scholastic thinkers who argued for a ban on interest charges also argued for the legitimacy of "lucrum cessans" profits (e.g. Pierre Jean Olivi and St. Bernardino of Siena). However, Hostiensis' exceptions, including for "lucrum cessans", were never accepted as official by the Catholic Church.


title: Usury

text: Pope Benedict XIV's encyclical "Vix Pervenit" (1745), operating in the pre-industrial mindset , gives the reasons why usury is sinful:


title: Usury

text:
The nature of the sin called usury has its proper place and origin in a loan contract… [which] demands, by its very nature, that one return to another only as much as he has received. The sin rests on the fact that sometimes the creditor desires more than he has given…, but any gain which exceeds the amount he gave is illicit and usurious.

One cannot condone the sin of usury by arguing that the gain is not great or excessive, but rather moderate or small; neither can it be condoned by arguing that the borrower is rich; nor even by arguing that the money borrowed is not left idle, but is spent usefully…


title: Usury

text: Martin Luther argued against several forms of usury, publishing and republishing multiple treatises on the subject. Christians, Luther argued, should not act in self-defense, should give when asked, and in the lowest degree should lend, expecting nothing in return. On those grounds, making a loan with anticipated profits (and with required repayment and hence little risk for the lender) is a form of self-service that goes against love of neighbor. Defining "lend" as lending without interest or fee, Luther encourages lending for the purpose of aiding the borrower.


title: Usury

text: The Westminster Larger Catechism, part of the Westminster Standards held as doctrinal documents by Presbyterian churches, teaches that usury is a sin prohibited by the eighth commandment.


title: Usury

text: Concerns about usury included the 19th century Rothschild loans to the Holy See and 16th century concerns over abuse of the zinskauf clause. This was problematic because the charging of interest (although not all interest – see above for Fifth Lateran Council) can be argued to be a violation of doctrine at the time, such as that reflected in the 1745 encyclical "Vix pervenit". To prevent any claims of doctrine violation, work-arounds would sometimes be employed. For example, in the 15th century, the Medici Bank lent money to the Vatican, which was lax about repayment. Rather than charging interest, "the Medici overcharged the pope on the silks and brocades, the jewels and other commodities they supplied." However, the 1917 Code of Canon Law switched position and allowed church monies to be used to accrue interest.


title: Usury

text: The Catholic Church has always condemned usury, but in modern times, with the rise of capitalism, the previous assumptions about the very nature of money have been challenged, and the Church had to update its understanding of what constitutes usury to also include the new reality. Thus, the Church refers, among other things, to the fact Mosaic Law doesn't ban all interest taking (proving interest-taking is not an inherently immoral act, same principle as with homicide), as well as the prevalence of bonds & loans paying interest. Because of this, as the old Catholic Encyclopedia put it, "Since the possession of an object is generally useful, I may require the price of that general utility, even when the object is of no use to me."


title: Usury

text: Jesuit philosopher Joseph Rickaby, writing at the beginning of the 20th century, put the development of economy in relation to usury this way:


title: Usury

text: The Congregation of the Missionary Sons of the Immaculate Heart of Mary, a Catholic Christian religious order, teaches that the charging of interest is sinful:


title: Usury

text: Riba (usury) is forbidden in Islam. As such, specialized codes of banking have developed to cater to investors wishing to obey Qur'anic law. "(See Islamic banking)"


title: Usury

text: Those who swallow usury cannot rise up save as he ariseth whom the devil hath prostrated by (his) touch. That is because they say: Trade is just like usury; whereas Allah permitteth trading and forbiddeth usury. He unto whom an admonition from his Lord cometh, and (he) refraineth (in obedience thereto), he shall keep (the profits of) that which is past, and his affair (henceforth) is with Allah. As for him who returneth (to usury) - Such are rightful owners of the Fire. They will abide therein. ("Al-Baqarah 2:275")


title: Usury

text: Allah hath blighted usury and made almsgiving fruitful. Allah loveth not the impious and guilty. Lo! those who believe and do good works and establish worship and pay the poor-due, their reward is with their Lord and there shall no fear come upon them neither shall they grieve. O ye who believe! Observe your duty to Allah, and give up what remaineth (due to you) from usury, if ye are (in truth) believers. And if ye do not, then be warned of war (against you) from Allah and His messenger. And if ye repent, then ye have your principal (without interest). Wrong not, and ye shall not be wronged. And if the debtor is in straitened circumstances, then (let there be) postponement to (the time of) ease; and that ye remit the debt as almsgiving would be better for you if ye did but know.("Al-Baqarah 2:276–280")


title: Usury

text: O ye who believe! Devour not usury, doubling and quadrupling (the sum lent). Observe your duty to Allah, that ye may be successful. ("Al-'Imran 3:130")


title: Usury

text: And of their taking usury when they were forbidden it, and of their devouring people's wealth by false pretences, We have prepared for those of them who disbelieve a painful doom. ("Al-Nisa 4:161")


title: Usury

text: That which ye give in usury in order that it may increase on (other) people's property hath no increase with Allah; but that which ye give in charity, seeking Allah's Countenance, hath increase manifold. ("Ar-Rum 30:39")


title: Usury

text: The attitude of Muhammad to usury is articulated in his Last Sermon:Verily your blood, your property are as sacred and inviolable as the sacredness of this day of yours, in this month of yours, in this town of yours. Behold! Everything pertaining to the Days of Ignorance is under my feet completely abolished. Abolished are also the blood-revenges of the Days of Ignorance. The first claim of ours on blood-revenge which I abolish is that of the son of Rabi'a b. al-Harith, who was nursed among the tribe of Sa'd and killed by Hudhail. And the usury of the pre-Islamic period is abolished, and the first of our usury I abolish is that of 'Abbas b. 'Abd al-Muttalib, for it is all abolished.One of the forbidden usury models in Islam is to take advantage when lending money. Examples of forbidden loans, such as a person borrowing 1000 dollars and the borrower is required to return 1100 dollars. The above agreement is a form of transaction which is a burden for people who borrow, because in Islam, lending and borrowing are social transactions aimed at helping others, not like a sale and purchase agreement that is allowed to be profitable. Hence, a rule of thumb used by Islamic scholars is, "Every loan (qardh) which gives additional benefits is called usury."


title: Usury

text: Interest on loans, and the contrasting views on the morality of that practice held by Jews and Christians, is central to the plot of Shakespeare's play "The Merchant of Venice". Antonio is the merchant of the title, a Christian, who is forced by circumstance to borrow money from Shylock, a Jew. Shylock customarily charges interest on loans, seeing it as good business, while Antonio does not, viewing it as morally wrong. When Antonio defaults on his loan, Shylock famously demands the agreed upon penalty: a measured quantity of muscle from Antonio's chest. This is the source of the metaphorical phrase "a pound of flesh" often used to describe the dear price of a loan or business transaction. Shakespeare's play is a vivid portrait of the competing views of loans and use of interest, as well as the cultural strife between Jews and Christians that overlaps it.


title: Usury

text: By the 18th century, usury was more often treated as a metaphor than a crime in itself, so Jeremy Bentham's "Defence of Usury" was not as shocking as it would have appeared two centuries earlier.


title: Usury

text: In Honoré de Balzac's 1830 novel "Gobseck", the title character, who is a usurer, is described as both "petty and great – a miser and a philosopher..." The character Daniel Quilp in "The Old Curiosity Shop" by Charles Dickens is a usurer.


title: Usury

text: In the early 20th century Ezra Pound's anti-usury poetry was not primarily based on the moral injustice of interest payments but on the fact that excess capital was no longer devoted to artistic patronage, as it could now be used for capitalist business investment.


title: Usury

text: "When money is lent on a contract to receive not only the principal sum again, but also an increase by way of compensation for the use, the increase is called "interest" by those who "think" it lawful, and "usury" by those who do not." (William Blackstone's "Commentaries on the Laws of England").


title: Usury

text: Japan has various laws restricting interest rates. Under civil law, the maximum interest rate is between 15% and 20% per year depending upon the principal amount (larger amounts having a lower maximum rate). Interest in excess of 20% is subject to criminal penalties (the criminal law maximum was 29.2% until it was lowered by legislation in 2010). Default interest on late payments may be charged at up to 1.46 times the ordinary maximum (i.e., 21.9% to 29.2%), while pawn shops may charge interest of up to 9% per month (i.e., 108% per year, however, if the loan extends more than the normal short-term pawn shop loan, the 9% per month rate compounded can make the annual rate in excess of 180%, before then most of these transaction would result in any goods pawned being forfeited).


title: Usury

text: "Usury laws" are state laws that specify the maximum legal interest rate at which loans can be made. In the United States, the primary legal power to regulate usury rests primarily with the states. Each U.S. state has its own statute that dictates how much interest can be charged before it is considered usurious or unlawful.


title: Usury

text: If a lender charges above the lawful interest rate, a court will not allow the lender to sue to recover the unlawfully high interest, and some states will apply all payments made on the debt to the principal balance. In some states, such as New York, usurious loans are voided "ab initio".


title: Usury

text: The making of usurious loans is often called loan sharking. That term is sometimes also applied to the practice of making consumer loans without a license in jurisdictions that requires lenders to be licensed.


title: Usury

text: On a federal level, Congress has never attempted to federally regulate interest rates on purely private transactions, but on the basis of past U.S. Supreme Court decisions, arguably the U.S. Congress might have the power to do so under the interstate commerce clause of Article I of the Constitution.


title: Usury

text: Congress imposed a federal criminal penalty for unlawful interest rates through the Racketeer Influenced and Corrupt Organizations Act (RICO Statute), and its definition of "unlawful debt", which makes it a potential federal felony to lend money at an interest rate more than twice the local state usury rate and then try to collect that debt.


title: Usury

text: Separate federal rules apply to most banks. The U.S. Supreme Court held unanimously in the 1978 case, "Marquette Nat. Bank of Minneapolis v. First of Omaha Service Corp.", that the National Banking Act of 1863 allowed nationally chartered banks to charge the legal rate of interest in their state regardless of the borrower's state of residence.


title: Usury

text: In 1980, Congress passed the Depository Institutions Deregulation and Monetary Control Act. Among the Act's provisions, it exempted federally chartered savings banks, installment plan sellers and chartered loan companies from state usury limits. Combined with the "Marquette" decision that applied to National Banks, this effectively overrode all state and local usury laws. The 1968 Truth in Lending Act does not regulate rates, except for some mortgages, but requires uniform or standardized disclosure of costs and charges.


title: Usury

text: In the 1996 "Smiley v. Citibank" case, the Supreme Court further limited states' power to regulate credit card fees and extended the reach of the "Marquette" decision. The court held that the word "interest" used in the 1863 banking law included fees and, therefore, states could not regulate fees.


title: Usury

text: Some members of Congress have tried to create a federal usury statute that would limit the maximum allowable interest rate, but the measures have not progressed. In July 2010, the Dodd–Frank Wall Street Reform and Consumer Protection Act, was signed into law by President Obama. The act provides for a Consumer Financial Protection Bureau to regulate some credit practices but has no interest rate limit.


title: Usury

text: State law in Texas also includes a provision for contracting for, charging, or receiving charges exceeding twice the amount authorized (A/K/A "double usury"). A person who violates this provision is liable to the obligor as an additional penalty for all principal or principal balance, as well as interest or time price differential. A person who is liable is also liable for reasonable attorney's fees incurred by the obligor.


title: Usury

text: In a partnership or joint venture where money is lent, the creditor only provides the capital yet is guaranteed a fixed amount of profit. The debtor, however, puts in time and effort, but is made to bear the risk of loss. Muslim scholars argue that such practice is unjust. As an alternative to usury, Islam strongly encourages charity and direct investment in which the creditor shares whatever profit or loss the business may incur (in modern terms, this amounts to an equity stake in the business).


title: Usury

text: Growth of the Internet internationally has enabled both business micro-lending through sites such as Kickstarter as well as through global micro-lending charities where lenders make small sums of money available on zero-interest terms. Persons lending money to on-line micro-lending charity Kiva for example do not get paid any interest, although the end users to whom the loans are made may be charged interest by Kiva's partners in the country where the loan is used.


title: Usury

text: A non-recourse loan is secured by the value of property (usually real estate) owned by the debtor. However, unlike other loans, which oblige the debtor to repay the amount borrowed, a non-recourse loan is fully satisfied merely by the transfer of the property to the creditor, even if the property has declined in value and is worth less than the amount borrowed. When such a loan is created, the creditor bears the risk that the property will decline sharply in value (in which case the creditor is repaid with property worth less than the amount borrowed), and the debtor does not bear the risk of decrease in property value (because the debtor is guaranteed the right to use the property, regardless of value, to satisfy the debt.)


title: Usury

text: Zinskauf was a financial instrument, similar to an annuity, that rose to prominence in the Middle Ages. The decline of the Byzantine Empire led to a growth of capital in Europe, so the Catholic Church tolerated zinskauf as a way to avoid prohibitions on usury. Since zinskauf was an exchange of a fixed amount of money for annual income it was considered a sale rather than a loan. Martin Luther made zinskauf a subject of his Treatise on Usury and his Sermon on Trade and Usury and criticized clerics of the Catholic Church for violating the spirit if not the letter of usury laws.


title: Positron emission tomography

text: Positron emission tomography (PET) is a functional imaging technique that uses radioactive substances known as radiotracers to visualize and measure changes in metabolic processes, and in other physiological activities including blood flow, regional chemical composition, and absorption. Different tracers are used for various imaging purposes, depending on the target process within the body. For example, -FDG is commonly used to detect cancer, NaF is widely used for detecting bone formation, and oxygen-15 is sometimes used to measure blood flow.


title: Positron emission tomography

text: PET is a common imaging technique, a medical scintillography technique used in nuclear medicine. A radiopharmaceutical —a radioisotope attached to a drug — is injected into the body as a tracer. When the radiopharmaceutical undergoes radioactive decay to form a positron, the positron combines with an electron to produce gamma rays. These gamma rays are detected by gamma cameras to form a three-dimensional image, in a similar way that an X-ray image is captured.


title: Positron emission tomography

text: PET scanners can incorporate a CT scanner and are known as PET-CT scanners. PET scan images can be reconstructed using a CT scan performed using one scanner during the same session.


title: Positron emission tomography

text: PET is both a medical and research tool used in pre-clinical and clinical settings. It is used heavily in the imaging of tumors and the search for metastases within the field of clinical oncology, and for the clinical diagnosis of certain diffuse brain diseases such as those causing various types of dementias. PET is a valuable research tool to learn and enhance our knowledge of the normal human brain, heart function, and support drug development. PET is also used in pre-clinical studies using animals. It allows repeated investigations into the same subjects over time, where subjects can act as their own control and substantially reduces the numbers of animals required for a given study. This approach allows research studies to reduce the sample size needed while increasing the statistical quality of its results.


title: Positron emission tomography

text: Physiological processes lead to anatomical changes in the body. Since PET is capable of detecting biochemical processes as well as expression of some proteins, PET can provide molecular-level information much before any anatomic changes are visible. PET scanning does this by using radiolabelled molecular probes that have different rates of uptake depending on the type and function of tissue involved. Regional tracer uptake in various anatomic structures can be visualized and relatively quantified in terms of injected positron emitter within a PET scan.


title: Positron emission tomography

text: PET imaging is best performed using a dedicated PET scanner. It is also possible to acquire PET images using a conventional dual-head gamma camera fitted with a coincidence detector. The quality of gamma-camera PET imaging is lower, and the scans take longer to acquire. However, this method allows a low-cost on-site solution to institutions with low PET scanning demand. An alternative would be to refer these patients to another center or relying on a visit by a mobile scanner.


title: Positron emission tomography

text: Alternative methods of medical imaging include single-photon emission computed tomography (SPECT), x-ray computed tomography (CT), magnetic resonance imaging (MRI) and functional magnetic resonance imaging (fMRI), and ultrasound. SPECT is an imaging technique similar to PET that uses radioligands to detect molecules in the body. SPECT is less expensive and provides inferior image quality than PET.


title: Positron emission tomography

text: PET scanning with the tracer F-FDG is widely used in clinical oncology. FDG is a glucose analog that is taken up by glucose-using cells and phosphorylated by hexokinase (whose mitochondrial form is significantly elevated in rapidly growing malignant tumors). Metabolic trapping of the radioactive glucose molecule allows the PET scan to be utilized. The concentrations of imaged FDG tracer indicate tissue metabolic activity as it corresponds to the regional glucose uptake. F-FDG is used to explore the possibility of cancer spreading to other body sites (cancer metastasis). These F-FDG PET scans for detecting cancer metastasis are the most common in standard medical care (representing 90% of current scans). The same tracer may also be used for the diagnosis of types of dementia. Less often, other radioactive tracers, usually but not always labelled with fluorine-18, are used to image the tissue concentration of different kinds of molecules of interest inside the body.


title: Positron emission tomography

text: A typical dose of FDG used in an oncological scan has an effective radiation dose of 7.6 mSv. Because the hydroxy group that is replaced by fluorine-18 to generate FDG is required for the next step in glucose metabolism in all cells, no further reactions occur in FDG. Furthermore, most tissues (with the notable exception of liver and kidneys) cannot remove the phosphate added by hexokinase. This means that FDG is trapped in any cell that takes it up until it decays, since phosphorylated sugars, due to their ionic charge, cannot exit from the cell. This results in intense radiolabeling of tissues with high glucose uptake, such as the normal brain, liver, kidneys, and most cancers, which have a higher glucose uptake than most normal tissue due to the Warburg effect. As a result, FDG-PET can be used for diagnosis, staging, and monitoring treatment of cancers, particularly in Hodgkin lymphoma, non-Hodgkin lymphoma, and lung cancer.


title: Positron emission tomography

text: A 2020 review of research on the use of PET for Hodgkin lymphoma found evidence that negative findings in interim PET scans are linked to higher overall survival and progression-free survival; however, the certainty of the available evidence was moderate for survival, and very low for progression-free survival.


title: Positron emission tomography

text: A few other isotopes and radiotracers are slowly being introduced into oncology for specific purposes. For example, C-labelled metomidate (11C-metomidate) has been used to detect tumors of adrenocortical origin. Also, FDOPA PET/CT (or F-18-DOPA PET/CT) has proven to be a more sensitive alternative to finding and also localizing pheochromocytoma than the MIBG scan.


title: Positron emission tomography

text: PET imaging with oxygen-15 indirectly measures blood flow to the brain. In this method, increased radioactivity signal indicates increased blood flow which is assumed to correlate with increased brain activity. Because of its 2-minute half-life, O must be piped directly from a medical cyclotron for such uses, which is difficult.


title: Positron emission tomography

text: PET imaging with F-FDG takes advantage of the fact that the brain is normally a rapid user of glucose. Standard F-FDG PET of the brain measures regional glucose use and can be used in neuropathological diagnosis.


title: Positron emission tomography

text: Brain pathologies such as Alzheimer's disease greatly decrease brain metabolism of both glucose and oxygen in tandem. Therefore F-FDG PET of the brain may also be used to successfully differentiate Alzheimer's disease from other dementing processes, and also to make early diagnoses of Alzheimer's disease. The advantage of F-FDG PET for these uses is its much wider availability. Some F based radioactive tracers used for Alzheimer's include florbetapir, flutemetamol, PiB and florbetaben, which are all used to detect amyloid-beta plaques (a potential biomarker for Alzheimer's) in the brain.


title: Positron emission tomography

text: PET imaging with FDG can also be used for localization of "seizure focus". A seizure focus will appear as hypometabolic during an interictal scan. Several radiotracers (i.e. radioligands) have been developed for PET that are ligands for specific neuroreceptor subtypes such as [C] raclopride, [F] fallypride and [F] desmethoxyfallypride for dopamine D2/D3 receptors, [C] McN 5652 and [C] DASB for serotonin transporters, [F] Mefway for serotonin 5HT1A receptors, [F] Nifene for nicotinic acetylcholine receptors or enzyme substrates (e.g. 6-FDOPA for the AADC enzyme). These agents permit the visualization of neuroreceptor pools in the context of a plurality of neuropsychiatric and neurologic illnesses.


title: Positron emission tomography

text: PET may also be used for the diagnosis of hippocampal sclerosis, which causes epilepsy. FDG, and the less common tracers flumazenil and MPPF have been explored for this purpose. If the sclerosis is unilateral (right hippocampus or left hippocampus), F-FDG uptake can be compared with the healthy side. Even if the diagnosis is difficult with MRI, it may be diagnosed with PET.


title: Positron emission tomography

text: The development of a number of novel probes for noninvasive, in vivo PET imaging of neuroaggregate in human brain has brought amyloid imaging close to clinical use. The earliest amyloid imaging probes included 2-(1-{6-[(2-[F]fluoroethyl)(methyl)amino]-2-naphthyl}ethylidene)malononitrile ([F]FDDNP) developed at the University of California, Los Angeles and N-methyl-[C]2-(4'-methylaminophenyl)-6-hydroxybenzothiazole (termed Pittsburgh compound B) developed at the University of Pittsburgh. These amyloid imaging probes permit the visualization of amyloid plaques in the brains of Alzheimer's patients and could assist clinicians in making a positive clinical diagnosis of AD pre-mortem and aid in the development of novel anti-amyloid therapies. [C]PMP (N-[C]methylpiperidin-4-yl propionate) is a novel radiopharmaceutical used in PET imaging to determine the activity of the acetylcholinergic neurotransmitter system by acting as a substrate for acetylcholinesterase. Post-mortem examination of AD patients have shown decreased levels of acetylcholinesterase. [C]PMP is used to map the acetylcholinesterase activity in the brain, which could allow for pre-mortem diagnoses of AD and help to monitor AD treatments. Avid Radiopharmaceuticals has developed and commercialized a compound called florbetapir that uses the longer-lasting radionuclide fluorine-18 to detect amyloid plaques using PET scans.


title: Positron emission tomography

text: Numerous compounds that bind selectively to neuroreceptors of interest in biological psychiatry have been radiolabeled with C-11 or F-18. Radioligands that bind to dopamine receptors (D1, D2 receptor, reuptake transporter), serotonin receptors (5HT1A, 5HT2A, reuptake transporter) opioid receptors (mu and kappa) cholinergic receptors (nicotinic and muscarinic) and other sites have been used successfully in studies with human subjects. Studies have been performed examining the state of these receptors in patients compared to healthy controls in schizophrenia, substance abuse, mood disorders and other psychiatric conditions.


title: Positron emission tomography

text: PET-image guided surgery facilitates treatment of intracranial tumors, arteriovenous malformations and other surgically treatable conditions.


title: Positron emission tomography

text: Cardiology, atherosclerosis and vascular disease study: F-FDG PET can help in identifying hibernating myocardium. However, the cost-effectiveness of PET for this role versus SPECT is unclear. F-FDG PET imaging of atherosclerosis to detect patients at risk of stroke is also feasible. Also, it can help test the efficacy of novel anti-atherosclerosis therapies.


title: Positron emission tomography

text: Imaging infections with molecular imaging technologies can improve diagnosis and treatment follow-up. Clinically, PET has been widely used to image bacterial infections using fluorodeoxyglucose (FDG) to identify the infection-associated inflammatory response. Three different PET contrast agents have been developed to image bacterial infections in vivo are [F] maltose, [F]maltohexaose, and [F]2-fluorodeoxysorbitol (FDS). FDS has the added benefit of being able to target only Enterobacteriaceae.


title: Positron emission tomography

text: In pre-clinical trials, a new drug can be radiolabeled and injected into animals. Such scans are referred to as biodistribution studies. The information regarding drug uptake, retention and elimination over time can be obtained quickly and cost-effectively compare to the older technique of killing and dissecting the animals. Commonly, drug occupancy at a purported site of action can be inferred indirectly by competition studies between unlabeled drug and radiolabeled compounds known apriori to bind with specificity to the site. A single radioligand can be used this way to test many potential drug candidates for the same target. A related technique involves scanning with radioligands that compete with an endogenous (naturally occurring) substance at a given receptor to demonstrate that a drug causes the release of the natural substance.


title: Positron emission tomography

text: A miniature animal PET has been constructed that is small enough for a fully conscious rat to be scanned. This RatCAP (Rat Conscious Animal PET) allows animals to be scanned without the confounding effects of anesthesia. PET scanners designed specifically for imaging rodents, often referred to as microPET, as well as scanners for small primates, are marketed for academic and pharmaceutical research. The scanners are based on microminiature scintillators and amplified avalanche photodiodes (APDs) through a system that uses single-chip silicon photomultipliers.


title: Positron emission tomography

text: In 2018 the UC Davis School of Veterinary Medicine became the first veterinary center to employ a small clinical PET-scanner as a pet-PET scan for clinical (rather than research) animal diagnosis. Because of cost as well as the marginal utility of detecting cancer metastases in companion animals (the primary use of this modality), veterinary PET scanning is expected to be rarely available in the immediate future.


title: Positron emission tomography

text: PET imaging has been used for imaging muscles and bones. F-FDG is the most commonly used tracer for imaging muscles, and NaF-F18 is the most widely used tracer for imaging bones.


title: Positron emission tomography

text: PET is a feasible technique for studying skeletal muscles during exercises like walking. Also, PET can provide muscle activation data about deep-lying muscles (such as the vastus intermedialis and the gluteus minimus) compared to techniques like electromyography, which can be used only on superficial muscles directly under the skin. However, a disadvantage is that PET provides no timing information about muscle activation because it has to be measured after the exercise is completed. This is due to the time it takes for FDG to accumulate in the activated muscles.


title: Positron emission tomography

text: Together with NaF-F18, PET for bone imaging has been in use for 60 years for measuring regional bone metabolism and blood flow using static and dynamic scans. Researchers have recently started using NaF-18 to study bone metastasis as well.


title: Positron emission tomography

text: F-FDG, which is now the standard radiotracer used for PET neuroimaging and cancer patient management, has an effective radiation dose of 14 mSv.


title: Positron emission tomography

text: The amount of radiation in F-FDG is similar to the effective dose of spending one year in the American city of Denver, Colorado (12.4 mSv/year). For comparison, radiation dosage for other medical procedures range from 0.02 mSv for a chest x-ray and 6.5–8 mSv for a CT scan of the chest. Average civil aircrews are exposed to 3 mSv/year, and the whole body occupational dose limit for nuclear energy workers in the USA is 50mSv/year. For scale, see Orders of magnitude (radiation).


title: Positron emission tomography

text: For PET-CT scanning, the radiation exposure may be substantial—around 23–26 mSv (for a 70 kg person—dose is likely to be higher for higher body weights).


title: Positron emission tomography

text: Radionuclides are incorporated either into compounds normally used by the body such as glucose (or glucose analogues), water, or ammonia, or into molecules that bind to receptors or other sites of drug action. Such labelled compounds are known as radiotracers. PET technology can be used to trace the biologic pathway of any compound in living humans (and many other species as well), provided it can be radiolabeled with a PET isotope. Thus, the specific processes that can be probed with PET are virtually limitless, and radiotracers for new target molecules and processes are continuing to be synthesized; as of this writing there are already dozens in clinical use and hundreds applied in research. In 2020 by far the most commonly used radiotracer in clinical PET scanning is the carbohydrate derivative fluorodeoxyglucose (F) (F-FDG). This radiotracer is used in essentially all scans for oncology and most scans in neurology, and thus makes up the large majority of radiotracer (>95%) used in PET and PET-CT scanning.


title: Positron emission tomography

text: Due to the short half-lives of most positron-emitting radioisotopes, the radiotracers have traditionally been produced using a cyclotron in close proximity to the PET imaging facility. The half-life of fluorine-18 is long enough that radiotracers labeled with fluorine-18 can be manufactured commercially at offsite locations and shipped to imaging centers. Recently rubidium-82 generators have become commercially available. These contain strontium-82, which decays by electron capture to produce positron-emitting rubidium-82.


title: Positron emission tomography

text: The use of positron-emitting isotopes of metals in PET scans has been reviewed, including elements not listed above, such as lanthanides.


title: Positron emission tomography

text: The isotope Zr has been applied to the tracking and quantification of molecular antibodies with positron emission tomography (PET) cameras (a method called "immuno-PET").


title: Positron emission tomography

text: The biological half-life of antibodies is typically on the order of days, see daclizumab and erenumab by way of example. To visualize and quantify the distribution of such antibodies in the body, the PET isotope Zr is well suited because its physical half-life matches the typical biological half-life of antibodies, see table above.


title: Positron emission tomography

text: To conduct the scan, a short-lived radioactive tracer isotope is injected into the living subject (usually into blood circulation). Each tracer atom has been chemically incorporated into a biologically active molecule. There is a waiting period while the active molecule becomes concentrated in tissues of interest; then the subject is placed in the imaging scanner. The molecule most commonly used for this purpose is F-18 labeled fluorodeoxyglucose (FDG), a sugar, for which the waiting period is typically an hour. During the scan, a record of tissue concentration is made as the tracer decays.


title: Positron emission tomography

text: As the radioisotope undergoes positron emission decay (also known as positive beta decay), it emits a positron, an antiparticle of the electron with opposite charge. The emitted positron travels in tissue for a short distance (typically less than 1 mm, but dependent on the isotope), during which time it loses kinetic energy, until it decelerates to a point where it can interact with an electron. The encounter annihilates both electron and positron, producing a pair of annihilation (gamma) photons moving in approximately opposite directions. These are detected when they reach a scintillator in the scanning device, creating a burst of light which is detected by photomultiplier tubes or silicon avalanche photodiodes (Si APD). The technique depends on simultaneous or coincident detection of the pair of photons moving in approximately opposite directions (they would be exactly opposite in their center of mass frame, but the scanner has no way to know this, and so has a built-in slight direction-error tolerance). Photons that do not arrive in temporal "pairs" (i.e. within a timing-window of a few nanoseconds) are ignored.


title: Positron emission tomography

text: The most significant fraction of electron–positron annihilations results in two 511 keV gamma photons being emitted at almost 180 degrees to each other; hence, it is possible to localize their source along a straight line of coincidence (also called the line of response, or LOR). In practice, the LOR has a non-zero width as the emitted photons are not exactly 180 degrees apart. If the resolving time of the detectors is less than 500 picoseconds rather than about 10 nanoseconds, it is possible to localize the event to a segment of a chord, whose length is determined by the detector timing resolution. As the timing resolution improves, the signal-to-noise ratio (SNR) of the image will improve, requiring fewer events to achieve the same image quality. This technology is not yet common, but it is available on some new systems.


title: Positron emission tomography

text: The raw data collected by a PET scanner are a list of 'coincidence events' representing near-simultaneous detection (typically, within a window of 6 to 12 nanoseconds of each other) of annihilation photons by a pair of detectors. Each coincidence event represents a line in space connecting the two detectors along which the positron emission occurred (i.e., the line of response (LOR)).


title: Positron emission tomography

text: Analytical techniques, much like the reconstruction of computed tomography (CT) and single-photon emission computed tomography (SPECT) data, are commonly used, although the data set collected in PET is much poorer than CT, so reconstruction techniques are more difficult. Coincidence events can be grouped into projection images, called sinograms. The sinograms are sorted by the angle of each view and tilt (for 3D images). The sinogram images are analogous to the projections captured by computed tomography (CT) scanners, and can be reconstructed in a similar way. The statistics of data thereby obtained are much worse than those obtained through transmission tomography. A normal PET data set has millions of counts for the whole acquisition, while the CT can reach a few billion counts. This contributes to PET images appearing "noisier" than CT. Two major sources of noise in PET are scatter (a detected pair of photons, at least one of which was deflected from its original path by interaction with matter in the field of view, leading to the pair being assigned to an incorrect LOR) and random events (photons originating from two different annihilation events but incorrectly recorded as a coincidence pair because their arrival at their respective detectors occurred within a coincidence timing window).


title: Positron emission tomography

text: In practice, considerable pre-processing of the data is required—correction for random coincidences, estimation and subtraction of scattered photons, detector dead-time correction (after the detection of a photon, the detector must "cool down" again) and detector-sensitivity correction (for both inherent detector sensitivity and changes in sensitivity due to angle of incidence).


title: Positron emission tomography

text: Filtered back projection (FBP) has been frequently used to reconstruct images from the projections. This algorithm has the advantage of being simple while having a low requirement for computing resources. Disadvantages are that shot noise in the raw data is prominent in the reconstructed images, and areas of high tracer uptake tend to form streaks across the image. Also, FBP treats the data deterministically—it does not account for the inherent randomness associated with PET data, thus requiring all the pre-reconstruction corrections described above.


title: Positron emission tomography

text: are now the preferred method of reconstruction. These algorithms compute an estimate of the likely distribution of annihilation events that led to the measured data, based on statistical principles. The advantage is a better noise profile and resistance to the streak artifacts common with FBP, but the disadvantage is higher computer resource requirements. A further advantage of statistical image reconstruction techniques is that the physical effects that would need to be pre-corrected for when using an analytical reconstruction algorithm, such as scattered photons, random coincidences, attenuation and detector dead-time, can be incorporated into the likelihood model being used in the reconstruction, allowing for additional noise reduction. Iterative reconstruction has also been shown to result in improvements in the resolution of the reconstructed images, since more sophisticated models of the scanner physics can be incorporated into the likelihood model than those used by analytical reconstruction methods, allowing for improved quantification of the radioactivity distribution.


title: Positron emission tomography

text: Research has shown that Bayesian methods that involve a Poisson likelihood function and an appropriate prior probability (e.g., a smoothing prior leading to total variation regularization or a Laplacian distribution leading to formula_1-based regularization in a wavelet or other domain), such as via Ulf Grenander's Sieve estimator


title: Positron emission tomography

text: or via I.J. Good's roughness method may yield superior performance to expectation-maximization-based methods which involve a Poisson likelihood function but do not involve such a prior.


title: Positron emission tomography

text: Attenuation correction: Quantitative PET Imaging requires attenuation correction. In these systems attenuation correction is based on a transmission scan using Ge rotating rod source.


title: Positron emission tomography

text: Transmission scans directly measure attenuation values at 511keV. Attenuation occurs when photons emitted by the radiotracer inside the body are absorbed by intervening tissue between the detector and the emission of the photon. As different LORs must traverse different thicknesses of tissue, the photons are attenuated differentially. The result is that structures deep in the body are reconstructed as having falsely low tracer uptake. Contemporary scanners can estimate attenuation using integrated x-ray CT equipment, in place of earlier equipment that offered a crude form of CT using a gamma ray (positron emitting) source and the PET detectors.


title: Positron emission tomography

text: While attenuation-corrected images are generally more faithful representations, the correction process is itself susceptible to significant artifacts. As a result, both corrected and uncorrected images are always reconstructed and read together.


title: Positron emission tomography

text: 2D/3D reconstruction: Early PET scanners had only a single ring of detectors, hence the acquisition of data and subsequent reconstruction was restricted to a single transverse plane. More modern scanners now include multiple rings, essentially forming a cylinder of detectors.


title: Positron emission tomography

text: There are two approaches to reconstructing data from such a scanner: 1) treat each ring as a separate entity, so that only coincidences within a ring are detected, the image from each ring can then be reconstructed individually (2D reconstruction), or 2) allow coincidences to be detected between rings as well as within rings, then reconstruct the entire volume together (3D).


title: Positron emission tomography

text: 3D techniques have better sensitivity (because more coincidences are detected and used) and therefore less noise, but are more sensitive to the effects of scatter and random coincidences, as well as requiring correspondingly greater computer resources. The advent of sub-nanosecond timing resolution detectors affords better random coincidence rejection, thus favoring 3D image reconstruction.


title: Positron emission tomography

text: Time-of-flight (TOF) PET: For modern systems with a higher time resolution (roughly 3 nanoseconds) a technique called "time-of-flight" is used to improve the overall performance. Time-of-flight PET makes use of very fast gamma-ray detectors and data processing system which can more precisely decide the difference in time between the detection of the two photons. It is impossible to localize the point of origin of the annihilation event exactly (currently within 10 cm). Therefore image reconstruction is still needed. TOF technique gives a remarkable improvement in image quality, especially signal-to-noise ratio.


title: Positron emission tomography

text: PET scans are increasingly read alongside CT or magnetic resonance imaging (MRI) scans, with the combination (called "co-registration") giving both anatomic and metabolic information (i.e., what the structure is, and what it is doing biochemically). Because PET imaging is most useful in combination with anatomical imaging, such as CT, modern PET scanners are now available with integrated high-end multi-detector-row CT scanners (so-called "PET-CT"). Because the two scans can be performed in immediate sequence during the same session, with the patient not changing position between the two types of scans, the two sets of images are more precisely registered, so that areas of abnormality on the PET imaging can be more perfectly correlated with anatomy on the CT images. This is very useful in showing detailed views of moving organs or structures with higher anatomical variation, which is more common outside the brain.


title: Positron emission tomography

text: At the Jülich Institute of Neurosciences and Biophysics, the world's largest PET-MRI device began operation in April 2009: a 9.4-tesla magnetic resonance tomograph (MRT) combined with a positron emission tomograph (PET). Presently, only the head and brain can be imaged at these high magnetic field strengths.


title: Positron emission tomography

text: For brain imaging, registration of CT, MRI and PET scans may be accomplished without the need for an integrated PET-CT or PET-MRI scanner by using a device known as the N-localizer.


title: Positron emission tomography

text: The minimization of radiation dose to the subject is an attractive feature of the use of short-lived radionuclides. Besides its established role as a diagnostic technique, PET has an expanding role as a method to assess the response to therapy, in particular, cancer therapy, where the risk to the patient from lack of knowledge about disease progress is much greater than the risk from the test radiation. Since the tracers are radioactive, the elderly and pregnant are unable to use it due to risks posed by radiation.


title: Positron emission tomography

text: Limitations to the widespread use of PET arise from the high costs of cyclotrons needed to produce the short-lived radionuclides for PET scanning and the need for specially adapted on-site chemical synthesis apparatus to produce the radiopharmaceuticals after radioisotope preparation. Organic radiotracer molecules that will contain a positron-emitting radioisotope cannot be synthesized first and then the radioisotope prepared within them, because bombardment with a cyclotron to prepare the radioisotope destroys any organic carrier for it. Instead, the isotope must be prepared first, then afterward, the chemistry to prepare any organic radiotracer (such as FDG) accomplished very quickly, in the short time before the isotope decays. Few hospitals and universities are capable of maintaining such systems, and most clinical PET is supported by third-party suppliers of radiotracers that can supply many sites simultaneously. This limitation restricts clinical PET primarily to the use of tracers labelled with fluorine-18, which has a half-life of 110 minutes and can be transported a reasonable distance before use, or to rubidium-82 (used as rubidium-82 chloride) with a half-life of 1.27 minutes, which is created in a portable generator and is used for myocardial perfusion studies. Nevertheless, in recent years a few on-site cyclotrons with integrated shielding and "hot labs" (automated chemistry labs that are able to work with radioisotopes) have begun to accompany PET units to remote hospitals. The presence of the small on-site cyclotron promises to expand in the future as the cyclotrons shrink in response to the high cost of isotope transportation to remote PET machines. In recent years the shortage of PET scans has been alleviated in the US, as rollout of radiopharmacies to supply radioisotopes has grown 30%/year.


title: Positron emission tomography

text: Because the half-life of fluorine-18 is about two hours, the prepared dose of a radiopharmaceutical bearing this radionuclide will undergo multiple half-lives of decay during the working day. This necessitates frequent recalibration of the remaining dose (determination of activity per unit volume) and careful planning with respect to patient scheduling.