certain molecular markers can be used as indicators of the status of the sentinel lymph node . for example , cytokine and chemokine gene expression in melanoma sentinel lymph nodes ( sln ) varies with disease stage , i . e ., whether cancer cells are present in the snl or not . the pattern of inflammatory cytokines can be used to determine the presence of cancer in these lymph nodes . for example , the expression of molecular markers interleukin - 13 ( il - 13 ), indoleamine 2 , 3 - dioxygenase ( ido ), interferon gamma ( ifn ), and interleukin - 10 ( il - 10 ) increases , and interleukin - 11ra expression decreases , in tumor - position lymph nodes . combinations of other molecular markers may determine the presence of cancer cells in other cancers such as breast cancer . as shown in fig1 - 5 , sentinel lymph nodes of stage iii patients ( tumor - bearing snl &# 39 ; s ) show significantly higher gene expression of interleukin - 13 ( il - 13 ), leptin , lymphotoxin beta receptor ( ltbr ), and macrophage inflammatory protein - 1b ( mip1b ), and lower expression of macrophage maturation / activation gene ( il - 11ra ) when compared with their levels in sln &# 39 ; s of patients that were stage i or ii ( sln that are free of cancer cells ). these genes can therefore serve as new molecular surrogates for detecting occult sln metastasis as they are reflective of the tumor - microenvironment and replace the need to slice and microscopically examine surgically removed sentinel nodes . as an example of a procedure that can be performed , rna was extracted from freshly preserved slns of 13 ajcc stage i / ii and 10 stage iii ( micromet & lt ; 2 mm ) melanoma patients . the rna was then converted into biotin - 16 - dutp labeled cdna and amplified with 30 cycles of pcr . expressed cytokine and chemokine genes were compared between the two groups by using a 96 - gene cdna microarray . expression levels of individual genes were normalized to β - actin . over - or under - expression was defined as a 2 - fold increase or decrease , respectively . statistical analysis was then performed with the student &# 39 ; s t - test and receiver - operator characteristics ( roc ) methods , demonstrating that the combination of all 5 markers is an excellent indicator of the stage of cancer ( fig7 .) sentinel nodes from melanoma can be immunosuppressed by cytokines during the process of tumor metastasis . accordingly , it has been found that conducting quantitative analysis of this melanoma induced cytokine - mediated immunosuppression in slns can be used to show the presence or absence of melanoma . further , the sentinel node immunosuppression can be reversed by cytokine therapy ; this reversal of immunosuppression in slns of stage i or ii melanomas may improve the cure rate of melanomas but can reduce the need for complete lymph node dissection . other cancers , such as breast cancer , can also exhibit a certain pattern of sln immunosuppression and may benefit in a similar fashion from cytokine therapy , gene therapy or rna or dna interference . several techniques for overcoming the shortcomings of prior techniques and for the use of percutaneous minimally invasive procedures for the determination of the status of slns , namely whether the sln contains any tumor cells , without a surgical procedure and resection of the whole lymph node , are set below : using the technique described herein only a small piece of the sentinel lymph node is required in order to determine if it contains cancer cells . instead of looking for the cancer cells , determining the level of a combination of molecular markers ( such as those mentioned above ) will provide information sufficient to establish the status of the lymph node and thereby the stage of the disease . the sequence of the events , with reference to fig8 - 11 , are : the patient was injected with a radioactive substance , such as tc - 99m labeled sulfur colloid , in the area around the tumor . 1 . after a time duration of about 1 to 48 hours , blue dye was injected around the tumor . 2 . a few minutes later , an ultrasound scanner 10 with a gamma probe 12 mounted thereto through a holder 14 on a hinge arrangement 16 was used to localize the sentinel lymph node 18 percutaneously ( fig8 and fig9 ) and the probe 12 was position to obtain the greatest radiation count 20 , indicating that the location of the labeled sentinel node had been determined . 3 . the position of the ultrasound scanner was held fixed , the probe was removed and , utilizing the established position of the holder 14 along with the ultrasound image 22 as a guide , a biopsy apparatus 24 was inserted into the lymph node 18 ( fig1 ). a tissue collector or biopsy needle 26 was then placed through the biopsy apparatus 24 and a tissue sample was collected from the node 18 ( fig1 ). 4 . the presence of a particular molecular marker or array of markers , such as those mentioned above , and the quantity thereof , were determined on the biopsy sample using molecular biology methods such as quantitative rt - pcr ( reverse transcriptase - polymerase chain reaction ). this determined whether the lymph node was tumor - bearing or free of cancer cells . 5 . using the same node location technique , the same node or tumor was located and the lymph node or the tumor was injected with a therapeutic agent . alternatively , a marker easily located by ultrasound techniques can be placed at the site of the sentinel lymph node so it can be readily located at a later time . this method is a modification of the procedure set forth in method 1 described above . in step 4 above , before inserting the tissue collector or biopsy needle into the node , a very narrow radiation detector probe 28 , such as shown in fig1 , is inserted through the biopsy apparatus 24 to ascertain if the tip of that apparatus 24 is inside the radioactive sentinel node 18 . the position of the biopsy apparatus is then adjusted such that maximum counts of the intra - luminal probe is achieved at the tip of the biopsy apparatus . if radioactivity is detected , the probe 28 is removed and the biopsy needle 26 is inserted and tissue collected followed by treatment . as a further alternative , as shown in fig1 , the mechanical hinge arrangement 16 between the probe and the ultrasound transducer can be replaced by a pair of electromagnetic , optical , or acoustic position sensors 30 . this allows the position and direction ( orientation ) of the gamma probe 12 in relationship to the ultrasound transducer to be registered on a computer . a similar sensor 30 on the biopsy apparatus 24 can then be used to place it in the same position . otherwise , all of the steps described above are followed . this method incorporates a radiation detector with a hole there through along a central axis of the detector , or parallel to its axis . the radiation detector is surrounded by a heavy metal collimator ( fig1 ) which can be placed on the skin surface in the vicinity of the sentinel node . an opening or hole 36 in the detector 32 is sized to receive the biopsy apparatus 24 and / or biopsy needle 26 . in one configuration this detector is made of a semiconductor material such as cdte or zncdte . alternatively , the detector is a scintillating crystal that is optically connected to a photo - detector such as photomultiplier tube ( pmt ), solid - state photomultiplier ( sspm or sipm ), avalanche photodiode , or pin photodiode . fig1 shows radiation detector assembly ( probe ) 42 comprising a radiation detector with an axial hole ( or a hole parallel to the axis ) in it comprising bgo scintillating crystals radiation detector 32 within a tungsten collimator 34 . the hole 36 in the detector provides a conduit for placement of a biopsy apparatus 24 and biopsy needle 26 . the light generated by radiation in the scintillating crystal 32 is carried via an optical fiber bundle 38 of more than 1000 strands to a light detector 40 such as a pmt or sspm or avalanche photodiode . fig1 shows the radiation detector assembly ( probe ) 42 of fig1 attached to a ultrasound detector 10 by a hinged connector 16 . the probe 42 identifies the sentinel node 18 and the ultrasound transducer 10 images the anatomy of the tissue surrounding the sentinel node 18 . this arrangement is operated in the same manner as set forth in example 1 . fig1 shows an array of detectors 44 used in place of the donut scintillator ring 32 to form an image of the radioactive distribution . a hole 36 is provided in the detector array 44 to accommodate a biopsy apparatus 24 and / or needle 26 . the detector array 44 can comprise scintillators , or semdiconductor detectors . a parallel - hole collimator ( not shown ) may be put in front of the detector array 44 in order to form the image of the gamma ray emissions . this radiation detector can also be a beta ray camera , and photodetectors can be avalanche photodiode , sspm or pmt . fig1 shows a detector assembly 42 which includes the array 44 coupled to an ultrasound transducer 10 through a hinge connector 16 and fig1 shows the same components , the relative positions of each being determined by wireless position sensors 30 mounted on each component . once a biopsy of the sentinel node 18 has been performed using one of the assemblies described , if treatment is appropriate the procedure described above can be used to once again locate this sentinel node or a second sln 18 . the localized sentinel lymph node 18 is then injected with therapeutic genetic materials , or cells that can reverse the immuno - suppression caused by the cancer ( such as melanoma cytokine - mediated immuno - suppression ). as an example , a plasmid dna vaccine ( tagawa et al . cancer ; 98 , p144 - 54 ( 2003 )), and / or cells engineered to secrete granulocyte - macrophage colony stimulating factor , and / or recombinant human granulocyte macrophage colony stimulating factor ( rhgm - csf ) can be delivered . injection of other compounds , or genetic materials or interfering nucleic acids and / or cells that boost the immune response of the sentinel node can also be beneficial . these may include recombinant gm - csf - encoding virus as gene therapy , or rna , dna interference ( rnai ). the direct injection of these materials into the sentinel node 18 is made possible by detection of the sentinel lymph node as described herein . an ultrasound or gamma probe detectable “ clip ” or particle can be placed on the sln as a method to relocate the sln for future evaluation or treatment with needle biopsy . a limitation of current technology intra - operative probes is the size of the pmt ( 1 cm diameter and 5 cm long ). although cdte , pin diode , or zcdte all have compact sizes , they are all low gain , noise sensitive , and have low efficiencies for absorption of gamma rays . as a further alternative it is proposed that a sipm or other solid state photomultiplier ( sspm ) devices be used for detection of scintillation light of lso , ylso , and bgo scintillators that have high densities and therefore high absorption efficiencies for gamma rays . an interoperative probe 50 incorporating an sipm is shown in fig2 a and 20 b . it comprises a scintillator 52 in front of a sipm 54 with the circumference thereof in a surrounding collimator 56 , preferably a gold collimator . a lead 58 extending from the sipm 54 carries the signal to electronic display means such as shown on fig8 , 9 , 13 , 16 and 17 . such an interoperative probe 50 can be used in any of the assemblies described above . another embodiment , shown in fig2 , is a simp containing interoperative probe 50 mounted on a ring so it can be worn on a finger and used to locate the sentinel node emitting radiation . in addition to use to locate sentinel nodes , as described above , beta or gamma probes constructed utilizing sspm can be used for endovascular , endoscopy thorascopic and laparoscopy since they are small in size . fig2 shows a cross sectional view of a new endo - surgical radiation detector probe tip 60 , which includes within a single tubular sheath 62 , the interoperative probe 50 , a biopsy port 64 , an irrigation channel 66 and a camera channel 68 , a channel for placing a biopsy needle , an irrigation channel and a camera . if a plastic scintillator is coupled to the sipm it becomes a detector that is preferentially sensitive to beta rays . a dual detector beta probe can be made similar to the one proposed by daghighian et al . in journal of medical physics , 1994 , pp53 . this dual detector probe is capable of simultaneously detecting the beta rays and gamma rays . a multidetector probe or radiation detection camera can be made for locating labeled tissue within the body containing isotopes emitting gamma or beta rays . a hand - held beta ray imaging camera for use in intra - operative detection of cancer can be made by coupling an array of sspm &# 39 ; s to a plate of plastic scintillator as shown in fig2 . an intraoperative gamma camera can be built in the same fashion by using sspms and a scintillator plate or individual pixels of scintillators ( such as csi ). however , in such an instance , a parallel hole collimator of lead or tungsten should be put in front of the scintillator . again the small size of the sspm allows the shielding of this camera to be short and therefore result in a decrease in the weight of the camera . an intra - vascular beta probe constructed with sspms and scintillator ( s ) has the advantage of being able to work under relatively low voltages ( 60 v ) and can be used for detection of inflammatory or vulnerable atherosclerosis plaques .
the present invention is directed to instruments and instrumental techniques for locating cancer cells in lymph nodes which utilize a radiation detector operatively connected to an ultrasound probe for locating the exact position of radiation tagged tissue , particularly in sentinel lymph nodes followed by placement of a biopsy device . also described are unique new interoperative radiation detection probes for use in these techniques which include structure for placement of a biopsy device or biopsy needle into the located lymph node and procedures for removal of small portions of detected radiation emitting sentinel lymph nodes for evaluation in a pathology laboratory by measurement of expressed genes located in the removed tissue . the instruments and instrumental techniques also facilitate the subsequent delivery of materials to reverse the unfavorable immune response or environment conducive for metastasis in the sentinel lymph node once cancer cells are located therein .