1. Field of the Invention
The present invention relates to an X-ray diagnostic apparatus which radiographs a subject to be examined by using pulse X-rays and an image processing apparatus suitable for coronary angiographic diagnosis using X-rays.
2. Description of the Related Art
There is available a method of performing angiography after an intravascular intervention treatment, observing a temporal change in the manner of the flow of a contrast medium into the cardiac muscle, and supporting the determination of the end of the treatment. Since the release of the article (by Gibson) in 2000 which stated that this method allowed to predict a prognosis, the method has often been used to evaluate beneficial effects and manipulations/techniques.
Although it has been evident that the index based on this method is clinically useful, the index has not been used in daily routine clinical practices. This is because the method increases radiation exposure and is low in quantitativeness.
A radiography whose examination purpose is blood vessel morphology observation generally performs radiography in the manner shown in FIG. 6. That is, this method obtains an image by applying X-rays for a period of three to five heartbeats in terms of cardiac motion or about five sec in terms of a radiography time.
If the examination purpose of this method is to measure myocardial perfusion, it is necessary to perform radiography for a long period of time. It is thought that continuous observation for at least five sec, or about 30 sec in general, or about 60 sec at most is preferable. For this reason, if this radiography whose purpose is myocardial perfusion is to be performed in addition to radiography whose purpose is to perform blood vessel morphology observation, it is necessary to perform radiography like that shown in FIG. 7.
It is conceivable to provide another proposal of separately performing radiography whose purpose is blood vessel morphology observation and radiography whose purpose is myocardial perfusion, i.e., a total of two radiographic cycles. In this case, however, the amount of contrast medium injected doubles. This is most undesirable.
In addition, a conventional X-ray diagnostic apparatus for blood vessel observation, i.e., a so-called X-ray angiography apparatus, performs coronary angiography, but cannot quantitatively measure a myocardial blood flow by using a contrast medium. It is therefore necessary to measure a myocardial blood flow in another room or in another time zone by using a nuclear medicine diagnosis apparatus or MRI apparatus.
Assume that there are a plurality of stenoses in a coronary artery. Currently no method is available in cathether room to determine which of plurality of stenosis is major reason of ischemia. When interventional treatment has been done for, embolus, or thrombus in a peripheral vessel of a coronary artery, it is difficult to verify that enough blood is now supplied to cardiac muscle so that treatment can be finished at this time, Note that the following two references (a) and (b) are related arts:
(a) Relationship of TIMI Myocardial Perfusion Grade to Mortality After Administration of Thrombolytic Drugs, C. Michael Gibson, MS, MD; Christopher P. Cannon, MD; Sabina A. Murphy, MPH; Kathryn A. Ryan, BS; Rebecca Mesley, BS; Susan J. Marble, RN, MS; Carolyn H. McCabe, BS; Frans Van de Werf, MD, PhD; Eugene Braunwald, MD;, Circulation, 101, 125-130, 2000
(b) Arnoud W. J. van't Hof, MD; Aylee Liem, MD; Harry Suryapranata, MD; Jan C. A. Hoorntje, MD; Menko-Jan de Boer, MD; Felix Zijlstra, MD;, Angiographic Assessment of Myocardial Reperfusion in Patients Treated With Primary Angioplasty for Acute Myocardial Infarction, Myocardial Blush Grade, Circulation, 97, 2302-2306, 1998)