Status of Nuclear Cardiology Progress in Japan 2020

Abstract

Various new imaging modalities provide multiple options with which to clinically diagnose coronary artery disease (CAD). Among such modalities, the major indications for nuclear cardiology remain the diagnosis of myocardial perfusion including stress-induced ischemia and infarction. However, the popularity of non-invasive X-ray computed tomography (CT) with coronary CT coronary angiography (CCTA) to visualize CAD, has rapidly increased , whereas nuclear imaging with Tcand I-labeled tracers has reached a plateau at ~200,000– 300,000 studies annually according to Japanese Radioisotope Association. Fusion imaging with combined CCTA and single-photon emission computed tomography (SPECT) is also a popular option for integrated displays of coronary artery and perfusion . The most pressing matter is how to integrate or effectively use information about coronary anatomy and perfusion in clinical practice. Myocardial perfusion reserve has so far been assessed in Japan only by positron emission computed tomography (PET) with N-ammonia and O-water. However, the number of cardiac PET studies has been lower than expected in Japan except for F-fluorodeoxy glucose (FDG) in cardiac sarcoidosis. In contrast, SPECT could be an alternative to PET for assessing myocardial flow reserve (MFR), if further validated. Newer solid-state, cadmium-zinc telluride (CZT) cameras offer 10-fold higher sensitivity than conventional gamma camera SPECT, which has enabled dynamic studies of tracer transit from intravenous injection to myocardial fixation that provides MFR . While fractional flow reserve (FFR) has provided adjunctive information during coronary angiography in patients with coronary stenosis , the roles of MFR and FFR need to be further validated from the viewpoint of diagnosis and prognosis. Compounds labeled with I such as I-β-methyliodophenylpentadecanoic acid (BMIPP) and I-metaiodobenzylguanidine (MIBG) are used in 20% of nuclear cardiology studies, which is unique in Japan. Current clinical guidelines include the Guidelines for Diagnosis of Chronic Coronary Heart Diseases Review Article