EVALUATION AND CLINICAL USE OF EARLY WASHOUT RATIO OF THALLIUM-201 IN NORMAL AND ISCHEMIC MYOCARDIUM AFTER DIPYRIDAMOLE-INDUCED VASODILATION USING RING-TYPE EMISSION COMPUTED TOMOGRAPHY

• Published in: JAPANESE CIRCULATION JOURNAL Vol. 55; no. 3; pp. 194 - 203
• Main Authors: HAYASHI, MASATAKA, KAMBARA, HIROFUMI, NOHARA, RYUJI, FUDO, TETSURO, HASHIMOTO, TETSUO, KAWAI, CHUICHI, TAMAKI, NAGARA, YONEKURA, YOSHIHARU, KONISHI, JUNJI
• Format: Journal Article
• Language: English
• Published: Kyoto The Japanese Circulation Society 1991; Japanese Circulation Society
• Subjects: Adult; Aged; Biological and medical sciences; Cardiology. Vascular system; Coronary Disease - diagnostic imaging; Coronary heart disease; Dipyridamole; Dipyridamole - pharmacology; Female; Heart; Hemodynamics - drug effects; Humans; Ischemic heart disease; Male; Medical sciences; Middle Aged; Ring-type single photon emission CT; Thallium Radioisotopes - metabolism; Thallium-201 washout ratio; Tomography, Emission-Computed - methods; Vasodilation - drug effects; Radionuclide study; Human; Thallium; Vasodilator agent; Ischemia; Myocardium; Cardiovascular disease; Exploration; Scintigraphy; Coronary heart disease
• ISSN: 0047-1828; 1347-4839
• DOI: 10.1253/jcj.55.194

Using newly developed ring-type emission computed tomography (SPECT), we investigated the washout ratio (WR) of Tl-201 in the myocardium quantitatively with fast dynamic scanning after infusion of dipyridamole (0.57mg/kg), and assessed the feasibility of early WR as a marker to detect coronary artery disease. Twenty-three patients with and 8 patients without coronary aryery disease had serial SPECT images obtained every 5 min for 45 min and at 180 min after dipyridamole and subsequent Tl-201 injection. The best appropriate transaxial slice was selected for WR analysis. Most appropriate diagnostic time was 25 min after infusion of Tl-201 (WR-25). Normal WR-25 was 7.1±4.0%. 5.9±3. 1% and 7.1±2.3%, at the septum, anterior and lateral wall, respectively. Sensitivity, specificity and accuracy to identify coronary stenosis > 50% with a usage of abnormal WR-25, defined as WR-25 < (mean of normals - 1 SD) in each region of inferest of the left ventricle (LV), were 96%. 100% and 97%. respectively. These results were better than those achieved by visual analysis (sensitivity 78%, specificity 100%, accuracy 84%). In patients with single as well as multivessel disease, the regional accuracy in assessing stenosis of more than 50% in the left anterior descending artery (LAD) and left circumflex artery (LCX) by WR-25 was 940/c and 83%, respectively, which was significant-ly better than using visual methods (LAD 72% and LCX 50%; p<0.05). Thus, evaluation of early washout ratios (WR-25) after dipyridamole injection is a valuable method to increase sensitivity in assessing regional myocardial perfu-sion abnormality and is helpful in detection of ischemic heart disease, even with multivessel disease.