TOMOGRAPHIC MYOCARDIAL IMAGING WITH TC-99M TETROFOSMIN - COMPARISON WITH TETROFOSMIN AND THALLIUM PLANAR IMAGING AND WITH ANGIOGRAPHY

Technetium-99m tetrofosmin is a new myocardial imaging agent with impr oved handling and kinetic characteristics. The purpose of this study w as to compare the ability of planar and SPECT Tc-99m tetrofosmin imagi ng with Thallium-201 planar data to detect coronary artery disease and individual vessel lesions (>50% diameter stenosis). Seventy-two patie nts with definite or suspected coronary artery disease were included. Sixty-three had angiographic evidence of coronary artery disease, amon g whom 42 had had a previous myocardial infarction, while 21 had not. The total number of diseased arteries was 111. Patients underwent symp tom-limited treadmill or bicycle exercise to similar endpoints. Thalli um and tetrofosmin images were analysed separately by consensus readin g. Interpretation was made for five standard anatomical regions (anter ior, septal, inferior, lateral and apex), classified into four categor ies (normal, reversible, fixed and mixed defects). Sensitivity and spe cificity to detect coronary artery disease were 71% and 78% for Thalli um-201 vs 68% and 78% for tetrofosmin by planar imaging, and 87% and 8 9% for tetrofosmin by SPECT. The improved sensitivity of SPECT was con firmed both in patients with and without previous myocardial infarctio n. The sensitivity to detect individual vessel lesions was improved by SPECT (59% tetrofosmin SPECT vs 50% thallium planar and 51% tetrofosm in planar). Individual vessel lesion detection by SPECT was 50% for th e left anterior descending coronary artery, 42% for the left circumfle x and 86% for the right coronary artery. This study confirms the value of technetium-99m tetrofosmin as a myocardial imaging agent. Improvem ents in diagnosis and in evaluating extent of disease can be expected from using SPECT.