Comparison of exercise, dipyridamole, adenosine, and dobutamine stress with the use of Tc-99m tetrofosmin tomographic imaging

Purpose, The purpose of this study was to compare defect extent and severit y and myocardial uptake with exercise and pharmacologic stress with technet ium-99m (Tc-99m) tetrofosmin tomographic myocardial perfusion imaging. Background, Detection of stress-induced myocardial perfusion defects depend s on;both a disparity in blood flow between normal and stenotic vessels and the extraction fraction and linearity of myocardial uptake of the tracer. There are limited clinical data for exercise or pharmacologic stress with T c-99m tetrofosmin tomographic myocardial perfusion imaging. Methods. Thirty-one patients with coronary artery disease and 7 with a <5% likelihood of coronary artery disease underwent on separate days Tc-99m tet rofosmin single-photon emission computed tomographic imaging at rest and af ter exercise, dipyridamole, adenosine, and dobutamine stress. Images were i nterpreted by a blinded consensus of 3 experienced readers with a 1.7-segme nt model and 5-point scoring system. Results, Compared with exercise, the summed stress score was smaller with d ipyridamole (P <.01), and the reversibility score was smaller with both dip yridamole (P <.01) and dobutamine (P <.05), whereas the number of abnormal and reversible segments was less with both dipyridamole (P <.01 and P <.001 , respectively) and dobutamine (both P <.05). No significant differences we re found in the summed stress or reversibility scores and the number of abn ormal or reversible segments between exercise and adenosine. Conclusions. Compared with exercise, defect extent, severity, and reversibi lity are less with dipyridamole and dobutamine with Tc-99m tetrofosmin sing le photon emission computed tomographic imaging.