Clinical Utility of a Slow( 201)Tl Washout Rate in the Detection of Multi-Vessel Coronary Artery Disease Using a Simultaneous Acquisition Rest Tc-99 m/Stress( 201)Tl Protocol and a Semiconducting Gamma Camera

Background: The diagnostic accuracy of stress myocardial perfusion single-photon emission computed tomography (SPECT) to detect coronary artery disease (CAD) is reduced by the balanced reduction of myocardial perfusion in patients with multi-vessel or left main trunk CAD (multi-vessel group). This study investigated the diagnostic performance of a simultaneous acquisition rest Tc-99m/ stress( 201)Tl dual-isotope protocol for myocardial perfusion SPECT (MPS) in a multi-vessel group by examining the assessment of a slow Tl-201 washout rate (WR) finding in comparison to the accuracy of perfusion assessments. Methods and Results: This study enrolled 91 patients who had undergone angiography within 3 months after MPS. The diagnos-tic performances of perfusion assessments and a slow Tl-201 WR parameter were compared using the area under the curve (AUC) in a multi-vessel group of patients with mild ischemia (2 <= summed difference score [SDS]<= 7). The AUC of a slow WR parameter was significantly larger compared with that for perfusion assessments, in patients with mild ischemia, (AUC, 0.736 vs. 0.504-0.558, P value: < 0.01-0.05). Conclusions: Among patients with mild ischemia, a slow Tl-201 WR parameter improved the detection of CAD in a multi-vessel group.