Clinical Utility of a Slow Tl Washout Rate in the Detection of Multi-Vessel Coronary Artery Disease Using a Simultaneous Acquisition Rest Tc/Stress 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/stress Tl dual-isotope protocol for myocardial perfusion SPECT (MPS) in a multi-vessel group by examining the assessment of a slow Tl 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 diagnostic performances of perfusion assessments and a slow Tl 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 WR parameter improved the detection of CAD in a multi-vessel group.