Single- vs. dual-head SPECT for detection of myocardial ischemia and viability in a large study population

As single-head data acquisition for thallium-201 myocardial SPECT is a frequently used method mainly in the outpatient medical care as well as in smaller hospitals, comparison to dual-head data collection is a still discussed issue mainly with regard to quality control and -assurance.

A total of 1334 patients undergoing thallium-201 myocardial SPECT for diagnosis of myocardial ischemia and/or viability have been retrospectively analyzed. In 554 patients, a single-head gamma camera (360 degrees rotation) has been applied, whereas a dual-head gamma camera (180 degrees rotation) has been used in 780 patients. Four hundred twenty-six patients received both myocardial SPECT as well as coronary angiography. The diagnostic value of both applied acquisition techniques has been analyzed.

Regarding myocardial viability, positive predictive value for the diagnosis of myocardial scar tissue was significantly higher for dual-head- as compared to single-head acquisition. Among the 426 patients undergoing diagnosis of myocardial ischemia, significant differences have only been found with regard to specificity being higher in the single-head acquisition. Diagnosis of myocardial ischemia related to a distinct myocardial perfusion region showed a significantly higher sensitivity of dual-head acquisition for the left anterior descending perfusion area, whereas specificity was significantly higher for single-head acquisition.

Our results indicate a beneficial effect of dual-head data collection with regard to sensitivity of the diagnosis of myocardial ischemia. In contrast, single-head data acquisition was superior with regard to specificity. However, it is justified to preferably apply dual-head data collection in clinical routine due to the shorter acquisition time leading to an evident time benefit of this acquisition technique.