Cadmium-Zinc-Telluride Myocardial Perfusion Imaging in Obese Patients

We have evaluated the impact of increased body mass on the quality of myocardial perfusion imaging using a latest-generation gamma-camera with cadmium-zinc-telluride semiconductor detectors in patients with high (>= 40 kg/m(2)) or very high (>= 45 kg/m(2)) body mass index (BMI). Methods: We enrolled 81 patients, including 18 with no obesity (BMI < 30 kg/m(2)), 17 in World Health Organization obese class I (BMI, 30-34.9 kg/m(2)), 15 in class II (BMI, 35-39.9 kg/m(2)), and 31 in class III (BMI >= 40 kg/m(2)), including 15 with BMI >= 45 kg/m(2). Image quality was scored as poor (1), moderate (2), good (3), or excellent (4). Patients with BMI >= 45 kg/m(2) and nondiagnostic image quality (<= 2) were rescanned after repositioning to better center the heart in the field of view. Receiver-operating-curve analysis was applied to determine the BMI cutoff required to obtain diagnostic image quality (>= 3). Results: Receiver-operating-curve analysis resulted in a cutoff BMI of 39 kg/m(2) (P < 0.001) for diagnostic image quality. In patients with BMI >= 40 kg/m(2), image quality was nondiagnostic in 81%; after CT-based attenuation correction this decreased to 55%. Repositioning further improved image quality. Rescanning on a conventional SPECT camera resulted in diagnostic image quality in all patients with BMI >= 45 kg/m(2). Conclusion: Patients with BMI >= 40 kg/m(2) should be scheduled for myocardial perfusion imaging on a conventional SPECT camera, as it is difficult to obtain diagnostic image quality on a cadmium-zinc-telluride camera.