Optimal thallium-201 dose in cadmium-zinc-telluride SPECT myocardial perfusion imaging

Background. We aimed to determine the optimal thallium 201 chloride (thallium-201) dose using a novel ultrafast cardiac gamma camera with cadmium-zinc-telluride (CZT) solid-state semiconductor detectors (D-SPECT). Methods and Results. The optimal thallium-201 dose for obtaining left ventricular (LV) myocardial counts was determined from a phantom study. Consecutive 292 patients underwent stress myocardial perfusion imaging with a thallium-201 injection. Stress test comprised exercise or pharmacological (adenosine) provocation. We calculated an optimal thallium-201 dose that resulted in better LV myocardial counts during 6 minutes of acquisition time. We corrected the respective values according to the patient's age, sex, body mass index (BMI), and type of stress test. The lowest thallium-201 dose for obtaining acceptable imaging was 1.2 million counts. Radiopharmaceutical doses showed a positive correlation with the patient's age (P < .001), sex (P = .012), BMI (P < .001), and type of stress test (P < .001). Multivariate analysis revealed that the patient's BMI and the type of stress test were statistically significant factors for determining the correct radiopharmaceutical dose (P < .001 for both). Conclusions. For clinical use of the CZT SPECT system, the optimal individual thallium-201 doses can be determined based on the patient's BMI and type of stress test.