Cardiac PET/CT Imaging with 82Rb

All ⁸²Rb PET/CT (Discovery Rx; GE Healthcare) acquisitions were performed in 2-dimensional mode. The 76.38-s half-life of ⁸²Rb and the corresponding requirement for pharmacologic vasodilation require that image acquisition be completed within 10 min of the ⁸²Rb infusion. The following protocol was used to collect the pharmacokinetic data needed for dosimetry while remaining within the required constraints. First, a whole-body transmission CT scan (120 kVp; 20–200 mA, automatically adjusted; pitch, 0.5; and rotation time, 0.5 s) was obtained. A series of 3 whole-body PET scans was subsequently acquired after an infusion of 1,534 ± 118 MBq of ⁸²Rb at rest. Stress was induced by administration of the vasodilator, dipyridamole. Four minutes after a 4-min infusion of dipyridamole (0.56 mg/kg), about 1,502 ± 158 MBq of ⁸²Rb were infused and 3 serial whole-body PET scans were acquired. The heart rate, blood pressure, and electrocardiogram were monitored continuously throughout pharmacologic vasodilation. Each whole-body PET scan was obtained with a maximum of six 20-s bed positions starting at the level of the femurs and extending to the base of the skull. The 3 serially collected whole-body PET scans were completed in approximately 9 min. The mean infusion time for the ⁸²Rb activity from the ⁸²Sr/⁸²Rb generator was 25 s (range, 18–32 s). The first scan was started from the base of the femurs 10 s after the end of ⁸²Rb infusion. Attenuation-corrected whole-body PET images were reconstructed for subsequent region-of-interest analysis.