Quantitative evaluation of myocardial blood flow and ejection fraction with a single dose of (13)NH(3) and Gated PET.

Abstract

To evaluate myocardial blood flow (MBF) and cardiac function with a single dose of (13)NH(3), electrocardiographically (ECG) gated PET acquisition was performed after a dynamic PET scan was obtained. Gated blood-pool (GBP) imaging with C(15)O PET was also performed to compare the left ventricular ejection fraction (LVEF) obtained using the 2 methods. Six healthy volunteers and 34 patients with cardiovascular disease were studied. Each subject underwent dynamic PET scanning after a slow intravenous injection of approximately 740 MBq (13)NH(3), followed by ECG gated PET scanning. MBF images were calculated by the Patlak plot method. Before obtaining the (13)NH(3) scan, the GBP image was obtained with a bolus inhalation of C(15)O. Twenty patients also underwent left ventriculography (LVG) to compare the value of the LVEF obtained using this technique with that determined using the gated PET method. The mean regional value of MBF calculated for healthy volunteers in the resting condition was 0.61 +/- 0.10 mL/min/g. The LVEF obtained using GBP PET (EF(CO)) was consistent with that obtained using LVG. The LVEF calculated from gated (13)NH(3) scans (EF(NH3)) correlated well with EF(CO), although EF(NH3) slightly underestimated the LVEF (EF(NH3) = 0.97. EF(CO) - 2.94; r = 0.87). EF(NH3) was significantly different from EF(CO) in patients with a perfusion defect in the cardiac wall (EF(NH3) = 39% +/- 11% vs. EF(CO) = 45% +/- 11%; n = 19; P < 0.001), whereas no significant difference was found between them in subjects with no defect (EF(NH3) = 58% +/- 13% vs. EF(CO) = 61% +/- 10%; n = 21). Gated PET acquisition accompanied by obtaining a dynamic PET scan with a single dose of (13)NH(3) is a promising method for the simultaneous clinical evaluation of MBF and cardiac function. However, in patients with a defect in the cardiac wall, EF(NH3) showed a tendency to underestimate the EF compared with EF(CO).