Electrocardiographically gated blood-pool SPECT and left ventricular function: comparative value of 3 methods for ejection fraction and volume estimation.

Abstract

The current major limitation to development of electrocardiographically (ECG) gated blood-pool SPECT (GBPS) for measurement of the left ventricular (LV) ejection fraction (LVEF) and volumes is the lack of availability of clinically validated automatic processing software. Recently, 2 processing software methods for quantification of the LV function have been described. Their LVEFs have been validated separately, but no validation of the LV volume measurement has been reported. We compared 3 processing methods for evaluation of the LVEF (n = 29) and volumes (n = 58) in 29 patients: automatic geometric method (GBPS(G)), semiautomatic activity method (GBPS(M)), and 35% maximal activity manual method (GBPS(35%)). The LVEF provided by the ECG gated equilibrium planar left anterior oblique view (planar(LAO)) and the LV volumes provided by LV digital angiography (Rx) were used as gold standards. Whereas the GBPS(G) and GBPS(M) methods present similar low percentage variabilities, the GBPS(35%) method provided the lowest percentage variabilities for the LVEF and volume measurements (P < 0.04 and P < 0.02, respectively). The LVEF and volume provided by the 3 methods were highly correlated with the gold standard methods (r > 0.98 and r > 0.83, respectively). The LVEFs provided by the GBPS(35%) and GBPS(M) methods are similar and higher than those of the GBPS(G) method and planar(LAO) method, respectively (P < 0.0001). For the LVEF, there is no correlation between the average and paired absolute difference for the 3 GBPS methods against the planar(LAO) method, and the limits of agreement are relatively large. LV volumes are lower when calculated with the GBPS(M), GBPS(G), and Rx methods (P < 0.0001). However, the GBPS(35%) and Rx methods provide LV volumes that are similar. There is no linear correlation between the average and the paired absolute difference of volumes calculated with the GBPS(G) and GBPS(35%) methods against Rx LV volumes. However, a moderate linear correlation was found with the GBPS(M) method (r = 0.6; P = 0.0001). The 95% limits of agreement between the Rx LV volumes and the 3 GBPS methods are relatively large. GBPS is a simple, highly reproducible, and accurate technique for the LVEF and volume measurement. The reported findings should be considered when comparing results of different methods (GBPS vs. planar(LAO) LVEF; GBPS vs. Rx volume) and results of different GBPS processing methods.