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

The current major limitation to development of electrocardiographically (EC G) gated blood-pool SPECT (GBPS) for measurement of the left ventricular (L V) ejection fraction (LVEF) and volumes is the lack of availability of clin ically validated automatic processing software. Recently, 2 processing soft ware methods for quantification of the LV function have been described. The ir LVEFs have been validated separately, but no validation of the LV Volume measurement has been reported. Methods: We compared 3 processing methods f or evaluation of the LVEF (n = 29) and volumes (n = 58) in 29 patients: aut omatic geometric method (GBPS(G)), semiautomatic activity method (GBPSF(M)) , and 35% maximal activity manual method (GBPS(35%)). The LVEF provided by the ECG gated equilibrium planar left anterior oblique view (planar(LAO)) a nd the LV volumes provided by LV digital angiography (Rx) were used as gold standards. Results: Whereas the GBPSG and GBPS(M) methods present similar low percentage variabilities, the GBPS,,, method provided the lowest percen tage 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 high ly correlated with the gold standard methods (r > 0.98 and r > 0.83, respec tively). The LVEFs provided by the GBPS(35%) and GBPS(M) methods are simila r and higher than those of the GBPSG method and planar(LAO) method, respect ively (P < 0.0001). For the LVEF, there is no correlation between the avera ge and paired absolute difference for the 3 GBPS methods against the planar ,, 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 < 0.000 1). However, the GBPS3,, and Rx methods provide LV volumes that are similar . There is no linear correlation between the average and the paired absolut e difference of volumes calculated with the GBPS(G) and GBPS(35%) methods a gainst 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 betw een the Rx LV volumes and the 3 GBPS methods are relatively large. Conclusi on: GBPS is a simple, highly reproducible, and accurate technique for the L VEF 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.