Comparison of gated blood-pool SPECT using CZT camera and M-mode echocardiogram for left ventricular ejection fraction estimation

Objectives Planar equilibrium radionuclide angiography (ERNA) and echocardiogram (Echo) are widely used for serial noninvasive measurement of left ventricular ejection fraction (LVEF). Gated blood-pool SPECT (GBPS) on solid state cadmium-zinc-telluride (CZT) detectors has the potential to replace planar ERNA to assess ventricular functions. In addition, the GBPS datasets can subsequently re-projected (CZT-repro) at an LAO orientation similar to that of planar ERNA. This study compares LVEF calculated by GBPS, CZT-repro and planar ERNA with M-mode Echo.

Methods Twenty-one patients underwent 24-frame gated ERNA for 6M counts using NaI gamma camera (NaI-planar) and GBPS for 8 minutes using CZT camera (CZT- SPECT) on the same day. Both the NaI-Planar and CZT-repro planar images were analyzed using semi-automated software to obtain the LVEF. The CZT-SPECT dataset used the Cedars-Sinai Blood-Pool Gated SPECT software that automatically calculates LVEF. Teichholz M-mode Echo was performed by an experienced cardiologist blinded to the scintigraphic results. The scintigraphic studies and Echo were performed within 25±22 days (range:0-75 days) of each other.

Results Mean LVEF values measured by NaI-planar, CZT-SPECT, CZT-repro and Echo were 42.2±22.1%, 40.3±21.9%, 43.4±21.8% and 43.4±21.5%, respectively. LVEF values calculated from both CZT-SPECT and CZT-repro showed excellent correlation with NaI-planar (r= 0.92 and 0.99). LVEF from NaI-planar, CZT-SPECT and CZT-repro with Echo yielded correlation coefficients of 0.940, 0.870 and 0.936, respectively. Neither LVEF from CZT-SPECT nor CZT-repro was significant lower in correlation with Echo compared to NaI-planar (P>.05).

Conclusions Both CZT-SPECT and CZT-repro correlated well with planar ERNA, and all demonstrated good correlation with Echo in the assessment of LVEF. GBPS using CZT camera has the ability to replace planar ERNA in the assessment of LVEF, thereby overcoming the difficulty of ventricles separation.