Volume measurements in nuclear medicine gated SPECT and 4D echocardiography: validation using a dynamic cardiac phantom

A dynamic cardiac phantom was used as a reference to compare volumes measured with gated SPECT and 4D echocardiography. Gated SPECT data were acquired with a standard single-head gamma camera, and the volume reconstructions were carried out using the Mirage software by Segami. 4D echocardiography used a new prototype of rotating scan head to acquire ultrasound images during a cardiac cycle, used to reconstruct the volume deformations as a function of time. End-diastolic volume, end-systolic volume, and ejection fraction were measured using both gated SPECT and 4D echocardiography. The results obtained showed a good correlation between volumes measured with the two modalities, but a slight overestimation of volumes with gated SPECT. The influence of filtering and pixel size parameters on the measured volumes was quantified for gated SPECT, in order to correct the overestimation. The agreement between gated SPECT (after correction) and 4D echocardiography confirmed the relevance of the comparisons. This study was an initial step before conducting clinical trials to compare exhaustively left ventricular volumes obtained with the two modalities.