Development of Digital Myocardial Phantom to Evaluate Software for Gated SPECT

Background: Real cardiac phantoms are often used to assess the performance of software for gated single-photon emission computed tomography(SPECT). However, these phantoms have disadvantages in that they are not very similar to actual hearts and setting a perfusion defect is not easy. To overcome these problems, we developed a digital myocardial phantom, named%Myo-Simu'. The aims of this study were to check its operation when being incorporated into gated SPECT software and to elucidate its usefulness to assess properties of software. Methods: Myo-Simu yields a simulated left ventricle(LV)approximated as a moving spheroid that preserves shape similarity during the cardiac cycle with a fixed total myocardial volume. Wall thickness, background activity, spatial resolution, statistical noise, and perfusion defects are incorporated into the phantom, and these conditions can be modified by changing the input parameters. We generated various types of hearts by changing the length of the short and long axes, patterns of perfusion defects, spatial resolution, and image noise. Generated SPECT images were applied to Quantitative Gated SPECT(QGS), Heart Function View, and EXINI Heart software to check the adaptability to gated SPECT analyses. We also evaluated the influences of wall thickness and spatial resolution on QGS analyses. Results: Myo-Simu successfully generated SPECT images of various geometries. These images can be applied to gated SPECT analyses without any problems in operation. In QGS, measured LV volumes changed greatly depending on wall thickness and spatial resolution. Conclusions: Myo-Simu is a feasible phantom for assessing gated SPECT software.