Feasibility studies of a high sensitivity, stationary dedicated cardiac SPECT with multi-pinhole collimators on a clinical dual-head scanner

In this study we proposed a novel design of the stationary multi-pinhole dedicated cardiac SPECT based on clinical dual-head scanner with high sensitivity and low cost for nuclear medicine myocardial perfusion imaging. The efficacy of proposed collimator design was confirmed by analytically calculating the sensitivity map of field of view (FOV) and the average resolution map weighted by each pinhole's sensitivity. We measured the spatial resolution and sensitivity of the proposed SPECT and low energy high resolution (LEHR) parallel-hole SPECT at central point with the same distance from the collimator with Monte Carlo simulation. A multi-pinhole MLEM reconstruction algorithm was developed with detector response and analytical pinhole projection model. The analytical projection of point source with delta model and pinhole projection model was compared with simulated projection by Gate. We simulated and reconstructed projections of two point with different location with no rotation, one step rotation and two step rotation and one uniform ellipsoid phantom, which covered the heart region. Analytically, the sensitivity was increased to 0.04% and average resolution was about 10 mm inside most of heart regions. The reconstruction spatial resolution of central point was 38% poorer than LEHR SPECT, while the sensitivity was increased by 10-fold, which was consistent with the analytical results. The comparison between the several pinholes' projection calculated with delta model, pinhole analytical model and simulation showed the pinhole analytical model agreed with the simulation in shape, especially when in oblique incidence. The reconstruction results of point source without rotation showed slight deformation on certain point source location. In contrast, with rotation, the deformation was suppressed and resolution was similar. However there was no significant difference in one step and two step rotation. The ellipsoid phantom reconstruction showed the imaging quality of the proposed SPECT although with the expected artifact outside FOV. In conclusion, our initial results demonstrated the feasibility of high sensitivity imaging with proposed stationary multi-pinhole dedicated cardiac SPECT.