Performance Evaluation of a Novel Multi-PinHole Collimator on Triple-detector SPECT/CT for dedicated myocardial imaging

Abstract BackgroundIn this study we evaluated the imaging capabilities of a novel Multi-pinhole collimator (MPH-Cardiac) specially designed for nuclear cardiology imaging on a triple head NaI(Tl) detector based SPECT/CT system.Methods99mTc point source measurements covering the field-of-view (FOV) were used to determine tomographic sensitivity (TSpointsource) and spatial resolution. Organ-size tomographic sensitivity (TSorgan) was measured with a left ventricle (LV) phantom filled with typical myocardial activity of a patient scan. Reconstructed image uniformity was measured with a 140 mm diameter uniform cylinder phantom. Using the LV phantom once filled with 99mTc and after with 123I, a polar map analysis was performed determining Spill-Over-Ratio in water (SORwater) and image noise. Results were compared with that of a dual-head parallel-hole low energy high resolution (LEHR) collimator system. A patient with suspected coronary artery disease (CAD) was scanned on the LEHR system using local protocol of 16 minutes total acquisition time, followed by a 4-minute MPH-Cardiac scan. ResultsPeak TSpointsource was found to be 1013 cps/MBq in the axial center of the FOV while it was decreasing towards the radial edges. TSorgan in the CFOV was found to be 134 cps/MBq and 700 cps/MBq for the LEHR and MPH-Cardiac respectively. Average spatial resolution throughout the FOV was 4.38 mm FWHM for the MPH-Cardiac collimator. Reconstructed image uniformity values were found to be 0.504 % versus 0.392 % for the LEHR and MPH-Cardiac measurements respectively. SORwater values were found to be 28.83% and 21.1 % for the 99mTc measurements, and 31.44 % and 24.33 % for the 123I measurements for LEHR and MPH-Cardiac respectively. Pixel noise of the 99mTc polar maps resulted in values of 0.38 % and 0.24 % and of the 123I polar maps 0.62 % and 0.21 % for LEHR and MPH-Cardiac respectively. Visually interpreting the patient scan images, MPH-Cardiac resulted in better image contrast compared to the LEHR technique with four times shorter scan duration.ConclusionsThe significant image quality improvement achieved with dedicated MPH-Cardiac collimator on triple head SPECT/CT system paves the way for short acquisition and low-dose cardiovascular SPECT applications.