Comparative image quality evaluation of unenhanced postmortem Photon-Counting CT and Energy-Integrating CT

This study evaluates the image quality of postmortem photon-counting computed tomography (PMPCCT) compared to conventional postmortem energy-integrating computed tomography (PMCT) for a protocol adapted to post-mortem imaging. The focus lies on objective image quality parameters such as noise, signal-to-noise ratio, and contrast-to-noise ratio, supplemented by subjective image quality evaluations. A Chest Phantom N1 and one decedent were scanned using PMCT (Siemens SOMATOM^® X-Cite; slice thicknesses of 1 mm and 0.5 mm; Br40, Br60) and PMPCCT (Siemens NAEOTOM Alpha.peak^®; slice thicknesses of 1 mm, 0.4 mm, and 0.2 mm; Br40, Br60). Image quality parameters were computed for regions of interest. In addition, two radiologists conducted subjective image quality evaluations (noise, overall image quality, sharpness, bone details, contour visibility, and artifact formation) using a modified Likert scale. The overall findings were mixed, with PMPCCT potentially demonstrating an advantage over PMCT in terms of SNR and CNR, particularly at moderate slice thicknesses of 1 mm and 0.4 mm. The results obtained from the phantom exhibit in some cases considerable differences compared to those from the decedent, so that model studies can hardly be transferred to reality without scrutiny. PMPCCT outperformed PMCT in subjective assessments of overall image quality, sharpness, and bone detail, particularly with Br40 reconstruction kernels. PMPCCT may demonstrate advantages in objective and subjective image quality, with improvements in soft tissue imaging, sharpness, and bone detail at moderate slice thicknesses. These results may suggest PMPCCTs promising potential in forensic imaging. Further studies are needed to investigate and optimize its utility in postmortem settings.