Medical Faculty, Department of Diagnostic and Interventional Radiology, University Dusseldorf, D-40225, Dusseldorf, Germany.
University Center of Legal Medicine Lausanne-Geneva, University Hospital of Lausanne, Chemin de la Vulliette 4, 1000, Lausanne 25, Switzerland.
Int J Legal Med. 2021 Sep;135(5):1869-1878. doi: 10.1007/s00414-021-02530-1. Epub 2021 Feb 24.
Postmortem multi-detector computed tomography (PMCT) has become an important part in forensic imaging. Modern reconstruction techniques such as iterative reconstruction (IR) are frequently used in postmortem CT angiography (PMCTA). The image quality of PMCTA depends on the strength of IR. For this purpose, we aimed to investigate the impact of different advanced IR levels on the objective and subjective PMCTA image quality.
We retrospectively analyzed the coronary arteries of 27 human cadavers undergoing whole-body postmortem CT angiography between July 2017 and March 2018 in a single center. Iterative reconstructions of the coronary arteries were processed in five different level settings (0%; 30%; 50%; 70%; 100%) by using an adaptive statistical IR method. We evaluated the objective (contrast-to-noise ratio (CNR)) and subjective image quality in several anatomical locations.
Our results demonstrate that the increasing levels of an IR technique have relevant impact on the image quality in PMCTA scans in forensic postmortem examinations. Higher levels of IR have led to a significant reduction of image noise and therefore to a significant improvement of objective image quality (+ 70%). However, subjective image quality is inferior at higher levels of IR due to plasticized image appearance.
Objective image quality in PMCTA progressively improves with increasing level of IR with the best CNR at the highest IR level. However, subjective image quality is best at low to medium levels of IR. To obtain a "classic" image appearance with optimal image quality, PMCTAs should be reconstructed at medium levels of IR.
死后多探测器计算机断层扫描（PMCT）已成为法医成像的重要组成部分。迭代重建（IR）等现代重建技术经常用于死后 CT 血管造影（PMCTA）。PMCTA 的图像质量取决于 IR 的强度。为此，我们旨在研究不同高级 IR 水平对 PMCTA 图像质量的客观和主观影响。
我们回顾性分析了 2017 年 7 月至 2018 年 3 月在单一中心进行的 27 例全身死后 CT 血管造影的冠状动脉。通过使用自适应统计 IR 方法，在五个不同的水平设置（0%；30%；50%；70%；100%）对冠状动脉进行迭代重建。我们评估了几个解剖部位的客观（对比噪声比（CNR））和主观图像质量。
我们的结果表明，IR 技术水平的提高对法医死后检查中 PMCTA 扫描的图像质量有相关影响。较高的 IR 水平导致图像噪声显著降低，从而显著提高了客观图像质量（+70%）。然而，由于图像出现塑性化，较高的 IR 水平会导致主观图像质量下降。
PMCTA 的客观图像质量随着 IR 水平的提高而逐渐提高，IR 水平最高时 CNR 最佳。然而，主观图像质量在低到中等 IR 水平时最佳。为了获得具有最佳图像质量的“经典”图像外观，PMCTA 应在中等 IR 水平重建。
