Center for Forensic Imaging and Virtopsy, Institute of Forensic Medicine, University of Bern, Buehlstrasse 20, CH-3012 Bern, Switzerland.
Eur J Radiol. 2012 Jun;81(6):1366-70. doi: 10.1016/j.ejrad.2011.02.062. Epub 2011 Mar 31.
To assess the temperature dependency of tissue contrast on post mortem magnetic resonance (PMMR) images both objectively and subjectively; and to visually demonstrate the changes of image contrast at various temperatures.
The study was approved by the responsible justice department and the ethics committee. The contrast of water, fat, and muscle was measured using regions of interest (ROI) in the orbit of 41 human corpses to assess how body temperature (range 2.1-39.8 °C) relates to image contrast of T1-weighted (T1W) and T2-weighted (T2W) sequences on PMMR. Regressions were calculated using the method of least squares. Three readers judged visible changes of image contrast subjectively by consensus.
There was a positive relationship between temperature and contrast on T1-weighted (T1W) images and between temperature and the contrast of fat/muscle on T2-weighted (T2W) images. There was a negative relationship between temperature and the contrast of water/fat and water/muscle on T2W images. Subjectively, the influence of temperature became visible below 20 °C on T2W images, and below 10 °C on T1W images.
Image contrast on PMMR depends on the temperature of a corpse. Radiologists involved in post mortem imaging must be aware of temperature-related changes in MR image contrast. To preserve technical quality, scanning corpses below 10 °C should be avoided.
客观和主观地评估死后磁共振（PMMR）图像中组织对比的温度依赖性；并直观地展示不同温度下图像对比度的变化。
本研究得到负责司法部和伦理委员会的批准。使用 41 具人体尸体眼眶中的感兴趣区域（ROI）测量水、脂肪和肌肉的对比度，以评估体温（范围 2.1-39.8°C）与 PMMR 上 T1 加权（T1W）和 T2 加权（T2W）序列图像对比度之间的关系。使用最小二乘法计算回归。三位读者通过共识主观判断图像对比度的可见变化。
T1 加权（T1W）图像的温度与对比度之间呈正相关，T2 加权（T2W）图像的温度与脂肪/肌肉对比度之间呈正相关。T2W 图像上的温度与水/脂肪和水/肌肉的对比度之间呈负相关。主观上，T2W 图像的温度影响在 20°C 以下可见，T1W 图像的温度影响在 10°C 以下可见。
PMMR 图像的对比度取决于尸体的温度。参与死后成像的放射科医生必须意识到 MR 图像对比度与温度有关的变化。为了保持技术质量，应避免在 10°C 以下扫描尸体。
