Postmortem Magnetic Resonance Imaging Dealing with Low Temperature Objects

Abstract

In Japan, the medical examiner system is not widespread, the rate of autopsy is low, and many medical institutions therefore perform postmortem imaging using clinical equipment. Postmortem imaging is performed to clarify cause of death, select candidates for autopsy, make a guide map for autopsy, or provide additional information for autopsy. Findings are classiˆed into 3 categories: cause of death and associated changes, changes induced by cardiopulmonary resuscitation, and postmortem changes. Postmortem magnetic resonance imaging shows characteristic changes in signal intensity related to low body temperature after death; they are low temperature images.

Optimization of Inversion Time for Postmortem Short-tau Inversion Recovery (STIR) MR Imaging

“…Therefore, PMMR imaging shows changes in SI in response to lowering body temperature after death. [12][13][14] It is difficult to achieve a consensus on the normal appearance of PMMR because these changes depend on temperature. Therefore, PMMR parameter optimization is needed to obtain appropriate image contrast for bodies at low temperatures.…”

“…15 However, routine parameters for MR imaging of the living body do not suppress the SI of cerebrospinal fluid (CSF) of cadavers. 12,13,16 Tofts and associates reported that T 1 values of the CSF can be derived by measuring the diffusion coefficient of the CSF at low temperatures. CSF signals of the cadaveric brain can then be suppressed effectively by using an optimized inversion time (TI).…”

Optimization of Inversion Time for Postmortem Fluid-attenuated Inversion Recovery (FLAIR) MR Imaging at 1.5T: Temperature-based Suppression of Cerebrospinal Fluid

“…21 Application of the inversion time (TI) for living bodies for PMMR imaging does not adequately suppress fat signals in STIR and CSF signals in FLAIR. [18][19][20] Suppression of the signal intensity (SI) of fat has been reported with STIR in PMMR imaging when using an optimized TI based on the measured rectal temperature (RT). 22 Therefore, we surmised that the SI of CSF can also be suppressed on postmortem FLAIR images by adjusting the TI according to the T 1 temperature dependence of water.…”

“…However, consensus regarding what constitutes a normal appearance on PMMR images is difficult because T 1 and T 2 values change according to body temperature. 12,[18][19][20] Therefore, acquisition of appropriate image contrast for deceased bodies at low temperatures re-*Corresponding author, Phone: +81-92-554-1255, Fax: +81-92-552-2707, E-mail: abe.k@junshin-u.ac.jp quires optimization of the parameters for PMMR imaging. Short-tau inversion recovery (STIR) and fluidattenuated inversion recovery (FLAIR) are typical sequences employed to suppress tissue signal.…”

“…22 Therefore, we surmised that the SI of CSF can also be suppressed on postmortem FLAIR images by adjusting the TI according to the T 1 temperature dependence of water. 18,20 In this study, we attempted to achieve sufficient SI suppression of the CSF on cerebral FLAIR PMMR images by optimizing the TI.…”