In situ temperature determination using magnetic resonance spectroscopy thermometry for noninvasive postmortem...

Area of Science:

• Forensic Science
• Medical Imaging
• Biophysics

Background:

• Magnetic resonance spectroscopy (MRS) thermometry noninvasively estimates temperature using water's chemical shift.
• Its application in postmortem examinations is promising for adjusting MRI protocols and data analysis.
• Postmortem changes and the decrease of common reference metabolites like N-acetylaspartate pose challenges.

Purpose of the Study:

• To evaluate the suitability of lactate as a reference metabolite for postmortem MRS thermometry.
• To assess the accuracy and reliability of MRS thermometry in postmortem brain tissue up to 60 hours after death.
• To validate MRS thermometry in a clinical forensic setting with deceased individuals.

Main Methods:

• Utilized lactate, a metabolite stable in chemical shift postmortem, as the reference for MRS thermometry.
• Calibrated MRS thermometry using established in vivo methods.
• Compared MRS thermometry results with MR-compatible temperature probes and rectal temperatures in sheep heads and human subjects.

Main Results:

• MRS thermometry with lactate achieved high accuracy (mean absolute error <0.5°C) in postmortem sheep brain tissue up to 60 hours postmortem.
• No significant deviations were observed between MRS thermometry and direct temperature measurements despite decomposition.
• MRS thermometry provided plausible brain temperatures in 84 deceased individuals, showing reliability even beyond 60 hours postmortem.

Conclusions:

• Lactate is a suitable reference metabolite for accurate postmortem MRS thermometry.
• MRS thermometry is a reliable and noninvasive tool for temperature estimation in forensic medicine and pathology.
• The technique demonstrates good potential for postmortem MR examinations, aiding in temperature adjustment and data correction.