Estimation of the postmortem interval by means of ¹H MRS of decomposing brain tissue: influence of ambient temperature

Ith, Michael; Scheurer, Eva; Kreis, Roland; Thali, Michael; Dirnhofer, Richard; Boesch, Chris (2011). Estimation of the postmortem interval by means of ¹H MRS of decomposing brain tissue: influence of ambient temperature. NMR in biomedicine, 24(7), pp. 791-8. London: Wiley Interscience 10.1002/nbm.1623

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Standard methods for the estimation of the postmortem interval (PMI, time since death), based on the cooling of the corpse, are limited to about 48 h after death. As an alternative, noninvasive postmortem observation of alterations of brain metabolites by means of (1)H MRS has been suggested for an estimation of the PMI at room temperature, so far without including the effect of other ambient temperatures. In order to study the temperature effect, localized (1)H MRS was used to follow brain decomposition in a sheep brain model at four different temperatures between 4 and 26°C with repeated measurements up to 2100 h postmortem. The simultaneous determination of 25 different biochemical compounds at each measurement allowed the time courses of concentration changes to be followed. A sudden and almost simultaneous change of the concentrations of seven compounds was observed after a time span that decreased exponentially from 700 h at 4°C to 30 h at 26°C ambient temperature. As this represents, most probably, the onset of highly variable bacterial decomposition, and thus defines the upper limit for a reliable PMI estimation, data were analyzed only up to this start of bacterial decomposition. As 13 compounds showed unequivocal, reproducible concentration changes during this period while eight showed a linear increase with a slope that was unambiguously related to ambient temperature. Therefore, a single analytical function with PMI and temperature as variables can describe the time courses of metabolite concentrations. Using the inverse of this function, metabolite concentrations determined from a single MR spectrum can be used, together with known ambient temperatures, to calculate the PMI of a corpse. It is concluded that the effect of ambient temperature can be reliably included in the PMI determination by (1)H MRS.

Item Type:	Journal Article (Original Article)
Division/Institute:	04 Faculty of Medicine > Department of Radiology, Neuroradiology and Nuclear Medicine (DRNN) > Institute of Diagnostic, Interventional and Paediatric Radiology > DCR Magnetic Resonance Spectroscopy and Methodology (AMSM) 04 Faculty of Medicine > Service Sector > Institute of Legal Medicine
UniBE Contributor:	Ith, Michael, Kreis, Roland, Thali, Michael, Boesch, Christoph Hans
ISSN:	0952-3480
Publisher:	Wiley Interscience
Language:	English
Submitter:	Factscience Import
Date Deposited:	04 Oct 2013 14:20
Last Modified:	02 Mar 2023 23:20
Publisher DOI:	10.1002/nbm.1623
PubMed ID:	21834003
Web of Science ID:	000294686900005
URI:	https://boris.unibe.ch/id/eprint/6508 (FactScience: 211487)