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Updated: Nov 3, 2025
Fiber Optic Distributed Sensors for High-resolution Temperature Field Mapping
Published on: November 7, 2016
Sensitivity of fiber orientation dependent to temperature and post mortem interval
Claudia Lenz1,2, Celine Berger1,2, Melanie Bauer1,2
1Institute of Forensic Medicine, Department of Biomedical Engineering, University of Basel, Basel, Switzerland.
Purpose:
imaging of brain white matter is well known for being sensitive to the orientation of nerve fibers with respect to the B0 field of the MRI scanner. The goal of this study was to evaluate whether and to which extent fiber orientation dependent differs between in vivo and post mortem in situ examinations, and to investigate the influence of varying temperatures and post mortem intervals (PMI).
Methods:
Post mortem in situ and in vivo MRI scans were conducted at 3T. was acquired with a multi-echo gradient-echo sequence, and the orientation of white matter fibers was computed using diffusion tensor imaging (DTI). Fitting of the measured fiber orientation dependent was performed using three different formulations of a previously proposed model.
Results:
increased with increasing fiber angle for in vivo and post mortem in situ examinations, whereby the orientation dependency was lower post mortem. The different formulations of the fiber orientation model resulted in an identical fit, but showed large variations of the estimated parameters. The higher order orientation dependent components significantly decreased with decreasing temperature, while the orientation independent components showed no significant correlation with either temperature or PMI.
Conclusion:
Although the mean diffusivity is strongly reduced post mortem, we could successfully estimate the fiber angle using DTI. Due to the strong correlation of the higher order orientation dependent components with temperature, the decreased fiber orientation dependency post mortem in situ might primarily be attributed to the lower brain temperature.
Insights
Post mortem brain imaging shows reduced white matter fiber orientation dependency due to lower temperatures. This study compared in vivo and post mortem MRI scans to understand these differences.
Area of Science:
- Neuroimaging
- Biophysics
- Magnetic Resonance Imaging
Background:
- Diffusion MRI is sensitive to white matter fiber orientation relative to the scanner's B0 field.
- Understanding post mortem changes is crucial for interpreting imaging data.
Purpose of the Study:
- Compare in vivo and post mortem brain white matter fiber orientation dependent diffusion MRI.
- Investigate the impact of temperature and post mortem interval (PMI) on these measurements.
Main Methods:
- Acquired diffusion MRI data at 3T using a multi-echo gradient-echo sequence.
- Computed white matter fiber orientation with diffusion tensor imaging (DTI).
- Fitted orientation-dependent diffusion MRI signals using a previously proposed model.
Main Results:
- Diffusion MRI signal orientation dependency decreased post mortem.
- Higher order orientation dependent signal components correlated negatively with temperature.
- Orientation independent signal components showed no significant correlation with temperature or PMI.
Conclusions:
- Lower brain temperature in post mortem samples likely explains the reduced diffusion MRI fiber orientation dependency.
- Diffusion tensor imaging successfully estimated fiber angles despite reduced post mortem diffusivity.
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