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Optimising imaging parameters for post mortem MR imaging of the human brain
A M Blamire1, J G Rowe, P Styles
1Department of Biochemistry, University of Oxford, United Kingdom.
Acta Radiologica (Stockholm, Sweden : 1987)
|December 22, 1999
Summary
Formalin fixation alters magnetic resonance (MR) imaging properties of postmortem brains. Spin density-weighted sequences offer better contrast than T2-weighted sequences for examining fixed brain tissue.
Area of Science:
- Neuroimaging
- Pathology
- Biophysics
Background:
- Postmortem brain MR imaging aids in assessing structural changes before pathological examination.
- Standard T2-weighted sequences may not provide optimal contrast for formalin-fixed brains.
Purpose of the Study:
- To investigate the impact of formalin fixation duration on transverse relaxation time (T2) and spin density in postmortem brains.
- To evaluate MR imaging contrast in formalin-fixed brain tissue.
Main Methods:
- Three postmortem brains were imaged weekly during 35 days of formalin fixation.
- Standard MR spin-echo imaging with 5 echo times (20-100 ms) was employed.
- Transverse relaxation time (T2) and spin density were calculated.
Main Results:
- Transverse relaxation time (T2) significantly decreased in grey and white matter within 7 days of fixation.
- Grey and white matter T2 values converged over time.
- The grey to white matter spin density ratio increased from 1.19 to 1.54 over five weeks.
Conclusions:
- Spin density-weighted MR imaging sequences enhance grey to white matter contrast compared to T2-weighted sequences.
- This improved contrast is beneficial for analyzing structural changes in formalin-fixed postmortem brains.