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P1‐234: Postmortem MRI of the human hippocampus: Comparison with histopathology
Author(s) -
Dawe Robert J.,
Bennett David A.,
Schneider Julie A.,
Vasireddi Sunil K.,
Arfanakis Konstantinos
Publication year - 2008
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2008.05.823
Subject(s) - nuclear medicine , hippocampus , medicine , cerebellar hemisphere , hippocampal formation , histopathology , sagittal plane , magnetic resonance imaging , pathology , anatomy , radiology
Background: Postmortem MRI allows for histological examination of the tissue specimen following imaging, an opportunity that has been exploited in the current study. MRI was used to measure the volume and T2 relaxation of postmortem human hippocampi, and these values were then compared with histological findings, as well as the subjects’ MMSE scores. Methods: Thirty-seven subjects underwent mini mental state examination (MMSE). Approximately 30 days after the death of each subject, one formaldehyde-fixed brain hemisphere was removed from refrigeration and imaged using a 3.0-T MRI scanner (General Electric, Waukesha, WI). A 2D fast spin echo sequence with two echo times (TE1 13.0 ms, TE2 52.0 ms) was used to acquire sagittal proton density weighted and T2-weighted images. Total scan time was 31 minutes per hemisphere. T2 maps were generated. The hippocampus in each hemisphere was manually outlined on T2-weighted images as a 3D region of interest (ROI), as shown in Figure 1. From the selected ROIs, the hippocampal volumes (normalized to total hemisphere volume) and the mean hippocampal T2 values were calculated. Fourteen of the hippocampi were histologically examined at a later date. Results: Mean T2 values were higher for hippocampi having more than 30 NFTs per mm2 (76.7 5.4 ms, n 7) compared to those having fewer NFTs (68.1 4.5 ms, n 7), a significant difference (t-test, p .02). Multiple linear correlation that accounted for several factors showed that MMSE score and age were strong indicators of hippocampal volume (p .001 and p .045, respectively). Conclusions: NFTs, the presence of which is used to diagnose Alzheimer’s postmortem, were associated with higher hippocampal T2 values in this study. It is not known whether NFTs themselves could be responsible for a T2 increase in postmortem tissue or if an accompanying degeneration of the tissue is the underlying cause. Lower MMSE scores and increased age were associated with reduced hippocampal volumes, as set forth by previous studies that used living subjects. It is thought that declines in cognitive function are related to degeneration of hippocampal tissue.