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Hippocampal layers on high resolution magnetic resonance images: real or imaginary?
Author(s) -
WIESHMANN U. C.,
SYMMS M. R.,
MOTTERSHEAD J. P.,
MACMANUS D. G.,
BARKER G. J.,
TOFTS P. S.,
REVESZ T.,
STEVENS J. M.,
SHORVON S. D.
Publication year - 1999
Publication title -
journal of anatomy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.932
H-Index - 118
eISSN - 1469-7580
pISSN - 0021-8782
DOI - 10.1046/j.1469-7580.1999.19510131.x
Subject(s) - hippocampal formation , dentate gyrus , voxel , granule cell , magnetic resonance imaging , hippocampus , granule (geology) , pyramidal cell , nuclear magnetic resonance , nuclear medicine , physics , anatomy , materials science , medicine , biology , neuroscience , radiology , composite material
To evaluate whether the lines occasionally detected on clinical magnetic resonance (MR) images are genuine hippocampal layers, a formalin fixed hippocampal specimen was scanned using T2 weighted sequences at 7 Tesla (voxel dimensions 0.064×0.064×1 mm) and at 1.5 Tesla (voxel dimensions: 0.156×0.156×1 mm) and compared with the results of histological examination. In addition, a healthy volunteer was scanned with a T2 weighted sequence at 1.5 Tesla (voxel dimensions: 0.469×0.469×2 mm). On 7 Tesla images hippocampal layers and the granule cell layer of the dentate were visible. On 1.5 Tesla images of the specimen, the hippocampal layers were again identified, but the granule cell layer of the dentate was not detectable. On 1.5 Tesla images of the hippocampus in vivo, 3 layers could be distinguished in the hippocampus on some slices. These mainly represented the alveus, pyramidal cell layer and stratum radiatum. A dark line consisting of a few pixels possibly represented the dentate gyrus. Our results show that the lines occasionally detected on clinical MR images are likely to be real hippocampal layers. However, the resolution currently used in clinical imaging (typically 0.469×0.469×2 mm or lower) is not sufficient for the detection of all hippocampal layers. For the reliable detection of all hippocampal layers on MR images an increase by a factor of approximately 20 would be necessary.