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Investigation of hippocampal substructures in focal temporal lobe epilepsy with and without hippocampal sclerosis at 7T
Author(s) -
Santyr Brendan G.,
Goubran Maged,
Lau Jonathan C.,
Kwan Benjamin Y.M.,
Salehi Fateme,
Lee Donald H.,
Mirsattari Seyed M.,
Burneo Jorge G.,
Steven David A.,
Parrent Andrew G.,
Ribaupierre Sandrine,
Hammond Robert R.,
Peters Terry M.,
Khan Ali R.
Publication year - 2017
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.25447
Subject(s) - hippocampal formation , hippocampal sclerosis , epilepsy , temporal lobe , hippocampus , atrophy , magnetic resonance imaging , medicine , nuclear medicine , epilepsy surgery , pathology , radiology , psychiatry
Purpose To provide a more detailed investigation of hippocampal subfields using 7T magnetic resonance imaging (MRI) for the identification of hippocampal sclerosis in temporal lobe epilepsy (TLE). Materials and Methods Patients ( n = 13) with drug‐resistant TLE previously identified by conventional imaging as having hippocampal sclerosis (HS) or not (nine without HS, four HS) and 20 age‐matched healthy controls were scanned and compared using a 7T MRI protocol. Using a manual segmentation scheme to delineate hippocampal subfields, subfield‐specific volume changes and apparent transverse relaxation rate ( R 2 * ) were studied between the two groups. In addition, qualitative assessment at 7T and clinical outcomes were correlated with measured subfield changes. Results Volumetry of the hippocampus at 7T in HS patients revealed significant ipsilateral subfield atrophy in CA1 ( P = 0.001) and CA4+DG ( P < 0.001). Volumetry also uncovered subfield atrophy in 33% of patients without HS, which had not been detected using conventional imaging.R 2 *was significantly lower in the CA4+DG subfields ( P = 0.001) and the whole hippocampus ( P = 0.029) of HS patients compared to controls but not significantly lower than the group without HS ( P = 0.077, P = 0.109). No correlation was found between quantitative volumetry and qualitative assessment as well as surgical outcomes (Sub, P = 0.495, P = 0.567, P = 0.528; CA1, P = 0.104 ± 0.171, P = 0.273, P = 0.554; CA2+CA3, P = 0.517, P = 0.952, P = 0.130 ± 0.256; CA4+DG, P = 0.052 ± 0.173, P = 0.212, P = 0.124 ± 0.204; WholeHipp, P = 0.187, P = 0.132 ± 0.197, P = 0.628). Conclusion These preliminary findings indicate that hippocampal subfield volumetry assessed at 7T is capable of identifying characteristic patterns of hippocampal atrophy in HS patients; however, difficulty remains in using imaging to identify hippocampal pathologies in cases without HS. Level of Evidence : 2 J. MAGN. RESON. IMAGING 2017;45:1359–1370