Partial loss of hippocampal striation in medial temporal lobe epilepsy: pilot evaluation with high-spatial-resolution T2-weighted MR imaging at 3.0 T.
OBJECTIVE
To determine whether partial loss of the hippocampal striation (PLHS) at 3.0 T is more accurate than the currently accepted methods of using conventional magnetic resonance (MR) imaging to detect hippocampal sclerosis in medial temporal lobe epilepsy (MTLE).


METHODS
This retrospective study had institutional review board approval, and informed consent was waived. Fluid-attenuated inversion-recovery (FLAIR) MR images and T2-weighted MR images in the oblique coronal plane in 22 consecutive patients (10 men, 12 female patients; mean age, 41.0 years; range, 14-76 years) (25 hemispheres) with a clinical diagnosis of MTLE were retrospectively evaluated. Twenty-five hippocampi in 15 subjects without epilepsy were evaluated as age-matched controls. The volumes and thicknesses of the four anatomic sections of the hippocampi were quantitatively measured on the T2-weighted images. Two radiologists independently reviewed the MR imaging findings of the hippocampus regarding atrophy, abnormal signal intensity, and PLHS on each side separately, without comparing both sides. Sensitivity and specificity were calculated among the MR imaging findings.


RESULTS
Signal intensity abnormality on FLAIR images had a sensitivity of 36%, a specificity of 96%, and an accuracy of 66% for the diagnosis of hippocampal sclerosis. PLHS on T2-weighted MR images had a sensitivity of 76% and a specificity of 80% for the diagnosis of hippocampal sclerosis. The sensitivity for PLHS was higher than that for atrophy (44%) and abnormal signal intensity (48%) of the hippocampus on T2-weighted MR images. Although the mean volume of the hippocampus and the thickness of the hippocampal body were significantly smaller for patients with MTLE than for control subjects (P < .001 for both), there was no clear distinguishing threshold value between abnormal and normal hippocampi.


CONCLUSIONS
PLHS showed the highest sensitivity for MTLE. This MR imaging feature might improve the accuracy of the diagnosis of bilateral hippocampal sclerosis, although further research is required.
Department of Radiology, University of Occupational and Environmental Health School of Medicine, Iseigaoka 1-1, Yahatanishi-ku, Kitakyushu 807-8555, Japan. hanamai@med.uoeh-u.ac.jp
Mai
M
Hanamiya
Yukunori
Y
Korogi
Shingo
S
Kakeda
Norihiro
N
Ohnari
Koji
K
Kamada
Junji
J
Moriya
Toru
T
Sato
Mika
M
Kitajima
Naoki
N
Akamatsu
Sadatoshi
S
Tsuji
D000293:Adolescent; D000328:Adult; D000368:Aged; D001284:Atrophy / Q000473:pathology; D016022:Case-Control Studies; D004833:Epilepsy, Temporal Lobe / Q000473:pathology*; D005260:Female; D006624:Hippocampus / Q000473:pathology*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric