Quantification of hippocampal signal intensity in patients with mesial temporal lobe epilepsy.
BACKGROUND
Refractory mesial temporal lobe epilepsy (MTLE) is frequently associated with hippocampal atrophy (HA) and an abnormal hippocampal signal (Hsig) on magnetic resonance imaging (MRI).


OBJECTIVE
To quantify Hsig on MRI using a simplified technique.


METHODS
The authors included 15 patients with refractory MTLE who underwent surgery and had preoperative MRI with hippocampal volumetry. Hsig was quantified on preoperative coronal T1-weighted and T2-weighted MRI using the NIH-Image program. Hsig was determined for the head, tail, and entire hippocampal extension. Abnormal Hsig was defined when values were above (for T2) or below (for T1) 2 standard deviations from the mean of normal control group.


RESULTS
The lateralization of abnormal Hsig values was concordant with electroencephalograms and HA in all patients. There was a significant difference in ipsilateral T2 Hsig between patients and controls (P < .0001), but not for contralateral T2 Hsig. T1 Hsig showed bilateral abnormalities more frequently, whereas T2 Hsig could lateralize better hippocampal abnormalities. Overall, there were no differences when comparing T2 Hsig for the entire hippocampus, head, or tail only. However, there were some individual differences. T2 Hsig abnormalities involved the entire hippocampus in most patients but were restricted to the head in one patient and to the tail in another.


CONCLUSIONS
This simplified method for the quantification of Hsig using NHI-Image is an efficient method for the identification and quantification of hippocampal abnormalities in patients with MTLE. The assessment of the entire extension of the hippocampal formation may provide important additional data, compared to T2 relaxometry maps limited to one segment of the hippocampus.
Coan
Ana Carolina
AC
Department of Neurology, Campinas State University (UNICAMP), Campinas, SP, Brazil.
Kobayashi
Eliane
E
Li
Li Min
LM
Cendes
Fernando
F
D000328:Adult; D000704:Analysis of Variance; D001284:Atrophy / Q000175:diagnosis; D004833:Epilepsy, Temporal Lobe / Q000473:pathology*; D005260:Female; D006624:Hippocampus / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012815:Signal Processing, Computer-Assisted