Subcortical and cerebellar atrophy in mesial temporal lobe epilepsy revealed by automatic segmentation.
OBJECTIVE
To determine the validity and utility of using automated subcortical segmentation to identify atrophy of the hippocampus and other subcortical and cerebellar structures in patients with mesial temporal lobe epilepsy (MTLE).


METHODS
Volumetric MRIs were obtained on 21 patients with MTLE (11 right, 10 left) and 21 age- and gender-matched healthy controls. Labeling of subcortical and cerebellar structures was accomplished using automated reconstruction software (FreeSurfer). Multivariate analysis of covariance (MANCOVA) was used to explore group differences in intracranial-normalized, age-adjusted volumes and structural asymmetries. Step-wise discriminant function analysis was used to identify the linear combination of volumes that optimized classification of individual subjects.


RESULTS
Results revealed the expected reduction in hippocampal volume on the side ipsilateral to the seizure focus, as well as bilateral reductions in thalamic and cerebellar gray matter volume. Analysis of structural asymmetries revealed significant asymmetry in the hippocampus and putamen in patients compared to controls. The discriminant function analysis revealed that patients with right and left MTLE were best distinguished from one another using a combination of subcortical volumes that included the right and left hippocampus and left thalamus (91-100% correct classification using cross-validation).


CONCLUSIONS
Volumetric data obtained with automated segmentation of subcortical and cerebellar structures approximate data from previous studies based on manual tracings. Our data suggest that automated segmentation can provide a clinically useful means of evaluating the nature and extent of structural damage in patients with MTLE and may increase diagnostic classification of patients, especially when hippocampal atrophy is mild.
McDonald
Carrie R
CR
Department of Psychiatry, University of California, San Diego, United States. camcdonald@ucsd.edu
Hagler
Donald J
DJ
Ahmadi
Mazyar E
ME
Tecoma
Evelyn
E
Iragui
Vicente
V
Dale
Anders M
AM
Halgren
Eric
E
D000328:Adult; D001284:Atrophy; D001921:Brain / Q000473:pathology*; D002531:Cerebellum / Q000473:pathology*; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis* / Q000473:pathology*; D005260:Female; D007839:Functional Laterality; D006624:Hippocampus / Q000473:pathology; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012984:Software; D013788:Thalamus / Q000473:pathology; D013997:Time Factors