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Single Subject Voxel Based Morphometry for atrophy detection in temporal epilepsy with hippocampal sclerosis

Hernán Claudio Külsgaard

  • Tnadil,
  • Argentina
  • Hernán Külsgaard ¹
  • , Juan Pablo Princich ²
  • , Ignacio Larrabide ¹
  • 1 Pladema Institute - UNICEN/CONICET, Tandil, Buenos Aires
  • 2 Estudios en Neurociencias y Sistemas Complejos (ENyS), UNAJ/CONICET, Florencio Varela, Buenos Aires

Single Subject Voxel Based Morphometry (SSVBM) is a technique used for cortical atrophy detection for individuals. However, is rarely used for Hippocampal Sclerosis (HS) detection. Our goal was to analyze the SSVBM performance on patients with unilateral HS.
We performed modulated SSVBM for the whole brain on MRI T1 images of 36 patients with HS on the left hemisphere, 22 on the right side and 59 healthy subjects. We used a statistical threshold of p<0.001 (uncorrected) and for those without detections on the hippocampus, we did another test at p<0.005. Additionally, we compared the patients with and without detections using group VBM (p<0.05 FDR corrected) and analyzed their normalized hippocampal volumes.
The sensitivity for hippocampal atrophy detection using p<0.001 was 72% and 86% for the left and right hemisphere respectively, with 86% specificity. For the test at p<0.005 only on those without detections at previous threshold (10 lefts and 3 rights), sensitivity was 70% and 30% respectively, with specificity of 71%. The group analysis showed significant greater hippocampus volumes for HS patients without detections at p<0.001, whereas their normalized hippocampal volumes were inside the range of healthy subjects.
SSVBM is sensitive and specific for atrophy identification in patients with HS. Although, there were limitations for those patients with partial hippocampal volume preservation. Using a threshold of p<0.005 increases sensitivity in detriment of specificity.