Abstract
Background and purposeAutomated subfield volumetry of hippocampus is desirable for use in temporal lobe epilepsy (TLE), but its utility has not been established. Automatic segmentation of hippocampal subfields (ASHS) and the new version of FreeSurfer software (ver.6.0) using high-resolution T2-weighted MR imaging are candidates for this volumetry. The aim of this study was to evaluate hippocampal subfields in TLE patients using ASHS as well as the old and new versions of FreeSurfer.Materials and methodsWe recruited 50 consecutive unilateral TLE patients including 25 with hippocampal sclerosis (TLE-HS) and 25 without obvious etiology (TLE-nonHS). All patients and 45 healthy controls underwent high-resolution T2-weighted and 3D-volume T1-weighted MRI scanning. We analyzed all of their MR images by FreeSurfer ver.5.3, ver.6.0 and ASHS. For each subfield, normalized z-scores were calculated and compared among groups.ResultsIn TLE-HS groups, ASHS and FreeSurfer ver.6.0 revealed maximal z-scores in ipsilateral cornu ammonis (CA) 1, CA4 and dentate gyrus (DG), whereas in FreeSurfer ver.5.3 ipsilateral subiculum showed maximal z-scores. In TLE-nonHS group, there was no significant volume reduction by either ASHS or FreeSurfer.ConclusionsASHS and the new version of FreeSurfer may have an advantage in compatibility with existing histopathological knowledge in TLE patients with HS compared to the old version of FreeSurfer (ver.5.3), although further investigations with pathological findings and/or surgical outcomes are desirable.
Highlights
Temporal lobe epilepsy (TLE) is the most common focal epilepsy in adults (Hauser et al, 1996)
FreeSurfer ver.6.0 accepts magnetic resonance imaging (MRI) scans acquired with weightings other than T2, we adopted high-resolution T2-weighted images because Automatic segmentation of hippocampal subfields (ASHS) needs them and we considered the same images would be appropriate for comparison
Our results showed that ASHS and FreeSurfer ver.6.0 detected severe volume loss of ipsilateral CA1 and CA4/dentate gyrus (DG) in temporal lobe epilepsy (TLE) patients with Hippocampal sclerosis (HS) compared with the other subfields and compared with the old version of FreeSurfer, which accords with pathological findings of HS (Thom, 2014)
Summary
Temporal lobe epilepsy (TLE) is the most common focal epilepsy in adults (Hauser et al, 1996). Regarding structural neuroimaging of hippocampal subfields, recent studies using manual procedures have achieved some successful results (Mueller et al, 2009; Coras et al, 2014; Na et al, 2014). Automatic segmentation of hippocampal subfields (ASHS) and the new version of FreeSurfer software (ver.6.0) using high-resolution T2-weighted MR imaging are candidates for this volumetry. The aim of this study was to evaluate hippocampal subfields in TLE patients using ASHS as well as the old and new versions of FreeSurfer. Conclusions: ASHS and the new version of FreeSurfer may have an advantage in compatibility with existing histopathological knowledge in TLE patients with HS compared to the old version of FreeSurfer (ver.5.3), further investigations with pathological findings and/or surgical outcomes are desirable
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