Hippocampal subfield segmentation in temporal lobe epilepsy: Relation to outcomes

Abstract

ObjectiveTo investigate the clinical and surgical outcome correlates of preoperative hippocampal subfield volumes in patients with refractory temporal lobe epilepsy (TLE) using a new magnetic resonance imaging (MRI) multisequence segmentation technique.MethodsWe recruited 106 patients with TLE and hippocampal sclerosis (HS) who underwent conventional T1‐weighted and T2 short TI inversion recovery MRI. An automated hippocampal segmentation algorithm was used to identify twelve subfields in each hippocampus. A total of 76 patients underwent amygdalohippocampectomy and postoperative seizure outcome assessment using the standardized ILAE classification. Semiquantitative hippocampal internal architecture (HIA) ratings were correlated with hippocampal subfield volumes.ResultsPatients with left TLE had smaller volumes of the contralateral presubiculum and hippocampus‐amygdala transition area compared to those with right TLE. Patients with right TLE had reduced contralateral hippocampal tail volumes and improved outcomes. In all patients, there were no significant relationships between hippocampal subfield volumes and clinical variables such as duration and age at onset of epilepsy. There were no significant differences in any hippocampal subfield volumes between patients who were rendered seizure free and those with persistent postoperative seizure symptoms. Ipsilateral but not contralateral HIA ratings were significantly correlated with gross hippocampal and subfield volumes.ConclusionsOur results suggest that ipsilateral hippocampal subfield volumes are not related to the chronicity/severity of TLE. We did not find any hippocampal subfield volume or HIA rating differences in patients with optimal and unfavorable outcomes. In patients with TLE and HS, sophisticated analysis of hippocampal architecture on MRI may have limited value for prediction of postoperative outcome.

Ex vivo mesoscopic diffusion MRI correlates with seizure frequency in patients with uncontrolled mesial temporal lobe epilepsy

“…Interestingly, cellular loss in CA3, CA4 and dentate gyrus in patients with mTLE were associated with a decline in declarative memory, but loss of cells in CA1 was not (Coras, Pauli, et al, 2014). Nevertheless, no significant relationship between in vivo MRI‐based hippocampal subfield volumes and clinical variables (i.e., duration and age of onset) have been found (Bower, Kilpatrick, Vogrin, Morris, & Cook, 2000; Kreilkamp, Weber, Elkommos, Richardson, & Keller, 2018).…”

Seven‐tesla susceptibility‐weighted analysis of hippocampal venous structures: Application to magnetic‐resonance–normal focal epilepsy

“…Previous work has shown that volume loss in selective hippocampal subfields is correlated to epilepsy. [39][40][41] It has been shown that different parts of the hippocampus show different levels of resistance to disruption in perfusion, with the CA1 region known to be particularly sensitive, whereas CA2 and CA3 are thought to be particularly resistant. 42 Thus, it may be possible that this change in VD is also associated with particular hippocampal subfields.…”

Hippocampal profiling: Localized magnetic resonance imaging volumetry and T2 relaxometry for hippocampal sclerosis

“…The widespread abnormalities observed in this work (Figure ) are concordant with evidence from both histopathology and imaging research indicating abnormalities in the CA1‐CA3 subfields and dentate gyrus, which run most of the length of the hippocampus (eg, Briellmann et al, von Oertzen et al, Stefanits et al); for comparison of the orientations of these subfields to the CSA profiles, please see Figure . Using automated tools for hippocampal subfield segmentation, group‐level differences in these subfields are also observed, but patient‐specific results at 3 or 7 T have so far remained inconclusive as to the use in either improved detection of HS or prediction of postoperative seizure outcome . Even when manual subfield delineation did provide a distinction between HS types 1 and 2, automated subfield volumetry did not …”