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Background and Purpose: To demonstrate the accuracy across different acquisition and analysis methods, we evaluated the variability in hippocampal volumetric and surface displacement measurements resulting from two different MRI (magnetic resonance imaging) acquisition protocols., Methods: Nine epilepsy patients underwent two independent T1-weighted magnetization prepared spoiled gradient sequences during a single 3T MRI session. Using high-dimension mapping-large deformation (HDM-LD) segmentation, we calculated volumetric estimates and generated a vector-based 3-dimensional surface model of each subject's hippocampi, and evaluated volume and surface changes, the latter using a cluster-based noise estimation model., Results: Mean hippocampal volumes and standard deviations for the left hippocampi were 2,750 (826) mm3 and 2,782 (859) mm3 (P = .13), and for the right hippocampi were 2,558 (750) mm3 and 2,547 (692) mm3 (P = .76), respectively for the MPR1 and MPR2 sequences. Average Dice coefficient comparing overlap for segmentations was 86%. There was no significant effect of MRI sequence on volume estimates and no significant hippocampal surface change between sequences., Conclusion: Statistical comparison of hippocampal volumes and statistically thresholded HDM-LD surfaces in TLE patients showed no differences between the segmentations obtained in the two MRI acquisition sequences. This validates the robustness across MRI sequences of the HDM-LD technique for estimating volume and surface changes in subjects with epilepsy., (Copyright © 2014 by the American Society of Neuroimaging.)

Objective: Selective amygdalohippocampectomy (AHC) has evolved to encompass a variety of techniques to resect the mesial temporal lobe. To date, there have been few large-scale evaluations of trans-middle temporal gyrus selective AHC. The authors examine a large series of patients who have undergone the trans-middle temporal gyrus AHC and assess its clinical and neuropsychological impact., Methods: A series of 76 adult patients underwent selective AHC via the trans-middle temporal gyrus approach over a 10-year period, 19 of whom underwent pre- and postoperative neuropsychological evaluations., Results: Favorable seizure response rates were achieved (92% Engel class I or II), with very low surgical morbidity and no mortality. Postoperative neuropsychological assessment revealed a decline in verbal memory for the left AHC group. No postoperative memory decline was identified for the right AHC group, but rather some improvements were noted within this group., Conclusions: The trans-middle temporal gyrus selective AHC is a safe and effective choice for management of medically refractory epilepsy in adults., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Purpose: To report the detection of structural and functional biological changes in living animals using small animal in vivo MRI that complements traditional ex vivo histological techniques. We report the development and validation of the application of large deformation high dimensional mapping (HDM-LD) segmentation for the hippocampus in the rat., Materials and Methods: High resolution volumetric T2 weighted MRI images were acquired at 4.7 Tesla from six male in-breed nonepileptic Wistar rats. Two HDM-LD segmentations of the hippocampus (automated 1 and automated 2) were compared with the manual segmentations of two investigators who independently segmented the hippocampi (manual 1 and manual 2)., Results: The mean overlap for the hippocampi between automated 1 and automated 2 for the right hippocampi was 94.4% (SD 1.0) and for the left hippocampi was 94.3% (SD 2.5), while the mean overlap between automated 1 and manual 1 for the right hippocampi was 91.4% (SD 1.3) and for the left hippocampi was 91.9% (SD 1.4). Mean values for absolute differences for comparisons of all the segmentations were the following: automated 1 versus automated 2, 3.2% (SD 1.0); manual 1 versus manual 2 6.82% (SD 5.22); automated 1 versus manual 1 13.0% (SD 1.8)., Conclusion: HDM-LD can be applied to obtain accurate and reproducible three-dimensional segmentations of the hippocampus from rat MR images. HDM-LD will be a useful tool for investigations of hippocampal structural changes in vivo in rat models of human disease.

The objectives of the present study were to illustrate three-dimensional hippocampal surface anatomy using deformation-based composite segmentations, superimposed on two-dimensional MRI (magnetic resonance images) in standard and oblique planes. The hippocampi from five normal volumetric MRI studies were segmented using a semiautomated, deformation-based technique. Segmentations were then processed to combine hippocampal surfaces, generating a composite (or average) deformation for each of the five left and five right hippocampi. Composite hippocampal surfaces were then projected on two-dimensional MRIs, with verification of projections using three-dimensional coordinate data. Composite hippocampal surfaces show anatomical details of hippocampal substructures, including the pes hippocampi, intralimbic gyrus, and uncinate gyrus. Projection on two-dimensional MRI helps to define hippocampal anatomy in relationship to surrounding structures. Composite images highlight specific features of normal hippocampal surface anatomy, and demonstrate the structural relationship of the hippocampus to surrounding structures on MRI., (Copyright (c) 2005 Wiley-Liss, Inc.)

MRI-based evaluation of the hippocampus is important in the assessment and treatment of patients with mesial temporal lobe epilepsy (MTLE). Using MRI-based large-deformation high-dimensional mapping (HDM-LD), which allows structural evaluation of regions of the hippocampus, we document the HDM-LD-defined pattern of hippocampal deformation in MTLE patients compared with matched controls. In 30 subjects with MTLE and confirmed medial temporal lobe sclerosis (MTS), we performed measurements of intracranial area, brain parenchymal volume and deformation-based hippocampal segmentations, and then grouped patients into right and left MTS groups (resulting in 15 subjects in each group). Using HDM-LD techniques, we compared the right and left MTS groups with a group of 15 matched controls. Analysis included both the MTS and contralateral hippocampi, and covariance for changes in brain parenchymal volume. Final results were interpreted using a segmentation showing normal hippocampal surface subfield anatomy. Comparing the MTS groups with controls, after covarying with brain parenchymal volume, the MTS hippocampi showed significant volume loss (P < 0.0001), contralateral hippocampi showed no significant volume loss. HDM-LD techniques showed significant shape changes, with marked inward deviation in the Sommer sector of the MTS hippocampi. In the contralateral hippocampi, the inferior surface of the hippocampal body showed inward deformation in the medial aspect of the subiculum, with minimal involvement of the Sommer sector. HDM-LD shows involvement of subregions of the hippocampus which are consistent with MTS histopathology. Contralateral hippocampi show different HDM-LD changes, suggesting that the underlying disease process in the contralateral hippocampi is different from MTS.

Purpose: To assess shape changes in patients with mesial temporal sclerosis (MTS) and temporal lobe epilepsy (TLE), by using deformation-based hippocampal shape analysis., Methods: We retrospectively reviewed magnetic resonance imaging (MRI) studies in 30 subjects with unilateral MTS (15 right-sided MTS, 15 left-sided MTS) and TLE. We defined the "average" hippocampus in the right- and left-MTS groups by generating a mean transformation for the 15 deformation images in each group. Further to quantify the difference between the hippocampi, we coregistered the mean transformation of the involved hippocampus (with MTS) to the contralateral hippocampus, considering the left- and right-MTS groups independently. We generated a color "flame" scale showing degrees of outward and inward deviation of the coregistered hippocampi., Results: Both the right- and left-MTS groups showed similar shape changes, with maximal inward deformation in the medial and lateral hippocampal head and the hippocampal tail. However, more extensive involvement was seen in the lateral hippocampal body in the right-MTS group as compared with the left., Conclusions: Deformation-based hippocampal shape analysis shows specific regions of hippocampal surface anatomy that are most affected in MTS. This technique may aid in detection of clinically significant anatomic abnormalities of the hippocampus in patients with epilepsy.

We performed MR imaging deformation-based hippocampal shape analysis in a 28-year-old woman in whom status epilepticus developed after acute encephalitis. Hippocampal shape analysis revealed severe global bilateral hippocampal atrophy. Regional volume loss was most accentuated in the medial and lateral aspects of the hippocampal head; the loss was similar to shape changes in hippocampal sclerosis of chronic temporal lobe epilepsy. This deformation pattern may reflect a common pathologic process that causes hippocampal volume loss in both of these conditions.

Abstract: Background: Imaging studies of epilepsy patients with comorbid affective disturbance demonstrate morphometric changes in limbic brain regions implicated in psychiatric disease. Genetic Absence Epilepsy Rats from Strasbourg (GAERS), specifically bred for their epilepsy phenotype, also exhibit elevated anxiety-like behaviors suggesting a common causality. Here we examined whether relevant cerebral morphological alterations exist in this rat strain using volumetric measurements and large deformation high dimensional mapping (HDM-LD), a tool recently validated to produce accurate three-dimensional surface representations of the hippocampus. Methods: Volumetric MRI and the Open Field test of anxiety were performed in adult female GAERS (n =12) and Non-Epileptic Controls (NEC; n =11). The volumes of selected brain regions, including cortex, hippocampus, amygdala, thalamus, hypothalamus and lateral ventricles, were measured using Region-Of-Interest analysis from the MRI data and total volumes compared between the two strains. Results: GAERS had increased amygdala (right: p =0.003; left p <0.001), cortices (right: p =0.006; left p =0.012) and ventricular volumes (p =0.002) when compared with NEC rats. Further, HDM-LD showed GAERS to have hippocampal volume loss in two regions: the medial hippocampal surface immediately caudal to the hippocampal commissure, and the lateral hippocampal surface over the mid-portion of the septotemporal axis. GAERS exhibited increased anxiety in the Open Field compared with NEC rats: reduced distance traveled (p <0.001) and reduced time in the centre area (p =0.042). Conclusions: Morphometric brain changes in GAERS could be relevant to their hyperanxious and epileptic phenotypes. This model may be useful in illuminating the pathogenesis of affective disorders generally, as well as modeling psychiatric comorbidities of epilepsy. [Copyright &y& Elsevier]