Temporal Lobe Epilepsy: Quantitative MR Volumetry in Detection of Hippocampal Atrophy

Abstract

Purpose:To determine the ability of fully automated volumetric magnetic resonance (MR) imaging to depict hippocampal atrophy (HA) and to help correctly lateralize the seizure focus in patients with temporal lobe epilepsy (TLE). Materials and Methods:This study was conducted with institutional review board approval and in compliance with HIPAA regulations.

3T MRI Quantification of Hippocampal Volume and Signal in Mesial Temporal Lobe Epilepsy Improves Detection of Hippocampal Sclerosis

“…27 However, this has only been evaluated for the detection of hippocampal abnormalities on 1.5T scanners. 13 In 1.5T MRI, a good correlation of volume and signal abnormalities detected by quantification analysis and histopathology of HS has been demonstrated. 29 More recently, histologic studies have proposed that different patterns of neuronal loss in the hippocampus might be associated with different seizure outcome after surgical removal of the temporal lobe.…”

“…Currently, most studies of hippocampal volumetry apply manual hippocampal delimitation, and whether manual 28 or automatic analysis has higher sensitivity and specificity is still debatable. 12,13 Despite this controversy, in the clinical context, the quantification of hippocampal abnormalities must be as fast and practical as possible. In this article, we used automated volumetry and a simple manual signal quantification in which it is necessary only to define a small region of interest in 3 sections of the T2 scan of each patient, without the need to define precisely the borders of the hippocampus.…”

“…Recently automatic analyses have been shown to be promising; however, there are few studies comparing their efficacy with the visual analyses of high-quality MR imaging by experts in the field. 12,13 Although it is clear that in studies with 1.5T MR imaging, volumetry and relaxometry have significantly higher sensitivity than the qualitative analysis of MR imaging, 8,9 today most epilepsy centers work with 3T MRI and specific epilepsy protocols, which make the determination of MR imaging signs of HS by visual analysis easier and more accurate. 14 It has been reported that there is no difference in the hippocampal volume measures of 1.5 and 3T 15,16 and that quantitative measures in 3T MRI can demonstrate ultrastructural details of HS pathology not detectable with lower field scanners.…”

Mesial Temporal Sclerosis: Accuracy of NeuroQuant versus Neuroradiologist

“…24 Automated methods for the analysis of hippocampal volumetry have recently been published in clinical journals. 13,25 However, there have been few reports using an FDA-approved solution that could be practical in a busy clinical practice. Brewer et al 10 et al confirmed the existence of a natural asymmetry, with the right hippocampus found to be larger than the left hippocampus (4.00 versus 3.82 mL, 4.6% difference): The level of asymmetry they observed differed slightly from ours.…”

“…The steps involved include sequence-checking to ensure that appropriate high-resolution and contrast image parameters are performed, correction for field/gradient inhomogeneities, removal of the overlying calvaria, alignment to the probabilistic atlas of stereotypical anatomy, and segmented volumetry of predetermined anatomic areas derived from multiple subjects of multiple age groups (Brewer et al). [10][11][12][13] We sought to assess the value of NeuroQuant volumetry of the temporal lobe in patients with MTS with the added goal of trying to determine the difference in right and left hippocampal volumes that can be detected by experienced neuroradiologists in the clinical assessment of patients with temporal lobe epilepsy. We hypothesized that because radiologists assess the hippocampi for other imaging findings above and beyond volume loss alone, the neuroradiologist's determination of the correct side of the MTS would be more accurate than basic NeuroQuant volumetry.…”