MRI volumetric measurement of amygdala and hippocampus in temporal lobe epilepsy

Abstract

We performed MRI volumetric measurements of the amygdala (AM), the hippocampal formation (HF), and the anterior temporal lobe in a group of 30 patients with intractable temporal lobe epilepsy (TLE) and in seven patients with extratemporal lobe foci. Measurements were analyzed with a semiautomated software program and the results compared with those of normal controls and correlated with the findings of all other investigations. In particular, we compared the results with the lateralization of epileptic abnormalities in the EEG. Volumetric studies of AM and HF showed lateralization of measurable atrophy consistent with that derived from extracranial and intracranial EEG examinations. The HF volumes were more sensitive and provided a lateralization in 87%. Combined measurements of AM and HF showed lateralization in 93%, always congruent with the results of EEG lateralization. This slight but important additional improvement in discrimination justifies using AM measurements in MRI volumetric studies of mesial temporal structures. Volumetric studies combined with other currently employed noninvasive techniques may diminish the need for invasive methods of investigation in patients with TLE.

Presurgical multimodality neuroimaging in electroencephalographic lateralized temporal lobe epilepsy

“…1 H-MRSI-Our relatively low sensitivity with 1 H-MRSI lateralization contrasts with the nearly 100% sensitivity reported in some earlier studies, including our own [7][8][9]14,30,31].…”

“…[29]. The value of T2 remains for both clinical and research purposes because it is simple to perform, is highly reliable (low variance in normals), and can be performed in any ROI.1 H-MRSI-Our relatively low sensitivity with 1 H-MRSI lateralization contrasts with the nearly 100% sensitivity reported in some earlier studies, including our own [7][8][9]14,30,31].Most studies included only a small number of patients, controls, or almost exclusively patients with MRI evidence for MTS. Some studies included patients suspected or proved to have bilateral independent TLE, a finding used to explain discordant or nonlateralized MRSI results [8,14].…”

MR-based in vivo hippocampal volumetrics: 1. Review of methodologies currently employed

“…Of those who do provide sufficient detail, the majority report using images reformatted perpendicularly to the long axis of the hippocampal formation. 56 A substantial number of protocols use different acquisition sequences (either perpendicular to the AC-PC line 25,94,84 or the Sylvian fissure 3,20 ), but do not reformat their images, and a very small number of studies employ head-tilt protocols. [95][96][97] 3D imaging techniques allow researchers to save valuable scan time by eliminating the need for pilot scans needed for consistent positioning of images based on internal landmarks, and accomplishing this after the scan using multiplanar image reconstruction capabilities.…”

“…One of the brain structures which has been a focus of research is the hippocampal formation. Magnetic resonance (MR)-based in vivo measurement of hippocampal volume is an accepted technique, which has been performed in the aged 1 and healthy subjects, 2 and has revealed a number of structural abnormalities in a variety of neurological and psychiatric disorders, such as temporal lobe epilepsy, 3 Huntington's disease, 4 Turner's syndrome, 5 Cushing's disease, 6 Down's syndrome, 7 Alzheimer's disease (AD), 8 mild cognitive impairment, 9 schizophrenia, 10 major depression (MD), 11 bipolar disorder, 12 post-traumatic stress disorder (PTSD), 13 borderline personality disorder, 14 chronic alcoholism, 15 obsessive-compulsive disorder, 16 and panic disorder. 17 The MR-derived hippocampal volumetric technique has demonstrated good validity and reproducibility, [18][19][20] and accuracy of the measurements has been shown by MRI volumetric measurement of phantoms with a known volume.…”

Reproducibility and reliability of volumetric measurements of olfactory eloquent structures

“…Several volumetric MR studies have recently been published in the neuroradiology literature [6][7][8][9][10][11][12][13][14].lt is remarkable how few of these studies have inyolved the use of phantoms with known volumes to gauge the accrracy of the techniques employed. In many cases, the structure being measured (the hippocampus or TL in a living host) was not available for verification of measured volumes, and the researchers relied solely on (intraclass) correlation coefficients or similar tests to assess the veracity of their findings [91.…”