Regional changes in hippocampal T2 relaxation and volume: a quantitative magnetic resonance imaging study of hippocampal sclerosis

Abstract

Objective-The principal MRI features of hippocampal sclerosis are volume loss and increased T2 weighted signal intensity. Minor and localised abnormalities may be overlooked without careful quantitation. Hippocampal T2 relaxation time (HT2) can be quantified, but previously has only been measured on a few thick coronal slices with interslice gaps. In this study HT2 was measured along the entire length of the hippocampus on contiguous slices and used, with quantitative measures of hippocampal volume (HV) and distribution of atrophy, to better define the range of hippocampal sclerosis. Methods-Thirty patients with temporal lobe epilepsy, 10 patients with extratemporal localisation related epilepsy and extratemporal lesions, and 20 control subjects were studied using MRI T2 relaxometry and volumetry. Results-In controls and patients, HT2 was higher in the anterior than the posterior hippocampus. Using HV, morphometric, and HT2 data, patients with temporal lobe epilepsy were classified as unilateral diVuse hippocampal sclerosis (n=16), unilateral focal (n=6), bilaterally aVected (n=6), and normal (n=2). In patients with unilateral hippocampal sclerosis, the anterior hippocampus was always aVected. In three patients with normal HV, HT2 measurements disclosed unilateral focal abnormalities that corresponded to the EEG lateralisation of epileptic activity. Patients with bilateral hippocampal involvement had an earlier onset of epilepsy than patients with unilateral hippocampal sclerosis. Conclusions-Measurement of regional abnormalities of HT2 along the length of the hippocampus provides further refinement to the MRI assessment of the hippocampi in patients with temporal lobe epilepsy and is complementary to volumetric and morphological data. (J Neurol Neurosurg Psychiatry 1998;65:656-664)

MR-based in vivo hippocampal volumetrics: 2. Findings in neuropsychiatric disorders

“…These methods have demonstrated considerable efficacy, especially with the addition of T2 relaxation time data. [36][37][38][39][40][41] Patients with mesial temporal lobe epilepsy exhibit smaller hippocampal volumes. 16,[42][43][44][45][46][47] This hippocampal volume reduction is highly concordant with the side of the epileptogenic focus, and hippocampal deficits are most pronounced ipsilateral to the epileptic focus.…”

T2 Relaxometry of the Hippocampus at 3T

“…Previous studies with dual-echo T2 have given good data for the evaluation of patients. 8,9 More recently, multiecho T2 relaxometry techniques have been introduced at 3T. 10 With the installation of a 3T Excite MR imaging scanner (GE Healthcare, Milwaukee, Wis), we decided to evaluate the improved fast spin-echo (FSE) options with respect to obtaining dual-echo data for the production of calculated T2 maps.…”

Optimization of Brain T2 Mapping Using Standard CPMG Sequence In A Clinical Scanner

“…It has been shown that measurement of the change in T 2 provides important information about the mobility and chemical environment of the tissues of interest [4], [9] - [11]. Previous studies examining the utility of T 2 mapping in the context of neurologic and psychiatric disease demonstrated variations in T 2 values, sometimes very subtle, in specific brain regions within conditions of autism [12], schizophrenia [13], [14], epilepsy [15], Parkinson's [16], multiple sclerosis [17], [18], Alzheimer disease [9], tumors [19], [20], [21] and a host of other disorders [6], [14], [16], [22], [23]. Nevertheless, mapping the T 2 parameter is rarely used in clinical diagnostics, the most common reported reasons being higher scanning times [4], [6], [10], [11] or its lack of specificity, in contrast to its high sensitivity [5], [6], [17], [24].…”

“…Nevertheless, mapping the T 2 parameter is rarely used in clinical diagnostics, the most common reported reasons being higher scanning times [4], [6], [10], [11] or its lack of specificity, in contrast to its high sensitivity [5], [6], [17], [24]. In clinical studies, T 2 relaxation data is most commonly obtained from single-slice MR sequences [15], [24] - [27]. For tissue mapping purposes, a multi-slice sequence is more suitable.…”