Clinical Usefulness of T2 Relaxometry in Temporal Lobe Epilepsy

ABSTRACT

BACKGROUND: Quantitative measurement of hippocampal T2 relaxation time is an objective means of determining the frequency and severity of signal abnormalities. To evaluate the diagnostic properties of T2 relaxometry in temporal lobe epilepsy(TLE), we measured T2 relaxation time of bilateral hippocampi in pathology-proven TLE patients and normal controls. METHODS: We investigated 10 TLE patients who had temporal lobectomy with MR T2 relaxation mapping. All patients underwent in phase I or II studies, and had pathologic diagnosis. Also we measured T2 relaxation time in 10 normal volunteers. RESULTS: The pathologic findings of 10 TLE patients were followings 8 hippocampal sclerosis (including dual pathology of necrotic granuloma), 1 calcified fibrous nodule, and 1 normal hippocampus. The mean T2 relaxation time of normal controls is 67.5msec, which is lower value than previous reports. All patients with hippocampal sclerosis in pathology showed increased T2 time greater than 2 SD of mean value of normal controls. But, the T2 values are upper normal range in non-hippocampal sclerosis. The lateralizing value of T2 relaxometry is 50% in TLE patients, and 62.5% in pathology-proven hippocampal sclerosis groups. CONCLUSIONS: There is a clear distinction of T2 relaxation time between the patients of hippocampal sclerosis and normal controls or non-hippocampal sclerosis. These findings suggest that the T2 relaxation time is a reliable objective measurement of hippocampal pathology, especially hippocampal sclerosis in TLE.