Contribution of T2Relaxation Time Mapping in the Evaluation of Cryptogenic Temporal Lobe Epilepsy

T2 hyperintense signal in patients with temporal lobe epilepsy with MRI signs of hippocampal sclerosis and in patients with temporal lobe epilepsy with normal MRI

“…Bernasconi et al conducted a study with 14 patients with TLE with unilateral hippocampal atrophy and 11 patients with unilateral TLE without hippocampal atrophy and found a frequency of T2 signal hyperintensity in 100% of patients with hippocampal atrophy in 82% of patients without hippocampal atrophy [13]. In addition, quantitative measurements of T2 relaxation time in the hippocampal region have proved useful in the lateralization of the epileptogenic zone in 90% of patients with TLE with HS and in 80% of patients with TLE without clear visual MRI signs of HS [14]. However, the reproducibility of these studies is difficult, possibly because of the inferior quality of MRI used in initial studies, which underestimated the visual analysis of MRI signs of HS, and the small number of patients included.…”

Whole-brain T2 mapping demonstrates occult abnormalities in focal epilepsy

“…33 Also, there is commonly reduced neuropil in the neocortex of patients with TLE that results in reduced macromolecules and hence prolonged T2 times. 58 Previous studies in MS 18,59,60 and TLE 11,39 have found altered T2 relaxation times in cerebral tissue that appeared normal macroscopically or on visual assessment of conventional MR images. It is likely, however, that some epileptogenic lesions are evident only on histopathologic examination and remain beyond even the most sensitive of current imaging methods.…”

“…21,[34][35][36] In patients with TLE, quantitative measurement of T2 relaxation time in the hippocampus and amygdala gives additional sensitivity over qualitative assessment. 6,8,[37][38][39] However, approximately 50% of patients with refractory focal epilepsy have seizures that arise from outside the mesial temporal lobe; in those patients, quantitative analysis of T2-weighted imaging of the neocortex may be profitable.Acquired lesions are an important cause of refractory focal epilepsy. Abnormalities of T2 were identified within the regions of cerebral damage in all patients with acquired lesions.…”

Voxel‐based T2 Relaxation Rate Measurements in Temporal Lobe Epilepsy (TLE) with and without Mesial Temporal Sclerosis

“…Hippocampal sclerosis is typically associated with a prolonged T 2 relaxation, i.e., with a visually apparent signal increase on T 2 ‐weighted images. Quantitative measurements of T 2 relaxation in the hippocampal formation have found to be very useful for focus lateralization in mTLE and not only correctly identify the epileptogenic hippocampus in over 90% of TLE‐MTS but also in up to 80% of TLE‐no (Namer et al, 1998; Bernasconi et al, 2000). Furthermore, histopathological studies showed the prolonged T 2 relaxation to be well correlated with the degree of hippocampal neuronal cell loss and/or gliosis (Briellmann et al, 2002; Von Oertzen et al, 2002).…”