Sensitivity evaluation of magnetization transfer ratio for diagnosing intractable mesial temporal lobe epilepsy with normal MRI: Experience in Indonesia

Background: Standardized Magnetic Resonance Imaging (MRI) cannot show the cause of intractable mesial temporal lobe epilepsy (MTLE) in 20-30% cases. These normal MRI patients need advanced imaging to visualize the epileptogenic zone to determine lateralization for surgery. Aim: To investigate sensitivity of Magnetization Transfer Ratio (MTR) in detecting lateralization and correlate the MTR with histopathological features of surgical resection on intractable MTLE. Method: Twenty-three consecutive surgical candidates with intractable focal temporal epilepsy, as determined with ictal scalp video-EEG and standarized MRI, were examined with MTR. The MTR was measured in hippocampus. The data were then compared with a healthy control group. Histopathological results of surgical specimens were stained with NeuN, GFAP, and Neuropeptide Y to assess neuronal loss, gliosis and axonal/ Mossy Fiber sprouting. Results: Ten of 23 patients had normal MRI. MTR patients had lower average than control. Despite MTR had no correlation with neuronal loss, gliosis and axonal fiber sprouting; its sensitivity and specificity reached approximately 81.8% and 68.2% respectively; and concordance with EEG on 6 out of 10 patients. Conclusion: MTR has fairly good sensitivity and EEG concordance, but low specificity so the result may be indicative for diagnostic accuracy to determine MTLE lateralization with normal MRI.