Comparison of different MR imaging techniques in localization and lateralization of patient with mesial temporal lobe epilepsy

The purpose of this study was to analyse the hippocampal volumemeasurement, MR Spectroscopy, DSC and pASL Perfusion MR techniques in localization and lateralization of epileptogenic focus in patients with mezial temporal lobe epilepsy (MTLE).42 patients with medically refractory temporal lobe epilepsy whounderwent preoperative evaluation and 11 normal controls were studied retrospectively. Pathologic and control hippocampus that was determined by Video EEG monitorizing and/or PET CT, were compared in terms of hippocampal volume measurement, NAA/Cre, NAA/Cho and NAA/Cho+Cre ratios obtained from MR Spectroscopy, relative CBF and CBV values obtained from pASL and DSC perfusion MR techniques. Cut-off points and related percentage of performance indicators in all methods, that will be used for differantiate the pathologic and control hippocampus, were calculated statistically. Also, by using cut-off points and asymmetry index, percentage of performance indicators werecalculated in groups of MR (+) MTLE, MR (-) MTLE and bilateral MTLE. For all techniques a statistically significant difference was found between the pathologic and control hippocampus groups (p<0,01). In differentation of control and pathologic hippocampus, cut-off point, sensitivity, selectivity, positiveand negative predictive values were respectievely, 2115 mm3, %98, %73, %81 and %97 for hippocampal volume measurement, 1,14, %86, %79, %83 and %83 for NAA/Cho ratio were, 0,89, %71, %78, %72 and %76 for pASL technique, 0,94, %79, %76, %73 and %82 for DSC technique. Each method achieved a comparable performance in lateralization, when used alone.Hippocampal volume measurement, MR Spectroscopy, non-enhanced and enhanced perfusion MR techniques provide important information about diagnosis and lateralization of MTLE. Although pASL has a slightly lower performance, with its independence of contrast injection, easy applicability and repeatability, can easily be used as an adjuct to other imaging techniques in order to increase diagnostic performance including MR (-) MTLE patients.