The Application Of Hippocampal Quantitative Measurement On MRI For Assessment Of Hippocampal Lesion In Temporal Lobe Epilepsy

Objective To determine the value and limitation of hippocampal quantitativemeasurement on MRI for assessment of hippocampal lesion in temporal lobeepilepsy(TLE), and provide primary quantitative data to predict its operationalprognosis.Methods 68 neurologically normal control(CL) peoples, 28 TLE, 25 non-temporallobe partial epilepsy(NTPE), 38 generalized epilepsy(GEP) patients were chosen toscan with Siemens Magnetom Impact 1.0 Tesla MR scanner, and to get visualqualitative evaluation including hippocampal atrophy and hippocampal hyperintensityon T₂ weighted imaging(T₂WI). The hippocampal volumes(HCVs) and hippocampalT₂ relaxation times(HCT₂s) including right side, left side, lower side, higher side, theHCV and HCT₂ ratios including right side to left side, lower side to higher side, werecalculated. Their differences in four groups of subjects were analyzed, in addition theirabilities to confirm hippocampal lesion and lateralize epileptic focus of TLE werecompared with visual qualitative evaluation.Results In control subjects, HCVs of right side and left side were significantlydifferent(P<0.05), both of them differed with gender(P<0.05), both HCT₂ of right sideand left side were significantly negative correlation to age with r=–0.628 and –0.564respectively(P<0.05). HCVs of lower side in TLE patients were 16.55%, 15.91%,18.34% smaller than those in NTPE, GEP patients and CL subjectsrespectively(P<0.05), HCV ratios of lower side to higher side were 14.77%, 14.18%,16.44% smaller(P<0.05), HCT₂s of higher side 4.10%, 4.61%, 8.65% larger(P<0.05),and HCT₂ ratios of lower side to higher side 4.37%, 4.67%, 4.97% smaller(P<0.05). Inaddition, HCT₂s of higher side in NTPE and GEP patients were 4.37% and 3.87%larger than that in CL subjects(P<0.05). In confirmation of hippocampal lesion of TLE,the combination of HCV ratio of right side to left side and HCT2 ratio of right side toleft side was best of quantitative measurements, achieving a sensitivity of 78.57%, aspecificity of 95.42%, and an accuracy of 92.45% on the standard of mean±3 standarddeviations of CL subjects. In visual qualitative evaluation, the application ofhippocampal atrophy alone was best, with a sensitivity of 57.14%, a specificity of95.42%, and an accuracy of 88.68%. The quantitative measurement was better thanvisual qualitative evaluation, but the differences were not statisticallysignificant(P>0.05). In the lateralization of epileptic focus of TLE, with lateralizationof EEG as golden standard, HCV measurement, HCT2 measurement, hippocampalatrophy of visual evaluation and hippocampal hyperintensity on T2WI had accuraciesof 86.36%, 90.91%, 72.73% and 68.18% respectively, but the differences were notstatistically significant(P>0.05).Conclusion Hippocampal quantitative measurement, particularly the combination ofHCV and HCT2 measurement, is a excellent objective method in the assessment ofhippocampal lesion of TLE, useful to the confirmation of hippocampal lesion andlateralization of epileptic focus, and possible to provide objective quantitative data topredict operational prognosis of TLE.