Comparative study of resting-state functional MRI and positron emission tomography-CT in the localization of temporal lobe epileptic focus / 中华放射学杂志

ABSTRACT

Objective To evaluate the efficacy of PET-CT brain imaging and resting-state fMRI in preoperative localization of temporal lobe epileptic (TLE)focus.Methods PET-CT and resting-state fMRI were performed in 17 patients with refractory TLE,who then underwent surgical treatment.Seventeen healthy volunteers matched with gender and age were recruited as the control group.The resting-state fMRI images were post processed by SPM5 software.Regional homogeneity(ReHo) values of the whole brain and bilateral hippocampus were obtained and analyzed.PET-CT images were analyzed by visual analysis method and asymmetry index method and the standardized uptake value (SUV) of bilateral hippocampus were obtained.The ReHo values and SUV of the bilateral hippocampus were compared by two independent samples t-test,and analyzed by receiver operating characteristic curve (ROC) for optimized diagnostic threshold.Pearson correlation analysis was employed for evaluating the correlation between the SUV and ReHo values of bilateral hippocampus.The consistency between the diagnostic accuracy of PET-CT and resting-state fMRI was assessed by Kappa consistency test.The outcome of the patient group was compared with that of the control group,and with the pathological results,to evaluate the diagnostic value of the two modalities for preoperative localization of temporal lobe epileptic focus.Results Regional or comprehensive low metabolism of 18F-FDG in temporal lobes was presented in all 17 patients,and 11 patients out of 17 showed lateral decreased ReHo value.The diagnostic accuracy of the two examinations was 70.6％ (12/17) and 64.7％ (11/17) for PET-CT and resting-state fMRI respectively compared with pathological results,and could be increased to 76.5％ (13/17) when the two methods were combined for diagnosis.The ReHo values of the TLE group (0.34 ± 0.12)were significantly lower than those of the control group (0.46 ± 0.07) (t =3.230,P =0.003).The sensitivity and specificity of resting-state fMRI were 88.2％ and 94.1％ respectively when the ReHo value was 0.36.There was significant difference between the SUV of the affected (4.17 ±0.63) and healthy side(4.77 ±0.56) of hippocampus in TLE group(t =2.930,P =0.006).The sensitivity and specificity of PET-CT were 88.2％ and 64.7％ respectively when SUV was 4.23.The two values could be used as a threshold in the localization of temporal lobe epileptic focus.Consistency of lesion detection was revealed between PET-CT and resting-state fMRI though it was not high,and the Kappa value was 0.49.However,no correlation was detected between the SUV and ReHo value using Pearson correlation test(r =0.280,P =0.314).Conclusion Combined PET-CT brain imaging and resting-state fMRI as a multi-modality imaging method might improve the diagnostic accuracy of the TLE focus's localization.