Application Of Multimodal MRI In Preoperative Evaluation Of Epilepsy In Tuberous Sclerosis Complex

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The application of tuberectomy in the treatment of epilepsy in children with tuberous sclerosis complex under 3 years of ageObjectives To evaluate the effectiveness and safety of tuberectomy in the treatment of epilepsy in children with tuberous sclerosis complex(TSC)under 3 years old,and to analyze the predictive factors leading to poor outcome,as well as evaluate the effects of surgery on cognitive development.Methods The clinical data of 19 children with TSC who underwent tuberectomy under 3 years of age were retrospectively reviewed.The Engel classification was used to classify the seizure status following surgery.The clinical features were compared between patients with good seizure control(Engel Class ?)and poor seizure control(Engel Class ? to ?).Patients' neurodevelopmental status were also evaluated before and after surgery.Results Fourteen patients(74%)were classified as Engel Class ?(complete seizure remission),3 patients(16%)were classified as Engel Class ?,and 2 patients(10%)were classified as Engel Class ? with a mean follow-up of 52 months.Compared to patients with good seizure control,patients with poor seizure were more likely to have a history of infantile spasms(P=0.002)and the duration of seizure was significantly longer(P=0.04).In terms of neurodevelopmental outcome,mental development was improved in 81%(13/16)of the patients after surgery,language skills were improved in 89%(16/18)of the patients,self-injury behavior were controlled in 100%(2/2)of the patients,visual hallucinations vanished in 100%(1/1)of the patients,and motor function were improved in 33%(1/3)of the patients.Conclusion Most patients achieved complete seizure remission after tuberectomy with a mean follow-up of more than 3 years,which confirmed the effectiveness and safety of early epilepsy surgery.Epilepsy surgery not only helped to control seizure,but also significantly improved neurodevelopmental outcome.History of infantile spasms and longer duration of seizure are related with poor prognosis.Part ? The usefulness of neurite orientation dispersion and density imaging in the detection of cortical tubers in patients with tuberous sclerosis complexObjectives To investigate the usefulness of neurite orientation dispersion and density imaging(NODDI)in detecting cortical tubers,especially epileptogenic tubers in tuberous sclerosis complex(TSC)patients.Methods High-resolution conventional MRI and multi-shell diffusion-weighted imaging were performed in 27 TSC patients.Diffusion images were fitted to NODDI and DTI models.NODDI including intracellular volume fraction(ICVF),orientation dispersion index(ODI)and isotropic volume fraction(ISO),as well as DTI parameters including fractional anisotropy,mean diffusivity,axial diffusivity and radial diffusivity were calculated.Tubers were visually assessed on different image types and scored by two neuroradiologists.The contrast ratios between lesion and background tissue were measured on different image types.Results There were significant differences in lesion conspicuity scores and lesion-background contrast ratios across different sequences(both P<0.001).The post hoc analysis showed that both the conspicuity scores and contrast ratios of ICVF derived from NODDI were higher than other image types.For the 10 epileptogenic tubers,lesion visibility on ICVF was better in 3 tubers compared with conventional MRI and better in 4 tubers compared with DTI.Conclusions For the first time,we demonstrated the value of NODDI,a novel diffusion technique in the detection of cortical tubers in TSC patients.ICVF presented with higher contrast than conventional MRI and DTI,which helped detection of cortical tubers,especially subtle epileptogenic tubers.Part ? The application of neurite orientation dispersion and density imaging in the differentiation between epileptogenic and non-epileptogenic tubersObjectives To evaluate the usefulness of NODDI in distinguishing epileptogenic tubers from non-epileptogenic ones in patients with TSC.Methods Ten TSC patients who underwent epilepsy surgery with epileptogenic tubers confirmed were enrolled.Multi-shell diffusion-weighted imaging were performed in all the patients.DTI parameters as well as NODDI parameters were calculated.Regions of interest(ROI)were manually delineated based on the border of cortical tubers which to generate ROItuber.ROIperituber was created by automatically expanding the ROItuber by 2mm.The maximum,minimum,mean,and median values of the diffusion parameters were measured using each ROI and then compared between epileptogenic and non-epileptogenic tubers.Results The epileptogenic group showed lower mean ICVF(Mann-Whitney U,P<0.001)and lower minimum ODI value(Mann-Whitney U,P=0.012)in tuber ROIs(ROItuber).There is no significant difference between epileptogenic and non-epileptogenic tubers in peri-tuber ROIs(ROIperituber).Receiver operating characteristic analysis demonstrated that using the mean ICVF to identify epileptogenic tubers had a sensitivity of 0.816,a specificity of 0.7 with a cut-off value of 0.14;while using the minimum ODI had a sensitivity of 0.755 and a specificity of 0.9 with a cut-off value of 0.044.Conclusion Diffusion parameters derived from NODDI could be used to distinguish epileptogenic tubers from non-epileptogenic ones,suggesting their potential value in epilepsy evaluation in TSC.The difference between these two tuber types originated from the tuber itself rather than the surrounding tissue,suggesting that cortical tubers are the origin of the epileptogenicity in TSC patients.Part ? Application of resting state functional magnetic resonance in the evaluation of epileptic foci in patients with TSCObjective To explore the usefulness of functional connectivity abnormality coefficients based on resting state functional magnetic resonance imaging(rs-fMRI)in the evaluation of brain lesions in patients with TSC,and to evaluate its value in identifying epileptic foci.Methods Ten TSC patients who underwent epilepsy surgery with epileptogenic tubers confirmed and 31 healthy volunteers were enrolled.Rs-fMRI scans were performed to all the subjects.The voxel based functional connectivity was calculated.The mean functional connectivity from the healthy control group was used to serve as a normal reference.For each TSC patient,the abnormality count(ABC)map was obtained by calculating the deviation degree of the functional connectivity from the normal reference.It was then compared with conventional MRI and positron emission tomography(PET)to observe the relationship between ABC map and brain lesions.We used the largest ABC values to determine the potential epileptic foci and evaluated their accordance with real epileptogenic region.Results Abnormal functional connectivity was observed in all TSC patients.Most of the abnormalities shown on the ABC map could be localized to cortical tubers or adjacent region,some were localized to the ventricle or around the ventricle,and a small part were localized to areas distant from cortical tubers.In 5 patients(50%),the location of the maximum ABC was in accordance with that of the epileptic foci,and in 3 patients(30%)the location of the second maximum ABC was in accordance with that of the epileptic foci.Conclusion TSC patients presented with widespread abnormalities in functional connectivity which could be related with tuber pathology.In addition,the degree of functional connectivity abnormalities was indicative of epileptogenicity,suggesting that rs-fMRI can be used as an important tool for epilepsy evaluation in patients with TSC.Part ? The application of the combination of fMRI and diffusion imaging in the evaluation of the epileptic foci in TSC patientsObjective To comprehensively analyze the accuracy of NODDI and rs-fMRI in the localization of epileptic foci,and to evaluate the added value of multimodal MRI relative to electroencephalography(EEG)in the assessment of epilepsy in TSC patients.Methods Ten TSC patients with epileptic foci confirmed by surgical resection were enrolled.Multi-shell diffusion imaging and resting-state functional magnetic resonance imaging were collected.For each patient,the lowest mean ICVF and minimum ODI,as well as the maximum ABC were used to define the potential epileptic foci.We evaluated the consistency between the localization based on MRI and the actual epileptic foci.In addition,the imaging results were compared with that of EEG.Multimodal MRI was regarded as contributory for patients whose EEG indicated multiple or wide range of discharges while multimodal MRI provided additional localization information.Results Both the lowest mean ICVF and the lowest minimum ODI accurately identified epileptic foci in 7 patients(70%),the combination of the two parameters accurately identified epileptic foci in 8 patients(80%).The maximum ABC accurately identified epileptic foci in 5 patients(50%).The combination of these two modalities accurately identified epileptic foci in 5 patients(50%).Multimodal MRI was considered as contributory in five patients(50%)compared to EEG.Conclusion Multimodal MRI has high accuracy in the localization of epileptic foci in TSC patients.In addition,it provided additional localization information over EEG in half of the patients.Multimodal MRI can be used as an important supplementary tool for preoperative evaluation of epilepsy in TSC patients.