Localization Of Epileptic Foci In Intractable Epilepsy Induced By Hippocampal Sclerosis By ¹¹C-choline Interval PET/CT Dynamic Brain Imaging

Objective:To evaluate the diagnostic value of ¹¹C-choline interval PET/CT brain imaging for localization of epileptogenic foci in hippocampal sclerosis-refractory temporal lobe epilepsy（HS-RTLE）,and compare it with ¹⁸F-fluorodeoxyglucose（FDG）and ¹¹C-flumazeni（FMZ）PET/CT.By comparing the positive detection rate and localization accuracy of the above three imaging agents for epileptic foci,the diagnostic efficacy of ¹¹C-choline in HS-RTLE epileptic foci was investigated.Methods:The study is divided into two parts,the first part is a retrospective study,the second part is a prospective study.Firstly,from March 2017 and June 2020,a total of62 patients（39 males,23 females,age（30.3±11.2）years）)with pathologically confirmed HS-RTLE in the General Hospital of the Northern Theater Command were retrospectively analyzed.All patients were preoperatively treated with multiple radionuclide(¹⁸F-FDG,¹¹C-FMZ,¹¹C-choline)interval PET/CT brain imaging.¹¹C-choline PET imaging was used to acquire dynamic imaging data and time-activity curves（TACs）of ¹¹C-choline in bilateral hippocampal regions were drawn.With postoperative pathology as the"gold standard",the positive detection rates and localization diagnostic efficacies of three radionuclide imaging agents for epileptogenic foci were analyzed.By using two sample paired t test,X²（Chi-square segmentation）inspection and Fisher’s exact probability method to analyze data.Then a prospective study including 46 patients（27 males,19females;age（32.9±11.9）years;between May 2019 and August 2020;）with drug-refractory epilepsy caused by clinically suspected hippocampal sclerosis was performed.The examination method was the same as that of retrospective study.Using intracranial electrode implantation or postoperative pathology as"gold standard",the diagnostic efficacy of ¹¹C-choline TAC for localization of epileptogenic foci was verified.The localization efficiency of the three imaging agents to epileptogenic focus was evaluated by receiver operating characteristics（ROC）curve.and the area was compared by Delong test.Results:In the retrospective study,62 patients with ¹⁸F-FDG PET/CT brain metabolism imaging showed hypometabolic areas in the hippocampus,with a positive rate of 100%（62/62）.21 patients could accurately locate the epileptogenic foci,with a localization accuracy of 33.87%（21/62）.In 59 patients,¹¹C-FMZ PET/CT brain receptor imaging showed localized hypometabolic areas in the hippocampus,with a positive rate of 95.16%（59/62）.In 57 patients,the epileptogenic foci could be accurately located,with an accuracy of 96.61%（57/59）.The positive rate of ¹¹C-choline PET/CT imaging in 53patients was 85.48%（53/62）.All the 53 positive patients were able to accurately locate the epileptogenic focus with an accuracy of 100%（53/53）.Interseizure(¹⁸F-FDG,¹¹C-FMZ,¹¹C-choline)PET/CT brain imaging epileptogenic zone for the positive detection rate of the Fisher’s exact test,get P<0.05（P=0.003）.That is to say,the positive detection rate of epileptic foci among the three groups is statistically different.Two kinds of imaging agents are compared by split chi-square.Comparison between ¹⁸F-FDG and ¹¹C-FMZ shows that P>0.017（P=0.244）,¹¹C-FMZ shows P>0.017（P=0.126）and ¹¹C-choline shows P<0.017（P=0.003）.In other words,the positive detection rate of ¹⁸F-FDG PET/CT was higher than that of ¹¹C-choline PET/CT.Interseizure(¹⁸F-FDG,¹¹C-FMZ,¹¹C-choline)PET/CT epileptogenic zone on the positioning accuracy of brain imaging by Fisher’s exact test,P<0.001,That is to say,the positive accuracy rate of epileptic foci among the three groups is statistically different.Two kinds of imaging agents are compared by split chi-square.¹⁸F-FDG and ¹¹C-FMZ epileptogenic zone on the positioning accuracy of the chi-squareX2=51.945,P<0.001.The accuracy of locating epileptic foci with ¹⁸F-FDG and ¹¹C-choline was P<0.001 by Fisher’s exact test,and the accuracy of locating epileptic foci with ¹¹C-FMZ and ¹¹C-choline was P>0.017（P=0.497）by Fisher’s exact test.In other words,¹¹C-choline and ¹¹C-FMZ PET/CT showed higher localization accuracy than ¹⁸F-FDG in epileptogenic foci.In the prospective study,25 of 46 patients were diagnosed as HS-RTLE and 21 were non-HS induced epilepsy.The sensitivity of ¹⁸F-FDG,¹¹C-FMZ,¹¹C-choline for HS epileptic foci were 92%（23/25）、92%（23/25）、84%（21/25）;The specificity of that were33.33%（7/21）、90.48%（19/21）、100%（21/21）;The accuracy of that were65.22%（30/46）、91.30%（42/46）、91.30%（42/46）;The positive predictivee value of that were62.16%（23/37）、92%（23/25）、100%（21/21）;The negative predictive value of that were 77.78%（7/9）、90.48%（19/21）、84%（21/25）.The areas under the curve of ¹⁸F-FDG,¹¹C-FMZ,¹¹C-choline were 0.627 and 0.912 and 0.920,respectively.The results of Delong test showed that the AUC of ¹¹C-choline and ¹¹C-FMZ was significantly higher than that of ¹⁸F-FDG（Z value:4.927,5.164,P<0.01）,and there was no statistical difference in the AUC between ¹¹C-choline and ¹¹C-FMZ（Z value:0.177,P=0.86>0.05）.There were statistical differences in the AUC between the single application and the combined application of the three imaging agents（P<0.05）.Conclusions:¹¹C-choline PET/CT could be used in the preoperative localization of epileptic foci.Compared with ¹⁸F-FDG and ¹¹C-FMZ PET/CT,the specificity of ¹¹C-choline PET/CT is higher,and the negative imaging of ¹¹C-choline is more significant for exclusion.