The Value Of ¹⁸F-FDG PET/MR For The Detection Of Epileptogenic Foci In Refractory Epilepsy With Negative Conventional MRI

PurposeTo investigate the value of ¹⁸F-FDG PET/MR for the detection of epileptogenic foci and surgical prognosis in conventional MRI-negative refractory epilepsy.MethodsResearch objectsClinical and ¹⁸F-FDG PET/MR imaging data of drug-refractory epilepsy diagnosed by the Department of Neurology of Henan Provincial People’s Hospital during October 2019 to April 2022 were collected.Inclusion criteria:（1）meet the diagnostic of clinical refractory epilepsy;（2）before PET/MRI imaging,the MRI within 2 months is negative.And two persons with intermediate or higher qualifications in nuclear medicine jointly read films to eliminate minor abnormalities;（3）informed consent for the PET/MR imaging and was seizure-free 2 days before and during the examination;（4）complete clinically relevant medical history and imaging data.Exclusion criteria:（1）conventional MRI positive;（2）contraindications related to ¹⁸F-FDG PET/MR examinations;（3）poor compliance and cooperation resulting in poor diagnostic quality of ¹⁸F-FDG PET/MR images;（4）people with current or previous mental illness or cerebrovascular disease;（5）lost contact after surgery.Image acquisition and result analysisThe imaging equipment is uPMR 790 PET/MR scanner,and the agent is ¹⁸F-FDG.MRI and PET start scanning together.The scanned raw data is processed and reconstructed by the internal machine and transferred to the reporting system workstation.The PET/MRI images of each patient were independently and double-blindly reviewed by a panel of two experienced nuclear medicine specialists of intermediate rank and above.In case of disagreement,the film is re-read by a third senior physician and a consensus opinion is obtained after discussion.PET brain metabolic images were analyzed visually,and abnormalities were considered when radioactive uptake was observed at two or more consecutive levels lower than the corresponding brain areas in the surrounding brain regions or the contralateral hemisphere,and if there was divergence,the asymmetry index was calculated by semi-quantitative analysis.The positive of ¹⁸F-FDG PET/MR fusion imaging means that any PET or MRI is positive.Statistical processingThe IBM SPSS Statistics（25.0）software was used to statistically analyze the data related to the 116 patients with conventional MRI-negative refractory epilepsy enrolled in this study.The measurement data conforming to normal distribution were expressed as mean±standard deviation（（?）±S）,while data not obeying normal distribution were expressed as median and interquartile range,M（P25,P75）,and the count data were expressed as number of cases and composition ratio（100%）were expressed,and Fisher’s exact probability method（sample size less than 40 cases）was used to compare between groups for the analysis of PET/MR data in 22 of 116 patients who eventually underwent surgery.When P<0.05,the difference was indicated as statistically significant.Results1.In this study,116 ¹⁸F-FDG PET/MR images were selected,there are 72 males and 44 females of them,aged 4～52 years old,average age 20.13±10.85 years old,initial onset age 2～42 years old,average onset age 12.85±9.16 years old,duration of epilepsy onset 1～31 years,average duration of epilepsy 7.28±6.23 years.2.Analysis of ¹⁸F-FDG PET/MR images in 116 patients with conventional MRI-negative refractory epilepsy revealed that 103（88.8%,103/116）patients exhibited hypoglucose metabolism on PET images,and 31（26.7%,31/116）of them had MRI images analyzed under ¹⁸F-FDG PET/MR fusion images that revealed minor The structural abnormal changes were consistent with the site of abnormal metabolism in PET,i.e.,the ¹⁸F-FDG PET/MR positive detection rate was 88.8%（103/116）in 116 patients with conventional MRI-negative refractory epilepsy.13 cases（11.2%,13/116）showed negative PET/MR results,with no abnormal metabolism seen in PET and no structural abnormalities seen in MRI.3.A total of 22 of the 116 included patients were eventually treated with surgical resection in neurosurgery after multidisciplinary consultation（MDT）for epilepsy at the request of the patients and their families.The analysis of the ¹⁸F-FDG PET/MR images of the 22 operated patients revealed that all 22patients（100%,22/22）showed glucose hypometabolism on PET images,including 16 patients（72.7%,16/22）with unilobar hypometabolism and 6 patients（27.3%,6/22）with multilobar hypometabolism;13patients（59.1%,13/22）had focal temporal lobe hypometabolism.The abnormal metabolism was located on the right side of the brain in 13 cases（59.1%,13/22）andon the left side of the brain in 9 cases（40.9%,9/22）;8 of 22 patients（36.4%,8/22）were found to have structural abnormalities on ¹⁸F-FDG PET/MR fusion images.The analysis revealed abnormal structural changes.100%of the 22 surgical patients（22/22）had a positive detection rate for ¹⁸F-FDG PET/MR..4.The pathological results of the 22 operated patients showed that the epileptogenic foci were located in the temporal lobe in 17 cases（FCDⅠa in 3 cases,Ⅱa in 9 cases,Ⅱb in 2 case,and hippocampal sclerosis in 3 cases）,in the frontal lobe in 4 cases（all FCDⅡa）and in the parietal lobe in 1 case（FCDⅠa）.All patients were followed up for more than 1 year,and Engel grade I and II were considered as good prognosis,and Engel grade III and IV were considered as poor prognosis.22 cases in this group had good prognosis in 16 cases（15 cases in the temporal lobe and 1 case in the frontal lobe）and poor prognosis in 6cases（2 cases in the temporal lobe,3 cases in the frontal lobe,and 1 case in the parietal lobe）.5.Among the 22 operated patients,13 cases showed focal temporal lobe hypometabolism,and all of them had a good prognosis after surgery,and no one had a poor prognosis after surgery;9 cases showed abnormal metabolism outside the temporal lobe,and 3 cases had a good prognosis after surgery,and 6 cases had a poor prognosis after surgery.Statistical correlation analysis showed a statistical difference between the presence or absence of extratemporal lobe abnormal metabolism on ¹⁸F-FDG PET/MR imaging and surgical prognosis in patients with conventional MRI-negative refractory epilepsy（P=0.001,P<0.05）.6.Among the 22 surgical patients,¹⁸F-FDG PET/MR abnormal metabolism showed single lobes in 16 cases:14 cases with good postoperative prognosis and 2 cases with poor prognosis;abnormal metabolism showed multiple lobes in 6 cases:2 cases with good postoperative prognosis and 4 cases with poor prognosis.Statistical correlation analysis showed a statistical difference between the number of¹⁸F-FDG PET/MR imaging abnormal metabolic lobes and surgical prognosis in patients with conventional MRI-negative refractory epilepsy（P=0.025,P<0.05）.Conclusion1.¹⁸F-FDG PET/MR imaging has a high sensitivity for the detection of epileptogenic foci in conventional MRI-negative refractory epilepsy,and the detection rate of MRI abnormalities can be improved to a certain extent by PET/MR fusion image analysis.2.¹⁸F-FDG PET/MR imaging combines the metabolic advantages of single PET imaging with the anatomical advantages of single MRI,providing a reliable basis for preoperative localization and surgical treatment of epileptogenic foci in conventional MRI-negative refractory epilepsy.3.The metabolic pattern of ¹⁸F-FDG PET/MR imaging correlates with surgical prognosis.The site and number of lobe of brain metabolic abnormalities can indicate the prognosis of surgery in patients with conventional MRI-negative refractory epilepsy.