[The value of simultaneous 18F-FDG PET/MR in detecting intracranial tubers in tuberous sclerosis complex patients with epilepsy and imaging-related factors associated with the presence of tubers in the epileptogenic zone].

Abstract

Objective: To investigate the value of fluorine-18 fluorodeoxyglucose simultaneous positron emission tomography/magnetic resonance (¹⁸F-FDG PET/MR) in detecting intracranial tubers in tuberous sclerosis complex (TSC) patients with epilepsy, and analyze the imaging-related factors associated with the presence of intracranial tubers in the epileptogenic zone. Methods: Five TSC patients with epilepsy who visited Zhongshan hospital affiliated to Fudan University from 2018 to 2025 were included in this study. All of them underwent integrated ¹⁸F-FDG PET/MR. The MR sequences, including the T₁ weighted imaging (T₁WI), T₂ fluid attenuated inversion recovery (T₂-FLAIR) and double inversion recovery (DIR), were performed simultaneously with PET. The number of tubers detected by each MR and ¹⁸F-FDG PET/MR sequence using the Friedman test was compared. The tubers were categorized based on the patient's clinical symptoms, interictal or ictal EEG findings, and the nodules' location and characteristics. Tubers were classified as either in the epileptogenic zones or the non-epileptogenic zones. The multivariate logistic regression model was conducted to identify the imaging-related factors associated with the presence of intracranial tubers in the epileptogenic zone. Result: A total of five patients aged (20.80±2.95) years were enrolled, including three males and two females. There were significant differences in the number of tubers detected among the six sets of images from MR sequences and ¹⁸F-FDG PET/MR sequences in TSC patients with epilepsy (P<0.001), with the highest average number detected by ¹⁸F-FDG PET/T₂-FLAIR [M(Q₁, Q₃): 13(12, 18)]. ¹⁸F-FDG PET/T₂-FLAIR detected a total of 70 nodules in five patients, among which 17 nodules were located in the epileptogenic zone and the remaining 53 nodules were in the non-epileptogenic zone. The proportion of tubers [(64.71%, 11/17) vs (5.66%, 3/53)] (P<0.001) and DIR signal value [(366±110) vs (258±74)] in the epileptogenic zone with adjacent hypometabolic cortex were higher than those in the non-epileptogenic zone, while PET standard uptake value (SUV) [1.95 (1.66, 2.21) vs 3.05 (2.41, 3.88)] and T₁WI signal intensity [(182±31) vs (207±47)] were lower than that those in the non-epileptogenic zone (all P<0.05). Low PET SUV values (OR=0.066, 95%CI: 0.008-0.583) and the presence of adjacent hypometabolic cortex (OR=9.541, 95%CI: 1.277-71.263) were identified as two imaging-related factors associated with intracranial sclerotic tubers located in the epileptogenic zone. Conclusions: ¹⁸F-FDG PET/T₂-FLAIR is more effective in detecting intracranial tubers in patients with TSC and epilepsy. Low SUV values of intracranial tubers on PET images and the presence of adjacent hypometabolic cortex are the imaging-related factors for determining whether intracranial tubers are located in the epileptogenic zone.