PET of Serotonin 1A Receptors and Cerebral Glucose Metabolism for Temporal Lobectomy

The objective of this study was to compare 5-hydroxytryptamine receptor 1A (5-HT1A) PET with cerebral metabolic rate of glucose (CMRgIc) PET for temporal lobectomy planning. Methods: We estimated 5-HT1A receptor binding preoperatively with F-18-trans-4-fluoro-N-2-[4-(2-methoxyphenyl) piperazin-1-yl]ethyl-N-(2-pyridyl) cyclohexane carboxamide (F-18-FCWAY) PET and CMRgIc measurement with F-18-FDG in regions drawn on coregistered MRI after partial-volume correction in 41 patients who had anterior temporal lobectomy with at least a 1-y follow-up. Surgery was tailored to individual preresection evaluations and intraoperative electrocorticography. Mean regional asymmetry values and the number of regions with asymmetry exceeding 2 SDs in 16 healthy volunteers were compared between seizure-free and non-seizure-free patients. F-18-FCWAY but not F-18-FDG and MRI data were masked for surgical decisions and outcome assessment. Results: Twenty-six of 41 (63%) patients seizure-free since surgery had significantly different mesial temporal asymmetries, compared with 15 non-seizure-free patients for both F-18-FCWAY (F-1.39 = 5.87; P = 0.02) and F-18-FDG PET (F-1.38 = 5.79; P = 0.021). The probability of being seizure-free was explained by both F-18-FDG and F-18-FCWAY PET, but not MRI, with a significant additional F-18-FCWAY effect (chi(2)(2) = 9.8796; P = 0.0072) after the probability of being seizure-free was explained by F-18-FDG. Although MRI alone was not predictive, any combination of 2 lateralizing imaging studies was highly predictive of seizure freedom. Conclusion: Our study provides class III evidence that both 5-HT1A receptor PET and CMRgIc PET can contribute to temporal lobectomy planning. Additional studies should explore the potential for temporal lobectomy based on interictal electroencephalography and minimally invasive imaging studies.