Abstract： Objective:To analyze the differences in 18F-fluorodeoxyglucose (FDG) PET/CT imaging and preoperative localization between patients with temporal lobe epilepsy (TLE) and extratemporal epilepsy (ETLE) caused by focal cortical dysplasia (FCD). Methods:From April 2015 to August 2018, a total of 71 patients (45 males, 26 females, age (24.3±9.1) years) with refractory epilepsy who underwent 18F-FDG PET/CT imaging before surgery and confirmed as FCD by pathology in Xuanwu Hospital were retrospectively analyzed. Patients were divided into TLE and ETLE groups based on pathological results. 18F-FDG PET/CT images were analyzed qualitatively and compared with the operation result, then region of interest (ROI) was used to calculate the asymmetry index (AI), and evaluated the hypometabolism of every cerebral region by |AI| semi-quantitatively. Engle classification were followed-up after surgery. Independent-sample t test and χ2 test were used to analyze data. Results:Of 71 FCD patients, 35 were TLE and 36 were ETLE. The onset age of ETLE patients were younger than TLE patients ((10.1±6.5) vs (14.9±9.7) years; t=2.48, P=0.02). In TLE group, 54.29%(19/35) were completely consistent with the operation results, and 42.86%(15/35) showed hypometabolized brain regions in extratemporal lobe. In ETLE group, 27.78%(10/36) were completely consistent with the operation results, and 47.22%(17/36) showed hypometabolized brain regions in temporal lobe. There were significant differences in the lateral accuracy and positioning accuracy of 18F-FDG PET/CT between TLE and ETLE patients (97.14%(34/35) vs 75.00%(27/36), 54.29%(19/35) vs 27.78%(10/36); χ2 values: 7.19, 6.27, both P<0.05). There was no significant difference in |AI| values between the brain regions of TLE and ETLE patients ( z values: from -1.25 to -0.06, all P>0.05). Conclusion:The lateral accuracy and positioning accuracy of 18F-FDG PET/CT in TLE patients are better than that in ETLE patients.