The anterior cingulate cortex (ACC) seems to play an important role in behavioral deficits and executive dysfunctions in patients with behavioral variant frontotemporal dementia (bvFTD), while its specific and independent contribution requires clarification.To identify whether ACC abnormalities in gray matter (GM) volume and standardized uptake value ratio (SUVR) images are associated with disease severity of bvFTD, by analyzing hybrid T1 and 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET).We enrolled 21 bvFTD patients and 21 healthy controls in the study. Each subject underwent a hybrid PET/MRI study and a standardized neuropsychologic assessment battery. GM volume and SUVR are voxel-wise calculated and compared. Then we estimate the mean value inside ACC for further partial Pearson's correlation to explore the association between GM volume/SUVR of the ACC and severity of behavioral deficit as well as executive dysfunction.ACC was shown to be involved in both atrophy and hypometabolism patterns. The partial Pearson's correlation analysis showed that the SUVR of the ACC was strongly correlated with frontal behavior inventory total score (left r = -0.85, right r = -0.85, p < 0.0001), disinhibition subscale score (left r = -0.72, p = 0.002; right = -0.75, p < 0.0001), and apathy subscale score (left = -0.87, right = -0.85, p < 0.0001).These findings demonstrated decreased ACC activity contributes to behavioral disturbances of both apathetic and disinhibition syndromes of bvFTD, which can be sensitively detected using 18F-FDG PET.