Threshold of Clinical Severity of Cervical Dystonia for Positive 18F-FDG PET/CT

OBJECTIVE To examine whether the clinical severity of cervical dystonia (CD) significantly correlates with (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) findings as well as to determine the threshold of the clinical severity of CD for positive (18)F-FDG PET/CT study findings. METHODS Forty-seven subjects with torticollis as one of the symptoms of CD were included. The clinical severity of CD was evaluated with the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) at the time of (18)F-FDG PET/CT. The correlation between the clinical severity of CD and the highest SUVmax was examined. The threshold of the clinical severity of CD necessary for positive (18)F-FDG PET/CT findings was determined using receiver operating characteristics curve analysis. RESULTS Thirty-three of the 47 subjects (70.21%) showed positive (18)F-FDG PET/CT findings. The ipsilateral splenius capitis/cervicis, oblique capitis inferior, and longus colli/capitis were the rotators most frequently involved. The highest SUVmax of (18)F-FDG PET/CT was significant correlated with the TWSTRS. Subjects with a total TWSTRS exceeding 39 showed positive (18)F-FDG PET/CT findings, with those having a total TWSTRS ≤22 showing negative (18)F-FDG PET/CT results. The cutoff value of the total TWSTRS for positive (18)F-FDG PET/CT findings was set at 27.5 with 90.9% sensitivity and 64.3% specificity. CONCLUSION A significant correlation was evident between the clinical severity of CD and (18)F-FDG PET/CT findings, providing a threshold of the clinical severity of CD for acquisition of positive (18)F-FDG PET/CT findings.