Background: To examine whether there is a significant correlation between the clinical severity of cervical dystonia (CD) and 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) findings and to determine the threshold of the clinical severity of CD for acquisition of positive 18F-FDG PET/CT study findings.
Methods: Forty-seven subjects who showed 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 the 18F-FDG PET/CT study. The correlation between the clinical severity of CD and the highest SUVmax was examined. The threshold of the clinical severity of CD for obtaining positive 18F-FDG PET/CT findings was determined using receiver operating characteristics curve analysis.
Results: Thirty-three subjects (70.21%) out of 47 showed positive 18F-FDG PET/CT findings. The most frequently involved, top 3 rotators were ipsilateral splenius capitis/cervicis, oblique capitis inferior and longus colli/capitis. The highest SUVmax of 18F-FDG PET/CT showed a significant correlation with the TWSTRS. All subjects with a total TWSTRS of more than 39 showed positive 18F-FDG PET/CT findings, and all subjects with a total TWSTRS of 22 or less showed negative 18F-FDG PET/CT study results. The cutoff value of the total TWSTRS for positive 18F-FDG PET/CT findings was set at 27.5, with 90.9% sensitivity and 64.3% specificity.
Conclusions: This study demonstrated a significant correlation between the clinical severity of CD and 18F-FDG PET/CT findings, providing a threshold of the clinical severity of CD for acquisition of positive 18F-FDG PET/CT findings. In conclusion, these findings are suggestive of the usefulness of 18F-FDG PET/CT for identification of dystonic muscles of CD with moderate to severe severity and further studies are required to verify these findings.
