Objective:To explore the potential clinical value of 99Tc m-methoxyisobutylisonitrile(MIBI) SPECT/CT muscle imaging in the diagnosis of cervical dystonia (CD). Methods:From January 2021 to April 2022, 50 patients with CD (14 males, 36 females; age (45.8±12.5) years) who were treated in Second Affiliated Hospital of Soochow University were prospectively included. The 99Tc m-MIBI SPECT/CT muscle imaging results of 400 pieces of muscle (bilateral sternocleidomastoid, musculus scapulae, splenius capitis and musculus trapezius; each of 100 pieces) in 50 patients were analyzed and divided into the dystonic muscle group and normal muscle group according to the electromyography (EMG). Toronto western spasmodic torticollis rating scale (TWSTRS) score, SUV max and target-to-background ratio (TBR) of single superficial cervical muscle and total cervical muscle, and EMG diagnosis results were obtained before botulinum toxin injection. ROC curves of SUV max and TBR of dystonic muscles were constructed to determine AUCs and the difference was compared by Delong test. Differences of SUV max and TBR between 2 groups were analyzed by Mann-Whitney U test. Spearman rank correlation analysis was used to analyze the correlation of SUV max, TBR and TWSTRS scores of total cervical muscle. Results:There were 205 pieces of muscle in dystonic muscle group and 195 pieces of muscle in normal muscle group. The uptake of 99Tc m-MIBI in dystonic muscle was significantly increased in CD patients, and the non-whole uptake of 99Tc m-MIBI was increased in some dystonic muscles, which was manifested as uneven uptake of the whole muscle. The sensitivity, specificity, accuracy, positive predictive value and negative predictive value of visual analysis were 95.12%(195/205), 75.90%(148/195), 85.75%(343/400), 85.58%(195/242) and 93.67%(148/158), respectively. There were significant differences of SUV max (1.74(1.42, 2.12) vs 0.92(0.81, 0.99)) and TBR (2.55(1.92, 3.27) vs 1.44(1.22, 1.73)) between the dystonic muscle group and the normal muscle group ( z value: -15.29, -12.69, both P<0.001). The diagnostic efficiency of SUV max in dystonic muscle was better than TBR (AUC: 0.942 vs 0.867; z=5.03, P<0.001). SUV max, TBR and TWSTRS score in the neck muscles of patients with CD showed positive correlation ( rs values: 0.44, 0.45, both P<0.001). Conclusion:99Tc m -MIBI SPECT/CT muscle imaging is a good diagnostic method for dystonic muscle in patients with CD.