Fast spin echo-T2-weighted sequences with fat saturation in toe dactylitis of spondyloarthritis.

We aimed to establish by using fast spin echo (FSE)-T2-weighted sequences with fat saturation if flexor tendon enthesitis is the primary lesion in spondyloarthritis (SpA) toe dactylitis. Consecutive patients showing toe dactylitis and meeting Amor criteria for the classification of SpA were enrolled. Dactylitic toes and their corresponding normal contralateral digits were studied by FSE-T2-weighted sequences with fat saturation. Twelve dactylitic toes belonging to ten SpA patients were studied. All dactylitic toes showed mild-to-moderate fluid collection in the synovial sheaths of flexor digitorum brevis and longus. Involvement of joint cavity was simultaneously seen in at least one joint of eight (66.6%) out of the 12 toes. A mild-to-severe peritendinous soft tissue edema was observed in all but one of the affected toes. In no dactylitic toe was bone edema observed either near the insertions of the flexor digitorum brevis and longus tendons or in other sites of the phalanges. No lesions were observed in the 12 contralateral clinically normal toes. In SpA toe dactylitis there is no evidence of enthesitis of the flexor digitorum brevis and longus tendons and joint capsules.