Fast spin echo-T2-weighted sequences with fat saturation in dactylitis of spondylarthritis: No evidence of entheseal involvement of the flexor digitorum tendons

Objective. To establish by means of fast spin echo (FSE)-T2-weighted sequences with fat saturation if enthesitis of the flexor digitorum superficialis and profundus tendons is the primary lesion in spondylarthritis (SpA) finger dactylitis. Methods. Eleven dactylitic fingers and their corresponding normal, contralateral fingers, belonging to 6 patients who met the Amor criteria for SpA, were studied by FSE-T2-weighted sequences with fat saturation. Results. All dactylitic fingers showed moderate or severe fluid collection in the flexor tendon synovial sheaths. Involvement of the joint cavity was simultaneously present in at least one joint in 3 (27.3%) of the 11 fingers. A mild to moderate peritendinous soft tissue edema was observed in 5 (45.5%) of the 11 affected fingers. In no dactylitic finger was bone edema observed near the insertions of the flexor digitorum superficialis or profundus tendons or in other sites of the phalanges. No lesions were observed in the 11 contralateral, clinically normal fingers. Conclusion. In SpA dactylitis there is no evidence of enthesitis of the flexor digitorum tendons and joint capsules.