Spin-echo and STIR MR imaging of sports-related muscle injuries at 1.5 T.

Seventy patients with clinically diagnosed athletic muscle injuries of varying severity were studied with MR imaging at 1.5 T. Twenty underwent follow-up MR studies. In all cases, SE T1-weighted and double-echo T2-weighted pulse sequences were used. These were supplemented by short T1 inversion recovery (STIR) sequence in 36 cases. Muscle injuries were more readily seen with STIR images than with SE T2-weighted images. In both initial assessment and follow-up of tears, the use of the STIR technique allowed the greatest lesion/muscle contrast. Short TR, short TE SE images provided anatomic detail and were an adjunct to T2-dependent SE images in the evaluation of organized hematomas (11 cases). Follow-up MR studies in 20 patients at variable time intervals allowed demonstration of regression of the tear in 11 cases, fibrous scar formation in 5 cases, and recurrence of the tear in 4 cases. Evolution of hematomas into scar and into cyst was demonstrated in three and two cases, respectively. Owing to the additive effect of T1 and T2 mechanisms, the STIR sequence is well suited for initial evaluation and can replace T2-weighted images in the follow-up of muscle trauma.