Pectoralis major muscle and tendon tears: diagnosis and grading using magnetic resonance imaging

Objective. To assess the accuracy and utility of magnetic resonance (MR) im aging in the detection and grading of pectoralis major muscle and tendon te ars. Design and patients. A retrospective review was carried out of 10 patients referred for MR imaging for suspected pectoralis muscle injury and possible operative therapy. The pectoralis muscle and tendon were imaged using thin (3-4 mm) axial sections with a variety of sequences combined for anatomica l delineation (T1-weighted SE or PD SE) and fluid detection (T2-weighted SE , T2-weighted FSE with fat suppression, or STIR). Surgical correlation was available in six patients. Clinical follow-up was available in four patient s treated by nonoperative therapy. Results. MR imaging identified five complete tears, four partial tears and one normal tendon. One complete and one partial tear were at the myotendino us junction. The remaining seven injuries were at the enthesis. Surgical co rrelation consisted of five complete tears and one partial tear. One comple te and one partial tear were at the myotendinous junction with the remainin g four complete tears at the enthesis. The MR interpretation and surgical f indings were in agreement in all six cases. All four patients treated with nonoperative therapy demonstrated improvement at a clinical follow-up exami nation, with restoration of function and strength consistent with a healed prior partial injury. Conclusion. MR imaging is accurate and useful in detecting and grading tear s involving the pectoralis major muscle and tendon, facilitating the identi fication of patients with complete tears who are candidates for operative t herapy.