Contracture of the deltoid muscle: sonographic evaluation with MRI correlation

OBJECTIVE: This article evaluates the sonographic features of deltoid contracture (DC) with MRI correlation. MATERIAL AND METHODS: Two reviewers evaluated the imaging features in 22 painful shoulders of 20 patients with a sonographic diagnosis of DC and a subsequent confirming MRI study. The sonographic and MRI findings with regard to the lesion extent (assessed by a 3-point scale: 1 = less than or equal to one third of the longitudinal deltoid length involved, 2 = greater than one third and less than or equal to two thirds involved, and 3 = greater than two thirds involved), transverse lesion morphologic appearance, and maximal transverse diameter measured were compared with kappa statistics and Wilcoxon's signed rank test, respectively. RESULTS: Compared with MRI, there were two false-positive diagnoses of DC on sonography. Among the 20 true-positive diagnoses, sonography showed good agreement with MRI in assessing the lesion extent (kappa = 0.796, p < 0.001). Three sonographic lesion morphologic patterns for hyperechoic lesions (I = with multiple < 8-mm hypoechoic spots, II = heteroechoic lesions with predominant 8-15-mm hypointense areas, and III = > 15-mm calcified nodules, respectively) showed excellent agreement with three MRI lesion patterns (I = multiple < 8-mm hypointense spots, II = predominant 8-15-mm hypointense areas, and III = > 15-mm hypointense nodules, respectively) (kappa = 0.921, p < 0.001). However, the maximum lesion diameters appeared significantly larger on sonography than on MRI (2.8 +/- 0.6 cm vs 2.0 +/- 0.8 cm, mean +/- SD; p < 0.001), which was plausibly ascribed to the better sonographic delineation of hyperechoic immature fibrotic tissues. CONCLUSION: Sonography is helpful for evaluating DC and correlates well with MRI.