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.