Chalmers PN, et al. - Authors ascertained if computed tomography (CT) provided an equivalent measurement of cuff muscle area to a previously validated magnetic resonance imaging (MRI) measurement. On both CT and MRI scans, experts measured the area of the supraspinatus, infraspinatus–teres minor, and subscapularis on 2 standardized slices as previously described. With previously validated reliability and accuracy, CT provided nearly equivalent measures of cuff muscle area to an MRI technique. While the infraspinatus area was underestimated by CT vs MRI, the difference was less than 1cm² and therefore likely clinically insignificant.