Abstract
Introduction Currently, there are no studies that evaluate the agreement between ultrasound (US) and magnetic resonance imaging (MRI) scans in rotator cuff (RC) tears by the observation of parameters such as the acromial index (AI) and critical shoulder angle (CSA). We hypothesize that the greater coverage of the footprint by increased AI or CSA could affect the proper visualization of the RC in US scans by its interposition between the tendinous complex and the US transducer.
Objective To estimate the agreement between US and MRI in the diagnosis of patients with RC tears confirmed by arthroscopy and with AI and CSA greater than the normal average values (0.7 and 35° respectively). The secondary objective is to determine if the diagnostic agreement is comparable regarding different types of tear (partial and complete).
Materials and Methods A retrospective study of a consecutive case series of 100 patients with partial or complete RC tears confirmed by arthroscopy.
Results The mean age of the study group was of 55.7 ± 10.5 years. The mean AI was of 0.77 ± 0.08, and the mean CSA was of 37.42° ± 5.88°. The agreement regarding the US, the MRI and the AI was > 0.7 of 56.7% (K = 0.27; p = 0.01); and < 0.7 of 35.7% (K = 0.01; p = 0.46) respectively. And the agreement regarding the US, the MRI and the CSA was > 35° of 61.5% (K = 0.32; p = 0.001); and < 35° of 33.3% (K = -0.00; p = 0.52) respectively.
Conclusion The diagnostic agreement of the US compared with the MRI, in patients with RC tears confirmed by arthroscopy and with AI and CSA greater than the normal average values was fair. The diagnostic agreement of the US compared with the MRI, in patients with AI and CSA lower than the normal average values was poor. The diagnostic performance of the IS and MRI was similar for partial and complete tears.
Keywords
rotator cuff - ultrasound - magnetic resonance imaging - acromial index - critical shoulder angle
