MRI goutallier classification, DECT and MRI IDEAL for evaluating supraspinatus fatty infiltration: A prospective comparison

BACKGROUND: The Goutallier classification has been used worldwide for evaluating fatty infiltration of rotator cuff muscles, but offers relatively low interobserver reliability because visual evaluations are subjective. We previously evaluated fatty infiltration of rotator cuff muscles using dual-energy computed tomography (DECT) in patients with rotator cuff tears and reported a significant positive correlation between the intramuscular muscle-to-fat ratio and the Goutallier stage. This study aimed to investigate the relationship between the Goutallier classification, DECT and iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) for fatty infiltration of the supraspinatus muscle in patients with rotator cuff tears. METHODS: This study examined 90 patients (92 shoulders; 50 men, 40 women; mean age, 71 years). Fatty infiltration of the supraspinatus was evaluated qualitatively by the Goutallier classification using magnetic resonance imaging (MRI), and quantitatively by both intramuscular muscle-to-fat ratio using DECT (DECT-%f/m) and fat fraction using IDEAL (IDEAL-ff). Each assessment was performed by three orthopedic surgeons independently. We evaluated the following: 1) interobserver reliability of the Goutallier classification and DECT-%f/m and IDEAL-ff; and 2) correlations between each evaluation. RESULTS: was 0.921 for DECT-%f/m and 0.983 for IDEAL-ff. Significant positive correlations with the Goutallier classification were seen for both DECT-%f/m and IDEAL-ff. Moreover, DECT-%f/m and IDEAL-ff displayed a significant positive correlation. CONCLUSIONS: Interobserver reliabilities were higher for both DECT-%f/m and IDEAL-ff than for the Goutallier classification, and both correlated positively with the Goutallier classification and with each other. These findings suggest that quantitative evaluations such as DECT-%f/m and IDEAL-ff may prove useful for assessing fatty infiltration of rotator cuff muscles, and DECT may be useful for evaluating the condition of rotator cuff muscle in patients who cannot be examined using MRI.