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K. Hoshikawa1, R. Oishi2, T. Yuri3, T. Uno2, J. Nagai2, H. Giambini4, N. Mura1
1Yamagata Prefectural University of Health Sciences, Physical Therapy, Yamagata, Japan, 2Yamagata University, Medicine, Yamagata, Japan, 3Yamagata Prefectural University of Health Sciences, Occupational Therapy, Yamagata, Japan, 4The University of Texas at San Antonio, Biomedical Engineering, San Antonio, United States
Background: Quantification of rotator cuff muscles fatty infiltration is important for clinical decision-making in patients with rotator cuff tears. The Goutallier classification [Goutallier 1994] is the most commonly used method and has been demonstrated to be correlated to the function of the fatty degenerated supraspinatus muscle [Yuri 2018]. However, it is a qualitative evaluation with poor reproducibility.
Purpose: The purpose of this study was to perform a quantitative analysis of fatty infiltration in the supraspinatus muscle using standard T1-weighted MR images and compare the outcomes to Goutallier classifications.
Methods: Forty-one patients (mean age 64.7±7.8; 30 males and eleven females) who underwent rotator cuff tear repair surgery were selected for the evaluations. Fatty infiltration (%) was evaluated
1) in the whole area and
2) in the intramuscular area of the supraspinatus muscle, using the Otsu thresholding technique [Otsu 1979], which mathematically determines an optimal threshold value that separates the image pixels into bright and dark colors by analyzing the distribution of the pixel intensities within the T1-weighted oblique sagittal-plane MRI images in which the scapular spine leads to the Y-section.
Goutallier classification was used to classify the same MRI images [Goutallier, 1994]. Real time tissue elastography (RTE) was implemented to evaluate muscle activity. Before surgery and during RTE assessment, participants were instructed to sit on a chair with the affected arm resting on a table and the shoulder abducted to 60 degrees for the scapular plane and in neutral rotation. Muscle elasticity outcomes were obtained at rest and during isometric contraction of the supraspinatus muscle belly. Muscle activity, a surrogate for contractility, was defined as the difference between the elasticities measured at rest and during isometric contraction. A one-way ANOVA and Spearman correlation were used to compare with the Goutallier classifications and fatty infiltration (%). Significance was set at p<0.05.
1) in the whole area and
2) in the intramuscular area of the supraspinatus muscle, using the Otsu thresholding technique [Otsu 1979], which mathematically determines an optimal threshold value that separates the image pixels into bright and dark colors by analyzing the distribution of the pixel intensities within the T1-weighted oblique sagittal-plane MRI images in which the scapular spine leads to the Y-section.
Goutallier classification was used to classify the same MRI images [Goutallier, 1994]. Real time tissue elastography (RTE) was implemented to evaluate muscle activity. Before surgery and during RTE assessment, participants were instructed to sit on a chair with the affected arm resting on a table and the shoulder abducted to 60 degrees for the scapular plane and in neutral rotation. Muscle elasticity outcomes were obtained at rest and during isometric contraction of the supraspinatus muscle belly. Muscle activity, a surrogate for contractility, was defined as the difference between the elasticities measured at rest and during isometric contraction. A one-way ANOVA and Spearman correlation were used to compare with the Goutallier classifications and fatty infiltration (%). Significance was set at p<0.05.
Results: The mean activity value of the supraspinatus muscle was 0.72 ± 0.30. Goutallier stage of grade 0 was present in seventeen patients, grade 1 in fifteen, grade 2 in six, and grade 3 in three. Fatty infiltration (%) in the whole area and the intramuscular area of the supraspinatus muscle were significantly different between various Goutallier grades (p<0.02). Fatty infiltration (%) in the whole area and the intramuscular area of the supraspinatus muscle significantly correlated with the activity value of the supraspinatus muscle (r=-0.583, p<0.001; r=-0.652, p<0.001), as in the Goutier classification (r=-0.659, p<0.001).
Conclusions: Quantitative fatty infiltration analysis resulted in comparable outcomes as compared to the conventional Goutallier grades. This method can serve as an alternative and quantitative approach for accurate fat evaluations in rotator cuff muscles.
Implications: The proposed analysis quantifies the rotator cuff muscular fatty infiltration and may contribute to selecting the most appropriate rehabilitation and surgical procedure.
Funding acknowledgements: This study was supported by a Grant-in-Aid for JSPS fellows (Grant number 22J22344).
Keywords:
Supraspinatus
Fatty infiltration analysis
Reel time tissue elastography
Supraspinatus
Fatty infiltration analysis
Reel time tissue elastography
Topics:
Musculoskeletal
Musculoskeletal: upper limb
Orthopaedics
Musculoskeletal
Musculoskeletal: upper limb
Orthopaedics
Did this work require ethics approval? Yes
Institution: Yoshioka Hospital, Tendo, Japan
Committee: Yoshioka Hospital
Ethics number: No. YHTB-2020-011
All authors, affiliations and abstracts have been published as submitted.
