Christian Sander Geannette MD, Abstract Co-Author: Nothing to Disclose

Yoshimi Endo MD, Presenter: Nothing to Disclose

Ronald Steven Adler MD, PhD, Abstract Co-Author: Nothing to Disclose

Assessment of echogenicity provides a measure of muscle atrophy during routine shoulder US. However, muscle echogenicity is subjective with significant inter- and intra-observer variability. This study sought to determine the value of quantifying muscle echogenicity in order to estimate the degree of rotator cuff atrophy as determined by MRI.

This was a retrospective review of patients who underwent ultrasound and MR shoulder examinations. The supraspinatus (SSM), infraspinatus (ISM) and teres minor (TM) muscles were evaluated. Muscle echogenicity was quantified using image analysis software and represented as dB (decibels)/mm2. 5 mm ROIs were randomly placed in the short-axis view of each muscle group, avoiding the myotendinous junction. On MR, muscle atrophy was scored in two ways: degree of fatty infiltration (Goutallier classification) and loss of muscle bulk (occupational ratios), provided by consensus of two musculoskeletal radiologists.

A total of 27 SSM, 32 ISM, and 32 TM muscles were evaluated. Goutallier scores were scored: 0: normal, 1: more muscle than fat, 2:equal muscle and fat, 3: more fat than muscle. Muscle echogenicity means were: SSM (mean: 42.7), ISM (53.81) and TM (46.89) dB/mm2. Spearman's rank correlation coefficient demonstrates moderate positive correlation between SSM and ISM gray values and Goutallier scores (0.54). Spearman's rank correlation coefficient demonstrates weak positive correlation between TM and Goutallier score (0.33). Spearman's rank correlation was weak between SSM and ISM gray value and occupational ratio.

Muscle echogenicity on US demonstrates moderate correlation of the supraspinatus and infraspinatus muscles when compared to MRI Goutaillier classification.

Muscle echogenicity on US relates in part to rotator cuff fatty infiltration and may provide valuable information during routine shoulder ultrasound. The paucity of Goutallier grade 2 and 3 muscles may account for the absence of a stronger correlation with muscle echogenicity and should be further investigated.  

Geannette, C, Endo, Y, Adler, R, Quantification of Rotator Cuff Muscle Atrophy: A Retrospective Study Comparing Ultrasound to MRI.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14005694.html