title: Quantitative Shear-Wave US Elastography of the Supraspinatus Muscle: Reliability of the Method and Relation to Tendon Integrity and Muscle Quality.
abstract: OBJECTIVE
  To evaluate the reliability of ultrasonographic (US) elastography of the supraspinatus (SSP) muscle, define normal shear-wave velocity (SWV) values, and correlate findings with tendon integrity and muscle quality.
  
  
  METHODS
  The study was approved by the local ethics committee, and written informed consent was obtained from all patients. SSP SWV (in meters per second) was prospectively assessed twice in 22 asymptomatic volunteers (mean age ± standard deviation, 53.8 years ± 15.3; 11 women and 11 men) by two independent examiners by using shear-wave elastography. Forty-four patients (mean age, 51.9 years ± 15.0; 22 women and 22 men) were prospectively included. SWV findings were compared with tendon integrity, tendon retraction (Patte classification), fatty muscle infiltration (Goutallier stages 0-IV), and muscle volume atrophy (tangent sign) on magnetic resonance (MR) images. Descriptive statistics, Spearman correlation, analysis of variance, two-sample t test, and intraclass correlation coefficient (ICC) were used.
  
  
  RESULTS
  Test-retest reliability for mean total SWV (MTSWV) was good for examiner 1 (ICC = 0.70; 95% confidence interval [CI]: 0.30, 0.87; P = .003) and excellent for examiner 2 (ICC = 0.80; 95% CI: 0.53, 0.92; P < .001). Interexaminer reliability was excellent (ICC = 0.89; 95% CI: 0.64, 0.96; P < .001). MTSWV in volunteers (3.0 m/sec ± 0.5) was significantly higher than that in patients (2.5 m/sec ± 0.5; P = .001). For tendon integrity, no significant difference in MTSWV was found. For tendon retraction, MTSWV varies significantly between patients with different degrees of retraction (P = .047). No significant differences were found for Goutallier subgroups. MTSWV was significantly lower with a positive tangent sign (P = .015; n = 10).
  
  
  CONCLUSIONS
  Shear-wave elastography is reproducible for assessment of the SSP muscle. Mean normal SSP SWV is 3.0 m/sec ± 0.5. SWV decreases with increasing fat content (Goutallier stage 0-III) and increases in the final stage of fatty infiltration (Goutallier stage IV).
authors.affiliation: From the Departments of Radiology (A.B.R., C.E., F.M.B., C.W.A.P.), Orthopedic Surgery (C.G.), and Orthopedic Research (M.F.), Orthopedic University Hospital Balgrist, Forchstrasse 340, CH-8008 Zurich, Switzerland; and University of Zurich, Faculty of Medicine, Zurich, Switzerland (A.B.R., C.E., F.M.B., C.G., M.F., C.W.A.P.).
authors.forename: Andrea B
authors.initials: AB
authors.lastname: Rosskopf
authors.affiliation: From the Departments of Radiology (A.B.R., C.E., F.M.B., C.W.A.P.), Orthopedic Surgery (C.G.), and Orthopedic Research (M.F.), Orthopedic University Hospital Balgrist, Forchstrasse 340, CH-8008 Zurich, Switzerland; and University of Zurich, Faculty of Medicine, Zurich, Switzerland (A.B.R., C.E., F.M.B., C.G., M.F., C.W.A.P.).
authors.forename: Christine
authors.initials: C
authors.lastname: Ehrmann
authors.affiliation: From the Departments of Radiology (A.B.R., C.E., F.M.B., C.W.A.P.), Orthopedic Surgery (C.G.), and Orthopedic Research (M.F.), Orthopedic University Hospital Balgrist, Forchstrasse 340, CH-8008 Zurich, Switzerland; and University of Zurich, Faculty of Medicine, Zurich, Switzerland (A.B.R., C.E., F.M.B., C.G., M.F., C.W.A.P.).
authors.forename: Florian M
authors.initials: FM
authors.lastname: Buck
authors.affiliation: From the Departments of Radiology (A.B.R., C.E., F.M.B., C.W.A.P.), Orthopedic Surgery (C.G.), and Orthopedic Research (M.F.), Orthopedic University Hospital Balgrist, Forchstrasse 340, CH-8008 Zurich, Switzerland; and University of Zurich, Faculty of Medicine, Zurich, Switzerland (A.B.R., C.E., F.M.B., C.G., M.F., C.W.A.P.).
authors.forename: Christian
authors.initials: C
authors.lastname: Gerber
authors.affiliation: From the Departments of Radiology (A.B.R., C.E., F.M.B., C.W.A.P.), Orthopedic Surgery (C.G.), and Orthopedic Research (M.F.), Orthopedic University Hospital Balgrist, Forchstrasse 340, CH-8008 Zurich, Switzerland; and University of Zurich, Faculty of Medicine, Zurich, Switzerland (A.B.R., C.E., F.M.B., C.G., M.F., C.W.A.P.).
authors.forename: Martin
authors.initials: M
authors.lastname: Flück
authors.affiliation: From the Departments of Radiology (A.B.R., C.E., F.M.B., C.W.A.P.), Orthopedic Surgery (C.G.), and Orthopedic Research (M.F.), Orthopedic University Hospital Balgrist, Forchstrasse 340, CH-8008 Zurich, Switzerland; and University of Zurich, Faculty of Medicine, Zurich, Switzerland (A.B.R., C.E., F.M.B., C.G., M.F., C.W.A.P.).
authors.forename: Christian W A
authors.initials: CW
authors.lastname: Pfirrmann
mesh_terms: D000273:Adipose Tissue / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D054459:Elasticity Imaging Techniques; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000473:pathology*; D056888:Patient Positioning; D015203:Reproducibility of Results; D017006:Rotator Cuff / Q000473:pathology*; D052256:Tendinopathy / Q000175:diagnosis*
chemical_list: D003287:Contrast Media