Shadpour Demehri MD, Presenter: Nothing to Disclose

Frank John Rybicki MD, PhD, Abstract Co-Author: Research grant, Toshiba Corporation Research grant, Bracco Group

Kirstin Marie Shu Small MD, Abstract Co-Author: Nothing to Disclose

Nehal Atul Shah MD, Abstract Co-Author: Nothing to Disclose

Michael Lally Steigner MD, Abstract Co-Author: Nothing to Disclose

Stacy Elaine Smith MD, Abstract Co-Author: Nothing to Disclose

To assess the supraspinatus (SS) muscle volume, its normalized value using teres minor as a reference standard, as well as other traditional metrics of SS muscle atrophy such as scapular ratio in predicting conservative treatment outcome in patients 40 years or older.

This IRB-approved, HIPAA-compliant study retrospectively reviewed 403 consecutive unenhanced shoulder MRIs performed in a single outpatient orthopedic clinic. Of 403 MRIs, 147 MRIs were interpreted as partial thickness tear of SS tendon in patients 40 years or older. Of these, a discernible outcome could be established in 72 MRI studies (M/F=0.97, mean age: 56 years, range: 40-86). Using commercial image post-processing software, two observers in consensus measured the SS volume using planimetry. The teres minor (TM) muscle volume (used to normalize the SS volume as SS/TM volume ratio) and the scapular ratio were measured. The observers also graded the depth of SS tendon partial-thickness tears as high-grade (> 50%) and low-grade (≤ 50%) tears. Receiver operating characteristic (ROC) analysis was used to compare the accuracy of volumetric measurements with scapular ratio for predicting the conservative treatment outcome.

Seventeen (24%) patients showed no improvement following the course of conservative treatment. SS/TM volume ratios, SS volumes, and scapular ratios in patients with successful conservative treatment (1.56 (p<0.001), 44 mm3 (p=0.06), and 1.04 (p=0.28), respectively) were compared to those that failed conservative management (1.16, 37 mm3, and 0.99 respectively). In patients with successful conservative treatment outcome, 16% had high-grade partial-thickness tear as opposed to 35% in patients who failed conservative management (p=0.16). The area under the ROC curve (AUC) of SS/TM volume ratios (0.79; p=0.02) was larger than the AUC (0.64) for SS volume or AUC (0.6) for scapular ratio measurements.

In comparison with scapular ratio and SS volume, normalized SS volume using TM as a reference standard has superior accuracy in predicting the success of conservative treatment in patients with partial thickness SS tear.

MRI-based methods can be used to measure supraspinatus volume and determine its normalized value using teres minor volume as reference standard that can predict the success of conservative treatment.

Demehri, S, Rybicki, F, Small, K, Shah, N, Steigner, M, Smith, S, MRI-based Volumetric Quantification of Supraspinatus as a Predictor for Conservative Management Outcome: A Retrospective Study in Patients with Partial-Thickness Supraspinatus Tendon Tear.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11005071.html