Quantitative Analysis of Three-Dimensional Distribution and Clustering of Intramuscular Fat in Muscles of the Rotator Cuff

Anthony C. Santago, Meghan E. Vidt, Christopher J. Tuohy, Gary G. Poehling, Michael T. Freehill, Jennifer H. Jordan, Robert A. Kraft, Katherine R. Saul

    Research output: Contribution to journalArticlepeer-review

    19 Scopus citations


    The purpose of this study was to (1) develop and present a technique to quantitatively assess three-dimensional distribution and clustering of intramuscular fat and (2) use the technique to compare spatial characteristics of intramuscular fat in rotator cuff muscles of older adults with and without a supraspinatus tear. Moran’s Index (I), an existing quantitative measure of clustering, was extended for use with MRI to allow comparisons across individuals with different size muscles. Sixteen older adults (>60 years) with (N = 6) and without (N = 10) a degenerative supraspinatus tear participated. Following 3D Dixon MRIs of the shoulder, which separates fat from water, rotator cuff muscles were segmented and sectioned and fat% and Moran’s I were calculated to assess distribution and clustering, respectively. Moran’s I ranged was 0.40–0.92 and 0.39–0.76 for the tear and control subjects, respectively. Compared to uninjured controls, tear subjects demonstrated increased fat distribution (p = 0.036) and clustering (p = 0.020) distally in the supraspinatus. Tear subjects had more pronounced distribution (p < 0.001) and clustering distally (p < 0.001) than proximally. Other rotator cuff muscles exhibited different patterns of fat clustering and distribution. This technique, which we applied to quantify spatial characteristics of intramuscular fat, can be applied to assess clustering of fat in other pathologies and tissues.

    Original languageEnglish (US)
    Pages (from-to)2158-2167
    Number of pages10
    JournalAnnals of Biomedical Engineering
    Issue number7
    StatePublished - Jul 1 2016


    • Fat percentage
    • MRI
    • Moran’s Index
    • Rotator cuff tear
    • Spatial characteristics of fat

    ASJC Scopus subject areas

    • Biomedical Engineering


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