title: Quantitative Analysis of Three-Dimensional Distribution and Clustering of Intramuscular Fat in Muscles of the Rotator Cuff.
abstract: 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.
authors.affiliation: Virginia Tech-Wake Forest School of Biomedical Engineering and Sciences, Winston-Salem, NC, 27157, USA. ACSantago@gmail.com.|Department of Biomedical Engineering, Wake Forest School of Medicine, Winston-Salem, NC, 27157, USA. ACSantago@gmail.com.|Department of Mechanical and Aerospace Engineering, North Carolina State University, 911 Oval Drive, Engineering Building 3, Campus Box 7910, Raleigh, NC, 27695-7910, USA. ACSantago@gmail.com.
authors.forename: Anthony C
authors.identifier: 0000-0003-4266-1790
authors.initials: AC
authors.lastname: Santago
authors.affiliation: Department of Kinesiology, University of Waterloo, Waterloo, ON, Canada.
authors.forename: Meghan E
authors.initials: ME
authors.lastname: Vidt
authors.affiliation: Department of Orthopaedic Surgery, Wake Forest School of Medicine, Winston-Salem, NC, 27157, USA.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Tuohy
authors.affiliation: Department of Orthopaedic Surgery, Wake Forest School of Medicine, Winston-Salem, NC, 27157, USA.
authors.forename: Gary G
authors.initials: GG
authors.lastname: Poehling
authors.affiliation: Department of Orthopaedic Surgery, Wake Forest School of Medicine, Winston-Salem, NC, 27157, USA.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Freehill
authors.affiliation: Department of Internal Medicine, Section on Cardiovascular Medicine, Wake Forest School of Medicine, Winston-Salem, NC, 27157, USA.
authors.forename: Jennifer H
authors.initials: JH
authors.lastname: Jordan
authors.affiliation: Virginia Tech-Wake Forest School of Biomedical Engineering and Sciences, Winston-Salem, NC, 27157, USA.|Department of Biomedical Engineering, Wake Forest School of Medicine, Winston-Salem, NC, 27157, USA.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Kraft
authors.affiliation: Department of Mechanical and Aerospace Engineering, North Carolina State University, 911 Oval Drive, Engineering Building 3, Campus Box 7910, Raleigh, NC, 27695-7910, USA.
authors.forename: Katherine R
authors.initials: KR
authors.lastname: Saul
mesh_terms: D000273:Adipose Tissue / Q000000981:diagnostic imaging* / Q000378:metabolism*; D000368:Aged; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D017006:Rotator Cuff / Q000000981:diagnostic imaging* / Q000378:metabolism*
keywords: Fat percentage; MRI; Moran’s Index; Rotator cuff tear; Spatial characteristics of fat