Inter- and intra-observer variability of an anatomical landmark-based, manual segmentation method by MRI for the assessment of skeletal muscle fat content and area in subjects from the general population

• Published in: British journal of radiology Vol. 91; no. 1089; p. 20180019
• Main Authors: Kiefer, Lena Sophie, Fabian, Jana, Lorbeer, Roberto, Machann, Jürgen, Storz, Corinna, Kraus, Mareen Sarah, Wintermeyer, Elke, Schlett, Christopher, Roemer, Frank, Nikolaou, Konstantin, Peters, Annette, Bamberg, Fabian
• Format: Journal Article
• Language: English
• Published: England The British Institute of Radiology 01.09.2018
• Subjects: Adipose Tissue - anatomy & histology; Adipose Tissue - diagnostic imaging; Adult; Aged; Body Fat Distribution; Body Mass Index; Female; Humans; Magnetic Resonance Imaging - methods; Male; Middle Aged; Muscle, Skeletal - anatomy & histology; Muscle, Skeletal - diagnostic imaging; Observer Variation; Prospective Studies; Reproducibility of Results; The role of imaging in obesity special feature: Full Paper
• ISSN: 0007-1285; 1748-880X; 1748-880X
• DOI: 10.1259/bjr.20180019

Changes in skeletal muscle composition, such as fat content and mass, may exert unique metabolic and musculoskeletal risks; however, the reproducibility of their assessment is unknown. We determined the variability of the assessment of skeletal muscle fat content and area by MRI in a population-based sample. A random sample from a prospective, community-based cohort study (KORA-FF4) was included. Skeletal muscle fat content was quantified as proton-density fat fraction (PDFF) and area as cross-sectional area (CSA) in multi-echo Dixon sequences (TR 8.90 ms, six echo times, flip angle 4°) by a standardized, anatomical landmark-based, manual skeletal muscle segmentation at level L3 vertebra by two independent observers. Reproducibility was assessed by intraclass correlation coefficients (ICC), scatter and Bland-Altman plots. From 50 subjects included (mean age 56.1 ± 8.8 years, 60.0% males, mean body mass index 28.3 ± 5.2) 2'400 measurements were obtained. Interobserver agreement was excellent for all muscle compartments (PDFF: ICC0.99, CSA: ICC0.98) with only minor absolute and relative differences (-0.2 ± 0.5%, 31 ± 44.7 mm ; -2.6 ± 6.4% and 2.7 ± 3.9%, respectively). Intra-observer reproducibility was similarly excellent (PDFF: ICC1.0, 0.0 ± 0.4%, 0.4%; CSA: ICC1.0, 5.5 ± 25.3 mm , 0.5%, absolute and relative differences, respectively). All agreement was independent of age, gender, body mass index, body height and visceral adipose tissue (ICC0.96-1.0). Furthermore, PDFF reproducibility was independent of CSA (ICC0.93-0.99).  Conclusions:  Quantification of skeletal muscle fat content and area by MRI using an anatomical landmark-based, manual skeletal muscle segmentation is highly reproducible. Advances in knowledge: An anatomical landmark-based, manual skeletal muscle segmentation provides high reproducibility of skeletal muscle fat content and area and may therefore serve as a robust proxy for myosteatosis and sarcopenia in large cohort studies.