title: Muscle and Myotendinous Tissue Properties at the Distal Tibia as Assessed by High-Resolution Peripheral Quantitative Computed Tomography.
abstract: High-resolution peripheral quantitative computed tomography (HR-pQCT) quantifies bone microstructure and density at the distal tibia where there is also a sizable amount of myotendinous (muscle and tendon) tissue (MT); however, there is no method for the quantification of MT. This study aimed (1) to assess the feasibility of using HR-pQCT distal tibia scans to estimate MTproperties using a custom algorithm, and (2) to determine the relationship between MTproperties at the distal tibia and mid-leg muscle density (MD) obtained from pQCT. Postmenopausal women from the Hamilton cohort of the Canadian Multicenter Osteoporosis Study had a single-slice (2.3 ± 0.5 mm) 66% site pQCT scan measuring muscle cross-sectional area (MCSA) and MD. A standard HR-pQCT scan was acquired at the distal tibia. HR-pQCT-derived MTcross-sectional area (MTCSA) and MTdensity (MTD) were calculated using a custom algorithm in which thresholds (34.22-194.32 mg HA/cm3) identified muscle seed volumes and were iteratively expanded. Pearson and Bland-Altman plots were used to assess correlations and systematic differences between pQCT- and HR-pQCT-derived muscle properties. Among 45 women (mean age: 74.6 ± 8.5 years, body mass index: 25.9 ± 4.3 kg/m2), MTD was moderately correlated with mid-leg MD across the 2 modalities (r = 0.69-0.70, p < 0.01). Bland-Altman analyses revealed no evidence of directional bias for MTD-MD. HR-pQCT and pQCT measures of MTCSA and MCSA were moderately correlated (r = 0.44, p < 0.01). Bland-Altman plots for MTCSA revealed that larger MCSAs related to larger discrepancy between the distal and the mid-leg locations. This is the first study to assess the ability of HR-pQCT to measure MTsize, density, and morphometry. HR-pQCT-derived MTD was moderately correlated with mid-leg MD from pQCT. This relationship suggests that distal MTmay share common properties with muscle throughout the length of the leg. Future studies will assess the value of HR-pQCT-derived MTproperties in the context of falls, mobility, and balance.
authors.affiliation: College of Kinesiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada. Electronic address: marta.erlandson@usask.ca.
authors.forename: M C
authors.initials: MC
authors.lastname: Erlandson
authors.affiliation: Department of Medicine and Joint Department of Medical Imaging, University Health Network, Toronto, Ontario, Canada; Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada.
authors.forename: A K O
authors.initials: AKO
authors.lastname: Wong
authors.affiliation: Department of Medicine and Joint Department of Medical Imaging, University Health Network, Toronto, Ontario, Canada.
authors.forename: E
authors.initials: E
authors.lastname: Szabo
authors.affiliation: SCANCO Medical AG, Bruettisellen, Switzerland.
authors.forename: N
authors.initials: N
authors.lastname: Vilayphiou
authors.affiliation: SCANCO Medical AG, Bruettisellen, Switzerland.
authors.forename: M A
authors.initials: MA
authors.lastname: Zulliger
authors.affiliation: Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada.
authors.forename: J D
authors.initials: JD
authors.lastname: Adachi
authors.affiliation: Department of Medicine and Joint Department of Medical Imaging, University Health Network, Toronto, Ontario, Canada.
authors.forename: A M
authors.initials: AM
authors.lastname: Cheung
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D000842:Ankle; D005260:Female; D006801:Humans; D007866:Leg; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D009929:Organ Size; D013710:Tendons / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D013977:Tibia / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Cross-sectional area; HR-pQCT; muscle and myotendinous tissue density; pQCT