title: Panoramic ultrasound: a novel and valid tool for monitoring change in muscle mass.
abstract: BACKGROUND
  The strong link between reduced muscle mass and morbidity and mortality highlights the urgent need for simple techniques that can monitor change in skeletal muscle cross-sectional area (CSA). Our objective was to examine the validity of panoramic ultrasound to detect change in quadriceps and gastrocnemius size in comparison with magnetic resonance imaging (MRI) in subjects randomized to 70 days of bed rest (BR) with or without exercise.
  
  
  METHODS
  Panoramic ultrasound and MRI images of the quadriceps and gastrocnemius muscles were acquired on the right leg of 27 subjects (26 male, 1 female; age: 34.6 ± 7.8 years; body mass: 77.5 ± 10.0 kg; body mass index: 24.2 ± 2.8 kg/m2; height: 179.1 ± 6.9 cm) before (BR-6), during (BR3, 7, 11, 15, 22, 29, 36, 53, 69), and after (BR+3, +6, +10) BR. Validity of panoramic ultrasound to detect change in muscle CSA was assessed by Bland-Altman plots, Lin's concordance correlation coefficient (CCC), sensitivity, specificity, positive predictive value, and negative predictive value.
  
  
  RESULTS
  Six hundred ninety-eight panoramic ultrasound CSA and 698 MRI CSA measurements were assessed. Concordance between ultrasound and MRI was excellent in the quadriceps (CCC: 0.78; P < 0.0001), whereas there was poor concordance in the gastrocnemius (CCC: 0.37; P < 0.0006). Compared with MRI, panoramic ultrasound demonstrated high accuracy in detecting quadriceps atrophy and hypertrophy (sensitivity: 73.7%; specificity: 74.2%) and gastrocnemius atrophy (sensitivity: 83.1%) and low accuracy in detecting gastrocnemius hypertrophy (specificity: 33.0%).
  
  
  CONCLUSIONS
  Panoramic ultrasound imaging is a valid tool for monitoring quadriceps muscle atrophy and hypertrophy and for detecting gastrocnemius atrophy.
authors.affiliation: Universities Space Research Association, Houston, TX, USA.
authors.forename: Jessica M
authors.initials: JM
authors.lastname: Scott
authors.affiliation: KBRwyle, Houston, TX, USA.
authors.forename: David S
authors.initials: DS
authors.lastname: Martin
authors.affiliation: Universities Space Research Association, Houston, TX, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Ploutz-Snyder
authors.affiliation: MEI Technologies, Houston, TX, USA.
authors.forename: Timothy
authors.initials: T
authors.lastname: Matz
authors.affiliation: KBRwyle, Houston, TX, USA.
authors.forename: Timothy
authors.initials: T
authors.lastname: Caine
authors.affiliation: University of Houston, Houston, TX, USA.
authors.forename: Meghan
authors.initials: M
authors.lastname: Downs
authors.affiliation: North Dakota State University, Fargo, ND, USA.
authors.forename: Kyle
authors.initials: K
authors.lastname: Hackney
authors.affiliation: University of Houston, Houston, TX, USA.
authors.forename: Roxanne
authors.initials: R
authors.lastname: Buxton
authors.affiliation: Universities Space Research Association, Houston, TX, USA.
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Ryder
authors.affiliation: Universities Space Research Association, Houston, TX, USA.
authors.forename: Lori
authors.initials: L
authors.lastname: Ploutz-Snyder
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D006984:Hypertrophy; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging* / Q000473:pathology; D009133:Muscular Atrophy / Q000000981:diagnostic imaging / Q000473:pathology; D009929:Organ Size; D052097:Quadriceps Muscle / Q000000981:diagnostic imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014463:Ultrasonography; D055815:Young Adult
keywords: Atrophy; Disuse; Hypertrophy; Magnetic resonance imaging; Panoramic ultrasound