title: Ultrasound method for estimating the cross-sectional area of the psoas major muscle.
abstract: OBJECTIVE
  The present study aimed to develop an ultrasonographic method for estimating the cross-sectional area of the psoas major muscle.
  
  
  METHODS
  The muscle cross-sectional area (CSA(MRI)) and thickness (MT(MRI)) of the psoas major muscle at L4-L5 on the right and left sides of the body were measured using magnetic resonance imaging in 11 healthy sedentary men age 21 to 25 yr. Ultrasonographic images were obtained at the corresponding sites where CSA(MRI) and MT(MRI) measurements were performed. From the ultrasonographic images, the thickness of the psoas major muscle (MT(US)) was analyzed on both sides of the body.
  
  
  RESULTS
  The interclass correlation coefficient of MT(US) measurements performed on two separated days was 0.951 for the right side and 0.971 for the left side. CSA(MRI) was significantly correlated to MT(MRI) (r = 0.934 for the right side and r = 0.910 for the left side). There was no significant difference between MT(MRI) (4.68 ± 0.39 cm for the right side and 4.73 ± 0.39 cm for the left side) and MT(US) (4.67 ± 0.40 cm for the right side and 4.72 ± 0.43 cm for the left side). The MT(US) was significantly correlated to MT(MRI) (r = 0.979 for the right side and r = 0.980 for the left side) and CSA(MRI) (r = 0.947 for the right side and r = 0.916 for the left side).
  
  
  CONCLUSIONS
  The current results indicate that the psoas major muscle thickness determined by the ultrasonographic method is useful for estimating the cross-sectional area of the psoas major muscle.
authors: National Institute of Fitness and Sports in Kanoya, Kagoshima, Japan.
authors: Yohei
authors: Y
authors: Takai
authors: Yoichi
authors: Y
authors: Katsumata
authors: Yasuo
authors: Y
authors: Kawakami
authors: Hiroaki
authors: H
authors: Kanehisa
authors: Tetsuo
authors: T
authors: Fukunaga
mesh_terms: D000328:Adult; D019412:Anatomy, Cross-Sectional / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D016658:Psoas Muscles / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D015203:Reproducibility of Results; D057185:Sedentary Behavior; D014463:Ultrasonography; D055815:Young Adult