title: Variation in the estimation of gallbladder volume using the sum-of-cylinders method.
abstract: OBJECTIVE
  Gallbladder contraction was measured by ultrasound, using the sum-of-cylinders method, as part of a study of the effects of lipid-lowering drugs. Although this method of measurement has been validated in the literature, paired measurements were obtained to provide an additional check on reproducibility.
  
  
  METHODS
  A total of 136 pairs of gallbladder measurements were made on 17 patients using the sum-of-cylinders method of calculating gallbladder volume. Each pair comprised a left posterior oblique and a supine measurement performed at the same ultrasound examination to assess measurement error.
  
  
  RESULTS
  There was a large average coefficient of variation of 21%.
  
  
  CONCLUSIONS
  Marked measurement variability limited the ability of the sum-of-cylinders technique to detect even modest alterations in gallbladder contractility, at least in this population subgroup.
authors.affiliation: Department of Radiology, Christchurch Hospital, New Zealand.
authors.forename: M A
authors.initials: MA
authors.lastname: Hurrell
authors.forename: B A
authors.initials: BA
authors.lastname: Chapman
authors.forename: I R
authors.initials: IR
authors.lastname: Wilson
mesh_terms: D001629:Bezafibrate / Q000494:pharmacology; D015992:Body Mass Index; D005704:Gallbladder / Q000000981:diagnostic imaging* / Q000502:physiology; D016473:Gallbladder Emptying / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D000960:Hypolipidemic Agents / Q000494:pharmacology; D008148:Lovastatin / Q000031:analogs & derivatives / Q000494:pharmacology; D008875:Middle Aged; D015203:Reproducibility of Results; D019821:Simvastatin; D014463:Ultrasonography / Q000379:methods
chemical_list: D000960:Hypolipidemic Agents; D008148:Lovastatin; D019821:Simvastatin; D001629:Bezafibrate