title: Vertebral scale system to measure heart size in radiographs of cats.
abstract: OBJECTIVE
  To determine absolute and relative heart size in clinically normal cats by correlating heart size and selected skeletal structures.
  
  
  METHODS
  Prospective radiographic study.
  
  
  METHODS
  100 cats that did not have thoracic radiographic abnormalities.
  
  
  METHODS
  Standardized measurements of the long and short axes of the heart, midthoracic vertebrae, and other structures were made. Measurements were recorded in millimeters and number of thoracic vertebral lengths spanned by each dimension, measured caudally from T4 in a lateral radiograph. The long- and short-axis measurements of the heart, expressed in vertebral lengths, were added to yield vertebral heart size.
  
  
  RESULTS
  Mean +/- SD vertebral heart size in lateral radiographs was 7.5 +/- 0.3 vertebrae. The long-axis dimension correlated with the length of 3 sternebrae, measured from S2 to S4. The cardiac short-axis dimension correlated moderately with the length of 3.2 vertebrae, measured from T4 to T6. The cardiac short-axis dimension in ventrodorsal radiographs was 3.4 +/- 0.25 vertebrae.
  
  
  CONCLUSIONS
  The vertebral heart-size method is easy to use, allows objective assessment of heart size, and may be helpful in determining cardiomegaly and comparing heart size in sequential radiographs.
authors.affiliation: Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia 19104, USA.
authors.forename: A L
authors.initials: AL
authors.lastname: Litster
authors.forename: J W
authors.initials: JW
authors.lastname: Buchanan
mesh_terms: D000818:Animals; D002415:Cats / Q000033:anatomy & histology*; D006321:Heart / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D011446:Prospective Studies; D011859:Radiography; D012016:Reference Values