title: When the diameter of the abdominal aorta should be considered as abnormal? A new ultrasonographic index using the wrist circumference as a body build reference.
abstract: OBJECTIVE
  To use US to evaluate the normal values of aortic diameter (AD), stratifying the population by age, gender and body build, as measured using wrist circumference (WC).
  
  
  METHODS
  Between April 2010 and February 2012, consecutive patients ≥ 30 years of age, without history of abdominal aortic aneurysm (AAA) were prospectively enrolled. They underwent an abdominal ultrasonography for reasons other than aorta evaluation. AD was measured at the infrarenal (AD₁), intermediate (AD₂), and iliac bifurcation (AD₃) levels: a diameter ≥ 3 cm was considered as an aneurysm. The maximal aortic diameter (AD(max)) was measured for AAA patients. WC was measured; AD/WC ratio was calculated and presented in percentage: the range of normal values was obtained excluding AAA cases and calculated as mean ± 1.96 × standard deviation. Pearson correlation coefficient was used.
  
  
  RESULTS
  We recruited 1200 patients, 15 (1.25%; age range=64-86 years) had AAA. AD ranges of the other patients were: AD₁=0.74-1.84 cm, AD₂=0.78-1.85 cm, and AD₃=0.68-1.76 cm for females; AD₁=0.86-2.02 cm, AD₂=0.91-2.08 cm, and AD₃=0.84-1.95 cm for males. AD₂/WC ratio of non-AAA patients range was 4-15%, with only one outlier at 18%, while AD(max)/WC ratio of AAA patients range was 15-35% (p<0.001). ADs were significantly correlated with WC (r=0.253, p<0.001 for AD₁, r=0.318, p<0.001 for AD₂ and r=0.280, p<0.001 for AD₃).
  
  
  CONCLUSIONS
  The definition of normal AD should consider body build. An AD₂/WC ratio of 15% may be regarded as a threshold to differentiate AAA- from non-AAA patients. Patients with AD₂/WC values comprised between 12% and 15% may be at risk for AAA.
authors.affiliation: Servizio di Radiologia, IRCCS Policlinico San Donato, Piazza Malan 2 - 20097 San Donato Milanese, Milano, Italy. io@lucasconfienza.it
authors.forename: Luca Maria
authors.initials: LM
authors.lastname: Sconfienza
authors.forename: Ilaria
authors.initials: I
authors.lastname: Santagostino
authors.forename: Giovanni
authors.initials: G
authors.lastname: Di Leo
authors.forename: Raffaella
authors.initials: R
authors.lastname: Piazza
authors.forename: Gino
authors.initials: G
authors.lastname: Gozzi
authors.forename: Santi
authors.initials: S
authors.lastname: Trimarchi
authors.forename: Francesco
authors.initials: F
authors.lastname: Sardanelli
mesh_terms: D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D001012:Aorta, Abdominal / Q000000981:diagnostic imaging*; D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging* / Q000453:epidemiology* / Q000517:prevention & control; D049628:Body Size; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000592:standards; D007558:Italy / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011379:Prognosis; D012016:Reference Values; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000592:standards; D012680:Sensitivity and Specificity; D017678:Sex Distribution; D014463:Ultrasonography / Q000379:methods* / Q000592:standards*; D014953:Wrist / Q000000981:diagnostic imaging*
keywords: Abdominal aorta aneurysm; Abdominal aorta diameter; Normal values; Ultrasonography