title: Novel measurements of periaortic adipose tissue in comparison to anthropometric measures of obesity, and abdominal adipose tissue.
abstract: BACKGROUND
  Perivascular adipose tissue may be associated with the amount of local atherosclerosis. We developed a novel and reproducible method to standardize volumetric quantification of periaortic adipose tissue by computed tomography (CT) and determined the association with anthropometric measures of obesity, and abdominal adipose tissue.
  
  
  METHODS
  Measurements of adipose tissue were performed in a random subset of participants from the Framingham Heart Study (n=100) who underwent multidetector CT of the thorax (ECG triggering, 2.5 mm slice thickness) and the abdomen (helical CT acquisition, 2.5 mm slice thickness). Abdominal periaortic adipose tissue (AAT) was defined by a 5 mm cylindrical region of interest around the aortic wall; thoracic periaortic adipose tissue (TAT) was defined by anatomic landmarks. TAT and AAT were defined as any voxel between -195 and -45 HU and volumes were measured using dedicated semiautomatic software. Measurement reproducibility and association with anthropometric measures of obesity, and abdominal adipose tissue were determined.
  
  
  RESULTS
  The intra- and inter-observer reproducibility for both AAT and TAT was excellent (ICC: 0.97 and 0.97; 0.99 and 0.98, respectively). Similarly, the relative intra- and inter-observer difference was small for both AAT (-1.85+/-1.28% and 7.85+/-6.08%; respectively) and TAT (3.56+/-0.83% and -4.56+/-0.85%, respectively). Both AAT and TAT were highly correlated with visceral abdominal fat (r=0.65 and 0.77, P<0.0001 for both) and moderately correlated with subcutaneous abdominal fat (r=0.39 and 0.42, P<0.0001 and P=0.009), waist circumference (r=0.49 and 0.57, P<0.0001 for both) and body mass index (r=0.47 and 0.58, P<0.0001 for both).
  
  
  CONCLUSIONS
  Standardized semiautomatic CT-based volumetric quantification of periaortic adipose tissue is feasible and highly reproducible. Further investigation is warranted regarding associations of periaortic adipose tissue with other body fat deposits, cardiovascular risk factors and clinical outcomes.
authors.affiliation: Cardiac MR PET CT Program, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA.
authors.forename: C L
authors.initials: CL
authors.lastname: Schlett
authors.forename: J M
authors.initials: JM
authors.lastname: Massaro
authors.forename: S J
authors.initials: SJ
authors.lastname: Lehman
authors.forename: F
authors.initials: F
authors.lastname: Bamberg
authors.forename: C J
authors.initials: CJ
authors.lastname: O'Donnell
authors.forename: C S
authors.initials: CS
authors.lastname: Fox
authors.forename: U
authors.initials: U
authors.lastname: Hoffmann
mesh_terms: D050153:Abdominal Fat / Q000000981:diagnostic imaging*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001018:Aortic Diseases / Q000000981:diagnostic imaging*; D001027:Aortography; D002114:Calcinosis / Q000000981:diagnostic imaging*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000000981:diagnostic imaging*; D015588:Observer Variation; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed