title: Interscan reproducibility of computer-aided epicardial and thoracic fat measurement from noncontrast cardiac CT.
abstract: BACKGROUND
  Epicardial fat volume (EFV) measured from noncontrast CT is associated with coronary atherosclerosis and increased risk of major adverse cardiovascular events. Interscan reproducibility of EFV quantification from noncontrast CT has not been reported.
  
  
  OBJECTIVE
  We evaluated the interscan (intrascanner and interscanner) reproducibility of EFV and thoracic fat volume (TFV) measurements from noncontrast CT.
  
  
  METHODS
  We studied 25 consecutive patients who were scanned twice with 4-slice multidetector CT (MDCT), with 120 kVp, 2.5-mm slice thickness (intrascanner) and 23 consecutive patients who were scanned with MDCT and electron beam CT (EBCT) with 3-mm slice thickness (interscanner). For each scan, EFV and TFV were measured from user-defined range of CT slices covering the heart by experienced imaging cardiologists. Voxels within -30 to -190 HU within the epicardial contours was quantified as EFV. TFV was quantified within the heart range automatically. Repeatability coefficient (RC), defined as 1.96 × SD of the differences between pairs of repeated measures, was determined.
  
  
  RESULTS
  Correlations for interscan measurements of EFV and TFV were high for both intrascanner (MDCT-MDCT) and interscanner (EBCT-MDCT) data (correlation coefficient ≥0.98). RC values were lowest (4.3% for EFV and 5.4% for TFV) for intrascanner same-observer measurement. For intrascanner cross-observer measurement, RC values were 10.7% for EFV and 9.0% for TFV. For interscanner data, RC values ranged from 6.8% to 8.2%.
  
  
  CONCLUSIONS
  Epicardial and thoracic fat measurements with the use of either MDCT or EBCT are highly reproducible.
authors.affiliation: Department of Imaging (Division of Nuclear Medicine), Cedars-Sinai Heart Institute, Cedars-Sinai Medical Center, 8700 Beverly Blvd, Los Angeles, CA 90048, USA.
authors.forename: Ryo
authors.initials: R
authors.lastname: Nakazato
authors.forename: Haim
authors.initials: H
authors.lastname: Shmilovich
authors.forename: Balaji K
authors.initials: BK
authors.lastname: Tamarappoo
authors.forename: Victor Y
authors.initials: VY
authors.lastname: Cheng
authors.forename: Piotr J
authors.initials: PJ
authors.lastname: Slomka
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Berman
authors.forename: Damini
authors.initials: D
authors.lastname: Dey
mesh_terms: D000273:Adipose Tissue / Q000000981:diagnostic imaging*; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D015141:Los Angeles; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010496:Pericardium; D011237:Predictive Value of Tests; D011857:Radiographic Image Interpretation, Computer-Assisted; D012042:Registries; D015203:Reproducibility of Results; D012189:Retrospective Studies; D035423:Thoracic Cavity; D014057:Tomography, X-Ray Computed