title: Threshold-dependent variability of coronary artery calcification measurements -- implications for contrast-enhanced multi-detector row-computed tomography.
abstract: BACKGROUND
  The present study investigated the threshold-dependent variability of coronary artery calcification (CAC) measurements and the potential to quantify CAC in contrast-enhanced multi-detector row-computed tomography (MDCT).
  
  
  METHODS
  We compared the mean CT attenuation of CAC to luminal contrast enhancement of the coronary arteries in 30 patients (n = 30) undergoing standard coronary contrast-enhanced spiral MDCT. The modified Agatston score [AS], calcified plaque volume [CV], and mineral mass [MM]) at four different thresholds (130, 200, 300, and 400 HU) were measured in 50 patients who underwent non-contrast-enhanced MDCT.
  
  
  RESULTS
  Mean CT attenuation of CAC was similar to the attenuation of the contrast-enhanced coronary lumen (CAC 297.1 +/- 68.7 HU versus 295 +/- 65 HU (p < 0.0001), respectively). Above a threshold of 300 HU CAC measurements significantly varied to standard measurements obtained at a threshold of 130 HU (p < 0.0001). The threshold-dependent variation of MM measurements was significantly smaller than for AS and CV (130 HU versus 400 HU: 63, 75, and 81, respectively; p < 0.001). These differences resulted in a change of age and gender based percentile category for AS in 78% of subjects.
  
  
  CONCLUSIONS
  We demonstrated that CAC measurements are threshold dependent with MM measurements having significantly less variation than AS or CV. Due to the similarity of mean CT attenuation of CAC and the contrast-enhanced coronary lumen accurate quantification of CAC may be difficult in standard coronary contrast-enhanced spiral MDCT.
authors.affiliation: Division of Cardiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA.
authors.forename: Fabian
authors.initials: F
authors.lastname: Moselewski
authors.forename: Maros
authors.initials: M
authors.lastname: Ferencik
authors.forename: Stephan
authors.initials: S
authors.lastname: Achenbach
authors.forename: Suhny
authors.initials: S
authors.lastname: Abbara
authors.forename: Ricardo C
authors.initials: RC
authors.lastname: Cury
authors.forename: Sarah L
authors.initials: SL
authors.lastname: Booth
authors.forename: Ik-Kyung
authors.initials: IK
authors.lastname: Jang
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Brady
authors.forename: Udo
authors.initials: U
authors.lastname: Hoffmann
mesh_terms: D002114:Calcinosis / Q000000981:diagnostic imaging*; D003287:Contrast Media; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging*; D003331:Coronary Vessels / Q000473:pathology*; D006801:Humans; D007089:Image Enhancement; D015203:Reproducibility of Results; D036542:Tomography, Spiral Computed / Q000379:methods*
chemical_list: D003287:Contrast Media