title: Calcium concentration of individual coronary calcified plaques as measured by multidetector row computed tomography.
abstract: BACKGROUND
  Characteristics of individual calcified plaques, especially calcium concentration (CC), may provide incremental value to global calcium scores in the assessment of plaque burden and risk of coronary events and evaluation of therapeutic intervention. In this study, therefore, we assessed the characteristics of individual calcified plaques and their relationship to other parameters derived from CT analysis of coronary calcium in a community-based cross-sectional cohort.
  
  
  RESULTS
  Coronary artery calcium (CAC) was analyzed in 612 participants of the Framingham Heart Study (third-generation and offspring cohorts) using prospectively ECG-triggered multidetector CT. We determined the CC, Agatston score, calcified volume, and mineral mass of individual calcified plaques in each subject. Heterogeneity of CC was defined as the standard deviation of CC of all individual calcified plaques in a subject. CAC was detected in 274 of 605 subjects. After excluding 57 subjects (21%) because of motion artifacts, we identified a total of 956 calcified coronary plaques in 217 subjects (74 women, 143 men; mean age, 57.1+/-10.8 years) with detectable CAC and no image artifacts. CC of individual calcified plaques was independent of subject age (P=0.76) and sex (197.8+/-74.8 versus 183.6+/-52.8 mg/cm3 for men versus women; P=0.21). Among a subgroup of 125 subjects with multiple (> or =3) individual calcified plaques, CC was heterogeneous within individual subjects (mean SD of CC, 43.6+/-23.1 mg/cm3). The degree of heterogeneity of CC in these subjects was independent of age (P=0.60), sex (P=0.99), and number of plaques (P=0.06).
  
  
  CONCLUSIONS
  The CC of individual calcified plaques is independent of age and sex but heterogeneous within a subject, which may reflect that the pathological process of calcified plaque formation and progression is the same in men and women regardless of age. CC may have incremental value to global calcium scores in the assessment of plaque burden and risk of coronary events and the evaluation of therapeutic intervention. Further studies are warranted to confirm that individual plaque analysis is preferable to global CAC scores to evaluate progression of atherosclerosis and to assess whether individual plaque analysis may be complementary to global CAC measures to assess coronary event risk.
authors.affiliation: Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, Mass 02114, USA.
authors.forename: Fabian
authors.initials: F
authors.lastname: Moselewski
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: O'Donnell
authors.forename: Stephan
authors.initials: S
authors.lastname: Achenbach
authors.forename: Maros
authors.initials: M
authors.lastname: Ferencik
authors.forename: Joe
authors.initials: J
authors.lastname: Massaro
authors.forename: Ann
authors.initials: A
authors.lastname: Nguyen
authors.forename: Ricardo C
authors.initials: RC
authors.lastname: Cury
authors.forename: Suhny
authors.initials: S
authors.lastname: Abbara
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: D000367:Age Factors; D000368:Aged; D002114:Calcinosis / Q000473:pathology*; D002118:Calcium / Q000032:analysis*; D015331:Cohort Studies; D003324:Coronary Artery Disease / Q000175:diagnosis / Q000473:pathology*; D003331:Coronary Vessels / Q000737:chemistry; D003430:Cross-Sectional Studies; D018450:Disease Progression; D005192:Family Health; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012306:Risk; D012737:Sex Factors; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods
chemical_list: D002118:Calcium