Reproducibility of coronary artery plaque volume and composition quantification by 64-detector row coronary computed tomographic angiography: An intraobserver, interobserver, and interscan variability study

Received 2 April 2009; accepted 20 July 2009. published online 31 July 2009.

Background

Interscan variability of coronary arterial plaque volume and composition quantification with coronary computed tomographic angiography (CCTA), an important attribute when considering CCTA as a serial modality, has not been examined.

Objective

We sought to systematically determine intraobserver- and interobserver-interscan reproducibility of these measures.

Methods

Two blinded, experienced readers independently evaluated proximal coronary segments on CCTAs from 30 patients who underwent 2 scans within 200 days (median, 124 days; interquartile range, 49–155 days) without experiencing an interim acute coronary event. Readers recorded number of plaques and, in plaques that met a preset minimal length criterion, quantified total, calcified plaque (CP), and noncalcified plaque (NCP) volumes and percentage of total plaque volume occupied by NCP.

Results

Of 89 total segments studied, 36 contained detectable plaque, and 26 met criterion for quantification. Intraobserver, interobserver, and interscan agreements for normal segments were 100%. Intraobserver-interscan correlations of total, CP, and NCP volumes and percentage of NCP were excellent (r=0.93–0.97, P values<0.001). Interobserver-interscan correlations for all measures were also very good (r=0.81–0.96, P values<0.001). Variability in plaque volume quantification was significant, exceeding 60% of the averaged paired plaque volumes in the best-case scenario (interobserver-interscan CP volume). Quantification of percentage of NCP composition by volume was more consistent, with <24% variation in the worst-case scenario (interobserver-interscan).

Conclusion

CCTA shows promise for quantifying serial coronary plaque change. Currently, the most robust measure seems to be percentage of plaque composition, rather than plaque volume. For smaller plaques, volume quantification remains challenging.

Keywords: Computed tomography, Coronary artery plaque, Reproducibility, Serial examination

a Department of Medicine, 8700 Beverly Boulevard, Taper Building Room 1258, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA

b Department of Imaging, 8700 Beverly Boulevard, Taper Building Room 1258, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA

c Johns Hopkins University, Baltimore, MD, USA

d Los Angeles Biomedical Research Institute at Harbor–University of California, Los Angeles, Torrance, CA, USA

e Cardiovascular Medical Group of Beverly Hills, Beverly Hills, CA, USA

f Greenberg Division of Cardiology, Weill Medical College of Cornell University, New York Presbyterian Hospital, New York, NY, USA

Corresponding author.

Conflict of interest: The authors report no conflicts of interest.

This study was supported by a grant from the Lincy Foundation, Beverly Hills, CA.

PII: S1934-5925(09)00403-1

doi:10.1016/j.jcct.2009.07.001

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