Computed tomography coronary angiography can accurately quantify coronary luminal area and plaque volume compared to invasive intravascular ultrasound.

AIM: To assess the accuracy of Computed-Tomography-Coronary- Angiography (CTCA) derived quantitative plaque analysis using Intravascular-Ultrasound (IVUS) as reference standard. METHOD(S): Patients who underwent IVUS and CTCA within a 3-month period at MonashHEART between October-2008 and December-2013 were retrospectively studied. Core-lab analysis was performed on all IVUS and CTCA datasets. CT images were analyzed using SurePlaquesoftware. Luminal (LCSA), vessel-cross-sectional-area (VCSA) and plaque volume (PV), defined as (VCSA-LCSA)/VCSA were manually quantified on IVUS and CTCA at 0.5mm cross-sections on all interrogated vessels. Bland-Altman analysis was performed to assess the agreement of measurements between IVUS and CTCA. Data is expressed as mean +/- standard error of mean (SEM), and two-tailed p<0.05 was accepted as significant. RESULT(S): Thirty-two vessels (23 patients), including 513 cross-sections were analyzed (left-main n=9, left-anterior-descending n=16, left-circumflex n=4 and right-coronaryartery n=3). Un-interpretable-segments, segments without fiduciarypoints and seven patients with poor CT images were excluded. There was no significant mean difference in LCSA (0.08 +/- 0.08mm2, p=0.33), VSCA (0.06 +/- 0.12 mm2, p=0.65 or PV (0.03+/-0.06mm3, p=0.64) as quantified by IVUS and CTCA. The agreement between IVUS and CTCA for PV was better in non-calcified vessels (0.12 +/- 0.07mm3) compared to calcified vessels (0.19 +/- 0.9mm3). There was no significant difference in per-patient total-atheroma-volume measured on IVUS and CTCA (3.4 +/- 2.1mm3, p=0.12). CONCLUSION(S): Quantification of coronary-luminal-area and plaque volume using CTCA is highly accurate when compared with IVUS. Observed difference in plaque volumes was lower in non-calcified plaque. CTCA has the potential accurately monitor coronary plaque progression and regression non-invasively.