Plaque quantification by coronary computed tomography angiography using intravascular ultrasound as a reference standard: a comparison between standard and last generation computed tomography scanners

Aims
The emerging role of coronary computed tomography angiography (CCTA) as a non-invasive tool for atherosclerosis evaluation is supported by data reporting a good correlation between CCTA and intravascular ultrasound (IVUS) for plaque volume quantification. Aim of the present study was to evaluate whether a last generation CT scanner may improve coronary plaque volume assessment using IVUS as standard-of-reference.

Methods and results
From a registry of 1915 consecutive, all-comers, patients who underwent a clinically indicated IVUS evaluation we
enrolled 59 patients who underwent CCTA with a 64-slice CT (Group 1) and 59 patients who underwent CCTA
with whole-heart coverage CT scanner (Group 2). Patients who underwent CCTA with unfavourable heart rhythm
were not excluded from the analysis. Image quality (4-point Likert scale) focused on plaque analysis was evaluated.
Plaque volume quantification by CCTA was compared to IVUS. No difference in clinical characteristics was found
between Group 1 and Group 2. Plaque volume quantification by CCTA was considered not feasible in 11 plaques
of Group 1 and in 4 plaques of Group 2 (P = 0.09). Higher correlation for plaque volume quantification by CCTA
vs. IVUS was demonstrated in Group 2 when compared with Group 1 (r = 0.9888 vs. 0.9499; P < 0.0001). The
Bland–Altman analysis showed plaque volume overestimation by CCTA of 11.9 mm3 in Group 1 and 4 mm2 in
Group 2 (P < 0.001). Effective radiation dose of CCTA was significantly lower in Group 2 vs. Group 1 (2.7 ± 0.9 vs.
8.1 ± 3.6 mSv, respectively; P < 0.001).
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Conclusions
CCTA using a new scanner generation showed to be an accurate non-invasive tool to assess and quantify coronaryplaque volume.