Prospective Validation of Standardized, 3-Dimensional, Quantitative Coronary Computed Tomographic Plaque Measurements Using Radiofrequency Backscatter Intravascular Ultrasound as Reference Standard in Intermediate Coronary Arterial Lesions Results From the ATLANTA (Assessment of Tissue Characteristics, Lesion Morphology, and Hemodynamics by Angiography With Fractional Flow Reserve, Intravascular Ultrasound and Virtual Histology, and Noninvasive Computed Tomography in Atherosclerotic Plaques) I Study

OBJECTIVES: This study sought to determine the accuracy of 3-dimensional, quantitative measurements of coronary plaque by computed tomography angiography (CTA) against intravascular ultrasound with radiofrequency backscatter analysis (IVUS/VH).  Quantitative, 3-dimensional coronary CTA plaque measurements have not been validated against IVUS/VH.

METHODS: Sixty patients in a prospective study underwent coronary X-ray angiography, IVUS/VH, and coronary CTA. Plaque geometry and composition was quantified after spatial coregistration on segmental and slice-by-slice bases. Correlation, mean difference, and limits of agreement were determined.

RESULTS: There was significant correlation for all pre-specified parameters by segmental and slice-by-slice analyses (r = 0.41 to 0.84; all p < 0.001). On a segmental basis, CTA underestimated minimal lumen diameter by 21% and overestimated diameter stenosis by 39%. Minimal lumen area was overestimated on CTA by 27% but area stenosis was only underestimated by 5%. Mean difference in noncalcified plaque volume and percent and calcified plaque volume and percent were 38%, -22%, 104%, and 64%. On a slice-by-slice basis, lumen, vessel, noncalcified-, and calcified-plaque areas were overestimated on CTA by 22%, 19%, 44%, and 88%. There was significant correlation for percentage of atheroma volume (0.52 vs. 0.54; r = 0.51; p < 0.001). Compositional analysis suggested that high-density noncalcified plaque on CTA best correlated with fibrous tissue and low-density noncalcified plaque correlated with necrotic core plus fibrofatty tissue by IVUS/VH.

CONCLUSIONS: This is the first validation that standardized, 3-dimensional, quantitative measurements of coronary plaque correlate with IVUS/VH. Mean differences are small, whereas limits of agreement are wide. Low-density noncalcified plaque correlates with necrotic core plus fibrofatty tissue on IVUS/VH.

PMID: 21349459

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  1. Very interesting paper from an experienced group. The limits of agreement are still wide between IVUS-VH and CTA measurements of plaque.

  2. Part of the wide limits of agreements are likely secondary to the lower spatial resolution of CT.
    Is there validation in larger vessels, e.g. carotid artery and aorta?

  3. Thanks for the comment, indeed possible a explanation. I am not sure if we measure the same “things” in both modalities. Different plaque definitions per CT may change results. Moreover, IVUS-VH has its own limitation and may be less accurate to define plaque types as previously thought. However, for evaluation of MLA and % stenosis, IVUS could be considered the reference standard.
    The validation with larger vessels may be interesting as well. There are several reports of IVUS VH in non-coronary vessels, but I am not aware of comparative studies with CTA.

  4. 21%, 39% ,27% ,38%, -22%, 104%, 64%, 22%, 19%, 44%, and 88%.
    Amlost 1/3 – 2/3 – 90%; it seems that CTA is useless.
    What about CTA to OCT?

  5. I believe that CTA is rather useful, but quantitative assessment tools still need more validation. OCT is indeed a promising imaging modality in several subgroups of patients, but clinical usefulness deserves further study. However, a comparative study would be interesting (CTA vs. OCT).

  6. A good Chinese book:
    Multi-slice CT cardiac imaging and invasive angiography by Dr. Chen, Buxing and Dr. Hu, dayi and Dr Hong, Nan 2007
    This has pictures comparing 128 MSCT and IVUS and OCT.

    I think Chinese books are more comprehensive, since Chinese doctors list research from diffrent languages.

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