Excellent Reproducibility of Total Coronary Plaque Volume By CCTA

Total coronary plaque volume by coronary CT angiography (CCTA) shows very good scan-rescan reproducibility and can be used as a patient centered index of atherosclerosis for clinical trials and therapy, according to a study presented Monday.

By Felicia Dechter

Puskar Pattanayak, M.D.

"For radiologists this means that in clinical trials, total plaque and calcified plaque burdens can be confidently followed up in serial scans, knowing that there is little variability between readers or intra-reader," said Puskar Pattanayak, M.D., a post-doctoral fellow in the radiology department at the National Institutes of Health Clinical Center in Bethesda, Md.

"For patients, the study shows that they can safely have repeat coronary CTs due to low radiation doses," Dr. Pattanayak continued. "They can therefore have scans before and after treatment or have serial scans in a clinical trial."

While both hard and soft plaque can be readily assessed with multidetector CT (MDCT) to determine the overall volume of coronary plaque, Dr. Pattanayak and colleagues sought to determine the scan-rescan reproducibility of plaque volume. Researchers analyzed 20 volunteers with a mean age of 64 at 11 segments per volunteer. Within a short period––a mean of 18 days––study subjects underwent baseline and repeat CCTA on a 320-detector scanner.

CTA images were analyzed for calcium and non-calcified plaque using Medis QAngio CT semi-automated software. A second reader interpreted the follow-up CT. Researchers measured total and plaque subtype amounts indexed by segment length and optimized plaque quantification using both standard and narrow vessel wall thickness settings using an adaptive algorithm that adjusted for coronary lumen density.

At a mean radiation dose per scan of 5.1 mSv, results showed that total plaque burden had excellent intra-observer reproducibility, inter-observer reproducibility. Calcified plaque also showed excellent intra-observer and inter-observer reproducibility. Non-calcified plaque showed excellent intraobserver reproducibility, but moderate interobserver reproducibility and scan-rescan reproducibility.

Not only does calcified plaque burden have excellent reproducibility but it also correlates well with Agatston calcium scores, Dr. Pattanayak said. He added that the study results can be used to inform sample size calculation for future clinical trials focused on evaluation of non-calcified plaque.

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