Quantification of abdominal aortic calcification on CT

Jayalath, Rumal W.;Jackson, Peter;Golledge, Jonathan

Abstract

[Extract] Calcification of the coronary arteries is associated with cardiovascular end-point, such as myocardial infarction, stroke, and vascular death.1 Techniques for quantifying vascular calcification in patients, particularly in arteries outside the chest, are not routinely available.2 In this prospective study, we examined whether CT angiography (CTA) could be used to reproducibly measure severity of infrarenal abdominal aortic calcification. The study involved 50 consecutive patients undergoing aortic CTA for investigation of peripheral vascular disease or aortic aneurysm in 3 stages. For the initial 14 patients, sequential plain and contrast-enhanced CT were obtained and then analyzed on a workstation using 5 different thresholds to define aortic calcification. The calcification volumes were assessed using a number of nonparametric statistical tests to compare clinical measurements to define the most appropriate threshold by which calcification should be measured on CTA by comparison with CT. For the next 24 patients, CTA alone was obtained and analyzed with the threshold defined as optimal from part 1 of the study. The calcification volume measurements were performed by one observer using three different workstation protocols: (1) manual threshold setting without image magnification, (2) manual threshold setting with twice image magnification, and (3) automatic threshold setting with twice image magnification. To assess the most appropriate protocol, the readings were repeated on a second occasion 24 hours apart by the same observer, and the intraobserver reproducibility was assessed by nonparametric statistical tests. Having defined the most appropriate thresholds and workstation settings to analyze the calcification volume on CTA, the interobserver reproducibility of calcification volume measurements was analyzed on the next 12 consecutive patients undergoing CTA and compared with those for CT (using the first cohort of patients).

Journal

Arteriosclerosis, Thrombosis and Vascular Biology

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1524-4636

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Lippincott, Williams & Wilkins

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Philadelphia, USA -PA

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DOI

10.1161/01.ATV.0000198390.34524.ba