Dr James Otton (St Vincent's Hospital, Sydney, Australia) and colleagues presented results from theirProspective Evaluation of an Algorithm for Coronary Calcium Estimation, a study of their algorithm for quantifying extraluminal coronary calcium in the major epicardial vessels from a contrast-enhanced CT scan.
Measuring calcium score from a single contrast CT has been tried before, but it has usually been impossible to accurately measure calcium across the whole range of Agatston scores, Otton told heartwire. "The key to [our] success was realizing, first, that it is not possible to adequately separate contrast from arterial-wall calcium using solely the traditional axial measurement approach, and second, that traditional calcium-score thresholds don't apply to high-resolution contrast-enhanced coronary CT."
Instead, Otton et al tested coaxial analysis—looking at the coronary artery in short axis—which allows for precise separation of the contrast-filled lumen and the vessel wall and can be mostly automated with standard software tools, he explained. The researchers also found that a lot of noncalcified material appears in the Hounsfield range of 130 to 200 Hounsfield units (HU) on high-resolution coronary CT scans, while the true calcium generally greatly exceeds 200 HU. This finding is supported by previous intravascular ultrasound (IVUS) studies.
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