Interobserver variability in the measurement of abdominal aortic calcification using unenhanced CT

Arterial calcification is well recognized as being associated with an increased risk of adverse cardiovascular events. Numerous methods for its quantification have been published, with no consensus on the technique used. In order to assess the reproducibility of a novel technique for quantifying aortic calcification, we measured the interobserver variability between two observers analysing the abdominal aortas of 34 volunteer patients. Using non-contrast abdominal CT images together with commercial imaging software, the quantity of calcium in a pre-determined section of aorta was calculated for each patient, and the difference in values obtained between the two observers compared using a Bland-Altman plot. Minimal interobserver variability was observed, with a significant difference in results occurring for only two patients. This protocol therefore represents a reliable technique that may be applied as a future standard in order to facilitate comparison between studies.