Detection of Coronary Artery Calcification by X-ray Computed Tomography and Its Significance: A New CT Scoring Technique

Abstract

In order to study the utility of X-ray computed tomography (CT) for the evaluation of coronary stenosis, the authors developed a scoring system for calcification seen through CT and compared the results with coronary angiographic (CAG) findings (Friesinger's scoring system). Their study included 143 patients (angina pectoris 53, myocardial infarction 44, control 46) who received both CT and CAG. Judkins method was selected for CAG, and stenosis ≧75% was defined as significant. Horizontal slices of CT from ascending aorta to cardiac apex at 1 cm intervals were imaged without contrast enhancement. CT scoring system was as follows: no calcification = 0, the length of calcification less than 1 cm = 1, 1-2 cm = 2, more than 2 cm = 3 points. They then totaled the separate scores of all the slices for each coronary artery. Sensitivity, specificity, and predictive value of CT against coronary stenosis were good (79%, 80%, 69%, respectively). The correlation between CT and CAG scores was significant (r = 0.644, p < 0.01). For all coronary arteries, no correlation was found between the CAG and CT findings for patients less than forty-five years of age. However, from 45 years of age upward, the results were significant. Until now, to the best of their knowledge, no satisfactory system to define the severity of coronary calcification has existed. Density cannot be used, because values are dependent on the area of the region of interest used. They demonstrated the considerable potential usefulness of CT in predicting the presence of coronary stenosis and analyzing its severity.