Improved detection of coronary artery calcifications using dual energy subtraction radiography

Abstract

PURPOSE: Detection of coronary artery calcifications (CAC) using conventional chest radiographs has a high positive predictive value but low sensitivity for coronary artery disease. We investigated the role of dual energy imaging to enhance reader performance in the detection of CAC, indicative of atherosclerotic plaques. METHODS: A sample of 53 patients with CT documented CAC and 23 patients without CT evidence of CAC, was imaged using a dual energy protocol on an amorphous silicon flat panel system (Revolution XR/d, GE Medical Systems). The acquisition sequence consisted of a 60kVp ("low energy") exposure, followed by a 120 kVp ("high energy") exposure with a time separation of 150ms. Subsequent image processing yielded conventional PA and lateral radiographs and a subtracted PA "bone image". For all patients and both data sets, CAC were evaluated by two experienced board-certified thoracic radiologists via Likert scale measurement (1-5 score). RESULTS: Sensitivity for CAC detection, using conventional radiographs, was 34.0% and 56.6% while specificity was 96.6% and 91.3%, for the two readers respectively. Using the "bone images", sensitivity was 92.4% and 83.0% while specificity was 100% and 91.3%. For patients with verified CAC, "bone images" resulted in at least a one Likert score increase in 73.6% and 54.7% of cases for the two readers. CONCLUSION: We conclude that using dual energy technology, "bone images" may allow higher sensitivity in detecting CAC compared with conventional radiographs, without decreased specificity. Thus, we believe our findings are useful in defining a role for dual energy subtraction radiography in improved detection of coronary artery disease.