Can nontriggered thoracic CT be used for coronary artery calcium scoring? A phantom study

• Published in: Medical physics (Lancaster) 2013-08, Vol.40 (8), p.081915-n/a
• Main Authors: Xie, Xueqian, Greuter, Marcel J. W., Groen, Jaap M., de Bock, Geertruida H., Oudkerk, Matthijs, de Jong, Pim A., Vliegenthart, Rozemarijn
• Format: Article
• Language: English
• Subjects: blood vessels; Calcinosis - diagnostic imaging; CALCIUM; Calcium - metabolism; calcium score; Cancer; Cardiac dynamics; CARDIOVASCULAR DISEASES; cardiovascular system; Computed tomography; Computerised tomographs; computerised tomography; COMPUTERIZED TOMOGRAPHY; CORONARIES; Coronary artery calcium; Coronary Vessels - diagnostic imaging; Coronary Vessels - metabolism; Digital computing or data processing equipment or methods, specially adapted for specific applications; diseases; Electrocardiography; Electrocardiography, i.e. ecg; Heart; Heart - diagnostic imaging; Image data processing or generation, in general; IMAGE PROCESSING; imaging phantoms; IN VITRO; Kinematics; Lungs; medical image processing; Medical imaging; nontriggered cardiac imaging technique; PHANTOMS; Phantoms, Imaging; Radiography, Thoracic - instrumentation; RADIOLOGY AND NUCLEAR MEDICINE; SENSITIVITY; Tomography, X-Ray Computed - instrumentation; Vascular system; Velocity measurement; X RADIATION; x‐ray computed tomography; X‐ray imaging
• ISSN: 0094-2405; 2473-4209
• DOI: 10.1118/1.4813904

Purpose: Coronary artery calcium score, traditionally based on electrocardiography (ECG)-triggered computed tomography (CT), predicts cardiovascular risk. However, nontriggered CT is extensively utilized. The study-purpose is to evaluate thein vitro agreement in coronary calcium score between nontriggered thoracic CT and ECG-triggered cardiac CT. Methods: Three artificial coronary arteries containing calcifications of different densities (high, medium, and low), and sizes (large, medium, and small), were studied in a moving cardiac phantom. Two 64-detector CT systems were used. The phantom moved at 0–90 mm/s in nontriggered low-dose CT as index test, and at 0–30 mm/s in ECG-triggered CT as reference. Differences in calcium scores between nontriggered and ECG-triggered CT were analyzed byt-test and 95% confidence interval. The sensitivity to detect calcification was calculated as the percentage of positive calcium scores. Results: Overall, calcium scores in nontriggered CT were not significantly different to those in ECG-triggered CT (p > 0.05). Calcium scores in nontriggered CT were within the 95% confidence interval of calcium scores in ECG-triggered CT, except predominantly at higher velocities (≥50 mm/s) for the high-density and large-size calcifications. The sensitivity for a nonzero calcium score was 100% for large calcifications, but 46% ± 11% for small calcifications in nontriggered CT. Conclusions: When performing multiple measurements, good agreement in positive calcium scores is found between nontriggered thoracic and ECG-triggered cardiac CT. Agreement decreases with increasing coronary velocity. From this phantom study, it can be concluded that a high calcium score can be detected by nontriggered CT, and thus, that nontriggered CT likely can identify individuals at high risk of cardiovascular disease. On the other hand, a zero calcium score in nontriggered CT does not reliably exclude coronary calcification.