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Objectives: Diagnostic accuracy of conventional coronary CT angiography (CCTA conv ) may be compromised by blooming artifacts from calcifications or stents. Blooming artifacts may be reduced by subtraction coronary CT angiography (CCTA sub ) in which non-contrast and contrast CT data sets are subtracted digitally. We tested whether CCTA sub in patients with severe coronary calcification or stents reduces the number of false-positive stenosis evaluations compared with CCTA conv ., Methods: In this study, 180 symptomatic patients scheduled for invasive coronary angiography (ICA) were prospectively enrolled and CT scanned (2013-2016) at three international centers. CCTA conv , and CCTA sub data sets were reconstructed. Target segments were defined as motion-free coronary segments with a suspected stenosis (> 50% of lumen) potentially due to blooming of either calcium or stents. Target segments were evaluated with respect to misregistration artifacts from the CCTA sub reconstruction process, in which case evaluation was omitted. CCTA sub and CCTA conv were compared with ICA. Primary outcome measure was the frequency of false positives by CCTA conv versus CCTA sub to identify > 50% coronary stenosis by ICA on a per-segment level., Results: After exclusion of 76 patients, 104 (14% females) with mean age 67 years and median Agatston score 852 were included. There were 136 target segments with misregistration and 121 target segments without. Accuracy calculations in target segments without misregistration showed a reduction of the false positives from 72% [95% confidence interval (CI): 63-80%] in CCTA conv to 33% (CI:25-42%) in CCTA sub , at the expense of 7% (CI:3-14%) false negatives in CCTA sub ., Conclusions: In severely calcified coronary arteries or stents, CCTA sub reduces the false-positive rate in well-aligned, calcified or stent segments suspected of significant stenosis on CCTA conv . Nevertheless, misregistration artifacts are frequent in CCTA sub ., Key Points: • A high calcium-score reduces the diagnostic accuracy in patients scanned with cardiac CT. • These patients would normally need an invasive angiogram for diagnosis. • In this prospective, multicenter study, subtraction CT, when evaluable, reduces false-positive stenosis evaluations. • Subtraction coronary CT angiography may, when evaluable, reduce excessive downstream testing.

Objective: Population studies have shown coronary calcium score to improve risk stratification in subjects suspected for cardiovascular disease. The aim of this work was to assess the validity of multidetector computed tomography (MDCT) for measurement of calibrated mass scores (MS) in a phantom study, and to investigate inter-scanner variability for MS and Agaston score (AS) recorded in a population study on two different high-end MDCT scanners., Materials and Methods: A calcium phantom was scanned by a first (A) and second (B) generation 320-MDCT. MS was measured for each calcium deposit from repeated measurements in each scanner and compared to known physical phantom mass. Random samples of human subjects from the Copenhagen General Population Study were scanned with scanner A (N=254) and scanner B (N=253) where MS and AS distributions of these two groups were compared., Results: The mean total MS of the phantom was 32.9±0.8mg and 33.1±0.9mg (p=0.43) assessed by scanner A and B respectively - the physical calcium mass was 34.0mg. Correlation between measured MS and physical calcium mass was R 2 =0.99 in both scanners. In the population study the median total MS was 16.8mg (interquartile range (IQR): 3.5-81.1) and 15.8mg (IQR: 3.8-63.4) in scanner A and B (p=0.88). The corresponding median total AS were 92 (IQR: 23-471) and 89 (IQR: 40-384) (p=0.64)., Conclusion: Calibrated calcium mass score may be assessed with very high accuracy in a calcium phantom by different generations of 320-MDCT scanners. In population studies, it appears acceptable to pool calcium scores acquired on different 320-MDCT scanners., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Background: Coronary artery calcification (CAC) is commonly assessed with Agatston score (AS). A higher sensitivity and precision for the detection of CAC has been demonstrated with calibrated mass score (cMS). We hypothesized that cMS would detect low-level CAC not detectable with AS in a large asymptomatic background population.Methods: Participants (N = 2985) from the Copenhagen General Population Study were evaluated for CAC using both conventional AS and cMS. The population was grouped according to number of traditional risk factors and heart score was used to assess the risk of event for those with no CAC, those with only cMS > 0 and those with both AS and cMS > 0.Results: In participants with an AS = 0, 11% had cMS > 0. The risk profile of this cMS-only group was between that of the CAC-negative participants and those with AS > 0 and cMS > 0. Overall, 6% of the population belonged to the cMS-only group independent of the number of risk factors.Conclusion: In individuals with AS = 0, a fraction was found to have cMS > 0. Based on traditional risk factors, this group has a higher 10-year risk than individuals with both AS = 0 and cMS = 0; cMS might offer very early cardiovascular risk assessment in asymptomatic individuals.Key Points: • In individuals with AS=0, a fraction has CAC with highly sensitive cMS. • This fraction has a higher 10-year risk of cardiovascular disease. • Regardless of risk factors, 6% has CAC detectable only with cMS. • cMS might offer very early cardiovascular risk assessment in asymptomatic individuals. [ABSTRACT FROM AUTHOR]