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Reduced Axial Scan Length Coronary Calcium Scoring Reduces Radiation Dose and Provides Adequate Clinical Decision-Making Before Coronary CT Angiography.

ABSTRACT: Extensive coronary artery calcium (CAC) diminishes the accuracy of coronary computed tomography angiography (CCTA). Many imagers adjust CCTA acquisition parameters depending on a preCCTA Agatston CAC score to optimize diagnostic accuracy. Typical preCCTA CAC imaging adds considerably to radiation exposure, partially attributable to imaging beyond the area known for highest CAC, the proximal coronary arteries. We aimed to determine whether a z-axis reduced scan length (RSL) would identify the majority of CAC and provide adequate information to computed tomography angiography providers relative to a standard full-scan length (FSL) preCCTA noncontrast CT. We retrospectively examined 200 subjects. The mean CAC scores detected in RSL and FSL were 77.4 (95% CI 50.6 to 104.3) and 93.9 (95% CI 57.3 to 130.5), respectively. RSL detected 81% of the FSL CAC. Among false negatives, with no CAC detected in RSL, FSL CAC severity was minimal (mean score 2.8). There was high concordance, averaging 88%, between CCTA imaging parameter adjustment decisions made by 2 experienced imagers based on either RSL or FSL. CAC detected and decision concordance decreased with increasing CAC burden. CAC detected was lower, and false negatives were more common in the right coronary artery owing to its anatomic course, placing larger segments outside RSL. Axial scan length and effective dose decreased 59% from FSL (?14.5?cm/?1.1 mSv) to RSL (?5.9?cm/?0.45 mSv). This retrospective study suggests that RSL identifies most CAC, results in similar CCTA acquisition parameter modifications, and reduces radiation exposure. Our colleagues corroborated these results in a recently published prospective study.

SUBMITTER: Young CR

PROVIDER: S-EPMC7744187 | biostudies-literature | 2020 Dec

REPOSITORIES: biostudies-literature

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Reduced Axial Scan Length Coronary Calcium Scoring Reduces Radiation Dose and Provides Adequate Clinical Decision-Making Before Coronary CT Angiography.

Young Colin R CR Reynolds David A DA Gambill Neil N Brooks Daniel I DI Villines Todd C TC

Tomography (Ann Arbor, Mich.) 20201201 4

Extensive coronary artery calcium (CAC) diminishes the accuracy of coronary computed tomography angiography (CCTA). Many imagers adjust CCTA acquisition parameters depending on a preCCTA Agatston CAC score to optimize diagnostic accuracy. Typical preCCTA CAC imaging adds considerably to radiation exposure, partially attributable to imaging beyond the area known for highest CAC, the proximal coronary arteries. We aimed to determine whether a <i>z</i>-axis reduced scan length (RSL) would identify ...[more]

PMID: 33364425

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Project description:ObjectivesCardiac computed tomography (CT) is essential in diagnosing coronary heart disease. However, a disadvantage is the associated radiation exposure to the patient which depends in part on the scan range. This study aimed to develop a deep neural network to optimize the delimitation of scan ranges in CT localizers to reduce the radiation dose.MethodsOn a retrospective training cohort of 1507 CT localizers randomly selected from calcium scoring and angiography scans and acquired between 2010 and 2017, optimized scan ranges were delimited by two radiologists in consensus. A neural network was trained to reproduce the scan ranges and was tested on two randomly selected and independent validation cohorts: an internal cohort of 233 CT localizers (January 2018-June 2020) and an external cohort from a nearby hospital of 298 CT localizers (July 2020-December 2020). Localizers where a bypass surgery was visible were excluded. The effective radiation dose to the patient was simulated using a Monte Carlo simulation. Scan ranges of radiographers, radiologists, and the network were compared using an equivalence test; likewise, the reduction in effective dose was tested using a superior test.ResultsThe network replicated the radiologists' scan ranges with a Dice score of 96.5 ± 0.02 (p < 0.001, indicating equivalence). The generated scan ranges resulted in an effective dose reduction of 10.0% (p = 0.002) in the internal cohort and 12.6% (p < 0.001) in the external cohort compared to the scan ranges delimited by radiographers in clinical routine.ConclusionsAutomatic delimitation of the scan range can result in a radiation dose reduction to the patient.Clinical relevance statementFully automated delimitation of the scan range using a deep neural network enables a significant reduction in radiation exposure during CT coronary angiography compared to manual examination planning. It can also reduce the workload of the radiographers.Key points• Scan range delimitation for coronary computed tomography angiography could be performed with high accuracy by a deep neural network. • Automated scan ranges showed a high agreement of 96.5% with the scan ranges of radiologists. • Using a Monte Carlo simulation, automated scan ranges reduced the effective dose to the patient by up to 12.6% (0.9 mSv) compared to the scan ranges of radiographers in clinical routine.

Project description:ObjectiveTo assess whether anthropometrics, clinical risk factors, and coronary artery calcium score (CACS) can predict the need of further testing after coronary CT angiography (CTA) due to non-diagnostic image quality and/or the presence of significant stenosis.MethodsConsecutive patients who underwent coronary CTA due to suspected coronary artery disease (CAD) were included in our retrospective analysis. We used multivariate logistic regression and receiver operating characteristics analysis containing anthropometric factors: body mass index, heart rate, and rhythm irregularity (model 1); and parameters used for pre-test likelihood estimation: age, sex, and type of angina (model 2); and also added total calcium score (model 3) to predict downstream testing.ResultsWe analyzed 4120 (45.7% female, 57.9 ± 12.1 years) patients. Model 3 significantly outperformed models 1 and 2 (area under the curve, 0.84 [95% CI 0.83-0.86] vs. 0.56 [95% CI 0.54-0.58] and 0.72 [95% CI 0.70-0.74], p < 0.001). For patients with sinus rhythm of 50 bpm, in case of non-specific angina, CACS above 435, 756, and 944; in atypical angina CACS above 381, 702, and 890; and in typical angina CACS above 316, 636, and 824 correspond to 50%, 80%, and 90% probability of further testing, respectively. However, higher heart rates and arrhythmias significantly decrease these cutoffs (p < 0.001).ConclusionCACS significantly increases the ability to identify patients in whom deferral from coronary CTA may be advised as CTA does not lead to a final decision regarding CAD management. Our results provide individualized cutoff values for given probabilities of the need of additional testing, which may facilitate personalized decision-making to perform or defer coronary CTA.Key points• Anthropometric parameters on their own are insufficient predictors of downstream testing. Adding parameters of the Diamond and Forrester pre-test likelihood test significantly increases the power of prediction. • Total CACS is the most important independent predictor to identify patients in whom coronary CTA may not be recommended as CTA does not lead to a final decision regarding CAD management. • We determined specific CACS cutoff values based on the probability of downstream testing by angina-, arrhythmia-, and heart rate-based groups of patients to help individualize patient management.

Project description:PurposeTo determine the impact of low tube voltage coronary CT angiography on detection of subclinical atherosclerosis.Materials and methodsRetrospective sampling of an emergency department coronary CT angiography registry was performed. All patients in the registry underwent a noncontrast coronary artery calcium (CAC) scoring scan at 120 kV before coronary CT angiography. The study sample (n = 264) constituted patients with subclinical atherosclerosis (Coronary Artery Disease Reporting and Data System™ [CAD-RADS] 1 or 2) randomly mixed one-to-one with patients without atherosclerosis (CAD-RADS 0). The patients with coronary CT angiography performed at 70-90 kV were considered the low tube voltage group (n = 159) and patients with coronary CT angiography performed at 100-120 kV were considered the standard tube voltage group (n = 105). The number of coronary plaques and overall CAD-RADS classification (per patient) were evaluated twice: initially, by reading coronary CT angiography alone, and then, by coronary CT angiography in combination with a CAC scan. Considering the combined reading (CT angiography plus CAC scan) as the reference standard, the performance of coronary CT angiography alone was assessed for plaque detection and appropriate CAD-RADS (per patient) classification. The comparisons were made between the low tube voltage and standard tube voltage groups by using a Fisher exact test and χ2 test for proportions and a Mann-Whitney test and Kruskal-Wallis test for means.ResultsIn total, 455 plaques were identified in 118 patients (70 of 159 patients in the low tube voltage group; 48 of 105 in the standard tube voltage group). When reading coronary CT angiographic images alone, 97 of 455 (21%) plaques were missed that led to an incorrect CAD-RADS classification in 16 of 264 (6%) studies (interpreted as CAD-RADS 0 instead of CAD-RADS 1 or 2). Missed plaques were significantly more frequent in the low tube voltage group versus the standard tube voltage group (41% [85 of 206] vs 5% [12 of 249], respectively; P < .001). Incorrect CAD-RADS classification was also seen more commonly in the low tube voltage group (8.8% [14 of 159] vs 2% [two of 105]; P = .01), typically at low plaque burden (median CAC score, 1; range, 1-4). Calcified plaques that appeared isodense to luminal contrast material attenuation were seen more frequently in the low tube voltage group compared with the standard tube voltage group (20% [32 of 159] vs 7.6% [eight of 105], respectively; P = .005).ConclusionCoronary artery plaques may be missed at low tube voltage coronary CT angiographic examination performed without a concomitant CAC scan.© RSNA, 2019Supplemental material is available for this article.See also the commentary by Truong in this issue.

Project description:BackgroundPeople with HIV (HIV+) may have increased cardiovascular event rates compared with HIV-negative (HIV-) persons. Cross-sectional data from the United States and Switzerland, based on coronary artery calcium scan (CAC) and coronary computed tomography angiography (CCTA), suggest, respectively, increased and similar prevalence of subclinical atherosclerosis in HIV+ vs HIV- persons.MethodsWe repeated CAC/CCTA in 340 HIV+ and 90 HIV- study participants >2 years after baseline CAC/CCTA. We assessed the association of HIV infection, Framingham risk score (FRS), and HIV-related factors with the progression of subclinical atherosclerosis.ResultsHIV+ were younger than HIV- participants (median age, 52 vs 56 years; P < .01) but had similar median 10-year FRS (8.9% vs 9.0%; P = .82); 94% had suppressed HIV viral load. In univariable and multivariable analyses, FRS was associated with the incidence rate ratio (IRR) of new subclinical atherosclerosis at the follow-up CAC/CCTA, but HIV infection was not: any plaque (adjusted IRR for HIV+ vs HIV- participants, 1.21; 95% CI, 0.62-2.35), calcified plaque (adjusted IRR for HIV+ vs HIV- participants, 1.06; 95% CI, 0.56-2), noncalcified/mixed plaque (adjusted IRR for HIV+ vs HIV- participants, 1.24; 95% CI, 0.69-2.21), and high-risk plaque (adjusted IRR for HIV+ vs HIV- participants, 1.46; 95% CI, 0.66-3.20). Progression of CAC score between baseline and follow-up CAC/CCTA was similar in HIV+ (median annualized change [interquartile range {IQR}], 0.41 [0-10.19]) and HIV- participants (median annualized change [IQR], 2.38 [0-16.29]; P = .11), as was progression of coronary segment severity score (HIV+: median annualized change [IQR], 0 [0-0.47]; HIV-: median annualized change [IQR], 0 [0-0.52]; P = .10) and coronary segment involvement score (HIV+: median annualized change [IQR], 0 [0-0.45]; HIV-: median annualized change [IQR], 0 [0-0.41]; P = .25).ConclusionsIn this longitudinal CAC/CCTA study from Switzerland, Framingham risk score was associated with progression of subclinical atherosclerosis, but HIV infection was not.

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Reduced Axial Scan Length Coronary Calcium Scoring Reduces Radiation Dose and Provides Adequate Clinical Decision-Making Before Coronary CT Angiography.

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Reduced Axial Scan Length Coronary Calcium Scoring Reduces Radiation Dose and Provides Adequate Clinical Decision-Making Before Coronary CT Angiography.

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