Coronary calcium screening with dual-source CT: reliability of ungated,high-pitch chest CT in comparison with dedicated calcium-scoring CT

Purpose

To investigate the reliability of ungated, high-pitch dual-source CT for coronary artery calcium (CAC) screening.

Materials and methods

One hundred and eighty-five smokers underwent a dual-source CT examination with acquisition of two sets of images during the same session: (a) ungated, high-pitch and high-temporal resolution acquisition over the entire thorax (i.e., chest CT); (b) prospectively ECG-triggered acquisition over the cardiac cavities (i.e., cardiac CT).

Results

Sensitivity and specificity of chest CT for detecting positive CAC scores were 96.4 % and 100 %, respectively. There was excellent inter-technique agreement for determining the quantitative CAC score (ICC = 0.986). The mean difference between the two techniques was 11.27, representing 1.81 % of the average of the two techniques. The inter-technique agreement for categorizing patients into the four ranks of severity was excellent (weighted kappa?=?0.95; 95 % CI 0.93–0.98). The inter-technique differences for quantitative CAC scores did not correlate with BMI (r?=?0.05, p?=?0.575) or heart rate (r?=?–0.06, p?=?0.95); 87.2 % of them were explained by differences at the level of the right coronary artery (RCA: 0.8718; LAD: 0.1008; LCx: 0.0139; LM: 0.0136).

Conclusion

Ungated, high-pitch dual-source CT is a reliable imaging mode for CAC screening in the conditions of routine chest CT examinations.

Key points

? CAC is an independent risk factor for major cardiac events.? ECG-gated techniques are the reference standard for calcium scoring.? Great interest is directed toward calcium scoring on non-gated chest CT examinations.? Reliable calcium scoring can be obtained with dual-source CT in a high-pitch mode.

     

High-pitch versus sequential mode for coronary calcium in individuals with a high heart rate: Potential for dose reduction

BackgroundTo determine the impact of high-pitch spiral acquisition on radiation dose and cardiovascular disease (CVD) risk stratification by coronary artery calcium (CAC) assessment with computed tomography in individuals with a high heart rate.MethodsOf the ROBINSCA trial, 1990 participants with regular rhythm and heart rates >65 beats per minute (bpm) were included. As reference, 390 participants with regular heart rates ≤65 bpm were used. All participants underwent prospectively electrocardiographically(ECG)-triggered imaging of the coronary arteries using dual source CT at 120 kVp, 80 ref mAs using both high-pitch spiral mode and sequential mode. Radiation dose, Agatston score, number of positive scores, as well as median absolute difference of the Agatston score were determined and participants were stratified into CVD risk categories.ResultsA similar percentage of participants with low heart rates and high heart rates had a positive CAC score in data sets acquired in high-pitch spiral (low heart rate: 57.7%, high heart rate: 55.8%) and sequential mode (58.0%, 54.7%, p = n.s.). The median absolute difference in Agatston scores between acquisition modes was 14.2% and 9.2%, for the high and low heart rate groups, respectively. Excellent agreement for risk categorization between the two data acquisition modes was found for the high (κ = 0.927) and low (κ = 0.946) heart rate groups. Radiation dose was 48% lower for high-pitch spiral versus sequential acquisitions.ConclusionRadiation dose for the quantification of coronary calcium can be reduced by 48% when using the high-pitch spiral acquisition mode compared to the sequential mode in participants with a regular high heart rate. CVD risk stratification agreement between the two modes of data acquisition is excellent.     

Use of coronary artery calcium testing to improve coronary heart disease risk assessment in a lung cancer screening population: The Multi-Ethnic Study of Atherosclerosis (MESA)

BackgroundAssessment of coronary artery calcium (CAC) during lung cancer screening chest computed tomography (CT) represents an opportunity to identify asymptomatic individuals at increased coronary heart disease (CHD) risk. We determined the improvement in CHD risk prediction associated with the addition of CAC testing in a population recommended for lung cancer screening.MethodsWe included 484 out of 6814 Multi-Ethnic Study of Atherosclerosis (MESA) participants without baseline cardiovascular disease who met U.S. Preventive Service Task Force CT lung cancer screening criteria and underwent gated CAC testing. 10 year-predicted CHD risks with and without CAC were calculated using a validated MESA-based risk model and categorized into low (<5%), intermediate (5%–10%), and high (≥10%). The net reclassification improvement (NRI) and change in Harrell's C-statistic by adding CAC to the risk model were subsequently determined.ResultsOf 484 included participants (mean age = 65; 39% women; 32% black), 72 (15%) experienced CHD events over the course of follow-up (median = 12.5 years). Adding CAC to the MESA CHD risk model resulted in 17% more participants classified into the highest or lowest risk categories and a NRI of 0.26 (p = 0.001). The C-statistic improved from 0.538 to 0.611 (p = 0.01).ConclusionsCHD event rates were high in this lung cancer screening eligible population. These individuals represent a high-risk population who merit consideration for CHD prevention measures regardless of CAC score. Although overall discrimination remained poor with inclusion of CAC scores, determining whether those reclassified to an even higher risk would benefit from more aggressive preventive measures may be important.     

Coronary risk assessment at X-ray dose equivalent ungated chest CT: Results of a multi-reader study

ObjectivesTo determine the value of ultra-low dose chest CT with tin filtration for ordinal coronary artery calcium (CAC) risk scoring.Methods50 patients were prospectively included and underwent clinical standard dose chest CT (1.8 ± 0.7 mSv) and ultra-low dose CT (0.13 ± 0.01 mSv). Four radiologists estimated presence and extent of CAC.ResultsWeighted kappa values for CAC were 0.76–0.97 in standard dose and 0.75–0.95 in ultra-low dose CT (p < 0.001). Good to excellent agreement was observed for CAC ordinal risk assessment, with readers reporting identical risk in 81% of cases.ConclusionCAC risk can be qualitatively assessed from X-ray dose equivalent ungated chest CT.     

Prospectively ECG-triggered high-pitch coronary angiography with third-generation dual-source CT at 70 kVp tube voltage: Feasibility,image quality,radiation dose,and effect of iterative reconstruction

BackgroundLow tube voltage reduces radiation exposure in coronary CT angiography (CTA). Using 70 kVp tube potential has so far not been possible because CT systems were unable to provide sufficiently high tube current with low voltage.ObjectiveWe evaluated feasibility, image quality (IQ), and radiation dose of coronary CTA using a third-generation dual-source CT system capable of producing 450 mAs tube current at 70 kVp tube voltage.MethodsCoronary CTA was performed in 26 consecutive patients with suspected coronary artery disease, selected for body weight <100 kg and heart rate <60 beats/min. High-pitch spiral acquisition was used. Filtered back projection (FBP) and iterative reconstruction (IR) algorithms were applied. IQ was assessed using a 4-point rating scale (1 = excellent, 4 = nondiagnostic) and objective parameters.ResultsMean age was 62 ± 9 years (46% males; mean body mass index, 27.7 ± 3.8 kg/m²; mean heart rate, 54 ± 5 beats/min). Mean dose-length product was 20.6 ± 1.9 mGy × cm; mean estimated effective radiation dose was 0.3 ± 0.03 mSv. Diagnostic IQ was found in 365 of 367 (FBP) and 366 of 367 (IR) segments (P nonsignificant). IQ was rated “excellent” in 53% (FBP) and 86% (IR) segments (P = .001) and “nondiagnostic” in 2 (FBP) and 1 segment (IR) (P nonsignificant). Mean IQ score was lesser in FBP vs IR (1.5 ± 0.4 vs 1.1 ± 0.2; P < .001). Image noise was lower in IR vs FBP (60 ± 10 HU vs 74 ± 8 HU; P < .001).ConclusionIn patients <100 kg and with a regular heart rate <60 beats/min, third-generation dual-source CT using high-pitch spiral acquisition and 70 kVp tube voltage is feasible and provides both robust IQ and very low radiation exposure.     

Lipoprotein (a) and risk for calcification of the coronary arteries,mitral valve,and thoracic aorta: The Multi-Ethnic Study of Atherosclerosis

BackgroundLipoprotein (a) [Lp(a)] is a risk factor for coronary heart disease and calcific aortic valve disease. We determined the relationships of Lp(a) with prevalence and progression of coronary artery calcification (CAC), mitral annular calcification (MAC), and thoracic aortic calcification (TAC) in a multi-ethnic cohort of middle to older-aged adults.MethodsThis analysis included 6705 Multi-Ethnic Study of Atherosclerosis participants. Lp(a) was measured with a turbidimetric immunoassay. CAC, MAC, and TAC were assessed by cardiac computed tomography both at baseline and once during follow-up.ResultsIn adjusted relative risk regression cross-sectional analysis, a Lp(a) level ≥50 ?mg/dL was associated with a 22% higher prevalence of MAC (relative risk (RR) ?= ?1.22, 95% confidence interval (CI) 1.00, 1.49). No significant associations were observed for prevalent CAC or TAC. In adjusted prospective analyses, participants with Lp(a) ≥50 ?mg/dL were at significantly higher risk for rapid CAC progression (median follow-up ?= ?8.9 years), defined as ≥100 units/year, compared to those with lower Lp(a) levels (RR ?= ?1.67, 95% CI ?= ?1.23, 2.27). The association between higher Lp(a) levels and incident CHD was no longer significant after adjusting for CAC progression. No significant associations were observed for MAC or TAC progression (median follow-up ?= ?2.6 years).ConclusionsHigher Lp(a) levels are associated with more rapid CAC progression. Additional study is needed to better understand how this relationship can further improve the ability of Lp(a) to enhance cardiovascular disease risk prediction.     

Prognostic value of CT-derived left atrial and left ventricular measures in patients with acute chest pain

PurposeTo determine which left atrial (LA) and left ventricular (LV) parameters are associated with future major adverse cardiac event (MACE) and whether these measurements have independent prognostic value beyond risk factors and computed tomography (CT)-derived coronary artery disease measures.Materials and methodsThis retrospective analysis was performed under an IRB waiver and in HIPAA compliance. Subjects underwent coronary CT angiography (CCTA) using a dual-source CT system for acute chest pain evaluation. LV mass, LV ejection fraction (EF), LV end-systolic volume (ESV) and LV end-diastolic volume (EDV), LA ESV and LA diameter, septal wall thickness and cardiac chamber diameters were measured. MACE was defined as cardiac death, non-fatal myocardial infarction, unstable angina, or late revascularization. The association between cardiac CT measures and the occurrence of MACE was quantified using Cox proportional hazard analysis.Results225 subjects (age, 56.2 ± 11.2; 140 males) were analyzed, of whom 42 (18.7%) experienced a MACE during a median follow-up of 13 months. LA diameter (HR:1.07, 95%CI:1.01–1.13 per mm) and LV mass (HR:1.05, 95%CI:1.00–1.10 per g) remained significant prognostic factor of MACE after controlling for Framingham risk score. LA diameter and LV mass were also found to have prognostic value independent of each other. The other morphologic and functional cardiac measures were no significant prognostic factors for MACE.ConclusionCT-derived LA diameter and LV mass are associated with future MACE in patients undergoing evaluation for chest pain, and portend independent prognostic value beyond traditional risk factors, coronary calcium score, and obstructive coronary artery disease.     

第3代双源CT低剂量Turbo Flash成像图像质量与诊断效能的临床研究

目的探讨第3代双源CT大螺距前瞻性心电门控扫描模式(Turbo Flash)冠状动脉CT成像(CCTA)评价冠状动脉狭窄的准确性、图像质量及有效辐射剂量。方法前瞻性收集2016年4月至2017年4月接受第3代双源CCTA检查的患者1003例,其中有70例患者在CCTA检查后30 d内行冠状动脉造影(CAG)。对冠状动脉各节段图像质量进行评分,计算有效辐射剂量。以CAG结果为“金标准”,计算CCTA显示冠状动脉病变的灵敏度、特异度、阳性预测值和阴性预测值;CCTA与CAG评价冠状动脉狭窄分级的一致性采用Kappa值并进行U检验。结果(1) 图像质量：右冠状动脉不可诊断血管节段为0,左冠状动脉主干及前降支不可诊断血管节段为0,左冠状动脉回旋支不可诊断血管节段为0.04% (3/835)。(2)准确性评价：基于节段水平分析,Force CT诊断冠状动脉狭窄的灵敏度为97.0% (289/298)、特异度为98.3% (706/718)、阳性预测值为96.0% (289/301)、阴性预测值为98.7% (706/715);基于血管分析,灵敏度为97.5% (159/163)、特异度为85.1% (40/47)、阳性预测值为95.8% (159/166)、阴性预测值为90.9% (40/44);基于患者分析,灵敏度、特异度、阳性预测值、阴性预测值均为100%。CCTA与CAG显示的冠状动脉狭窄部位高度一致(U=2.4,P=0.008)。(3)辐射剂量：有效辐射剂量为(1.17±0.29)mSv。结论第3代双源CT Turbo Flash模式可以在自然呼吸、无心率干预下进行冠状动脉成像,扫描成功率高,图像质量佳,评价冠状动脉狭窄的准确性高,有效辐射剂量低。     

Low thigh muscle mass is associated with coronary artery stenosis among HIV-infected and HIV-uninfected men: The Multicenter AIDS Cohort Study (MACS)

BackgroundHIV-infected individuals are at increased risk for both sarcopenia and cardiovascular disease. Whether an association between low muscle mass and subclinical coronary artery disease (CAD) exists, and if it is modified by HIV serostatus, are unknown.MethodsWe performed cross-sectional analysis of 513 male MACS participants (72% HIV-infected) who underwent mid-thigh computed tomography (CT) and non-contrast cardiac CT for coronary artery calcium (CAC) during 2010–2013. Of these, 379 also underwent coronary CT angiography for non-calcified coronary plaque (NCP) and obstructive coronary stenosis ≥50%. Multivariable-adjusted Poisson regression was used to estimate prevalence risk ratios of associations between low muscle mass (<20th percentile of the HIV-uninfected individuals in the sample) and CAC, NCP and obstructive stenosis.ResultsThe prevalence of low thigh muscle mass was similar by HIV serostatus (20%). There was no association of low muscle mass with CAC or NCP. However, low thigh muscle mass was significantly associated with a 2.5-fold higher prevalence of obstructive coronary stenosis, after adjustment for demographics and traditional CAD risk factors [PR 2.46 (95% CI 1.51, 4.01)]. This association remained significant after adjustment for adiposity, inflammation, and physical activity. There was no significant interaction by HIV serostatus (p-interaction = 0.90).ConclusionsIn this exploratory analysis, low thigh muscle mass was significantly associated with subclinical obstructive coronary stenosis. Additional studies involving larger sample sizes and prospective analyses are needed to confirm the potential utility of measuring mid-thigh muscle mass for identifying individuals at increased risk for obstructive CAD who might benefit from more aggressive risk factor management.     

Value of multislice CT coronary arteries calcification scoring in the prediction of coronary arteries pathology in chronic kidney disease patients

PurposeTo determine the value of multislice CT coronary artery calcification (CAC) scoring in the prediction of future cardiac events in known chronic kidney disease (CKD) patients using conventional coronary angiography as the standard reference.Patients and methodsFifty-eight patients with CKD on hemodialysis underwent CT CAC scoring using multislice scanner and conventional coronary angiography. Results of CAC scoring were compared to the findings of conventional coronary angiography.ResultsMean CAC scoring in patients with significant coronary arteries stenotic lesions was higher than in patients with no significant coronary arteries stenotic lesions with significant difference (P < 0.001).Mean patient CAC scoring was strongly correlated with the number of coronary arteries with significant stenotic lesions (r = 0.910).ConclusionCT CAC scoring is a non-invasive technique which can be used in the evaluation and follow up of CKD patients’ coronary arteries without the use of contrast medium reducing the number of invasive coronary angiography needed.     

Detection of Cardiac Incidental Findings on Routine Chest CT: The Impact of Dedicated Training in Cardiac Imaging

PurposeRoutine chest CT and cardiac CT angiography (CTA) both image the heart, albeit with different precision and intent. The aim of this study was to evaluate the diagnostic ability of radiologists with different levels of cardiac training to identify cardiac findings on chest CT without electrocardiographic gating compared with a reference standard of electrocardiographically gated cardiac CTA.MethodsElectrocardiographically gated cardiac CT angiographic studies performed between January 2005 to January 2010 in patients with routine chest CT within six months were retrospectively identified. Fourteen radiologists at four stages of training (stage 1, residents with no cardiac training [n = 4]; stage 2, residents who had completed at least one dedicated rotation of cardiac imaging [n = 3]; stage 3, radiologists without cardiac training [n = 3]; and stage 4, radiologists with formal cardiac fellowship training [n = 4]) performed blinded, anonymized cardiac readings of chest CT images. Findings were categorized (coronary arterial, noncoronary vessel, cardiac chamber, myocardial, pericardial, and valve findings) with cardiac CTA as a reference standard.ResultsOverall, 140 cardiac CT angiographic findings were reported in 63 of 77 patients. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of nongated CTA were 43.6%, 96.8%, 83.0%, 81.6%, and 81.8%, respectively, for all readers. Increasing training was associated with higher sensitivity (30.3%, 35.7%, 45.7%, and 61.2% from stages 1 to 4) but similar specificity (96.4%, 96.7%, 96.3%, and 97.6% from stages 1 to 4). Frequently missed findings categories were coronary arterial, myocardial, and cardiac chamber findings.ConclusionsIncreasing cardiac imaging training correlates with increased sensitivity and stable specificity to detect cardiac findings on routine chest CT without electrocardiographic gating. Cardiac findings should be noted on chest CT when observed, and cardiac training should be encouraged.     

The accuracy of coronary CT angiography in patients with coronary calcium score above 1000 Agatston Units: Comparison with quantitative coronary angiography

BackgroundHigh amounts of coronary artery calcium (CAC) pose challenges in interpretation of coronary CT angiography (CCTA). The accuracy of stenosis assessment by CCTA in patients with very extensive CAC is uncertain.MethodsRetrospective study was performed including patients who underwent clinically directed CCTA with CAC score >1000 and invasive coronary angiography within 90 days. Segmental stenosis on CCTA was graded by visual inspection with two-observer consensus using categories of 0%, 1–24%, 25–49%, 50–69%, 70–99%, 100% stenosis, or uninterpretable. Blinded quantitative coronary angiography (QCA) was performed on all segments with stenosis ≥25% by CCTA. The primary outcome was vessel-based agreement between CCTA and QCA, using significant stenosis defined by diameter stenosis ≥70%. Secondary analyses on a per-patient basis and inclusive of uninterpretable segments were performed.Results726 segments with stenosis ≥25% in 346 vessels within 119 patients were analyzed. Median coronary calcium score was 1616 (1221–2118). CCTA identification of QCA-based stenosis resulted in a per-vessel sensitivity of 79%, specificity of 75%, positive predictive value (PPV) of 45%, negative predictive value (NPV) of 93%, and accuracy 76% (68 false positive and 15 false negative). Per-patient analysis had sensitivity 94%, specificity 55%, PPV 63%, NPV 92%, and accuracy 72% (30 false-positive and 3 false-negative). Inclusion of uninterpretable segments had variable effect on sensitivity and specificity, depending on whether they are considered as significant or non-significant stenosis.ConclusionsIn patients with very extensive CAC (>1000 Agatston units), CCTA retained a negative predictive value ​> ​90% to identify lack of significant stenosis on a per-vessel and per-patient level, but frequently overestimated stenosis.     

Association of left ventricular diastolic function with coronary artery calcium score: A Project Baseline Health Study

BackgroundCoronary artery calcium (CAC) and left ventricular diastolic dysfunction (LVDD) are strong predictors of cardiovascular events and share common risk factors. However, their independent association remains unclear.MethodsIn the Project Baseline Health Study (PBHS), 2082 participants underwent cardiac-gated, non-contrast chest computed tomography (CT) and echocardiography. The association between left ventricular (LV) diastolic function and CAC was assessed using multidimensional network and multivariable-adjusted regression analyses. Multivariable analysis was conducted on continuous LV diastolic parameters and categorical classification of LVDD and adjusted for traditional cardiometabolic risk factors. LVDD was defined using reference limits from a low-risk reference group without established cardiovascular disease, cardiovascular risk factors or evidence of CAC, (n ?= ?560). We also classified LVDD using the American Society of Echocardiography recommendations.ResultsThe mean age of the participants was 51 ?± ?17 years with 56.6% female and 62.6% non-Hispanic White. Overall, 38.1% had hypertension; 13.7% had diabetes; and 39.9% had CAC >0. An intertwined network was observed between diastolic parameters, CAC score, age, LV mass index, and pulse pressure. In the multivariable-adjusted analysis, e’, E/e’, and LV mass index were independently associated with CAC after adjustment for traditional risk factors. For both e’ and E/e’, the effect size and statistical significance were higher across increasing CAC tertiles. Other independent correlates of e’ and E/e’ included age, female sex, Black race, height, weight, pulse pressure, hemoglobin A1C, and HDL cholesterol. The independent association with CAC was confirmed using categorical analysis of LVDD, which occurred in 554 participants (26.6%) using population-derived thresholds.ConclusionIn the PBHS study, the subclinical coronary atherosclerotic disease burden detected using CAC scoring was independently associated with diastolic function.Clinicaltrials.gov identifierNCT03154346.     

The impact of dose reduction on the quantification of coronary artery calcifications and risk categorization: A systematic review

Multiple dose reduction techniques have been introduced for coronary artery calcium (CAC) computed tomography (CT), but few have emerged into clinical practice while an increasing number of patients undergo CAC scanning. We sought to determine to what extend the radiation dose in CAC CT can be safely reduced without a significant impact on cardiovascular disease (CVD) risk stratification. A systematic database-review of articles published from 2002 until February 2018 was performed in Pubmed, WebOfScience, and Embase. Eligible studies reported radiation dose reduction for CAC CT, calcium scores and/or risk stratification for phantom or patient studies. Twenty-eight studies were included, under which 17 patient studies, 10 phantom/ex-vivo studies, and 1 study evaluated both phantom and patients. Dose was reduced with tube voltage reduction and tube current reduction with and without iterative reconstruction (IR), and tin-filter spectral shaping. The different dose reduction techniques resulted in varying final radiation doses and had varying impact on CAC scores and CVD risk stratification. In 78% of the studies the radiation dose was reduced by ≥ 50% ranging from (CTDI_vol) 0.6–5.5 mGy, leading to reclassification rates ranging between 3% and 21%, depending on the acquisition technique. Specific dose reduced protocols, including either tube current reduction and IR or spectral shaping with tin filtration, that showed low reclassification rates may potentially be used in CAC scanning and in future population-based screening for CVD risk stratification.     

CT dose reduction using prospectively triggered or fast-pitch spiral technique employed in cardiothoracic imaging (the CT dose study)

ObjectivesTo establish current radiation dose levels with contemporary scanners capable of prospectively triggered or high-pitch spiral scan modes to previous generation scanners among patients evaluated for coronary artery disease, pulmonary embolism, aortic disease, and “triple rule out” in a large population of patients at multiple centers.BackgroundPrevious small-scale studies with carefully controlled scan protocols report that CT scanners that facilitate prospectively triggered scanning and provide high-pitch spiral CT scan modes drastically lower radiation doses. However, diagnostic reference levels should be selected by medical bodies on the basis of large surveys of representative sites and reviewed at appropriate time intervals.MethodsScan data including dose and image quality parameters were collected retrospectively from 64 slice scanners (control) and prospectively after sites installed 128-slice dual-source scanners with high-pitch capability (study). Protocol selection was purposely not specified to survey “real world” results. Blinded quantitative image analysis was performed on every fifth scan.ResultsFrom April 2011 to March 2012, 2085 patients at 9 sites completed the study: 1051 coronary artery disease (509 control, 542 study), 528 pulmonary embolism (267 control, 261 study), 419 aortic disease (268 control, 151 study), and 87 triple rule out (53 control, 34 study). There was a significant reduction in median dose-length product (DLP) from 669 mGy∙cm (interquartile range [IQR]: 419–1026 mGy∙cm) in the control group to 260 mGy∙cm (IQR: 159–441 mGy∙cm) in the study group, a reduction by 61% (P < .0001) and was lower in all categories. No significant differences were noted in image quality.ConclusionUse of advanced scanners facilitating prospectively triggered or high-pitch spiral scan modes results in marked dose reduction across a variety of cardiovascular studies, with no compromise in image quality. These findings may contribute to new target dose recommendations in societal guidelines.     

Contrast medium application in pediatric high-pitch cardiovascular CT angiography: Manual or power injection?

BackgroundDual-source CT offers accurate depiction of cardiac structures in children with congenital heart disease. For cardiac CT, optimal enhancement of the cardiovascular structures is essential. There is considerable controversy about the administration of contrast medium (CM) in infants and small children, with either a power injector or a manual (hand) injection.ObjectiveThe aim of this study was to compare image quality with power injection of CM (study group) and manual injection (control group).MethodsThirty-four patients (study group, 6.8 ± 9.6 months and control group, 4.6 ± 8.9 months, nonrandomized) underwent dual-source CT angiography of the chest using a prospective electrocardiography-triggered high-pitch spiral mode (pitch, 3.4; 80 kV). In the study group (17 patients), a power injector was used, and in the control group (17 patients, historical group), manual CM injection had been performed. To assess image quality, both subjective and objective parameters were evaluated independently by 2 experienced radiologists.ResultsSubjective overall image quality, signal-to-noise ratio, and contrast-to-noise ratio were significantly higher using power injection compared with manual injection (P < .05). However, depiction of cardiovascular structures did not differ significantly between both groups in all evaluated regions except the superior vena cava and the coronary arteries.ConclusionIn infants and small children with congenital heart disease, both manual and power injector protocols allowed for diagnostic imaging of cardiac and extracardiac structures. However, image quality and vascular attenuation were superior using a power injector.     

Morphomic calcification score from clinical CT scans: A proxy for coronary artery calcium

BackgroundScreening of cardiovascular risk is essential in preventing cardiac events and quantifying asymptomatic risk. Coronary artery calcium (CAC) scores are a well-established in predicting cardiovascular risk, but require specialized computed tomography (CT) scans. Given the relationship of aortic calcification with cardiovascular risk, we sought to determine whether aortic calcification measures from incidental CT scans may approximate CAC.Study designRetrospective CT scans and corresponding volumetric CAC scores were obtained from patients at the University of Michigan. Aortic calcifications were measured in 166 scans. Correlations between a novel morphomic calcium (MC) percent score and CAC score were evaluated using Kendall's correlation coefficients. Comparison of receiver operating characteristic (ROC) curves based on MC at different vertebral levels showed the highest predictive values for measures taken at L4.ResultsMC at L4 shows promise in predicting CAC (AUC 0.90 in non-contrast scans, 0.70 in post-contrast scans). Proposed MC threshold are (4.21% for best sensitivity, B 12.93% for balance, C = 19.26% for specificity) in scans without contrast enhancement and (D = 7.31 for sensitivity, E 8.06 for specificity) in scans with contrast enhancement.ConclusionThe MC score demonstrates promising potential in approximating CAC, particularly at the L4 level. The utilization of MC from incidental CT scans may be useful for assessment of cardiovascular risk. The ability to extract MC from contrast scans makes it especially valuable to patients receiving additional medical or surgical care. Recognition of high-risk patients would allow the use of indicated preventative strategies to avoid hard cardiovascular events in at risk patients.     

第二代双源CT前门控FLASH扫描与序列扫描冠状动脉成像比较

目的:比较第二代双源CT前门控大螺距螺旋扫描(FLASH扫描)与序列扫描模式在冠状动脉CT成像中的图像质量及辐射剂量。方法:回顾性分析采用第二代双源CT行前门控FIASH扫描(A组)与序列扫描(B组)冠状动脉CTA连续各50例患者,入组标准为心率70次/min以下,窦性心律,心率波动范围在10次/min以内。评价这2种成像模式的图像质量及辐射剂量。扫描参数:2组均采用Z轴飞焦点技术采集,探测器准直宽度0.6 mm,重建层厚0.75 mm,扫描时间0.28 s/r,单扇区时间分辨率75 ms,根据患者体质量指数(BMI)值设定管电压:100kV(BMI<24 kg/m~2)、120 kV(BMI≥24 kg/m~2),参考管电流370 mAs,采用管电流调制方案;FLASH扫描前门控心电触发选在60%R-R间期,螺距3.4;序列扫描采集时相为35%～75%R-R间期,步进采集宽度34.5 mm。冠状动脉图像质量分为4级(1级为优异,1～3级为可评价血管,4级为不可评价血管),相应评为1～4分。应用秩和检验比较2组患者冠状动脉段图像质量评分,应用两独立样本t检验比较2组患者所接受的辐射剂量。结果:A、B 2组患者的年龄及BMI差异无统计学意义。A、B 2组可评价的冠状动脉节段百分比分别为98.21%和98.56%,差异无统计学意义(χ~2=0.244,P=0.621),平均图像质量评分分别为1.30±0.60和1.28±0.56,差异无统计学意义(Z=-0.489,P=0.625)。A、B 2组扫描的平均有效辐射剂量分别为(0.99±0.34)mSv和(4.80±2.21)mSv,差异有统计学意义(t=-12.048,P=0.000),FLASH扫描剂量明显低于序列扫描。结论:在心率低于70次/min、心律稳定的情况下,第二代双源CT前门控FLASH扫描可获得与序列扫描相似的高质量图像,但辐射剂量明显降低。     

Coronary artery calcification in COVID-19 patients: an imaging biomarker for adverse clinical outcomes

BackgroundRecent studies have demonstrated a complex interplay between comorbid cardiovascular disease, COVID-19 pathophysiology, and poor clinical outcomes. Coronary artery calcification (CAC) may therefore aid in risk stratification of COVID-19 patients.MethodsNon-contrast chest CT studies on 180 COVID-19 patients ≥ age 21 admitted from March 1, 2020 to April 27, 2020 were retrospectively reviewed by two radiologists to determine CAC scores. Following feature selection, multivariable logistic regression was utilized to evaluate the relationship between CAC scores and patient outcomes.ResultsThe presence of any identified CAC was associated with intubation (AOR: 3.6, CI: 1.4–9.6) and mortality (AOR: 3.2, CI: 1.4–7.9). Severe CAC was independently associated with intubation (AOR: 4.0, CI: 1.3–13) and mortality (AOR: 5.1, CI: 1.9–15). A greater CAC score (UOR: 1.2, CI: 1.02–1.3) and number of vessels with calcium (UOR: 1.3, CI: 1.02–1.6) was associated with mortality. Visualized coronary stent or coronary artery bypass graft surgery (CABG) had no statistically significant association with intubation (AOR: 1.9, CI: 0.4–7.7) or death (AOR: 3.4, CI: 1.0–12).ConclusionCOVID-19 patients with any CAC were more likely to require intubation and die than those without CAC. Increasing CAC and number of affected arteries was associated with mortality. Severe CAC was associated with higher intubation risk. Prior CABG or stenting had no association with elevated intubation or death.     

超低剂量胸部CT联合钙感知算法评估冠状动脉钙化积分的可行性

目的:评估超低剂量胸部CT平扫(ULD-CT)联合钙感知算法对冠状动脉钙化(CAC)检测、量化和风险分类的可行性。方法:前瞻性收集2022年4月至10月于浙江省人民医院同时行标准钙化积分CT(CACS-CT)和ULD-CT扫描的患者115例。CACS-CT采用前瞻性心电门控120 kVp序列扫描，重建卷积核为Qr36(CACS-CT Qr组)。ULD-CT采用非心电门控大螺距锡滤过100 kVp(Sn100 kVp)扫描，分别采用标准卷积核Qr36(ULD-CT Qr组)和钙感知卷积核Sa36(ULD-CT Sa组)重建两组图像。以CACS-CT的CAC检出结果为参照，计算ULD-CT检测CAC的准确性，并使用kappa评估扫描协议间CAC检测一致性。使用组内相关系数和Bland-Altman图评估扫描协议间CACS量化的一致性，使用加权kappa评估扫描协议间风险分类的一致性。 结果:CACS-CT Qr组中66.96%(77/115)的患者发现CAC。以CACS-CT Qr组的CAC检出为对照，ULD-CT Qr和ULD-CT Sa检测CAC的敏感性分别为96.1%和97.4%，特异性均为94.73% ( k＝ 0.902，0.921)。ULD-CT Qr和ULD-CT Sa的CACS均低于CACS-CT Qr(3.6、6.2 vs. 8.5， P<0.001)，但均与CACS-CT Qr有强相关性( r＝ 0.983， P<0.001)。ULD-CT Sa与CACS-CT Qr间CACS的平均差值(12.33)更小，一致性更好(ICC＝0.992)。ULD-CT Sa与CACS-CT Qr风险分类的一致性(加权 k＝ 0.936)相对较高，重新分类率6.08%(7/115)较低。ULD-CT的有效辐射剂量比CACS-CT减少了约77.22%。 结论:非心电门控ULD-CT联合钙感知算法评估CACS具有可行性。