Impact of coronary calcium score on the prevalence of coronary artery stenosis on dual source CT coronary angiography in caucasian patients with an intermediate risk.

PURPOSE: To investigate the prevalence of significant coronary artery stenosis on coronary computed tomography angiography (cCTA) in symptomatic Caucasian patients with an intermediate risk score at different levels of coronary artery calcification (CAC). METHOD: In total, 383 consecutive symptomatic Caucasian patients (147 females, 60 ± 13 years) with an intermediate risk score underwent nonenhanced CT for CAC scoring immediately before contrast-enhanced cCTA on a dual-source CT scanner. Additionally clinically indicated invasive coronary angiography (ICA) was performed in 90 patients. The prevalence of significant coronary artery stenosis (>50%) on cCTA and ICA was correlated at different CAC score levels. RESULTS: Of 121 patients with a zero CAC score, none had significant coronary artery stenosis on cCTA or ICA. Coronary CTA diagnosed in 54 of 70 patients with high CAC score (>400), a significant stenosis. Subsequent ICA confirmed significant stenosis in 30 of 32 patients. Sensitivity and a negative predictive value of CAC score ruling out significant stenosis on cCTA were 100% and 100%, respectively, using cutoff value of zero and specificity and positive predictive value to predict significant stenosis on cCTA were 79% and 51%, respectively, using a cutoff value of >400. CONCLUSION: Significant coronary artery stenosis is extremely unlikely, with an estimated risk of 4 in 1000 patients in symptomatic Caucasian patients with an intermediate risk score and negative CAC score. To reduce radiation exposure, radiation-free tests should be considered for differential diagnosis of chest pain in these patients.

Incremental prognostic value of different components of coronary atherosclerotic plaque at cardiac CT angiography beyond coronary calcification in patients with acute chest pain.

PURPOSE: To systematically evaluate the incremental predictive value of cardiac computed tomographic (CT) angiography beyond the assessment of coronary artery calcium (CAC) in patients who present with acute chest pain but without evidence of acute coronary syndrome (ACS). MATERIALS AND METHODS: The human research committee approved this study and waived the need for individual written informed consent. The study was HIPAA compliant. A total of 458 patients (36% male; mean age, 55 years ± 11) with acute chest pain at low to intermediate risk for coronary artery disease underwent coronary calcification assessment with cardiac CT angiography. All patients who did not experience ACS at index hospitalization were followed for instances of a major adverse cardiac event (MACE), such as a myocardial infarct, revascularization, cardiac death, or angina requiring hospitalization. CAC score and cardiac CT angiography were used to derive the presence and extent of atherosclerotic plaque (calcified, noncalcified, or mixed), and obstructive lesions (>50% luminal narrowing) were related to outcomes by using univariate and adjusted Cox proportional hazards models. RESULTS: Of the 458 patients, 70 (15%) experienced MACE (median follow-up, 13 months). Patients with no plaque at cardiac CT angiography remained free of events during the follow-up period, while 11 (5%) of 215 patients with no CAC had MACE. The extent of plaque was the strongest predictor of MACE independent of traditional risk factors (hazard ratio [HR], 151.77 for four or more segments containing plaque as compared with those containing no plaque; P < .001). Patients with mixed plaque were more likely to experience MACE (HR, 86.96; P = .002) than those with exclusively noncalcified plaque (HR, 58.06; P = .005) or exclusively calcified plaque (HR, 32.94; P = .02). CONCLUSION: The strong prognostic value of cardiac CT angiography is incremental to its known diagnostic value in patients with acute chest pain without ACS and is independent of traditional risk factors and CAC.

Apicoaortic conduits: indications, complications, and imaging techniques.

Left ventricular apex to descending aorta conduits may be used as a last resort treatment of severe left ventricular outflow tract obstruction in cases in which alternative therapies are contraindicated. Although this technique is rarely used in current practice for congenital cases, its use in the elderly population is increasing, largely due to the expansion of this patient cohort and associated comorbidities precluding aortic valve replacement, the most common of which are a severely calcified "porcelain" aorta and/or previous coronary artery bypass grafts preventing aortic root manipulation. Diagnostic imaging is essential in the presurgical workup and subsequent follow-up of these patients, as complications of the procedure are potentially life threatening and are not rare. Several imaging modalities may be used, each with advantages and disadvantages. Both anatomic and functional assessments play a role in the comprehensive evaluation of both presurgical and postsurgical patients.

Quantification of left and right ventricular function and myocardial mass: comparison of low-radiation dose 2nd generation dual-source CT and cardiac MRI.

OBJECTIVE: To prospectively evaluate the accuracy of left and right ventricular function and myocardial mass measurements based on a dual-step, low radiation dose protocol with prospectively ECG-triggered 2nd generation dual-source CT (DSCT), using cardiac MRI (cMRI) as the reference standard. MATERIALS AND METHODS: Twenty patients underwent 1.5T cMRI and prospectively ECG-triggered dual-step pulsing cardiac DSCT. This image acquisition mode performs low-radiation (20% tube current) imaging over the majority of the cardiac cycle and applies full radiation only during a single adjustable phase. Full-radiation-phase images were used to assess cardiac morphology, while low-radiation-phase images were used to measure left and right ventricular function and mass. Quantitative CT measurements based on contiguous multiphase short-axis reconstructions from the axial CT data were compared with short-axis SSFP cardiac cine MRI. Contours were manually traced around the ventricular borders for calculation of left and right ventricular end-diastolic volume, end-systolic volume, stroke volume, ejection fraction and myocardial mass for both modalities. Statistical methods included independent t-tests, the Mann-Whitney U test, Pearson correlation statistics, and Bland-Altman analysis. RESULTS: All CT measurements of left and right ventricular function and mass correlated well with those from cMRI: for left/right end-diastolic volume r=0.885/0.801, left/right end-systolic volume r=0.947/0.879, left/right stroke volume r=0.620/0.697, left/right ejection fraction r=0.869/0.751, and left/right myocardial mass r=0.959/0.702. Mean radiation dose was 6.2±1.8mSv. CONCLUSIONS: Prospectively ECG-triggered, dual-step pulsing cardiac DSCT accurately quantifies left and right ventricular function and myocardial mass in comparison with cMRI with substantially lower radiation exposure than reported for traditional retrospective ECG-gating.

CT signs of right ventricular dysfunction: prognostic role in acute pulmonary embolism.

OBJECTIVES: The purpose of this study was to compare the prognostic role of various computed tomography (CT) signs of right ventricular (RV) dysfunction, including 3-dimensional ventricular volume measurements, to predict adverse outcomes in patients with acute pulmonary embolism (PE). BACKGROUND: Three-dimensional ventricular volume measurements based on chest CT have become feasible for routine clinical application; however, their prognostic role in patients with acute PE has not been assessed. METHODS: We evaluated 260 patients with acute PE for the following CT signs of RV dysfunction obtained on routine chest CT: abnormal position of the interventricular septum, inferior vena cava contrast reflux, right ventricle diameter (RVD) to left ventricle diameter (LVD) ratio on axial sections and 4-chamber (4-CH) views, and 3-dimensional right ventricle volume (RVV) to left ventricle volume (LVV) ratio. Comorbidities and fatal and nonfatal adverse outcomes according to the MAPPET-3 (Management Strategies and Prognosis in Pulmonary Embolism Trial-3) criteria within 30 days were recorded. RESULTS: Fifty-seven patients (21.9%) had adverse outcomes, including 20 patients (7.7%) who died within 30 days. An RVD(axial)/LVD(axial) ratio >1.0 was not predictive for adverse outcomes. On multivariate analysis (adjusting for comorbidities), abnormal position of the interventricular septum (hazard ratio [HR]: 2.07; p = 0.007), inferior vena cava contrast reflux (HR: 2.57; p = 0.001), RVD(4-CH)/LVD(4-CH) ratio >1.0 (HR: 2.51; p = 0.009), and RVV/LVV ratio >1.2 (HR: 4.04; p < 0.001) were predictive of adverse outcomes, whereas RVD(4-CH)/LVD(4-CH) ratio >1.0 (HR: 3.68; p = 0.039) and RVV/LVV ratio >1.2 (HR: 6.49; p = 0.005) were predictive of 30-day death. CONCLUSIONS: Three-dimensional ventricular volume measurement on chest CT is a predictor of early death in patients with acute PE, independent of clinical risk factors and comorbidities. Abnormal position of the interventricular septum, inferior vena cava contrast reflux, and RVD(4-CH)/LVD(4-CH) ratio are predictive of adverse outcomes, whereas RVD(axial)/LVD(axial) ratio >1.0 is not.

Coronary atherosclerosis in African American and white patients with acute chest pain: characterization with coronary CT angiography.

PURPOSE: To use coronary computed tomographic (CT) angiography to compare the prevalence, extent, and composition of coronary atherosclerotic lesions in African American and white patients with acute chest pain. MATERIALS AND METHODS: The institutional review board waived the requirement for informed consent for this retrospective, HIPAA-compliant matched-cohort study. The authors analyzed the CT angiographic data of 301 patients (150 consecutive African American patients; 151 white control patients; mean age, 55 years ± 11 [standard deviation]; 33% male) with acute chest pain. Each coronary artery segment was evaluated for presence of atherosclerotic plaque, plaque composition (calcified, noncalcified, or mixed), and stenosis. In addition, the noncalcified plaque volume was quantified by using a threshold-based automated algorithm. The presence and extent of atherosclerotic plaque were compared between the groups by using univariate and multivariate regression analyses. RESULTS: While there was no significant difference between the African American and white patients with respect to presence of any plaque (118 [79%] of 150 vs 112 [74%] of 151 patients, respectively; P = .36) or presence of stenosis (26 [17%] vs 37 [24%] patients, respectively; P = .13), the African American patients had a significantly higher prevalence (96 [64%] vs 62 [41%] patients, respectively; P < .001) and volume (median volume, 2.2 vs 1.4 mL, respectively; P < .001) of noncalcified plaque, independent of diabetes and other cardiovascular risk factors (odds ratio, 2.45; 95% confidence interval: 1.52, 4.04). In contrast, the African American patients had a lower prevalence of calcified plaque (39 [26%] vs 68 [45%] white patients, P = .001). CONCLUSION: Study results suggest that atherosclerotic plaque burden and composition, as measured by using coronary CT angiography, differ between African American and white patients, with relatively more noncalcified disease in African Americans and more calcified disease in white individuals. Further research is warranted to determine whether CT plaque characterization can improve cardiac risk prediction in African Americans.

Cardiothoracic CT angiography: current contrast medium delivery strategies.

OBJECTIVE: Over the last decade, rapid technologic evolution in CT has resulted in improved spatial and temporal resolution and acquisition speed, enabling cardiothoracic CT angiography to become a viable and effective noninvasive alternative in the diagnostic algorithm. These new technologic advances have imposed new challenges for the optimization of contrast medium delivery and image acquisition strategies. CONCLUSION: Thorough understanding of contrast medium dynamics is essential for the design of effective acquisition and injection protocols. This article provides an overview of the fundamentals affecting contrast enhancement, emphasizing the modifications to contrast material delivery protocols required to optimize cardiothoracic CT angiography.

CT imaging of acute pulmonary embolism.

CT pulmonary angiography (CTPA) has become the de facto clinical "gold standard" for the diagnosis of acute pulmonary embolism (PE) and has replaced catheter pulmonary angiography and ventilation-perfusion scintigraphy as the first-line imaging method. The factors underlying this algorithmic change are rooted in the high-sensitivity and specificity, cost-effectiveness, and 24-hour availability of CTPA. In addition, CTPA is superior to other imaging methods in its ability to diagnose and exclude, in a single examination, a variety of diseases that mimic the symptoms of PE. This article reviews the current role of CTPA in the diagnosis of acute PE as well as more recent developments, such as the use of CT parameters of right ventricular dysfunction for patient prognostication and the assessment of lung perfusion with CT.