SCCT curriculum guidelines for general (level 1) cardiovascular CT training.

The Society of Cardiovascular Computed Tomography has developed general (level 1) cardiovascular CT (CCT) training guidelines for radiology resident and cardiology fellow education. As CCT use has expanded over the past decade, it is essential to incorporate such training in both diagnostic radiology residency programs and cardiology fellowship programs. This curriculum will ensure residents and fellows-in-training obtain a fundamental understanding of CCT to stay current in the evolving landscape of cardiovascular imaging and know how and when to use CCT. The curriculum will also help narrow the present knowledge and training gap that exists for CCT between different programs and may encourage trainees to pursue additional training in advanced cardiovascular imaging.

Imaging of the right heart--CT and CMR.

Right ventricular (RV) structure and function is of substantial importance in a broad variety of clinical conditions. Cardiac magnetic resonance (CMR) and computed tomography (CT) each provide three-dimensional RV imaging, high-resolution evaluation of RV structure/anatomy, and accurate functional assessment without geometric assumptions. This is of particular significance for the RV, where complex geometry compromises reliance on indices derived from two-dimensional (2D) imaging planes. CMR flow-based imaging can be applied to right-sided heart valves, enabling evaluation of hemodynamic and valvular dysfunction that may contribute to or result from RV dysfunction. Tissue characterization imaging by both CMR and CT provides valuable complementary assessment of the RV. Changes in myocardial tissue composition provide a mechanistic substrate for RV dysfunction and cardiac arrhythmias. This review provides an overview of RV imaging by both CMR and CT, with focus on assessment of RV structure/function, flow, and tissue characterization. Emerging evidence and established guidelines are discussed in the context of imaging contributions to diagnosis, prognostic risk stratification and disease management of clinical conditions that impact the right ventricle.

Routine cine-CMR for prosthesis-associated mitral regurgitation: a multicenter comparison to echocardiography.

BACKGROUND AND AIM OF THE STUDY: Mitral regurgitation (MR) is an important complication after prosthetic mitral valve (PMV) implantation. Transthoracic echocardiography is widely used to screen for native MR, but can be limited with PMV. Cine-cardiac magnetic resonance (CMR) holds the potential for the non-invasive assessment of regurgitant severity based on MR-induced inter-voxel dephasing. The study aim was to evaluate routine cine-CMR for the visual assessment of PMV-associated MR. METHODS: Routine cine-CMR was performed at nine sites. A uniform protocol was used to grade MR based on jet size in relation to the left atrium (mild < 1/3, moderate 1/3-2/3, severe > 2/3). MR was graded in each long-axis orientation, with overall severity based on cumulative grade. Cine-CMR was also scored for MR density and pulmonary vein systolic flow reversal (PVSFR). Visual interpretation was compared to quantitative analysis in a single-center (derivation) cohort, and to transesophageal echocardiography (TEE) in a multicenter (validation) cohort. RESULTS: The population comprised 85 PMV patients (59% mechanical valves, 41% bioprostheses). Among the derivation cohort (n = 25), quantitative indices paralleled visual scores, with stepwise increases in jet size and density in relation to visually graded MR severity (both p = 0.001). Patients with severe MR had an almost three-fold increase in quantitative jet area (p = 0.002), and a two-fold increase in density (p = 0.04) than did other patients. Among the multicenter cohort, cine-CMR and TEE (Δ =. 2 ± 3 days) demonstrated moderate agreement (κ = 0.44); 64% of discordances differed by ≤ 1 grade (Δ = 1.2 ± 0.5). Using a TEE reference, cine-CMR yielded excellent diagnostic performance for severe MR (sensitivity, negative predictive value = 100%). Patients with visually graded severe MR also had more frequent PVSFR (p < 0.001), denser jets (p < 0.001), and larger left atria (p = 0.01) on cine-CMR. CONCLUSION: Cine-CMR is useful for the assessment of PMV-associated MR, which manifests concordant quantitative and qualitative changes in size and density of inter-voxel dephasing. Visual MR assessment based on jet size provides an accurate non-invasive means of screening for TEE-evidenced severe MR.

Geometry-independent inclusion of basal myocardium yields improved cardiac magnetic resonance agreement with echocardiography and necropsy quantified left-ventricular mass.

OBJECTIVES: Left-ventricular mass (LVM) is widely used to guide clinical decision-making. Cardiac magnetic resonance (CMR) quantifies LVM by planimetry of contiguous short-axis images, an approach dependent on reader-selection of images to be contoured. Established methods have applied different binary cut-offs using circumferential extent of left-ventricular myocardium to define the basal left ventricle (LV), omitting images containing lesser fractions of left-ventricular myocardium. This study tested impact of basal slice variability on LVM quantification. METHODS: CMR was performed in patients and laboratory animals. LVM was quantified with full inclusion of left-ventricular myocardium, and by established methods that use different cut-offs to define the left-ventricular basal-most slice: 50% circumferential myocardium at end diastole alone (ED50), 50% circumferential myocardium throughout both end diastole and end systole (EDS50). RESULTS: One hundred and fifty patients and 10 lab animals were studied. Among patients, fully inclusive LVM (172.6±42.3g) was higher vs. ED50 (167.2±41.8g) and EDS50 (150.6±41.1g; both P<0.001). Methodological differences yielded discrepancies regarding proportion of patients meeting established criteria for left-ventricular hypertrophy and chamber dilation (P<0.05). Fully inclusive LVM yielded smaller differences with echocardiography (Δ=11.0±28.8g) than did ED50 (Δ=16.4±29.1g) and EDS50 (Δ=33.2±28.7g; both P<0.001). Among lab animals, ex-vivo left-ventricular weight (69.8±13.2g) was similar to LVM calculated using fully inclusive (70.1±13.5g, P=0.67) and ED50 (69.4±13.9g; P=0.70) methods, whereas EDS50 differed significantly (67.9±14.9g; P=0.04). CONCLUSION: Established CMR methods that discordantly define the basal-most LV produce significant differences in calculated LVM. Fully inclusive quantification, rather than binary cut-offs that omit basal left-ventricular myocardium, yields smallest CMR discrepancy with echocardiography-measured LVM and non-significant differences with necropsy-measured left-ventricular weight.

Mitral apparatus assessment by delayed enhancement CMR: relative impact of infarct distribution on mitral regurgitation.

OBJECTIVES: This study sought to assess patterns and functional consequences of mitral apparatus infarction after acute myocardial infarction (AMI). BACKGROUND: The mitral apparatus contains 2 myocardial components: papillary muscles and the adjacent left ventricular (LV) wall. Delayed-enhancement cardiac magnetic resonance (DE-CMR) enables in vivo study of inter-relationships and potential contributions of LV wall and papillary muscle infarction (PMI) to mitral regurgitation (MR). METHODS: Multimodality imaging was performed: CMR was used to assess mitral geometry and infarct pattern, including 3D DE-CMR for PMI. Echocardiography was used to measure MR. Imaging occurred 27 ± 8 days after AMI (CMR, echocardiography within 1 day). RESULTS: A total of 153 patients with first AMI were studied; PMI was present in 30% (n = 46 [72% posteromedial, 39% anterolateral]). When stratified by angiographic culprit vessel, PMI occurred in 65% of patients with left circumflex, 48% with right coronary, and only 14% of patients with left anterior descending infarctions (p <0.001). Patients with PMI had more advanced remodeling as measured by LV size and mitral annular diameter (p <0.05). Increased extent of PMI was accompanied by a stepwise increase in mean infarct transmurality within regional LV segments underlying each papillary muscle (p <0.001). Prevalence of lateral wall infarction was 3-fold higher among patients with PMI compared to patients without PMI (65% vs. 22%, p <0.001). Infarct distribution also impacted MR, with greater MR among patients with lateral wall infarction (p = 0.002). Conversely, MR severity did not differ on the basis of presence (p = 0.19) or extent (p = 0.12) of PMI, or by angiographic culprit vessel. In multivariable analysis, lateral wall infarct size (odds ratio 1.20/% LV myocardium [95% confidence interval: 1.05 to 1.39], p = 0.01) was independently associated with substantial (moderate or greater) MR even after controlling for mitral annular (odds ratio 1.22/mm [1.04 to 1.43], p = 0.01), and LV end-diastolic diameter (odds ratio 1.11/mm [0.99 to 1.23], p = 0.056). CONCLUSIONS: Papillary muscle infarction is common after AMI, affecting nearly one-third of patients. Extent of PMI parallels adjacent LV wall injury, with lateral infarction-rather than PMI-associated with increased severity of post-AMI MR.

Scout view X-ray attenuation versus weight-based selection of reduced peak tube voltage in cardiac CT angiography.

OBJECTIVES: The study evaluated the relationship between cardiac computed tomography (CT) scout view x-ray attenuation and CT image noise compared with weight or body mass index (BMI). BACKGROUND: Decreasing peak tube voltage from 120 to 100 kVp on the basis of body size reduces radiation exposure. Methods to better predict CT image noise may lead to more effective selection of reduced tube voltage in cardiac CT. METHODS: Image quality was graded subjectively (1 [excellent] to 4 [nondiagnostic]) and objectively (SD of the aortic attenuation value) in cardiac CT angiograms (N = 106) acquired at either 100 or 120 kVp. X-ray attenuation characteristics on the scout view (120 kVp, 30 mA) were measured within a 3-cm region of interest across the chest in the frontal x-ray. Receiver-operating characteristic curve analysis was performed comparing scout view attenuation versus weight and BMI in predicting CT image noise and quality. RESULTS: CT image noise correlated with both BMI (r = 0.40; p < 0.001) and the scout view attenuation value (r = 0.52; p < 0.001). In linear regression models with controlling for BMI (or weight) and tube potential, scout view attenuation was the best predictor of the CT image noise (p < 0.001), and increased model fit statistic from 0.23 to 0.41 (p model <0.001). At 120 kVp, scout view attenuation predicted CT image noise <30 Hounsfield units (HU) more accurately than BMI (area under the curve: 0.89 vs. 0.77). For CT images acquired at 120 kVp, those with a scout view attenuation <-120 HU had significantly lower noise and higher signal-to-noise ratios, with similar mean aortic attenuation values. A majority (89.3%) of "low-noise" CT images at 120 kVp had scout view attenuation values of <-120 HU. CONCLUSIONS: Scout view attenuation predicts cardiac CT image noise better than weight or BMI and could enable broader application of reduced x-ray tube voltage as a radiation sparing technique.

Prospective evaluation of the updated 2010 ACCF Cardiac CT Appropriate Use Criteria.

BACKGROUND: The cardiac CT Appropriate Use Criteria (AUC) were updated in 2010 to reflect technical advances, evolving expert consensus, and rapidly expanding clinical evidence. OBJECTIVE: We evaluated the effect of the AUC update on their clinical performance, including the completeness and distribution of appropriateness ratings and test outcomes among a consecutive series of patients referred for CT angiography (CTA). METHODS: The 2006 and 2010 criteria were prospectively applied at the point of service to a consecutive series of patients referred for CTA at a single center (n = 1216). Patient interview and review of available health records were used to determine the CTA indication. The proportions of patients within categories of appropriate (A), uncertain (U), inappropriate (I), and not covered were described and compared between the 2006 and 2010 criteria. RESULTS: The 2010 criteria significantly reduced the proportion of uncertain (30.5%-11.4%), inappropriate (16.0%-12.9%), and no covered (12.1%-4.7%; P < 0.001) indications, while increasing the proportion of appropriate tests from 41.4% to 71%. By the 2010 criteria, appropriate indications were more likely to lead to the detection of coronary artery stenosis (11.5% vs 6.7%; P = 0.03) and complete examinations (95.0% vs 90.8%; P = 0.03). CONCLUSION: The 2010 cardiac CT AUC update lead to more complete classification and to large shifts in the appropriateness ratings, underscoring the importance of ensuring the periodic revision of AUCs for evolving imaging technologies such that they perform optimally as quality measurement and reimbursement tools.

The relationship between subclinical atherosclerosis, non-high-density lipoprotein cholesterol, exercise, and diet among male participants of the PACC Project.

BACKGROUND: Non-high-density lipoprotein (HDL) cholesterol is recommended as a secondary lipid goal treated initially with lifestyle modification. However, the relationship between non-HDL and subclinical atherosclerosis is unknown. We examined the independent relationships between coronary artery calcium (CAC), lipids including non-HDL, exercise, and diet among healthy male participants of the Prospective Army Coronary Calcium (PACC) Project. METHODS: Male participants from the PACC Project (n = 1637, mean age 42.8 years; no history of coronary heart disease) were studied. We used validated surveys to measure dietary quality and habitual physical exercise. Fasting lipid concentrations and other cardiovascular risk variables were measured. Subclinical atherosclerosis was detected with the use of electron beam computed tomography for CAC. Factors independently associated with the presence of any detectable CAC (CAC score > 0), including standard CV risk variables, non-HDL, exercise, and diet, were evaluated with the use of logistic regression. RESULTS: The mean Framingham risk score was 4.6 ± 2.6%; CAC was present in 22.4%. Fasting lipid concentrations showed mean LDL-C 128 ± 32 mg/dL, HDL-C 50 ± 13 mg/dL, TG-C 130 ± 86 mg/dL, and non-HDL-C 154 ± 37 mg/dL. Men with CAC had significantly greater levels of LDL-C (135 vs 127 mg/dL), TG (148 vs 124 mg/dL), and non-HDL-C (164 vs 151 mg/dL) and less habitual physical activity (P = 0.006). There were nonsignificant trends between prevalent CAC, greater amounts of dietary fat intake, and lower HDL-C. In successive multivariable logistic regression models for the dependent variable CAC, only non-HDL-C (odds ratio [OR] 1.012 per mg/dL; 95% CI 1.002-1.023; P = .019) and age (OR 1.119 per year; 95% CI 1.063-1.178; P < .001) were independently associated with the presence of CAC, and exercise (OR 0.808; 95% CI 0.703-0.928; P = 0.003) was associated with the absence of CAC. CONCLUSIONS: Non-HDL-C and exercise are independently predictive of the presence of subclinical CAC among healthy lower-risk middle-aged men.

Cardiac CT in women: clinical application and considerations.

Cardiac computed tomography (CT) has special considerations and applications in women for the evaluation of coronary heart disease (CHD). Unique aspects of cardiovascular disease (CVD) in women include atypical symptoms and a later presentation of CHD. Disparities exist in mortality trends of CVD between men and women along with a lack of patient awareness of CVD as a significant cause of mortality for women. Differences have also become evident among plaque characteristics between the 2 sexes, with a relative increased prevalence of noncalcified plaque in women. Traditional risk prediction models, such as the Framingham Risk Score (FRS), have limitations in this population. Coronary calcium scanning contributes significantly to the accuracy of CHD detection on top of traditional CV risk factors in asymptomatic women. Coronary CT angiography has proven accurate for the diagnosis of significant CHD as well as cost effective in the evaluation of symptomatic women. The safety issue of radiation exposure with cardiac CT warrants special consideration for women. Concern for radiation-related cancer risks and organ-specific dose delivered to the breast is being addressed by radiation-reducing techniques. Future technologic advances in CT may allow for simultaneous screening for CHD and other disease processes, such as osteoporosis, breast cancer, and visceral adiposity in one routine test.

Catheter-directed ultrasound-accelerated thrombolysis for the treatment of acute pulmonary embolism.

BACKGROUND: Systemic thrombolysis rapidly improves right ventricular (RV) dysfunction in patients with acute pulmonary embolism (PE) but is associated with major bleeding complications in up to 20%. The efficacy of low-dose, catheter-directed ultrasound-accelerated thrombolysis (USAT) on the reversal of RV dysfunction is unknown. MATERIALS AND METHODS: We performed a retrospective analysis of 24 PE patients (60 ± 16 years) at intermediate (n = 19) or high risk (n = 5) from the East Jefferson General Hospital who were treated with USAT (mean rt-PA dose 33.5 ± 15.5mg over 19.7 hours) and received multiplanar contrast-enhanced chest computed tomography (CT) scans at baseline and after USAT at 38 ± 14 hours. All CT measurements were performed by an independent core laboratory. RESULTS: The right-to-left ventricular dimension ratio (RV/LV ratio) from reconstructed CT four-chamber views at baseline of 1.33 ± 0.24 was significantly reduced to 1.00 ± 0.13 at follow-up by repeated-measures analysis of variance (p < 0.001). The CT-angiographic pulmonary clot burden as assessed by the modified Miller score was significantly reduced from 17.8 ± 5.3 to 8.7 ± 5.1 (p < 0.001). All patients were discharged alive, and there were no systemic bleeding complications but four major access site bleeding complications requiring transfusion and one suspected recurrent massive PE event. CONCLUSIONS: In patients with intermediate and high risk PE, low-dose USAT rapidly reverses right ventricular dilatation and pulmonary clot burden.

Nonobstructive coronary artery disease as detected by 64-detector row cardiac computed tomographic angiography is associated with increased left ventricular mass.

BACKGROUND: Cardiac computed tomographic angiography (CCTA) permits simultaneous assessment of coronary artery disease (CAD) and left ventricular mass (LVM). While increased LVM predicts mortality and is associated with obstructive CAD, the relationship of LVM with non-obstructive CAD is unknown. METHODS: We evaluated 212 consecutive patients undergoing 64-detector row CCTA at 2 sites without evident cardiovascular disease or obstructive (≥70%) CAD by CCTA. LVM was measured by CCTA using Simpson's method of disks and indexed to body surface area (LVMI) and height to the allometric power of 2.7(LVM/ht2.7). CCTAs were evaluated by scoring a modified AHA 16-segment coronary artery model for none = 0 (0% stenosis), mild = 1 (1-49% stenosis) or moderate = 2 (50-69% stenosis). Overall CAD plaque burden was estimated by summing scores across all segments for a segment stenosis score (SSS, max = 32). RESULTS: The mean age was 53.3 ± 12.8 with 52% female, 48% hypertensive, and 7.4% diabetic. The mean LVM was 109 ± 32.5 g; 58.5% had any coronary artery plaque. In multivariable linear regression, SSS was significantly associated with increased LVM, LVMI and LVM/ht2.7. LVM increased by 2.0 g for every 1-point increase in SSS (95% CI 0.06-3.4, p = 0.006). Agatston scores provided no additional predictive value for increased LVM above and beyond SSS. CONCLUSION: Non-obstructive CAD visualized by CCTA is associated with increased LVM independent of effects of clinical risk factors and calcium scoring. Whether addition of LVM to stenosis assessment in patients undergoing CCTA enhances risk prediction of future CAD events warrants investigation.

The right sided great vessels by cardiac multidetector computed tomography: normative reference values among healthy adults free of cardiopulmonary disease, hypertension, and obesity.

RATIONALE AND OBJECTIVES: We sought to derive normative reference values for the thoracic great vessels using multidetector computed tomography (MDCT) in a healthy normotensive non-obese population free of cardiovascular disease. MATERIALS AND METHODS: Non-gated axial computed tomography (CT) of the chest has traditionally been used to evaluate normal great vessel anatomy for prognosis and management. However, non-gated axial chest CT cannot account for the obliquity, systolic expansion, and non-axial motion of the great vessels during the cardiac cycle and may misclassify patients as normal or abnormal for prognostic and management purposes. To date, normative reference values for double-oblique, short-axis great vessel diameters have not been established using current generation electrocardiogram (ECG)-gated 64-detector row MDCT. A total of 103 (43% women, age 51 +/- 14 years) consecutive normotensive, non-obese adults free of cardiopulmonary or great vessel structural disease, arrhythmias, or significant coronary artery disease were studied by MDCT. Individuals underwent examination for determination of end-diastolic (ED) pulmonary artery (PA) and superior vena cava (SVC) dimensions in double-oblique short axes for comparison with the ascending aorta and the right-sided cardiac chambers. RESULTS: For right sided great vessels, the 5th to 95th interval was 1.89-3.03 cm for ED PA diameter and 1.08-4.42 cm(2) for SVC cross-sectional area. The pulmonary artery to ascending aortic (PA-to-Ao) ratio was 0.66-1.13. In multivariate analysis, the PA was significantly associated with weight, whereas the PA-to-Ao ratio was inversely associated with age. Axial PA measurements were significantly higher and PA-to-Ao measurements significantly lower than corresponding short axis measurements (P = .04 and P < .001, respectively). CONCLUSIONS: This study establishes ECG-gated MDCT reference values for right-sided great vessel dimensions derived from a healthy population of individuals free of cardiovascular disease, hypertension, and obesity. The traditional axial PA-to-Ao discriminant value of 1 for pulmonary hypertension is a poor diagnostic tool because it encompasses normal patients and is negatively affected by age. Thoracic great vessels should be measured by CT in ECG-gated double-oblique short-axis for accurate quantitation. These data may serve as a reference to identify right-sided great vessel pathology in individuals being referred for ECG-gated MDCT imaging.