Quantitative Analysis of Left Ventricular Dyssynchrony using Cardiac Computed Tomography versus Three-Dimensional Echocardiography

OBJECTIVES: We investigated whether cardiac computed tomography (CCT) can determine intraventricular dyssynchrony in comparison to real-time three-dimensional echocardiography (RT3DE) in patients who are considered for cardiac resynchronisation therapy (CRT).

METHODS: 35 patients considered for CRT were examined. Left ventricular (LV) dyssynchrony was quantified by calculating the standard deviation index (SDI) of 17 myocardial LV segments by RT3DE and ECG-gated contrast-enhanced 64-slice dual-source CCT. For both analyses the same software algorithm (4D LV-Analysis) was used.

RESULTS: Close correlations were observed for end-systolic volume, end-diastolic volume and LV ejection fraction between the two techniques (r = 0.94, r = 0.92 and r = 0.95, respectively, P < 0.001 for all). For the global dyssynchrony index SDI, a high correlation was found between RT3DE and CCT (r = 0.84, P < 0.001), which further increased after exclusion of segments with poor image quality by echocardiography (r = 0.90, P < 0.001). The required time for quantitative analysis was significantly shorter (162 ± 22 s vs. 608 ± 112 s per patient, P < 0.001) and reproducibility was significantly higher for CCT compared with RT3DE (interobserver variability of 4.5 ± 3.1% vs. 7.9 ± 6.1%, P < 0.05).

CONCLUSIONS: Quantitative assessment of LV dyssynchrony is feasible by CCT. Owing to its higher reproducibility and faster analysis time compared with RT3DE, this technique may represent a valuable alternative for dyssynchrony assessment. Key Points : • Quantitative assessment of left ventricular dyssynchrony is feasible by cardiac computed tomography (CCT). • This technique has been compared with real-timethree-dimensional echocardiography (RT3DE). • Reproducibility is significantly higher for CCT compared with RT3DE. • Time spent for analysis is significantly shorter for CCT. • Computed tomography may represent a valuable alternative to ultrasound for dyssynchrony assessment.

PMID: 22270144

The Year in Cardiac Imaging

N/A.

PMID:

Head-to-Head Comparison of Left Ventricular Function Assessment with 64-Row Computed Tomography, Biplane Left Cineventriculography, and Both 2- and 3-Dimensional Transthoracic Echocardiography – Comparison With Magnetic Resonance Imaging as the Reference Standard

OBJECTIVES: This study was designed to compare the accuracy of 64-row contrast computed tomography (CT), invasive cineventriculography (CVG), 2-dimensional echocardiography (2D Echo), and 3-dimensional echocardiography (3D Echo) for left ventricular (LV) function assessment with magnetic resonance imaging (MRI). Cardiac function is an important determinant of therapy and is a major predictor for long-term survival in patients with coronary artery disease. A number of methods are available for assessment of function, but there are limited data on the comparison between these multiple methods in the same patients.

METHODS: A total of 36 patients prospectively underwent 64-row CT, CVG, 2D Echo, 3D Echo, and MRI (as the reference standard). Global and regional LV wall motion and ejection fraction (EF) were measured. In addition, assessment of interobserver agreement was performed.

RESULTS: For the global EF, Bland-Altman analysis showed significantly higher agreement between CT and MRI (p < 0.005, 95% confidence interval: ±14.2%) than for CVG (±20.2%) and 3D Echo (±21.2%). Only CVG (59.5 ± 13.9%, p = 0.03) significantly overestimated EF in comparison with MRI (55.6 ± 16.0%). CT showed significantly better agreement for stroke volume than 2D Echo, 3D Echo, and CVG. In comparison with MRI, CVG—but not CT—significantly overestimated the end-diastolic volume (p < 0.001), whereas 2D Echo and 3D Echo significantly underestimated the EDV (p < 0.05). There was no significant difference in diagnostic accuracy (range: 76% to 88%) for regional LV function assessment between the 4 methods when compared with MRI. Interobserver agreement for EF showed high intraclass correlation for 64-row CT, MRI, 2D Echo, and 3D Echo (intraclass correlation coefficient >0.8), whereas agreement was lower for CVG (intraclass correlation coefficient = 0.58).

CONCLUSIONS: 64-row CT may be more accurate than CVG, 2D Echo, and 3D Echo in comparison with MRI as the reference standard for assessment of global LV function.

PMID:

Prevalence of Thoracic Aortic Calcification and its Relationship to Cardiovascular Risk Factors and Coronary Calcification in an Unselected Population-Based Cohort: The Heinz Nixdorf Recall Study

OBJECTIVES: Thoracic aortic calcification (TAC) and coronary artery calcium (CAC) have been proposed for risk assessment of coronary artery and cardiovascular disease events. The aim of this analysis is to assess the prevalence of TAC and to determine its relationship with cardiovascular risk factors and CAC in a general unselected population.

METHODS: TAC was measured from electron beam computed tomography scans and quantified by Agatston-Score in 4,025 participants aged 45-75 years (mean age 59.4 ± 7.8 years, 53 % female) from the Heinz Nixdorf Recall Study. Multivariable generalized linear regression was used to evaluate relationships between TAC and cardiovascular risk factors and CAC.

RESULTS: Overall 2,538/4,025 (63.1 %) participants revealed TAC. Prevalence of TAC was greater in men than in women (65.2 vs. 61.7 %, p = 0.009). TAC was most strongly associated with age, systolic blood pressure, smoking and high levels of LDL-cholesterol. Prevalence of CAC was significantly higher in participants with TAC than without (74.0 vs. 57.6 %, p < 0.0001) demonstrating an increased risk of having CAC in the presence of TAC (prevalence ratio (PR) 1.29 [95 % CI: 1.22-1.35], p < 0.0001, PR adjusted for risk factors 1.14 [1.09-1.20], p < 0.0001).

CONCLUSIONS: In general population, TAC has high prevalence and largely shares cardiovascular risk factors with CAD while being independently associated with present CAC.

PMID: 22527262

Coronary Arterial 18F-Sodium Fluoride Uptake: A Novel Marker of Plaque Biology

OBJECTIVES: With combined positron emission tomography and computed tomography (CT), we investigated coronary arterialuptake of 18F-sodium fluoride (18F-NaF) and 18F-fluorodeoxyglucose (18F-FDG) as markers of active plaque calcification and inflammation, respectively. The noninvasive assessment of coronary artery plaque biology would be a major advance particularly in the identification of vulnerable plaques, which are associated with specific pathological characteristics, including micro-calcification and inflammation.

METHODS: We prospectively recruited 119 volunteers (72 ± 8 years of age, 68% men) with and without aortic valve disease and measured their coronary calcium score and 18F-NaF and 18F-FDG uptake. Patients with a calcium score of 0 were used as control subjects and compared with those with calcific atherosclerosis (calcium score >0).

RESULTS: Inter-observer repeatability of coronary 18F-NaF uptake measurements (maximum tissue/background ratio) was excellent (intra-class coefficient 0.99). Activity was higher in patients with coronary atherosclerosis (n = 106) versus control subjects (1.64 ± 0.49 vs. 1.23 ± 0.24; p = 0.003) and correlated with the calcium score (r = 0.652, p < 0.001), although 40% of those with scores >1,000 displayed normal uptake. Patients with increased coronary 18F-NaF activity (n = 40) had higher rates of prior cardiovascular events (p = 0.016) and angina (p = 0.023) and higher Framingham risk scores (p = 0.011). Quantification ofcoronary 18F-FDG uptake was hampered by myocardial activity and was not increased in patients with atherosclerosis versus control subjects (p = 0.498).

CONCLUSIONS: 18F-NaF is a promising new approach for the assessment of coronary artery plaque biology. Prospective studies with clinical outcomes are now needed to assess whether coronary 18F-NaF uptake represents a novel marker of plaque vulnerability, recent plaque rupture, and future cardiovascular risk. (An Observational PET/CT Study Examining the Role of Active Valvular Calcification and Inflammation in Patients With Aortic Stenosis; NCT01358513).

PMID: 22516444

Trabeculated (Non-Compacted) and Compact Myocardium in Adults: The Multi-Ethnic Study of Atherosclerosis

OBJECTIVES: A high degree of non-compacted (trabeculated) myocardium in relationship to compact myocardium (T/M ratio >2.3) has been associated with a diagnosis of left ventricular non-compaction (LVNC). The purpose of this study was to determine the normal range of the T/M ratio in a large population-based study and to examine the relationship to demographic and clinical parameters.

METHODS: The thickness of trabeculation and the compact myocardium were measured in eight LV regions on long axis cardiac magnetic resonance (CMR) steady-state free precession cine images in 1000 participants (551 women; 68.1±8.9 years) of the Multi-Ethnic Study of Atherosclerosis cohort.

RESULTS: Of 323 participants without cardiac disease or hypertension and with all regions evaluable 140 (43%) had a T/M ratio >2.3 in at least one region; in 20/323 (6%), T/M>2.3 was present in more than two regions. Multivariable linear regression model revealed no association of age, gender, ethnicity, height and weight with maximum T/M ratio in participants without cardiac disease or hypertension (p>0.05). In the entire cohort (n=1000) LVEF (β=-0.02/%; p=0.015), LVEDV (β=0.01/ml; p=<0.0001) and LVESV (β=0.01/ml; p<0.001) were associated with maximum T/M ratio in adjusted models while there was no association with hypertension or myocardial infarction (p>0.05). At the apical level T/M ratios were significantly lower when obtained on short- compared to long-axis images (p=0.017).

CONCLUSIONS: A ratio of trabeculated to compact myocardium of more than 2.3 is common in a large population based cohort. These results suggest reevaluation of the current CMR criteria for LVNC may be necessary.

PMID: 22499849

Automated Quantification of Coronary Plaque With Computed Tomography: Comparison With Intravascular Ultrasound Using a Dedicated Registration Algorithm for Fusion-Based Quantification

OBJECTIVES: Previous studies have used semi-automated approaches for coronary plaque quantification on multi-detector row computed tomography (CT), while an automated quantitative approach using a dedicated registration algorithm is currently lacking. Accordingly, the study aimed to demonstrate the feasibility and accuracy of automated coronary plaque quantification on cardiac CT using dedicated software with a novel 3D coregistration algorithm of CT and intravascular ultrasound (IVUS) data sets.

METHODS: Patients who had undergone CT and IVUS were enrolled. Automated lumen and vessel wall contour detection was performed for both imaging modalities. Dedicated automated quantitative software (QCT) with a unique registration algorithm was used to fuse a complete IVUS run with a CT angiography volume using true anatomical markers. At the level of the minimal lumen area (MLA), percentage lumen area stenosis, plaque burden, and degree of remodelling were obtained on CT. Additionally, mean plaque burden was assessed for the whole coronary plaque. At the identical level within the coronary artery, the same variables were derived from

RESULTS: IVUS. Fifty-one patients (40 men, 58 ± 11 years, 103 coronary arteries) with 146 lesions were evaluated. Quantitative computed tomography and IVUS showed good correlation for MLA (n = 146, r = 0.75, P < 0.001). At the level of the MLA, both techniques were well-correlated for lumen area stenosis (n = 146, r = 0.79, P < 0.001) and plaque burden (n = 146, r = 0.70, P < 0.001). Mean plaque burden (n = 146, r = 0.64, P < 0.001) and remodelling index (n = 146, r = 0.56, P < 0.001) showed significant correlations between QCT and IVUS.

CONCLUSIONS: Automated quantification of coronary plaque on CT is feasible using dedicated quantitative software with a novel 3D registration algorithm.

PMID: 22285583

Metabolic Syndrome, Diabetes, and Incidence and Progression of Coronary Calcium

OBJECTIVES: This study sought to examine and compare the incidence and progression of coronary artery calcium (CAC) among persons with metabolic syndrome (MetS) and diabetes mellitus (DM) versus those with neither condition. MetS and DM are associated with subclinical atherosclerosis as evidenced by CAC.

METHODS: The MESA (Multiethnic Study of Atherosclerosis) included 6,814 African American, Asian, Caucasian, and Hispanic adults 45 to 84 years of age, who were free of cardiovascular disease at baseline. Of these, 5,662 subjects (51% women, mean age 61.0 ± 10.3 years) received baseline and follow-up (mean 2.4 years) cardiac computed tomography scans. We compared the incidence of CAC in 2,927 subjects without CAC at baseline and progression of CAC in 2,735 subjects with CAC at baseline in those with MetS without DM (25.2%), DM without MetS (3.5%), or both DM and MetS (9.0%) to incidence and progression in subjects with neither MetS nor DM (58%). Progression of CAC was also examined in relation to coronary heart disease events over an additional 4.9 years.

RESULTS: Relative to those with neither MetS nor DM, adjusted relative risks (95% confidence intervals [CI]) for incident CAC were 1.7 (95% CI: 1.4 to 2.0), 1.9 (95% CI: 1.4 to 2.4), and 1.8 (95% CI: 1.4 to 2.2) (all p < 0.01), and absolute differences in mean progression (volume score) were 7.8 (95% CI: 4.0 to 11.6; p < 0.01), 11.6 (95% CI: 2.7 to 20.5; p < 0.05), and 22.6 (95% CI: 17.2 to 27.9; p < 0.01) for those with MetS without DM, DM without MetS, and both DM and MetS, respectively. Similar findings were seen in analysis using Agatston calcium score. In addition, progression predicted coronary heart disease events in those with MetS without DM (adjusted hazard ratio: 4.1, 95% CI: 2.0 to 8.5, p < 0.01) and DM (adjusted hazard ratio: 4.9 [95% CI: 1.3 to 18.4], p < 0.05) among those in the highest tertile of CAC increase versus no increase.

CONCLUSIONS: Individuals with MetS and DM have a greater incidence and absolute progression of CAC compared with individuals without these conditions, with progression also predicting coronary heart disease events in those with MetS and DM.

PMID:

Artifact Reduction Strategies for Prosthetic Heart Valve CT Imaging

OBJECTIVES: Multislice CT evaluation of prosthetic heart valves (PHV) is limited by PHV-related artifacts. We assessed the influence of different kV settings, a metal artifact reduction filter (MARF) and an iterative reconstruction algorithm (IR) on PHV-induced artifacts in an in vitro model.

METHODS: A Medtronic-Hall tilting disc and St Jude bileafet PHV were imaged using a 64-slice scanner with 100 kV/165 mAs, 120 kV/100 mAs, 140 kV/67 mAs at an equal CTDI(vol). Images were reconstructed with (1) filtered back projection (FBP), (2) IR, (3) MARF and (4) MARF and IR. Hypo- and hyperdense artifacts volumes (mean mm(3) ± SD) were quantified with 2 thresholds (≤-50 and ≥175 Hounsfield Units). Image noise was measured and the presence of secondary artifacts was scored by 2 observers independently.

RESULTS: Mean hypodense artifacts for the Medtronic-Hall/St Jude valve (FBP) were 966 ± 23/1,738 ± 21 at 100 kV, 610 ± 13/991 ± 12 at 120 kV, and 420 ± 9/634 ± 9 at 140 kV. Compared to FBP, hypodense artifact reductions for IR were 9/8 %, 10/7 % and 12/6 % respectively, for MARF 92 %/84 %, 89/81 % and 86/77 % respectively; for MARF + IR 94/85 %, 92/82 %, and 90/79 % respectively. Mean hyperdense artifacts for the Medtronic-Hall/St Jude valve were 5,530 ± 48/6,940 ± 70 at 100 kV, 5,120 ± 42/6,250 ± 53 at 120 kV, and 5,011 ± 52/6,000 ± 0 at 140 kV. Reductions for IR were 2/2 %, 2/3 % and 3/4 % respectively, for MARF were 9/30 %, 0/25 %, 5/22 % respectively, MARF + IR 12/32 %, 4/27 % and 7/25 % respectively. Secondary artifacts were found in all MARF images.

CONCLUSIONS: Image noise was reduced in the IR images. In vitro PHV-related artifacts can be reduced by increasing kV despite maintaining identical CTDI(vol). Although MARF is more effective than IR, it induces secondary artifacts.

PMID: 22476910

Relation Between Anemia and Vulnerable Coronary Plaque Components in Patients with Acute Coronary Syndrome: Virtual Histology-Intravascular Ultrasound Analysis

OBJECTIVES: The aim of the present study was to evaluate the plaque components and the predictors of thin-cap fibroatheroma (TCFA) in anemic patients with acute coronary syndrome using virtual histology-intravascular ultrasound (VH-IVUS).

METHODS: Anemia was defined according to criteria of the World Health Organization, (i.e. , hemoglobin levels < 13 g/dL in men and < 12 g/dL in women) and we compared VH-IVUS findings between anemia group (171 patients, 260 lesions) and non-anemia group (569 patients, 881 lesions).

RESULTS: Anemia group had greater % necrotic core (NC) volume (21% ± 9% vs 19% ± 9%, P = 0.001) compared with non-anemia group. Hemoglobin level correlated negatively with absolute NC volume (r = -0.235, P < 0.001) and %NC volume (r = -0.209, P < 0.001). Independent predictors of TCFA by multivariate analysis were diabetes mellitus (odds ratio [OR], 2.213; 95% confidence interval [CI], 1.403-3.612, P = 0.006), high-sensitivity C-reactive protein (OR, 1.143; 95% CI, 1.058-1.304, P = 0.012), microalbuminuria (albumin levels of 30 to 300 mg/g of creatinine) (OR, 2.124; 95% CI, 1.041-3.214, P = 0.018), and anemia (OR: 2.112; 95% CI 1.022-3.208, P = 0.028).

CONCLUSIONS: VH-IVUS analysis demonstrates that anemia at the time of clinical presentation is associated with vulnerable plaque component in patients with acute coronary syndrome.

PMID: 22468099

Impact of Intravascular Ultrasound Guidance in Routine Percutaneous Coronary Intervention for Conventional Lesions: Data From the EXCELLENT Trial

OBJECTIVES: Intravascular ultrasound (IVUS) offers tomographic images of coronary artery, helping physicians refine percutaneous coronary intervention (PCI) procedures. However, it is still controversial whether routine use of IVUS in conventional lesions leads to improvement in clinical outcomes after PCI.

METHODS: From the EXCELLENT trial, patients were grouped into IVUS-guided versus IVUS-non-guided PCI (619 and 802 patients, respectively). The crude patients as well as the propensity score matched pairs were compared with regard to clinical outcomes.

RESULTS: Baseline characteristics showed younger age and lower incidence of comorbidities in the IVUS group. IVUS-guided PCI was associated with more aggressive treatment such as longer stenting length, larger stent diameter, and greater number of stents implanted. In the total population, IVUS guidance was associated with a significantly higher risk of periprocedural MI with no significant differences in other outcomes. In the matched cohort (463 matched pairs, 926 patients), IVUS guidance was associated with significantly increased risk of target lesion failure (4.3% vs. 2.4%; p=0.047 by conditional logistic regression) and major adverse cardiovascular events at 1year almost exclusively due to increased risk of periprocedural myocardial infarction (MI) (1.6% vs. 0.2%; p=0.050), while the rates of cardiac death, spontaneous MI, and target lesion revascularization did not differ significantly between the two groups.

CONCLUSIONS: The adjunctive use of IVUS during PCI was associated with more stents implanted, longer stenting, and bigger stenting. There were no significant advantages of IVUS guidance, but rather a significant increase in periprocedural enzyme elevation, reflecting more aggressive procedures performed with IVUS guidance.

PMID: 22481046

Calcium Scoring in Patients with a History of Kawasaki Disease

OBJECTIVES: The goal of this study was to assess coronary artery calcification in patients ≥10 years or age with a history of Kawasaki disease (KD). Patients with a history of KD and coronary artery aneurysms are at risk for late morbidity from coronary artery events. It is unknown whether patients with KD with acutely normal or transiently dilated coronary arteries also have increased risk of late coronary artery complications. Coronary calcium scoring using noncontrast computed tomography is a well-established tool for risk-stratifying patients with atherosclerotic coronary artery disease, but there are limited data on its role in evaluating patients with a history of KD.

METHODS: We performed coronary artery calcium (CAC) volume scoring using a low radiation dose computed tomography protocol on 70 patients (median age 20.0 years) with a remote history of KD (median interval from acute KD to imaging 14.8 years). Forty-four (63%) patients had no history of coronary dilation, 12 (17%) had a history of transient dilation, and 14 (20%) had coronary aneurysms.

RESULTS: All of the patients with normal coronary artery internal diameter during the acute phase of KD and 11 of 12 patients with transient dilation had CAC scores of zero. Coronary calcification was observed in 10 of the 14 patients with coronary aneurysms, with the degree of calcification ranging from mild to severe and occurring years after the patients’ acute KD.

CONCLUSIONS: Coronary calcification was not observed in patients with a history of KD and normal coronary arteries during the acute phase. Therefore, CAC scanning may be a useful tool to screen patients with a remote history of KD or suspected KD and unknown coronary artery status. Coronary calcification, which may be severe, occurs late in patients with coronary aneurysms. The pathophysiology and clinical implications of coronary calcification in patients with aneurysms are currently unknown and warrant further study.

PMID: 22421171

Association of Pericardial Fat and Coronary High-Risk Lesions as Determined by Cardiac CT

OBJECTIVE: Pericardial adipose tissue (PAT) is a pathogenic fat depot associated with coronary atherosclerosis and cardiovascular events. We hypothesized that higher PAT is associated with coronary high-risk lesions as determined by cardiac CT.

METHODS: We included 358 patients (38% female; median age 51 years) who were admitted to the ED with acute chest pain and underwent 64-slice CT angiography. The cardiac CT data sets were assessed for presence and morphology of CAD and PAT. Coronary high-risk lesions were defined as >50% luminal narrowing and at least two of the following characteristics: positive remodeling, low-density plaque, and spotty calcification. PAT was defined as any pixel with CT attenuation of -190 to -30HU within the pericardial sac.

RESULTS: Based on cardiac CT, 50% of the patients (n=180) had no CAD, 46% (n=165) had CAD without high-risk lesions, and 13 patients had CAD with high-risk lesions. The median PAT in patients with high-risk lesions was significantly higher compared to patients without high-risk lesions and without any CAD (151.9 [109.0-179.4]cm(3) vs. 110.0 [81.5-137.4]cm(3), vs. 74.8 [58.2-111.7]cm(3), respectively p=0.04 and p<0.0001). These differences remained significant after adjusting for traditional risk factors including BMI (all p<0.05). The area under the ROC curve for the identification of high-risk lesions was 0.756 in a logistic regression model with PAT as a continuous predictor.

CONCLUSION: PAT volume is nearly twice as high in patients with high-risk coronary lesions as compared to those without CAD. PAT volume is significantly associated with high risk coronary lesion morphology independent of clinical characteristics and general obesity.

PMID: 22417843

Exposure to Ionizing Radiation and Estimate of Secondary Cancers in the Era of High-Speed CT Scanning: Projections From the Medicare Population

PMID:

Cross-Sectional Computed Tomographic Assessment Improves Accuracy of Aortic Annular Sizing for Transcatheter Aortic Valve Replacement and Reduces the Incidence of Paravalvular Aortic Regurgitation

OBJECTIVES: In an effort to define the gold standard for annular sizing for transcatheter aortic valve replacement (TAVR), we sought to critically analyze and compare the predictive value of multiple measures of the aortic annulus for post-TAVR paravalvular (PV) regurgitation and then assess the impact of a novel cross-sectional computed tomographic (CT) approach toannular sizing. Recent studies have shown clear discrepancies between conventional 2-dimensional (2D) echocardiographic and CT measurements. In terms of aortic annular measurement for TAVR, such findings have lacked the outcome analysis required to inform clinical practice.

METHODS: The discriminatory value of multiple CT annular measures for post-TAVR PV aortic regurgitation was compared with 2D echocardiographic measures. TAVR outcomes with device selection according to aortic annular sizing using a traditional 2D transesophageal echocardiography-guided or a novel CT-guided approach were also studied.

RESULTS: In receiver-operating characteristic models, cross-sectional CT parameters had the highest discriminatory value for post-TAVR PV regurgitation: This was with the area under the curve for [maximal cross-sectional diameter minus prosthesis size] of 0.82 (95% confidence interval: 0.69 to 0.94; p < 0.001) and that for [circumference-derived cross-sectional diameter minus prosthesis size] of 0.81 (95% confidence interval: 0.7 to 0.94; p < 0.001). In contrast, traditional echocardiographic measures were nondiscriminatory in relation to post-TAVR PV aortic regurgitation. The prospective application of a CT-guided annular sizing approach resulted in less PV aortic regurgitation of grade worse than mild after TAVR (7.5% vs. 21.9%; p = 0.045).

CONCLUSIONS: Our data lend strong support to 3-dimensional cross-sectional measures, using CT as the new gold standard foraortic annular evaluation for TAVR with the Edwards SAPIEN device.

PMID: 22365424