Alexander Leber

Correlation of coronary calcification and angiographically documented stenoses in patients with suspected coronary artery disease: results of 1,764 patients

OBJECTIVES This study correlated the electron beam computed tomographic (EBCT) calcium scores with the results of coronary angiography in symptomatic patients in order to assess its value to predict or exclude significant coronary artery disease (CAD). BACKGROUND Electron beam computed tomography is a sensitive method to detect coronary calcium. However, it is unclear whether it may play a role as a filter before invasive procedures in symptomatic patients. METHODS A total of 1,764 patients (1,225 men and 539 women) with suspected CAD from a single center were included in our study. All patients underwent calcium screening with EBCT (C150XP Imatron) and conventional coronary angiography. RESULTS Fifty-six percent of men and 47% of women revealed significant coronary stenoses (> or =50%). Total exclusion of coronary calcium (14% of the study group) was associated with an extremely low probability of stenosis (<1%). With calcium scores > or =20th, > or =100th or > or =75th percentile of age groups, the sensitivity to detect stenoses decreased to 97%, 93% and 81%, respectively, in men and to 98%, 82% and 76%, respectively, in women. At the same time, the specificity increased up to 77% in men and women. There was a significant difference in coronary calcium between men and women in all age groups; however, receiver-operating characteristic curves indicated that the test can be performed with equal accuracy in all of these subgroups. CONCLUSIONS Calcium screening with EBCT is a highly sensitive and moderately specific test to predict stenotic disease. Exclusion of coronary calcium defines a substantial subgroup of patients, albeit symptomatic, with a very low probability of significant stenoses.

Dual-source CT cardiac imaging: initial experience

The relation of heart rate and image quality in the depiction of coronary arteries, heart valves and myocardium was assessed on a dual-source computed tomography system (DSCT). Coronary CT angiography was performed on a DSCT (Somatom Definition, Siemens) with high concentration contrast media (Iopromide, Ultravist 370, Schering) in 24 patients with heart rates between 44 and 92 beats per minute. Images were reconstructed over the whole cardiac cycle in 10% steps. Two readers independently assessed the image quality with regard to the diagnostic evaluation of right and left coronary artery, heart valves and left ventricular myocardium for the assessment of vessel wall changes, coronary stenoses, valve morphology and function and ventricular function on a three point grading scale. The image quality ratings at the optimal reconstruction interval were 1.24±0.42 for the right and 1.09±0.27 for the left coronary artery. A reconstruction of diagnostic systolic and diastolic images is possible for a wide range of heart rates, allowing also a functional evaluation of valves and myocardium. Dual-source CT offers very robust diagnostic image quality in a wide range of heart rates. The high temporal resolution now also makes a functional evaluation of the heart valves and myocardium possible.

Influence of Lipid-Lowering Therapy on the Progression of Coronary Artery Calcification: A Prospective Evaluation

Background—Coronary calcification measured by fast computed tomography techniques is a surrogate marker of coronary atherosclerotic plaque burden. In a cohort study, we prospectively investigated whether lipid-lowering therapy with a cholesterol synthesis enzyme inhibitor reduces the progression of coronary calcification. Methods and Results—In 66 patients with coronary calcifications in electron beam tomography (EBT), LDL cholesterol >130 mg/dL, and no lipid-lowering treatment, the EBT scan was repeated after a mean interval of 14 months and treatment with cerivastatin was initiated (0.3 mg/d). After 12 months of treatment, a third EBT scan was performed. Coronary calcifications were quantified using a volumetric score. Cerivastatin therapy lowered the mean LDL cholesterol level from 164±30 to 107±21 mg/dL. The median calcified volume was 155 mm3 (range, 15 to 1849) at baseline, 201 mm3 (19 to 2486) after 14 months without treatment, and 203 mm3 (15 to 2569) after 12 months of cerivastatin treatment. The median annualized absolute increase in coronary calcium was 25 mm3 during the untreated versus 11 mm3 during the treatment period (P =0.01). The median annual relative increase in coronary calcium was 25% during the untreated versus 8.8% during the treatment period (P <0.0001). In 32 patients with an LDL cholesterol level <100 mg/dL under treatment, the median relative change was 27% during the untreated versus −3.4% during the treatment period (P =0.0001). Conclusions—Treatment with the cholesterol synthesis enzyme inhibitor cerivastatin significantly reduces coronary calcium progression in patients with LDL cholesterol >130 mg/dL.

Accuracy of 64-MDCT in the Diagnosis of Ischemic Heart Disease

OBJECTIVE The aim of this study was to evaluate the potential clinical value of a new generation of 64-MDCT systems with that of invasive coronary angiography in the diagnosis of coronary artery disease (CAD). SUBJECTS AND METHODS Seventy-two consecutive patients with known or suspected CAD underwent both 64-MDCT and quantitative coronary angiography (QCA). A CT system with acquisition of 64 slices per gantry rotation was used with a spatial resolution of 0.4 x 0.4 x 0.4 mm and a gantry rotation time of 330 milliseconds. Sensitivity, specificity, and diagnostic accuracy of 64-MDCT in the detection or exclusion of CAD were evaluated on both a per patient and a per segment basis. RESULTS Sixty-eight of 72 coronary CT angiograms (CTAs) (94%) were of diagnostic image quality. QCA showed significant CAD (i.e., one or more stenoses in > 50%) in 57% (39/68) and nonsignificant disease or healthy CTAs in 43% (29/68) of the patients. Sensitivity, specificity, and the negative predictive value (NPV) of 64-MDCT per patient were 97%, 79%, and 96%, respectively. Per segment, 923 of 1,020 coronary artery segments were assessable (90%). For the detection of stenoses of more than 50% and more than 75% per segment, 64-MDCT showed a sensitivity of 82% and 86%, respectively. Per segment, specificity and NPV were as high as 95% and 97%, respectively. CONCLUSION In clinical routine, coronary CTA will primarily be used for risk stratification on a per patient basis. In the present study, coronary 64-MDCT showed a high diagnostic accuracy on both per patient and per segment analyses.

Chemerin is associated with markers of inflammation and components of the metabolic syndrome but does not predict coronary atherosclerosis

OBJECTIVES Chemerin is a recently discovered adipokine that regulates adipocyte differentiation and modulates chemotaxis and activation of dendritic cells and macrophages. Given the convergence of adipocyte and macrophage function, chemerin may provide an interesting link between obesity, inflammation and atherosclerosis in humans. We sought to examine the relationship of i) chemerin and markers of inflammation, ii) chemerin and components of the metabolic syndrome, and iii) chemerin and coronary atherosclerotic plaque burden and morphology. DESIGN Serum chemerin levels were determined in 303 patients with stable typical or atypical chest pain who underwent dual-source multi-slice CT-angiography to exclude coronary artery stenosis. Atherosclerotic plaques were classified as calcified, mixed, or non-calcified. RESULTS Chemerin levels were highly correlated with high sensitivity C-reactive protein (r=0.44, P<0.0001), interleukin-6 (r=0.18, P=0.002), tumor necrosis factor-alpha (r=0.24, P<0.0001), resistin (r=0.28, P<0.0001), and leptin (r=0.36, P<0.0001) concentrations. Furthermore, chemerin was associated with components of the metabolic syndrome including body mass index (r=0.23, P=0.0002), triglycerides (r=0.29, P<0.0001), HDL-cholesterol (r=-0.18, P=0.003), and hypertension (P<0.0001). In bivariate analysis, chemerin levels were weakly correlated with coronary plaque burden (r=0.16, P=0.006) and the number of non-calcified plaques (r=0.14, P=0.02). These associations, however, were lost after adjusting for established cardiovascular risk factors (odds ratio, OR 1.17, 95% confidence interval (CI) 0.97-1.41, P=0.11 for coronary plaque burden; OR 1.06, 95% CI 0.96-1.17, P=0.22 for non-calcified plaques). CONCLUSIONS Chemerin is strongly associated with markers of inflammation and components of the metabolic syndrome. However, chemerin does not predict coronary atherosclerosis.

Pericardial Adipose Tissue Determined by Dual Source CT Is a Risk Factor for Coronary Atherosclerosis

Objectives—Pericardial fat as a visceral fat depot may be involved in the pathogenesis of coronary atherosclerosis. To gain evidence for that concept we sought to investigate the relation of pericardial fat volumes to risk factors, serum adiponectin levels, inflammatory biomarkers, and the quantity and morphology of coronary atherosclerosis. Methods and Results—Using Dual source CT angiography pericardial fat volume and coronary atherosclerosis were assessed simultaneously. Plaques were classified as calcified, mixed, and noncalcified, and the number of affected segments served as quantitative score. Patients with atherosclerotic lesions had significant larger PAT volumes (226 cm3±92 cm3) than patients without atherosclerosis (134 cm3±56 cm3; P>0.001). No association was found between BMI and coronary atherosclerosis. PAT volumes >300 cm3 were the strongest independent risk factor for coronary atherosclerosis (odds ratio 4.1; CI 3.63 to 4.33) also significantly stronger compared to the Framingham score. We furthermore demonstrated that elevated PAT volumes are significantly associated with low adiponectin levels, low HDL levels, elevated TNF-&agr; levels, and hsCRP. Conclusion—In the present study we demonstrated that elevated PAT volumes are associated with coronary atherosclerosis, hypoadiponectinemia, and inflammation and represent the strongest risk factor for the presence of atherosclerosis and may be important for risk stratification and monitoring.

Image quality, motion artifacts, and reconstruction timing of 64-slice coronary computed tomography angiography with 0.33-second rotation speed.

Objectives:We sought to evaluate the impact of patients’ heart rate (HR) on coronary CTA image quality (IQ) and motion artifacts using a 64-slice scanner with 0.33/360° rotation. Materials and Methods:Coronary CTA data sets of 32 patients (HR ≤ 65 beats per minute [bpm], n = 15; HR > 65 bpm to ≤75 bpm, n = 10; HR > 75 bpm, n = 7) examined on a 64-slice scanner (Sensation 64, Siemens Medical Solutions, Forchheim, Germany) with 0.33s/360° gantry rotation speed were analyzed. All patients had suspicion of coronary artery disease. Data acquisition was performed using 64 × 0.6-mm collimation, and contrast enhancement was provided by injection of 80 mL of iopromide (5 mL/s + NaCl). Images were reconstructed throughout the RR interval using half-scan and dual-segment reconstruction. IQ was rated by 2 observers using a 3-point scale from excellent (1) to nondiagnostic (3) for coronary segments. Quality was correlated to the HR, time point of optimal IQ analyzed, and the benefit of dual-segment reconstruction evaluated. Results:Overall mean IQ was 1.31 ± 0.32 for all HR, with IQ being 1.08 ± 0.12 for HR ≤ 65 bpm, 1.62 ± 0.27 for HR > 65 bpm ≤ 75 bpm and 1.36 ± 0.31 for HR > 75 bpm (P = 0.0003). Dual-segment reconstruction did not significantly improve IQ in any HR group (P = NS). Mean IQ was significantly better for LAD than for RCA (P < 0.0001) and LCX (P < 0.01). A total of 3.5% (11/318) of coronary artery segments were rated nondiagnostic by at least one reader based on motion artifacts. Although in HR < 65 bpm, the best IQ was predominately in diastole (93%), in HR > 75 bpm, the best IQ shifted to systole in most cases (86%). Conclusions:Temporal resolution at 0.33-second rotation allows for diagnostic IQ within a wide range of HR using half-scan reconstruction. With increasing HR the time point of best IQ shifts from mid-diastole to systole.

Diagnostic accuracy of dual-source computed tomography in the diagnosis of coronary artery disease.

Purpose:The aim of this study was to evaluate the diagnostic accuracy of dual-source computed tomography (DSCT) with reference to invasive coronary angiography in the diagnosis of coronary artery disease (CAD) on a per-patient as well as on a per-segment basis. Materials and Methods:Thirty-five patients with known or suspected CAD underwent both DSCT (Somatom Definition, Siemens Medical Solutions) and quantitative x-ray coronary angiography (QCA). Parameters of CT acquisition were gantry rotation time 0.330 seconds (ie, temporal resolution 83 milliseconds), tube voltage 120 kV, tube current 560 mA with ECG-triggered tube current modulation and full current at 70% of the cardiac cycle for heart rates below 70 beats per minute or full current between 30% and 80% for higher and arrhythmic heart rates. The pitch was also adapted to the heart rate, ranging from 0.2 to 0.43. Volume and flow rate of contrast material (Ultravist 370, Schering AG) were adapted to the patients body weight. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of DSCT in the detection or exclusion of significant CAD (ie, stenoses >50%) were evaluated on a per-patient and per-segment basis. Results:All 35 CT angiograms were of diagnostic image quality. QCA demonstrated significant CAD in 48% (n = 17) and nonsignificant disease or normal coronary angiograms in 52% (n = 18) of the patients. Sensitivity, specificity, PPV, and NPV of DSCT on a per-patient basis were 100%, 89%, 89%, and 100%, respectively. On a per-segment basis, 473 of 481 coronary artery segments were assessable (98%). QCA demonstrated stenoses >50% in 32 segments (7%), and no disease or nonsignificant disease in 433 segments (93%). For the detection of stenoses >50% on a per-segment basis, DSCT showed a sensitivity, specificity, PPV, and NPV of 88%, 98%, 78%, and 99%, respectively. Conclusions:The comparison of coronary DSCT with QCA shows a very robust image quality and a high diagnostic accuracy in a patient-based as well as a per-segment analysis. Maximal sensitivity and NPV in the per-patient analysis show the strength of the technique in ruling out significant CAD.

Detection of coronary artery stenoses with multislice helical CT angiography

Objectives The authors compared multislice CT angiography and selective angiography for the assessment of coronary artery disease. Methods In 28 patients, the presence and degree of coronary artery stenoses were determined in coronary segments prepared with &bgr;-blocker for good image quality with multislice CT. Results In 187 coronary artery segments, sensitivity, specificity, and negative predictive value for the detection of stenoses >50% with multislice CT angiography were 81%, 90%, and 97%, respectively. The agreement for determining the degree of stenoses with multislice CT angiography and selective coronary angiography was only moderate (&kgr; = 0.58). Conclusions Because of the limited spatial resolution, it is not possible with multislice CT angiography to determine the degree the coronary artery stenoses precisely. However, the high negative predictive value indicates that multislice CT may be a suitable tool to reliably rule out coronary artery disease.

Determination of coronary calcium with Multi-slice Spiral Computed Tomography: a comparative study with Electron-beam CT

Electron-beam Computed Tomography (EBCT) has been used for years to quantify coronary artery calcification as a marker of coronary atherosclerosis. The aim of this study was to determine the diagnostic accuracy of a new scanner, the Multi-slice Spiral CT (MSCT), for the assessment of coronary calcification and to compare this new technique to EBCT. The study population consisted of 99 male patients, aged 60 ± 10 years with suspected or known coronary artery disease. With EBCT 40 axial slices, ECG-triggered (scan time = 100 ms, slice thickness = 3 mm), were acquired in one breath-hold (35 ± 5 s). For MSCT simultaneous acquisition of four axial slices (scan time = 250 ms, slice thickness = 2.5 mm), allowed the entire heart (48 slices) to be covered in one breath-hold of 25 ± 5 s. For quantification of coronary calcium the Volumetric Calcium Score (VCS) was calculated. There was an excellent correlation for the VCS (r = 0.994, p = 0.01, mean difference = 97 ± 115) between both scanners. Comparison of low (1–100), moderate (101–400), high (401–1000) and very high score values (>1000) showed no significant differences. The number of calcified lesions and densities were statistically not different. Mean variability of the two scans was 17%. The MSCT scanner is equivalent to EBCT for the determination and quantification of coronary calcium and can therefore be used for calcium screening. With application of the spiral mode technique further improvement in variability can be expected, thus allowing for follow-up studies to determine progression or regression of atherosclerosis with high accuracy.