Lisan A. Neefjes

Three dimensional evaluation of the aortic annulus using multislice computer tomography: are manufacturer's guidelines for sizing for percutaneous aortic valve replacement helpful?

AIMS To evaluate the effects of applying current sizing guidelines to different multislice computer tomography (MSCT) aortic annulus measurements on Corevalve (CRS) size selection. METHODS AND RESULTS Multislice computer tomography annulus diameters [minimum: D(min); maximum: D(max); mean: D(mean) = (D(min) + D(max))/2; mean from circumference: D(circ); mean from surface area: D(CSA)] were measured in 75 patients referred for percutaneous valve replacement. Fifty patients subsequently received a CRS (26 mm: n = 22; 29 mm: n = 28). D(min) and D(max) differed substantially [mean difference (95% CI) = 6.5 mm (5.7-7.2), P < 0.001]. If D(min) were used for sizing 26% of 75 patients would be ineligible (annulus too small in 23%, too large in 3%), 48% would receive a 26 mm and 12% a 29 mm CRS. If D(max) were used, 39% would be ineligible (all annuli too large), 4% would receive a 26 mm, and 52% a 29 mm CRS. Using D(mean), D(circ), or D(CSA) most patients would receive a 29 mm CRS and 11, 16, and 9% would be ineligible. In 50 patients who received a CRS operator choice corresponded best with sizing based on D(CSA) and D(mean) (76%, 74%), but undersizing occurred in 20 and 22% of which half were ineligible (annulus too large). CONCLUSION Eligibility varied substantially depending on the sizing criterion. In clinical practice both under- and oversizing were common. Industry guidelines should recognize the oval shape of the aortic annulus.

Image Quality and Radiation Exposure Using Different Low-Dose Scan Protocols in Dual-Source CT Coronary Angiography: Randomized Study

PURPOSE To compare image quality, radiation dose, and their relationship with heart rate of computed tomographic (CT) coronary angiographic scan protocols by using a 128-section dual-source CT scanner. MATERIALS AND METHODS Institutional review board approved the study; all patients gave informed consent. Two hundred seventy-two patients (175 men, 97 women; mean ages, 58 and 59 years, respectively) referred for CT coronary angiography were categorized according to heart rate: less than 65 beats per minute (group A) and 65 beats per minute or greater (group B). Patients were randomized to undergo prospective high-pitch spiral scanning and narrow-window prospective sequential scanning in group A (n = 160) or wide-window prospective sequential scanning and retrospective spiral scanning in group B (n = 112). Image quality was graded (1 = nondiagnostic; 2 = artifacts present, diagnostic; 3 = no artifacts) and compared (Mann-Whitney and Student t tests). RESULTS In group A, mean image quality grade was significantly lower with high-pitch spiral versus sequential scanning (2.67 ± 0.38 [standard deviation] vs 2.86 ± 0.21; P < .001). In a subpopulation (heart rate, <55 beats per minute), mean image quality grade was similar (2.81 ± 0.30 vs 2.94 ± 0.08; P = .35). In group B, image quality grade was comparable between sequential and retrospective spiral scanning (2.81 ± 0.28 vs 2.80 ± 0.38; P = .54). Mean estimated radiation dose was significantly lower (high-pitch spiral vs sequential scanning) in group A (for 100 kV, 0.81 mSv ± 0.30 vs 2.74 mSv ± 1.14 [P < .001]; for 120 kV, 1.65 mSv ± 0.69 vs 4.21 mSv ± 1.20 [P < .001]) and in group B (sequential vs retrospective spiral scanning) (for 100 kV, 4.07 mSv ± 1.07 vs 5.54 mSv ± 1.76 [P = .02]; for 120 kV, 7.50 mSv ± 1.79 vs 9.83 mSv ± 3.49 [P = .1]). CONCLUSION A high-pitch spiral CT coronary angiographic protocol should be applied in patients with regular and low (<55 beats per minute) heart rates; a sequential protocol is preferred in all others.

Accelerated subclinical coronary atherosclerosis in patients with familial hypercholesterolemia

OBJECTIVES We determined the extent, severity, distribution and type of coronary plaques in cardiac asymptomatic patients with familial hypercholesterolemia (FH) using computed tomography (CT). BACKGROUND FH patients have accelerated progression of coronary artery disease (CAD) with earlier major adverse cardiac events. Non-invasive CT coronary angiography (CTCA) allows assessing the coronary plaque burden in asymptomatic patients with FH. MATERIALS AND METHODS A total of 140 asymptomatic statin treated FH patients (90 men; mean age 52 ± 8 years) underwent CT calcium scoring (Agatston) and CTCA using a Dual Source CT scanner with a clinical follow-up of 29 ± 8 months. The extent, severity (obstructive or non-obstructive plaque based on >50% or <50% lumen diameter reduction), distribution and type (calcified, non-calcified, or mixed) of coronary plaque were evaluated. RESULTS The calcium score was 0 in 28 (21%) of the patients. In 16% of the patients there was no CT-evidence of any CAD while 24% had obstructive disease. In total 775 plaques were detected with CT coronary angiography, of which 11% were obstructive. Fifty four percent of all plaques were calcified, 25% non-calcified and 21% mixed. The CAD extent was related to gender, treated HDL-cholesterol and treated LDL-cholesterol levels. There was a low incidence of cardiac events and no cardiac death occurred during follow-up. CONCLUSION Development of CAD is accelerated in intensively treated male and female FH patients. The extent of CAD is related to gender and cholesterol levels and ranges from absence of plaque in one out of 6 patients to extensive CAD with plaque causing >50% lumen obstruction in almost a quarter of patients with FH.

CT coronary plaque burden in asymptomatic patients with familial hypercholesterolaemia

Objective To determine the calcium score and coronary plaque burden in asymptomatic statin-treated patients with heterozygous familial hypercholesterolaemia (FH) compared with a control group of patients with low probability of coronary artery disease, having non-anginal chest pain, using CT. Design, setting and patients 101 asymptomatic patients with FH (mean age 53±7 years; 62 men) and 126 patients with non-anginal chest pain (mean age 56±7 years; 80 men) underwent CT calcium scoring and CT coronary angiography. All patients with FH were treated with statins during a period of 10±8 years before CT. The coronary calcium score and plaque burden were determined and compared between the two patient groups. Results The median total calcium score was significantly higher in patients with FH (Agatston score=87, IQR 5–367) than in patients with non-anginal chest pain (Agatston score=7, IQR 0–125; p<0.001). The overall coronary plaque burden was significantly higher in patients with FH (p<0.01). Male patients with FH, whose low-density lipoprotein cholesterol levels were reduced by statins below 3.0 mmol/l, had significantly less coronary calcium (p<0.01) and plaque burden (p=0.02). Conclusion The coronary plaque burden is high in asymptomatic middle-aged patients with FH despite intense statin treatment.

Coronary Lumen Segmentation Using Graph Cuts and Robust Kernel Regression

This paper presents a novel method for segmenting the coronary lumen in CTA data. The method is based on graph cuts, with edge-weights depending on the intensity of the centerline, and robust kernel regression. A quantitative evaluation in 28 coronary arteries from 12 patients is performed by comparing the semi-automatic segmentations to manual annotations. This evaluation showed that the method was able to segment the coronary arteries with high accuracy, compared to manually annotated segmentations, which is reflected in a Dice coefficient of 0.85 and average symmetric surface distance of 0.22 mm.

Comparison of the Value of Coronary Calcium Detection to Computed Tomographic Angiography and Exercise Testing in Patients With Chest Pain

The aim of this study was to investigate the value of coronary calcium detection by computed tomography compared to computed tomographic angiography (CTA) and exercise testing to detect obstructive coronary artery disease (CAD) in patients with stable chest pain. A total of 471 consecutive patients with new stable chest complaints were scheduled to undergo dual-source multislice computed tomography (Siemens, Germany; coronary calcium score [CCS] and coronary CTA) and exercise electrocardiography (XECG). Clinically driven invasive quantitative angiography was performed in 98 patients. Only 3 of 175 patients (2%) with a negative CCS had significant CAD on CT angiogram, with only 1 confirmed by quantitative angiography. In patients with a high calcium score (Agatston score >400), CTA could exclude significant CAD in no more than 4 of 65 patients (6%). In patients with a low-intermediate CCS, CTA more often yielded diagnostic results compared to XECG and could rule out obstructive CAD in 56% of patients. For patients with CAD on CT angiogram, those with abnormal exercise electrocardiographic results more often showed severe CAD (p <0.034). In patients with diagnostic results for all tests, the sensitivity and specificity to detect >50% quantitative angiographic diameter stenosis were 100% and 15% for CCS >0, 82% and 64% for CCS >100, 97% and 36% for CTA, and 70% and 76% for XECG, respectively. In conclusion, nonenhanced computed tomography for calcium detection is a reliable means to exclude obstructive CAD in stable, symptomatic patients. Contrast-enhanced CTA can exclude significant CAD in patients with a low-intermediate CCS but is of limited value in patients with a high CCS.

Robust Shape Regression for Supervised Vessel Segmentation and its Application to Coronary Segmentation in CTA

This paper presents a vessel segmentation method which learns the geometry and appearance of vessels in medical images from annotated data and uses this knowledge to segment vessels in unseen images. Vessels are segmented in a coarse-to-fine fashion. First, the vessel boundaries are estimated with multivariate linear regression using image intensities sampled in a region of interest around an initialization curve. Subsequently, the position of the vessel boundary is refined with a robust nonlinear regression technique using intensity profiles sampled across the boundary of the rough segmentation and using information about plausible cross-sectional vessel shapes. The method was evaluated by quantitatively comparing segmentation results to manual annotations of 229 coronary arteries. On average the difference between the automatically obtained segmentations and manual contours was smaller than the inter-observer variability, which is an indicator that the method outperforms manual annotation. The method was also evaluated by using it for centerline refinement on 24 publicly available datasets of the Rotterdam Coronary Artery Evaluation Framework. Centerlines are extracted with an existing method and refined with the proposed method. This combination is currently ranked second out of 10 evaluated interactive centerline extraction methods. An additional qualitative expert evaluation in which 250 automatic segmentations were compared to manual segmentations showed that the automatically obtained contours were rated on average better than manual contours.

Computed tomography versus exercise electrocardiography in patients with stable chest complaints: real-world experiences from a fast-track chest pain clinic

Objective: To compare the diagnostic performance of CT angiography (CTA) and exercise electrocardiography (XECG) in a symptomatic population with a low–intermediate prevalence of coronary artery disease (CAD). Design: Prospective registry. Setting: Tertiary university hospital. Patients: 471 consecutive ambulatory patients with stable chest pain complaints, mean (SD) age 56 (10), female 227 (48%), pre-test probability for significant CAD >5%. Intervention: All patients were intended to undergo both 64-slice, dual-source CTA and an XECG. Clinically driven quantitative catheter angiography was performed in 98 patients. Main outcome measures: Feasibility and interpretability of, and association between, CTA and XECG, and their diagnostic performance with invasive coronary angiography as reference. Results: CTA and XECG could not be performed in 16 (3.4%) vs 48 (10.2%, p<0.001), and produced non-diagnostic results in 3 (0.7%) vs 140 (33%, p<0.001). CTA showed ⩾1 coronary stenosis (⩾50%) in 140 patients (30%), XECG was abnormal in 93 patients (33%). Results by CTA and XECG matched for 185 patients (68%, p = 0.63). Catheter angiography showed obstructive CAD in 57/98 patients (58%). Sensitivity, specificity, positive and negative predictive value of CTA to identify patients with ⩾50% stenosis was 96%, 37%, 67% and 88%, respectively; compared with XECG: 71%, 76%, 80% and 66%, respectively. Quantitative CTA slightly overestimated diameter stenosis: 6 (21)% (R = 0.71), compared with QCA. Of the 312 patients (66%) with a negative CTA, 44 (14%) had a positive XECG, but only 2/17 who underwent catheter angiography had significant CAD. Conclusion: CTA is feasible and diagnostic in more patients than XECG. For interpretable studies, CTA has a higher sensitivity, but lower specificity for detection of CAD.

Patient Specific 4D Coronary Models from ECG-gated CTA Data for Intra-operative Dynamic Alignment of CTA with X-ray Images

We present an approach to derive patient specific coronary models from ECG-gated CTA data and their application for the alignment of CTA with mono-plane X-ray imaging during interventional cardiology. A 4D (3D+t) deformation model of the coronary arteries is derived by (i) extraction of a 3D coronary model at an appropriate cardiac phase and (ii) non-rigid registration of the CTA images at different ECG phases to obtain a deformation model. The resulting 4D coronary model is aligned with the X-ray data using a novel 2D+t/3D+t registration approach. Model consistency and accuracy is evaluated using manually annotated coronary centerlines at systole and diastole as reference. Improvement of registration robustness by using the 2D+t/3D+t registration is successfully demonstrated by comparison of the actual X-ray cardiac phase with the automatically determined best matching phase in the 4D coronary model.

Statistical coronary motion models for 2D + t/3D registration of X-ray coronary angiography and CTA

Accurate alignment of intra-operative X-ray coronary angiography (XA) and pre-operative cardiac CT angiography (CTA) may improve procedural success rates of minimally invasive coronary interventions for patients with chronic total occlusions. It was previously shown that incorporating patient specific coronary motion extracted from 4D CTA increases the robustness of the alignment. However, pre-operative CTA is often acquired with gating at end-diastole, in which case patient specific motion is not available. For such cases, we investigate the possibility of using population based coronary motion models to provide constraints for the 2D+t/3D registration. We propose a methodology for building statistical motion models of the coronary arteries from a training population of 4D CTA datasets. We compare the 2D+t/3D registration performance of the proposed statistical models with other motion estimates, including the patient specific motion extracted from 4D CTA, the mean motion of a population, the predicted motion based on the cardiac shape. The coronary motion models, constructed on a training set of 150 patients, had a generalization accuracy of 1mm root mean square point-to-point distance. Their 2D+t/3D registration accuracy on one cardiac cycle of 12 monoplane XA sequences was similar to, if not better than, the 4D CTA based motion, irrespective of which respiratory model and which feature based 2D/3D distance metric was used. The resulting model based coronary motion estimate showed good applicability for registration of a subsequent cardiac cycle.