Tineke P. Willems

Quantification of global left ventricular function : Comparison of multidetector computed tomography and magnetic resonance imaging. A meta-analysis and review of the current literature

Cardiac morbidity and mortality are closely related to cardiac volumes and global left ventricular (LV) function, expressed as left ventricular ejection fraction. Accurate assessment of these parameters is required for the prediction of prognosis in individual patients as well as in entire cohorts. The current standard of reference for left ventricular function is analysis by short-axis magnetic resonance imaging. In recent years, major extensive technological improvements have been achieved in computed tomography. The most marked development has been the introduction of the multidetector CT (MDCT), which has significantly improved temporal and spatial resolutions. In order to assess the current status of MDCT for analysis of LV function, the current available literature on this subject was reviewed. The data presented in this review indicate that the global left ventricular functional parameters measured by contemporary multi-detector row systems combined with adequate reconstruction algorithms and post-processing tools show a narrow diagnostic window and are interchangeable with those obtained by MRI.

Multidetector computed tomography-guided treatment strategy in patients with non-ST elevation acute coronary syndromes: a pilot study

Patients with non-ST elevation acute coronary syndrome (ACS) and evidence of myocardial ischaemia are scheduled for coronary angiography (CAG). In most patients CAG remains a single diagnostic procedure only. A prospective study was performed to evaluate whether 16-slice multidetector CT (MDCT) could predict treatment of the patients and to determine how many CAGs could have been prevented by MDCT scanning prior to CAG. Twenty-two patients with ACS were scanned prior to CAG. Based on MDCT data, a fictive treatment was proposed and compared to CAG-based treatment. Excellent accuracy was observed to detect significant stenoses using MDCT (sensitivity 94%, specificity 96%). In 45%, no PCI was performed during CAG, because of the absence of significant coronary artery disease (27%) or severe coronary artery disease, demanding CABG (18%). MDCT predicted correct treatment in 86%. By using MDCT data, 32% of the CAGs could have been prevented.

Calcification as a Risk Factor for Rupture of Abdominal Aortic Aneurysm

OBJECTIVES Abdominal aortic aneurysm (AAA) is a major cause of death in developed countries. The AAA diameter is still the only validated prognostic measure for rupture, and therapeutic interventions are initiated accordingly. This still leads to unnecessary interventions in some cases or unidentified impending ruptures. Vascular calcification has been validated abundantly as a risk factor in the cardiovascular field and may strengthen the rupture risk assessment of the AAA. With this study we aim to assess the correlation between AAA calcification and rupture risk in a retrospective unmatched case-control population. METHODS A database of 334 AAA patients was evaluated. Three groups were formed: elective (eAAA; n = 233), ruptured (rAAA; n = 73) and symptomatic non-ruptured (sAAA; n = 28) AAA patients. The Abdominal Aortic Calcification-8 score (AAC-8) was used to measure the severity of vascular calcification. RESULTS The AAA diameter (61 ± 12 mm vs. 74 ± 21 mm; p < .001) and AAC-8 score (3.4 ± 2 points vs. 4.9 ± 2.3 points; p < .001) of the eAAA and the combined rAAA and sAAA groups, respectively, were significantly different after univariate analysis. Multivariate analysis showed that larger AAA diameter (odds ratio [OR]: 1.048/mm increase; 95% confidence interval [CI]: 1.042-1.082; p < .001) and a higher AAC-8 score (OR: 1.34/point increase; 95% CI: 1.19-1.53; p < .001) were significantly associated with development into a sAAA or rAAA. Peripheral artery disease was significantly correlated to eventual elective treatment (OR: 0.39; 95% CI: .15-1; p = .049). CONCLUSION This study suggests a trend of an increased degree of calcification in symptomatic or even ruptured AAA patients compared with elective AAA patients.

Diagnostic value of imaging in infective endocarditis: a systematic review

Sensitivity and specificity of the modified Duke criteria for native valve endocarditis are both suboptimal, at approximately 80%. Diagnostic accuracy for intracardiac prosthetic material-related infection is even lower. Non-invasive imaging modalities could potentially improve diagnosis of infective endocarditis; however, their diagnostic value is unclear. We did a systematic literature review to critically appraise the evidence for the diagnostic performance of these imaging modalities, according to PRISMA and GRADE criteria. We searched PubMed, Embase, and Cochrane databases. 31 studies were included that presented original data on the performance of electrocardiogram (ECG)-gated multidetector CT angiography (MDCTA), ECG-gated MRI, 18F-fluorodeoxyglucose (18F-FDG) PET/CT, and leucocyte scintigraphy in diagnosis of native valve endocarditis, intracardiac prosthetic material-related infection, and extracardiac foci in adults. We consistently found positive albeit weak evidence for the diagnostic benefit of 18F-FDG PET/CT and MDCTA. We conclude that additional imaging techniques should be considered if infective endocarditis is suspected. We propose an evidence-based diagnostic work-up for infective endocarditis including these non-invasive techniques.

Current state of experimental imaging modalities for risk assessment of abdominal aortic aneurysm

BACKGROUND Abdominal aortic aneurysm (AAA) is a major cause of death in developed countries. Patients often lack clinical symptoms, most acute AAA patients do not survive rupture, and subsequent surgical repair has a significant postoperative mortality. Diagnostics for AAAs are currently centered on aneurysm diameter, but recent studies claim this method to be insufficiently accurate. More accurate diagnostic criteria need to be indentified to minimize the amount of unnecessary interventions and to provide earlier diagnosis of rupture-prone AAAs. METHODS A literature study using the MEDLINE database followed by manual cross-referencing provided original studies concerning AAA diagnostics. RESULTS The currently validated imaging modalities such as ultrasound, computed tomography, and magnetic resonance imaging allow AAA research to develop in several directions. Some studies investigate whether clinically visible entities like thrombus, calcification, and vascular anatomy could be implemented directly into clinical practice through use of ultrasound or computed tomography. Experimental studies on intravascular ultrasound, positron emission tomography-computed tomography, ultrasound particle image velocimetry and superparamagnetic particles in magnetic resonance imaging propose new methodologies to benefit AAA research. Other studies focus on available technology toward inflammation, metabolism, and the effects of hemodynamics on vascular integrity. CONCLUSIONS Contradictory outcomes, low availability of experimental imaging modalities, and an often small population size hamper research in this field. Introducing new techniques and biomarkers in current or experimental modalities may prove to be the next step in the development of new diagnostic criteria for the risk assessment of AAA rupture. Until then, the AAA diameter remains the gold standard as a clinical risk factor.

Assessment of image quality of 64-row Dual Source versus Single Source CT coronary angiography on heart rate: A phantom study

PURPOSE To assess the influence of temporal resolution on image quality of computed tomographic (CT) coronary angiography by comparing 64-row Dual Source CT (DSCT) and Single Source CT (SSCT) at different heart rates. METHODS An anthropomorphic moving heart phantom was scanned at rest, and at 50 beats per minute (bpm) up to 110 bpm, with intervals of 10 bpm. 3D volume rendered images and curved multi-planar reconstructions (MPRs) were acquired and image quality of the coronary arteries was rated on a 5-points scale (1=poor image quality with many artefacts, 5=excellent image quality) for each heart rate and each scanner by 3 observers. Paired sample t-test and Wilcoxon Signed Ranks test were used to assess clinically relevant differences between both modalities. RESULTS The mean image quality scores at 70, 100 and 110 bpm were significantly higher for DSCT compared to SSCT. The overall mean image quality scores for DSCT (4.2+/-0.6) and SSCT (3.0+/-1.1) also differed significantly (p<0.001). CONCLUSION These initial results show a clinically relevant overall higher image quality for DSCT compared to SSCT, especially at heart rates of 70, 100 and 110 bpm. With its comparatively high image quality and low radiation dose, DSCT appears to be the method of choice in CT coronary angiography at heart rates above 70 bpm.

Initial results on visualization of coronary artery stents at multiple heart rates on a moving heart phantom using 64-MDCT.

Objective: Evaluation of the image quality of coronary artery stents at various heart rates using Multi Detector Computed Tomography (MDCT). Methods: Nine different coronary stents were attached to a moving heart phantom and scanned using a 64-MDCT with a rotation time of 330 milliseconds (ms). The heart rate of the phantom was varied between 0 and 115 beats per minute (bpm). Two independent methods were used to investigate image quality. After reconstruction the average Houndsfield Unit (HU) value in the stent lumen was measured in the longitudinal and the cross-sectional plane. The stent images were then presented to two radiologists. The radiologists were asked to rank the images from good to bad based on lumen visibility and overall image quality. A second ranking was obtained using the CT density values. Finally two rankings were compared. Results: Compared to the value for air, the HU-values measured in the lumen increased by 50 to 700 HU. Average slope value in the longitudinal plane was 1.7 ± 0.6 HU/bpm, and the average slope value in the cross-sectional plane was 1.7 ± 0.8 HU/bpm. This shows increased attenuation with increasing heart rate and thus a negative correlation between image quality and heart rate in both planes for all stents. The ranking acquired from the radiologists resembled the measured results as they also showed a negative correlation between the two variables. Using the results of the CT density measurements an analysis was done on multi-segment reconstruction (MSR). Conclusion: A negative correlation between the heart rate and image quality of coronary stents was found by two independent methods. MSR showed no benefit for image quality in this study.

Reduced regional myocardial perfusion reserve is associated with impaired contractile performance in idiopathic dilated cardiomyopathy

Background. In idiopathic dilated cardiomyopathy (IDC) an imbalance between myocardial oxygen consumption and supply has been postulated. Subclinical myocardial ischaemia may contribute to progressive deterioration of left ventricular function. The relation between regional myocardial perfusion reserve (MPR) and contractile performance was investigated.Methods. Patients with newly diagnosed IDC underwent positron emission tomography (PET) scanning using both 13N-ammonia as a perfusion tracer (baseline and dypiridamole stress), and 18F-fluorodeoxyglucose viability tracer and a dobutamine stress MRI. MPR (assessed by PET) as well as wall motion score (WMS, assessed by MRI) were evaluated in a 17-segment model.Results. Twenty-two patients were included (age 49±11 years; 15 males, LVEF 33±10%). With MRI, a total of 305 segments could be analysed. Wall motion abnormalities at rest were present in 127 (35.5%) segments and in 103 (29.9%) during dobutamine stress. Twenty-one segments deteriorated during stress and 43 improved. MPR was significantly higher in those segments that improved, compared with those that did not change or were impaired during stress (1.87±0.04 vs. 1.56± 0.07 p<0.01.)Conclusion. Signs of regional ischaemia were clearly present in IDC patients. Ischaemic regions displayed impaired contractility during stress. This suggests that impaired oxygen supply contributes to cardiac dysfunction in IDC. (Neth Heart J 2009;17:470–4.)

An evaluation of automatic coronary artery calcium scoring methods with cardiac CT using the orCaScore framework

PURPOSE The amount of coronary artery calcification (CAC) is a strong and independent predictor of cardiovascular disease (CVD) events. In clinical practice, CAC is manually identified and automatically quantified in cardiac CT using commercially available software. This is a tedious and time-consuming process in large-scale studies. Therefore, a number of automatic methods that require no interaction and semiautomatic methods that require very limited interaction for the identification of CAC in cardiac CT have been proposed. Thus far, a comparison of their performance has been lacking. The objective of this study was to perform an independent evaluation of (semi)automatic methods for CAC scoring in cardiac CT using a publicly available standardized framework. METHODS Cardiac CT exams of 72 patients distributed over four CVD risk categories were provided for (semi)automatic CAC scoring. Each exam consisted of a noncontrast-enhanced calcium scoring CT (CSCT) and a corresponding coronary CT angiography (CCTA) scan. The exams were acquired in four different hospitals using state-of-the-art equipment from four major CT scanner vendors. The data were divided into 32 training exams and 40 test exams. A reference standard for CAC in CSCT was defined by consensus of two experts following a clinical protocol. The framework organizers evaluated the performance of (semi)automatic methods on test CSCT scans, per lesion, artery, and patient. RESULTS Five (semi)automatic methods were evaluated. Four methods used both CSCT and CCTA to identify CAC, and one method used only CSCT. The evaluated methods correctly detected between 52% and 94% of CAC lesions with positive predictive values between 65% and 96%. Lesions in distal coronary arteries were most commonly missed and aortic calcifications close to the coronary ostia were the most common false positive errors. The majority (between 88% and 98%) of correctly identified CAC lesions were assigned to the correct artery. Linearly weighted Cohens kappa for patient CVD risk categorization by the evaluated methods ranged from 0.80 to 1.00. CONCLUSIONS A publicly available standardized framework for the evaluation of (semi)automatic methods for CAC identification in cardiac CT is described. An evaluation of five (semi)automatic methods within this framework shows that automatic per patient CVD risk categorization is feasible. CAC lesions at ambiguous locations such as the coronary ostia remain challenging, but their detection had limited impact on CVD risk determination.

Accuracy of noninvasive coronary stenosis quantification of different commercially available dedicated software packages.

Purpose: The purpose of this study was to investigate the noninvasive quantification of coronary artery stenosis using cardiac software packages and vessel phantoms with known stenosis severity. Materials and Methods: Four different sizes of vessel phantoms were filled with contrast agent and scanned on a 64-slice multidetector computed tomography. Diameter and area stenosis were evaluated by 2 observers blinded from the true measures using 5 different software packages. Measurements were compared with the true measure of the vessel phantoms. The absolute difference in stenosis measurements and intraobserver and interobserver variabilities were assessed. Results: All software packages show a trend toward larger differences for the smaller vessel phantoms. The absolute difference of the automatic measurements was significantly higher compared with that of the manual measurements in all 5 evaluated software packages for all vessel phantoms (P < 0.05). Conclusion: Manual stenosis measurements are significantly more accurate compared with automatic measurements, and therefore, manual adjustments are still essential for noninvasive assessment of coronary artery stenosis.