First the VG-RVPO as a monitoring for PAH in SSc patients was evaluated, here serial measurements of the VG-RVPO, can be used as a follow-up instrument to detect early changes in RV pressure over... Show moreFirst the VG-RVPO as a monitoring for PAH in SSc patients was evaluated, here serial measurements of the VG-RVPO, can be used as a follow-up instrument to detect early changes in RV pressure over time. Then we investigated the role of the VG-RVPO in improving the efficiency of the YEARS algorithm. Neither as a stand-alone diagnostic test nor when combined with the YEARS algorithm, it had any diagnostic value. Then the role of VG-RVPO in estimating the presence of PH, and the prognostic value of an abnormal VG-RVPO in PE patients was evaluated. There was an association between VG-RVPO and RV overload as measured by CTPA. In Chapter 5, the outcome of AAOCA patients is described and linked to pre-and postoperative symptoms. Overall, surgical correction significantly reduces symptoms. The CTOA on pre-and post-operative CTAs of patients with AAOCA was compared and related to anatomy and post-operative outcome. It suggests that CTA can be used to look at the anatomy of AAOCA patients before and after surgery. The last study re-evaluates the late clinical outcome and hemodynamics in patients with TOF. The findings shows, after 17.1 years there was a stabilization of RV function and an impressive durability of the homograft. Show less
Thrombus volume in posterior circulation stroke (PCS) has been associated with outcome, through recanalization. Manual thrombus segmentation is impractical for large scale analysis of image... Show moreThrombus volume in posterior circulation stroke (PCS) has been associated with outcome, through recanalization. Manual thrombus segmentation is impractical for large scale analysis of image characteristics. Hence, in this study we develop the first automatic method for thrombus localization and segmentation on CT in patients with PCS. In this multi-center retrospective study, 187 patients with PCS from the MR CLEAN Registry were included. We developed a convolutional neural network (CNN) that segments thrombi and restricts the volume-of-interest (VOI) to the brainstem (Polar-UNet). Furthermore, we reduced false positive localization by removing small-volume objects, referred to as volume-based removal (VBR). Polar-UNet is benchmarked against a CNN that does not restrict the VOI (BL-UNet). Performance metrics included the intra-class correlation coefficient (ICC) between automated and manually segmented thrombus volumes, the thrombus localization precision and recall, and the Dice coefficient. The majority of the thrombi were localized. Without VBR, Polar-UNet achieved a thrombus localization recall of 0.82, versus 0.78 achieved by BL-UNet. This high recall was accompanied by a low precision of 0.14 and 0.09. VBR improved precision to 0.65 and 0.56 for Polar-UNet and BL-UNet, respectively, with a small reduction in recall to 0.75 and 0.69. The Dice coefficient achieved by Polar-UNet was 0.44, versus 0.38 achieved by BL-UNet with VBR. Both methods achieved ICCs of 0.41 (95% CI: 0.27-0.54). Restricting the VOI to the brainstem improved the thrombus localization precision, recall, and segmentation overlap compared to the benchmark. VBR improved thrombus localization precision but lowered recall. Show less
The 2016 National Institute of Health and Care Excellence clinical guideline for the assessment and diagnosis of chest pain positions coronary computed tomography angiography as the first test for... Show moreThe 2016 National Institute of Health and Care Excellence clinical guideline for the assessment and diagnosis of chest pain positions coronary computed tomography angiography as the first test for all stable chest pain patients without confirmed coronary artery disease and discards the previous emphasis on calculation of pre-test likelihood recommended in their 2012 edition of the guidelines. On the other hand, the American College of Cardiology Foundation/American Heart Association and the European Society of Cardiology guidelines continue to present the stress testing functional modalities as the tests of choice. The aim of this review is to present, in the form of a debate, the pros and cons of these paradigm changing recommendations, with an emphasis on literature review and projection of future needs, with conclusions to be drawn by the reader. Show less
The primary objective of this dissertation is to determine the diagnostic performance of 320-row CTA for cardiac applications, particularly in the assessment of significant coronary stenosis in... Show moreThe primary objective of this dissertation is to determine the diagnostic performance of 320-row CTA for cardiac applications, particularly in the assessment of significant coronary stenosis in patients with known or suspected CAD. It was shown that 320-row CTA allows accurate, non-invasive assessment of significant CAD and global left ventricular function in patients with suspected CAD, as well as in patients with a history of revascularization. Furthermore, the prognostic value of CTA and its role in clinical management of patients with suspected CAD were investigated. The potential of CTA to serve as a gatekeeper prior to CTA was explored. It was shown that CTA has the potential to serve as a gatekeeper for invasive coronary angiography in patients with a low-to-intermediate pre-test likelihood of obstructive CAD. Subsequently, it was shown that the assessment of left ventricular function analysis on CTA may further enhance risk stratification beyond the assessment of degree of stenosis. Finally, in patients with type 2 diabetes mellitus, the combined presence of increased waist circumference and elevated plasma triglyceride levels was shown to translate into an increased likelihood of CAD on CTA and may therefore serve as a practical clinical biomarker to improve risk stratification. Show less
During the past few years CTA has rapidly developed into a versatile non-invasive imaging modality. While imaging of the coronary arteries to determine or rule out the presence of stenosis will... Show moreDuring the past few years CTA has rapidly developed into a versatile non-invasive imaging modality. While imaging of the coronary arteries to determine or rule out the presence of stenosis will remain one of the main indications, additional information on plaque severity and composition can be obtained. The improvements in technology (faster gantry rotation times, an increasing number of detectors, volumetric image acquisition) and consequential improvement in image quality have resulted in advances in the characterization of coronary atherosclerosis and vulnerable plaque. Interestingly, the diagnostic performance of CTA was superior in the evaluation of presence or absence of clinically relevant atherosclerosis as compared to the evaluation of signifi cant stenosis. Regarding plaque observations with the novel 320-row CTA scanner, the results showed good agreement to relative plaque composition on invasive VH IVUS. Moreover, mixed plaques on 320-row CTA paralleled the more vulnerable plaque on VH IVUS. In addition, lesions with spotty calcifi cations and positive remodeling on CTA were associated with a higher percentage necrotic core and a higher prevalence of vulnerable plaques. Accordingly, evaluation of spotty calcifi cations and remodeling on CTA may be valuable markers for plaque vulnerability. The relation between characterization of atherosclerosis on CTA and its effect on clinical management was also evaluated. As a result of rapid developments in coronary CTA technology, high diagnostic accuracies of 320-row CTA for detecting coronary stenosis were obtained in patients with stable chest pain complaints as well as in patients presenting with acute chest pain. In addition, although a zero calcium score has important prognostic value, patients with acute coronary syndrome and zero calcium had increased plaque burden as well as increased vulnerability as compared to patients with stable chest pain. Accordingly, absence of coronary calcifi cation did not exclude the presence of clinically relevant and potentially vulnerable atherosclerotic plaque burden in patients with acute coronary syndrome. Lastly, in addition to the degree of stenosis, CTA variables of atherosclerosis describing plaque extent, composition and location were predictive of the presence of ischemia on myocardial perfusion imaging. Possibly, these results may allow a more refi ned and individualized assessment of patients undergoing CTA imaging and provide the basis for the development of an algorithm to improve identifi cation of patients requiring more aggressive therapy or intervention. Show less
