Background Myocardial extracellular volume fraction (ECV) assessment can be affected by various technical and subject-related factors. Purpose To evaluate the role of contour-based registration in... Show moreBackground Myocardial extracellular volume fraction (ECV) assessment can be affected by various technical and subject-related factors. Purpose To evaluate the role of contour-based registration in quantification of ECV and investigate normal segment-based myocardial ECV values at 3T. Material and Methods Pre- and post-contrast T1 mapping images of the left ventricular basal, mid-cavity, and apical slices were obtained in 26 healthy volunteers. ECV maps were generated using motion correction with and without contour-based registration. The image quality of all ECV maps was evaluated by a 4-point scale. Slices were dichotomized according to the occurrence of misregistration in the source data. Contour-registered ECVs and standard ECVs were compared within each subgroup using analysis of variance for repeated measurements and generalized linear mixed models. Results In all three slices, higher quality of ECV maps were found using contour-registered method than using standard method. Standard ECVs were statistically different from contour-registered ECVs in global (26.8% +/- 2.8% vs. 25.8% +/- 2.4%; P = 0.001), mid-cavity (25.4% +/- 3.1% vs. 24.3% +/- 2.5%; P = 0.016), and apical slices (28.7% +/- 4.1% vs. 27.2% +/- 3.4%; P = 0.010). In the misregistration subgroups, contour-registered ECVs were lower with smaller SDs (basal: 25.2% +/- 1.8% vs. 26.7% +/- 2.6%; P = 0.038; mid-cavity: 24.4% +/- 2.3% vs. 26.8% +/- 3.1%; P = 0.012; apical: 27.5% +/- 3.6% vs. 29.7% +/- 4.5%; P = 0.016). Apical (27.2% +/- 3.4%) and basal-septal ECVs (25.6% +/- 2.6%) were statistically higher than mid-cavity ECV (24.3% +/- 2.5%; both P < 0.001). Conclusion Contour-based registration can optimize image quality and improve the precision of ECV quantification in cases demonstrating ventricular misregistration among source images. Show less
Cardiovascular magnetic resonance imaging is an important noninvasive imaging modality for the diagnosis, clinical work‐up and treatment planning in patients suspected for a wide range of... Show moreCardiovascular magnetic resonance imaging is an important noninvasive imaging modality for the diagnosis, clinical work‐up and treatment planning in patients suspected for a wide range of cardiovascular pathology. CMR imaging is accurate and reliable, and provides invaluable information to evaluate the cardiovascular system without the need of ionizing radiation. The studies described in this thesis evaluate new CMR imaging techniques in clinical practice and explore the prognostic value of new CMR imaging biomarkers in patients with symptomatic peripheral arterial occlusive disease. New advances and innovations in MR imaging technology improve and further expand the clinical applications of cardiovascular imaging in daily clinical practice. In this thesis, a new, fast free‐breathing 2D delayed‐enhancement MRI sequence is validated and demonstrated to be a reliable tool for detecting myocardial infarction. Furthermore, new technical developments allow single‐injection, three‐station, moving‐table MRA protocol at 3Tesla with similar diagnostic performance when compared to 1.5Tesla. Additionally, submillimeter isotropic voxel acquisition in the lower legs at 1.5Tesla improves the diagnostic accuracy and depicts more open infragenual arterial segments.Additionally, it is demonstrated that new MRI biomarkers as distal aortic pulse wave velocity statistically significantly correlate with stenosis severity in symptomatic patients with peripheral arterial occlusive disease. Finally, we showed that CMR derived biomarkers relating to stenosis severity, aortic stiffness and left ventricular function play a role in prognosis of outcome in patients with symptomatic PAOD. In the future, incorporation of the described new MRI biomarkers in the clinical workup of peripheral arterial occlusive disease may play an important role for full vascular risk assessment and ultimately, patients may benefit in clinical practice. Show less
Shmuely, S.; Lende, M. van der; Lamberts, R.J.; Sander, J.W.; Thijs, R.D. 2017
The Ross-Konno procedure is a durable solution for multilevel LVOTO in a highly complex patient population with high incidence of previous procedures. High early mortality rates in patients with... Show moreThe Ross-Konno procedure is a durable solution for multilevel LVOTO in a highly complex patient population with high incidence of previous procedures. High early mortality rates in patients with impaired left ventricular function emphasize the importance of patient selection. Freedom from reoperation shows a continuous attrition rate. Reoperation for autograft failure may occur late after the Ross-Konno procedure. Show less
Cardiovascular diseases are highly prevalent in the western world. With the aging of the population, the number of people suffering from CVD is still increasing. Therefore, the amount of diagnostic... Show moreCardiovascular diseases are highly prevalent in the western world. With the aging of the population, the number of people suffering from CVD is still increasing. Therefore, the amount of diagnostic assessments and thus, the number of image acquisitions will increase accordingly. Considering the high quantities of data produced by 3D and 4D imaging modalities, such as CT and MRI, manual contouring and diagnosis currently require much time and attention of the radiologists and cardiologists. This justifies the need for (semi-) automatic segmentation methods; developing these as the focus of the research presented in this thesis. Show less
Cardiopulmonary bypass (CPB) induces a systemic inflammatory response syndrome (SIRS) in patients following cardiac surgery that can lead to major organ injury and postoperative morbidity.... Show moreCardiopulmonary bypass (CPB) induces a systemic inflammatory response syndrome (SIRS) in patients following cardiac surgery that can lead to major organ injury and postoperative morbidity. Initiation of CPB sets in motion an extremely complex and multifaceted response involving complement activation along with activation of platelets, neutrophils, monocytes, and macrophages. This in turn initiates the coagulation, fibrinolytic, and kallikrein cascades, increasing blood concentrations of various endotoxins and cytokines and increasing endothelial cell permeability. The basic physiological insults caused by CPB have been associated with major postoperative morbidity, including neurological, pulmonary adrenal dysfunction, and/or haematological abnormalities. Additional clinical manifestations associated with the SIRS include increased metabolism (fever), fluid retention, myocardial oedema, and detrimental haemodynamic alterations. The use of steroids to minimize or prevent the consequences of SIRS in the postoperative period has been extensively investigated in adults. Clinical investigations in the paediatric population are scarce. Our aim was to investigate how dexamethasone could influence the associated side effects of CPB in two organs, the small intestine and the heart. To that effect we chose two surrogate markers, gut permeability and cardiac troponin T production. Intestinal mucosal ischaemia, although transient, can occur in infants and children during and after CPB. Gut permeability had not been previously investigated in children undergoing cardiac surgery. In chapter two we describe, in an observational study, the natural course of gut permeability in patients undergoing cardiac surgery with and without CPB. Gut permeability has been investigated in healthy children and neonates not undergoing surgical or medical interventions during the study period. Patients with congenital cardiac diseases have preoperative gut permeability values up to seven times what we could expect in healthy children of similar age. In patients operated without CPB gut permeability was reduced in the postoperative period returning to near normal values 24 hours after surgery. On the other hand, in patients undergoing surgery with CPB gut permeability deteriorated even further in the postoperative period. 98 In chapter three we report the results of a study designed to test the hypothesis that dexamethasone has beneficial effects on intestinal permeability during the postoperative period. Dexamethasone given before CPB starts reduced intestinal permeability within 24 h after surgery. The differences are highly significant when compared to control patients not given dexamethasone. In the investigation reported in chapter four we studied the changes in intestinal permeability in patients undergoing stage I of the Norwood procedure. Neonates with hypoplastic left heart syndrome (HLHS) undergo surgical repair in three stages. These patients suffer from an imbalanced circulation potentially exposing the intestine to chronic ischaemia. The surgical repair requires a period of circulatory arrest. It comes as no surprise, therefore, that HLHS patients are at high risk of developing necrotizing enterocolitis in the postoperative period, with devastating consequences. We found that HLHS patients have abnormal intestinal permeability before and after surgery. Rhamnose is one of the four sugars used to test intestinal permeability. For the last thirty years it has been assumed that rhamnose is an inert sugar not metabolized by the human body. We have found this not to be the case, and the results are presented in chapter five. The type of anaesthetic agent used during adult coronary bypass surgery may influence considerably the postoperative production of cardiac troponin T (cTnT), a protein that reflects the extent of myocardial damage after a period of hypoxia. In particular halogenated ethers may exert its effect through a process called anaesthetic preconditioning, a phenomenon similar to ischaemic preconditioning. Anaesthetic preconditioning has not been investigated in paediatric cardiac surgery to the same extent as in adult cardiac surgery. In chapter six we present a study of the effects of three different anaesthetic agents, propofol, midazolam and sevoflurane, on the postoperative production of cTnT in paediatric cardiac surgical patients. Contrary to what happens in adult patients we could not find significant differences in the postoperative production of cTnT when midazolam, propofol or sevoflurane were used as anaesthetic agents. In chapter seven, we report on a study designed to test the hypothesis that dexamethasone given before CPB starts may have myocardial protective effects as assessed by the postoperative production of cTnT. Subgroup analysis in cyanotic and neonatal patients was also evaluated for the same hypothesis. 99 We found that dexamethasone did reduce postoperative cTnT concentrations. However, the reduction was short lived and was not accompanied by improvements in any of the other clinical parameters measured. Show less
