Quantitative MRI in obesity & reno-cardiovascular function

The aim of this thesis was to evaluate quantitative MRI techniques in reno-cardiovascular health, and to study the links between obesity and reno-cardiovascular health using quantitative MRI metrics. Furthermore, we aimed to address novel insights on the safety of contrast media with regard to the use of gadolinium. The general introduction (Chapter 1) of this thesis introduces the concept of quantitative MRI, its application in epidemiological research, reno-cardiovascular health, and in obesity. In addition, the general introduction addresses the safety of gadolinium as an MRI contrast agent. Following the general introduction a review of the clinical application and technical considerations of quantitative MRI using T1 and T2(*) mapping in cardiac and renal imaging was provided in Chapter 2. Part 1 of this thesis focused on the reproducibility and clinical validity of T1 mapping and proton magnetic resonance spectroscopy (1H-MRS) in renal imaging. Part 2, described different studies evaluating the association between obesity and reno-cardiovascular function which was analyzed in population-based imaging studies using different quantitative MRI metrics. Part 3, provides an overview of the safety profile of gadolinium containing contrast agents, and reflection on the recent EMA recommendations. Hart Onderzoek Nederland, HartstichtingLUMC / Geneeskund

Cardiorenal syndrome: emerging role of medical imaging for clinical diagnosis and management

Cardiorenal syndrome (CRS) concerns the interconnection between heart and kidneys in which the dysfunction of one organ leads to abnormalities of the other. The main clinical challenges associated with cardiorenal syndrome are the lack of tools for early diagnosis, prognosis, and evaluation of therapeutic effects. Ultrasound, computed tomography, nuclear medicine, and magnetic resonance imaging are increasingly used for clinical management of cardiovascular and renal diseases. In the last decade, rapid development of imaging techniques provides a number of promising biomarkers for functional evaluation and tissue characterization. This review summarizes the applicability as well as the future technological potential of each imaging modality in the assessment of CRS. Furthermore, opportunities for a comprehensive imaging approach for the evaluation of CRS are defined.Cardiovascular Aspects of Radiolog

The impact of visceral and general obesity on vascular and left ventricutar function and geometry: a cross-sectional magnetic resonance imaging study of the UK Biobank

Aims We aimed to evaluate the associations of body fat distribution with cardiovascular function and geometry in the middle-aged general population.Methods and results Four thousand five hundred and ninety participants of the UK Biobank (54% female, mean age 61.1 +/- 7.2 years) underwent cardiac magnetic resonance for assessment of left ventricular (LV) parameters [end-diastolic volume (EDV), ejection fraction (EF), cardiac output (CO), and index (CI)] and magnetic resonance imaging for body composition analysis [subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT)]. Body fat percentage (BF%) was assessed by bioetectrical impedance. Linear regressions were performed to assess the impact of visceral (VAT) and general (SAT and BF%) obesity on cardiac function and geometry. Visceral obesity was associated with a smaller EDV [VAT: beta -1.74 (-1.15 to -2.33)1, lower EF NAT: beta -0.24 (-0.12 to -0.35), SAT: beta 0.02 (-0.04 to 0.08), and BF%: beta 0.02 (-0.02 to 0.06)] and the strongest negative association with CI [VAT: beta -0.05 (-0.06 to -0.04), SAT: beta -0.02 (-0.03 to -0.01), and BF% beta -0.01 (-0.013 to -0.007)]. In contrast, general obesity was associated with a larger EDV [SAT: beta 1.01 (0.72-1.30), BF%: beta 0.37 (0.23-0.51)] and a higher CO [SAT: beta 0.06 (0.05-0.07), BF%: beta 0.02 (0.01-0.03)]. In the gender-specific analysis, only men had a significant association between VAT and EF [beta -0.35 (-0.19 to -0.51)].Conclusions Visceral obesity was associated with a smaller LV EDV and subclinical lower LV systolic function in men, suggesting that visceral obesity might play a more important role compared to general obesity in LV remodelling.Cardiolog

Associations between left ventricular function, vascular function and measures of cerebral small vessel disease: a cross-sectional magnetic resonance imaging study of the UK Biobank

Cardiolog

The effect of glycemic control on renal triglyceride content assessed by proton spectroscopy in patients with type 2 diabetes mellitus: a single-center parallel-group trial

Objective: Ectopic lipid accumulation in the kidney (fatty kidney) is a potential driver of diabetic kidney disease, and tight glycemic control can reduce risk of diabetic nephropathy. We assessed whether glycemic control influences renal triglyceride content (RTGC). Furthermore, we compared glucagon-like peptide-1 receptor agonist liraglutide versus standard glucose-lowering therapy. Design andMethods: In this single-center parallel-group trial, patients with type 2 diabetes mellitus were randomized to liraglutide or placebo added to standard care (metformin/sulfonylurea derivative/insulin). Changes in RTGC after 26 weeks of glycemic control measured by proton spectroscopy and difference in RTGC between treatment groups were analyzed.Results: Fifty patients with type 2 diabetes mellitus were included in the baseline analysis (mean age, 56.5 +/- 9.1 years; range, 33-73 years; 46% males). Seventeen patients had baseline and follow-up measurements. Mean glycated hemoglobin was 7.8 +/- 0.8%, which changed to 7.3 +/- 0.9% after 26 weeks of glycemic control irrespective of treatment group (P = .046). Log-transformed RTGC was -0.68 +/- 0.30% and changed to -0.83 +/- 0.32% after 26 weeks of glycemic control irrespective of treatment group (P = .049). A 26-week-to-baseline RTGC ratio (95% confidence interval) was significantly different between liraglutide (-0.30 [-0.50, -0.09]) and placebo added to standard care (-0.003 [-0.34, 0.34]) (P = .04).Conclusion: In this exploratory study, we found that 26 weeks of glycemic control resulted in lower RTGC, in particular for liraglutide; however, larger clinical studies are needed to assess whether these changes reflect a true effect of glycemic control on fatty kidney. (C) 2020 The Authors. Published by Elsevier Inc. on behalf of the National Kidney Foundation, Inc.Cardiovascular Aspects of Radiolog

Normal and reference values for cardiovascular magnetic resonance-based pulse wave velocity in the middle-aged general population

Background Aortic stiffness, assessed through pulse wave velocity (PWV), is an independent predictor for cardiovascular disease risk. However, the scarce availability of normal and reference values for cardiovascular magnetic resonance imaging (CMR) based PWV is limiting clinical implementation. The aim of this study was to determine normal and reference values for CMR assessed PWV in the general population. Methods From the 2,484 participants of the Netherlands Epidemiology of Obesity (NEO) study that have available CMR-PWV data, 1,394 participants free from cardiovasculard disease, smokers or treatment for diabetes, hypertension or dyslipidaemia were selected (45-65 years, 51% female). Participants were divided into sex, age and blood pressure (BP) subgroups. Normal values were specified for participants with a BP = 130/80 and = 140/90 mmHg). Differences between groups were tested with independent samples t-test or ANOVA. Due to an oversampling of obese individuals in this study, PWV values are based on a weighted analysis making them representative of the general population. Results Normal mean PWV was 6.0 m/s [95% CI 5.8-6.1]. PWV increased with advancing age and BP categories (both p 140/90 mmHg women had a higher PWV (p = 0.005). The interpercentile ranges were smaller for participants = 55 years, indicating an increasing variability of PWV with age. PWV upper limits were particularly elevated in participants >= 55 years old in the high blood pressure subgroups. Conclusion This study provides normal and reference values for CMR-assessed PWV per sex, age and blood pressure category in the general population.Clinical epidemiolog

Estimated pulse wave velocity (ePWV) as a potential gatekeeper for MRI-assessed PWV: a linear and deep neural network based approach in 2254 participants of the Netherlands Epidemiology of Obesity study

Pulse wave velocity (PWV) assessed by magnetic resonance imaging (MRI) is a prognostic marker for cardiovascular events. Prediction modelling could enable indirect PWV assessment based on clinical and anthropometric data. The aim was to calculate estimated-PWV (ePWV) based on clinical and anthropometric measures using linear ridge regression as well as a Deep Neural Network (DNN) and to determine the cut-off which provides optimal discriminative performance between lower and higher PWV values. In total 2254 participants from the Netherlands Epidemiology of Obesity study were included (age 45-65 years, 51% male). Both a basic and expanded prediction model were developed. PWV was estimated using linear ridge regression and DNN. External validation was performed in 114 participants (age 30-70 years, 54% female). Performance was compared between models and estimation accuracy was evaluated by ROC-curves. A cut-off for optimal discriminative performance was determined using Youden's index. The basic ridge regression model provided an adjusted R-2 of 0.33 and bias of < 0.001, the expanded model did not add predictive performance. Basic and expanded DNN models showed similar model performance. Optimal discriminative performance was found for PWV < 6.7 m/s. In external validation expanded ridge regression provided the best performance of the four models (adjusted R-2: 0.29). All models showed good discriminative performance for PWV < 6.7 m/s (AUC range 0.81-0.89). ePWV showed good discriminative performance with regard to differentiating individuals with lower PWV values (< 6.7 m/s) from those with higher values, and could function as gatekeeper in selecting patients who benefit from further MRI-based PWV assessment.Clinical epidemiolog

Consensus‐based technical recommendations for clinical translation of renal phase contrast MRI

Background Phase‐contrast (PC) MRI is a feasible and valid noninvasive technique to measure renal artery blood flow, showing potential to support diagnosis and monitoring of renal diseases. However, the variability in measured renal blood flow values across studies is large, most likely due to differences in PC‐MRI acquisition and processing. Standardized acquisition and processing protocols are therefore needed to minimize this variability and maximize the potential of renal PC‐MRI as a clinically useful tool. Purpose To build technical recommendations for the acquisition, processing, and analysis of renal 2D PC‐MRI data in human subjects to promote standardization of renal blood flow measurements and facilitate the comparability of results across scanners and in multicenter clinical studies. Study Type Systematic consensus process using a modified Delphi method. Population Not applicable. Sequence Field/Strength Renal fast gradient echo‐based 2D PC‐MRI. Assessment An international panel of 27 experts from Europe, the USA, Australia, and Japan with 6 (interquartile range 4–10) years of experience in 2D PC‐MRI formulated consensus statements on renal 2D PC‐MRI in two rounds of surveys. Starting from a recently published systematic review article, literature‐based and data‐driven statements regarding patient preparation, hardware, acquisition protocol, analysis steps, and data reporting were formulated. Statistical Tests Consensus was defined as ≥75% unanimity in response, and a clear preference was defined as 60–74% agreement among the experts. Results Among 60 statements, 57 (95%) achieved consensus after the second‐round survey, while the remaining three showed a clear preference. Consensus statements resulted in specific recommendations for subject preparation, 2D renal PC‐MRI data acquisition, processing, and reporting. Data Conclusion These recommendations might promote a widespread adoption of renal PC‐MRI, and may help foster the set‐up of multicenter studies aimed at defining reference values and building larger and more definitive evidence, and will facilitate clinical translation of PC‐MRI. Level of Evidence 1 Technical Efficacy Stage