| 1. |
- Brundin, Martin, et al.
(author)
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Circulating microRNA-29-5p can add to the discrimination between dilated cardiomyopathy and ischaemic heart disease
- 2021
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In: ESC Heart Failure. - : John Wiley & Sons. - 2055-5822. ; 8:5, s. 3865-3874
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Journal article (peer-reviewed)abstract
- Aims: Heart failure describes a large and heterogeneous spectrum of underlying cardiac diseases. MicroRNAs (miRs) are small non-coding RNAs that in recent years have been shown to play an important role in the pathogenesis of heart failure. Cardiac magnetic resonance imaging is a powerful imaging modality for the evaluation of cardiac characteristics in heart failure. In this study, we sought to compare heart failure patients with a diagnosis of either idiopathic dilated cardiomyopathy (DCM) or ischaemic heart disease (IHD), in the context of serum levels of certain miRs and also magnetic resonance imaging parameters of cardiac structure and function.Methods and results: A total of 135 subjects were studied: 53 patients with DCM (age: 59 +/- 12 years, mean +/- SD), 34 patients with IHD (66 +/- 9 years), and 48 controls (64 +/- 5 years). The participants underwent baseline medical examination, blood sampling, and a cardiac magnetic resonance imaging examination at 3 Tesla (Philips Ingenia). The serum levels of seven different miRs were analysed and assessed: 16-5p, 21-5p, 29-5p, 133a-3p, 191-5p, 320a, and 423-5p, all of which have been demonstrated to play potential roles in the pathogenesis of heart failure. The patients in the DCM and IHD groups had left ventricles that had larger end-diastolic volume (P < 0.001), larger mass ( P < 0.001), and lower ejection fraction (P < 0.001) compared with controls. Serum levels of miR-29-5p were increased in DCM compared with IHD (P < 0.005) and serum levels of miR-320a were elevated in DCM compared with healthy controls ( P < 0.05). There was no significant association between miR levels and magnetic resonance imaging parameters of left ventricular structure and function.Conclusions: Circulating miR-320a can add to the discrimination between patients with DCM and healthy controls and circulating miR-29-5p can add to the discrimination between DCM and IHD.
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| 2. |
- Carlén, Anna, et al.
(author)
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Systolic Blood Pressure Response to Exercise in Endurance Athletes in Relation to Oxygen Uptake, Work Rate and Normative Values
- 2022
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In: Journal of cardiovascular development and disease. - : MDPI AG. - 2308-3425. ; 9:7
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Journal article (peer-reviewed)abstract
- Work rate has a direct impact on the systolic blood pressure (SBP) during aerobic exercise, which may be challenging in the evaluation of the SBP response in athletes reaching high work rates. We aimed to investigate the exercise SBP response in endurance athletes in relation to oxygen uptake (VO2), work rate and to recent reference equations for exercise SBP in the general population. Endurance athletes with a left-ventricular end-diastolic diameter above the reference one performed a maximal bicycle cardiopulmonary exercise test. The increase in SBP during exercise was divided by the increase in VO2 (SBP/VO2 slope) and in Watts, respectively (SBP/W slope). The maximum SBP (SBPmax) and the SBP/W slope were compared to the predicted values. In total, 27 athletes (59% men) were included; mean age, 40 ± 10 years; mean VO2max, 50 ± 5 mL/kg/min. The mean SBP/VO2 slope was 29.8 ± 10.2 mm Hg/L/min, and the mean SBP/W slope was 0.27 ± 0.08 mm Hg/W. Compared to the predicted normative values, athletes had, on average, a 12.2 ± 17.6 mm Hg higher SBPmax and a 0.12 ± 0.08 mm Hg/W less steep SBP/W slope (p < 0.01 and p < 0.001, respectively). In conclusion, the higher SBPmax values and the less steep SBP/W slope highlight the importance of considering work rate when interpreting the SBP response in endurance athletes and suggest a need for specific normative values in athletes to help clinicians distinguish physiologically high maximal blood pressure from a pathological blood pressure response.
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| 3. |
- Ekblom Bak, Elin, 1981-, et al.
(author)
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Accelerometer derived physical activity and subclinical coronary and carotid atherosclerosis : cross-sectional analyses in 22 703 middle-aged men and women in the SCAPIS study
- 2023
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In: BMJ Open. - : BMJ Publishing Group Ltd. - 2044-6055. ; 13:11
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Journal article (peer-reviewed)abstract
- OBJECTIVES: The aim included investigation of the associations between sedentary (SED), low-intensity physical activity (LIPA), moderate-to-vigorous intensity PA (MVPA) and the prevalence of subclinical atherosclerosis in both coronaries and carotids and the estimated difference in prevalence by theoretical reallocation of time in different PA behaviours.DESIGN: Cross-sectional.SETTING: Multisite study at university hospitals.PARTICIPANTS: A total of 22 670 participants without cardiovascular disease (51% women, 57.4 years, SD 4.3) from the population-based Swedish CArdioPulmonary bioImage study were included. SED, LIPA and MVPA were assessed by hip-worn accelerometer.PRIMARY AND SECONDARY OUTCOMES: Any and significant subclinical coronary atherosclerosis (CA), Coronary Artery Calcium Score (CACS) and carotid atherosclerosis (CarA) were derived from imaging data from coronary CT angiography and carotid ultrasound.RESULTS: High daily SED (>70% ≈10.5 hours/day) associated with a higher OR 1.44 (95% CI 1.09 to 1.91), for significant CA, and with lower OR 0.77 (95% CI 0.63 to 0.95), for significant CarA. High LIPA (>55% ≈8 hours/day) associated with lower OR for significant CA 0.70 (95% CI 0.51 to 0.96), and CACS, 0.71 (95% CI 0.51 to 0.97), but with higher OR for CarA 1.41 (95% CI 1.12 to 1.76). MVPA above reference level, >2% ≈20 min/day, associated with lower OR for significant CA (OR range 0.61-0.67), CACS (OR range 0.71-0.75) and CarA (OR range 0.72-0.79). Theoretical replacement of 30 min of SED into an equal amount of MVPA associated with lower OR for significant CA, especially in participants with high SED 0.84 (95% CI 0.76 to 0.96) or low MVPA 0.51 (0.36 to 0.73).CONCLUSIONS: MVPA was associated with a lower risk for significant atherosclerosis in both coronaries and carotids, while the association varied in strength and direction for SED and LIPA, respectively. If causal, clinical implications include avoiding high levels of daily SED and low levels of MVPA to reduce the risk of developing significant subclinical atherosclerosis.
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| 4. |
- Ekström, Magnus, et al.
(author)
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Exertional breathlessness related to medical conditions in middle-aged people: the population-based SCAPIS study of more than 25,000 men and women.
- 2024
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In: Respiratory research. - : BioMed Central (BMC). - 1465-993X .- 1465-9921. ; 25:1
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Journal article (peer-reviewed)abstract
- Breathlessness is common in the population and can be related to a range of medical conditions. We aimed to evaluate the burden of breathlessness related to different medical conditions in a middle-aged population.Cross-sectional analysis of the population-based Swedish CArdioPulmonary bioImage Study of adults aged 50-64years. Breathlessness (modified Medical Research Council [mMRC]≥2) was evaluated in relation to self-reported symptoms, stress, depression; physician-diagnosed conditions; measured body mass index (BMI), spirometry, venous haemoglobin concentration, coronary artery calcification and stenosis [computer tomography (CT) angiography], and pulmonary emphysema (high-resolution CT). For each condition, the prevalence and breathlessness population attributable fraction (PAF) were calculated, overall and by sex, smoking history, and presence/absence of self-reported cardiorespiratory disease.We included 25,948 people aged 57.5±[SD] 4.4; 51% women; 37% former and 12% current smokers; 43% overweight (BMI 25.0-29.9), 21% obese (BMI≥30); 25% with respiratory disease, 14% depression, 9% cardiac disease, and 3% anemia. Breathlessness was present in 3.7%. Medical conditions most strongly related to the breathlessness prevalence were (PAF 95%CI): overweight and obesity (59.6-66.0%), stress (31.6-76.8%), respiratory disease (20.1-37.1%), depression (17.1-26.6%), cardiac disease (6.3-12.7%), anemia (0.8-3.3%), and peripheral arterial disease (0.3-0.8%). Stress was the main factor in women and current smokers.Breathlessness mainly relates to overweight/obesity and stress and to a lesser extent to comorbidities like respiratory, depressive, and cardiac disorders among middle-aged people in a high-income setting-supporting the importance of lifestyle interventions to reduce the burden of breathlessness in the population.
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| 5. |
- Ashkir, Zakariye, et al.
(author)
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Four-dimensional flow cardiac magnetic resonance assessment of left ventricular diastolic function
- 2022
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In: Frontiers in Cardiovascular Medicine. - : FRONTIERS MEDIA SA. - 2297-055X. ; 9
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Research review (peer-reviewed)abstract
- Left ventricular diastolic dysfunction is a major cause of heart failure and carries a poor prognosis. Assessment of left ventricular diastolic function however remains challenging for both echocardiography and conventional phase contrast cardiac magnetic resonance. Amongst other limitations, both are restricted to measuring velocity in a single direction or plane, thereby compromising their ability to capture complex diastolic hemodynamics in health and disease. Time-resolved three-dimensional phase contrast cardiac magnetic resonance imaging with three-directional velocity encoding known as 4D flow CMR is an emerging technology which allows retrospective measurement of velocity and by extension flow at any point in the acquired 3D data volume. With 4D flow CMR, complex aspects of blood flow and ventricular function can be studied throughout the cardiac cycle. 4D flow CMR can facilitate the visualization of functional blood flow components and flow vortices as well as the quantification of novel hemodynamic and functional parameters such as kinetic energy, relative pressure, energy loss and vorticity. In this review, we examine key concepts and novel markers of diastolic function obtained by flow pattern analysis using 4D flow CMR. We consolidate the existing evidence base to highlight the strengths and limitations of 4D flow CMR techniques in the surveillance and diagnosis of left ventricular diastolic dysfunction.
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| 6. |
- Ashkir, Z., et al.
(author)
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Novel insights into diminished cardiac reserve in non-obstructive hypertrophic cardiomyopathy from four-dimensional flow cardiac magnetic resonance component analysis
- 2023
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In: European Heart Journal Cardiovascular Imaging. - : OXFORD UNIV PRESS. - 2047-2404 .- 2047-2412. ; 24:9, s. 1192-1200
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Journal article (peer-reviewed)abstract
- Aims Hypertrophic cardiomyopathy (HCM) is characterized by hypercontractility and diastolic dysfunction, which alter blood flow haemodynamics and are linked with increased risk of adverse clinical events. Four-dimensional flow cardiac magnetic resonance (4D-flow CMR) enables comprehensive characterization of ventricular blood flow patterns. We characterized flow component changes in non-obstructive HCM and assessed their relationship with phenotypic severity and sudden cardiac death (SCD) risk. Methods and results Fifty-one participants (37 non-obstructive HCM and 14 matched controls) underwent 4D-flow CMR. Left-ventricular (LV) end-diastolic volume was separated into four components: direct flow (blood transiting the ventricle within one cycle), retained inflow (blood entering the ventricle and retained for one cycle), delayed ejection flow (retained ventricular blood ejected during systole), and residual volume (ventricular blood retained for >two cycles). Flow component distribution and component end-diastolic kinetic energy/mL were estimated. HCM patients demonstrated greater direct flow proportions compared with controls (47.9 +/- 9% vs. 39.4 +/- 6%, P = 0.002), with reduction in other components. Direct flow proportions correlated with LV mass index (r = 0.40, P = 0.004), end-diastolic volume index (r = -0.40, P = 0.017), and SCD risk (r = 0.34, P = 0.039). In contrast to controls, in HCM, stroke volume decreased with increasing direct flow proportions, indicating diminished volumetric reserve. There was no difference in component end-diastolic kinetic energy/mL. Conclusion Non-obstructive HCM possesses a distinctive flow component distribution pattern characterised by greater direct flow proportions, and direct flow-stroke volume uncoupling indicative of diminished cardiac reserve. The correlation of direct flow proportion with phenotypic severity and SCD risk highlight its potential as a novel and sensitive haemodynamic measure of cardiovascular risk in HCM.
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| 7. |
- Bustamante, Mariana, et al.
(author)
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Automatic Time-Resolved Cardiovascular Segmentation of 4D Flow MRI Using Deep Learning
- 2023
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In: Journal of Magnetic Resonance Imaging. - Hoboken, NJ, United States : John Wiley & Sons. - 1053-1807 .- 1522-2586. ; 57:1, s. 191-203
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Journal article (peer-reviewed)abstract
- Background Segmenting the whole heart over the cardiac cycle in 4D flow MRI is a challenging and time-consuming process, as there is considerable motion and limited contrast between blood and tissue.Purpose To develop and evaluate a deep learning-based segmentation method to automatically segment the cardiac chambers and great thoracic vessels from 4D flow MRI. Study Type Retrospective.Subjects A total of 205 subjects, including 40 healthy volunteers and 165 patients with a variety of cardiac disorders were included. Data were randomly divided into training (n = 144), validation (n = 20), and testing (n = 41) sets.Field Strength/Sequence A 3 T/time-resolved velocity encoded 3D gradient echo sequence (4D flow MRI).Assessment A 3D neural network based on the U-net architecture was trained to segment the four cardiac chambers, aorta, and pulmonary artery. The segmentations generated were compared to manually corrected atlas-based segmentations. End-diastolic (ED) and end-systolic (ES) volumes of the four cardiac chambers were calculated for both segmentations.Statistical tests Dice score, Hausdorff distance, average surface distance, sensitivity, precision, and miss rate were used to measure segmentation accuracy. Bland-Altman analysis was used to evaluate agreement between volumetric parameters.Results The following evaluation metrics were computed: mean Dice score (0.908 +/- 0.023) (mean +/- SD), Hausdorff distance (1.253 +/- 0.293 mm), average surface distance (0.466 +/- 0.136 mm), sensitivity (0.907 +/- 0.032), precision (0.913 +/- 0.028), and miss rate (0.093 +/- 0.032). Bland-Altman analyses showed good agreement between volumetric parameters for all chambers. Limits of agreement as percentage of mean chamber volume (LoA%), left ventricular: 9.3%, 13.5%, left atrial: 12.4%, 16.9%, right ventricular: 9.9%, 15.6%, and right atrial: 18.7%, 14.4%; for ED and ES, respectively.Data conclusion The addition of this technique to the 4D flow MRI assessment pipeline could expedite and improve the utility of this type of acquisition in the clinical setting. Evidence Level 4Technical Efficacy Stage 1
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| 8. |
- Bustamante, Mariana, et al.
(author)
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Using Deep Learning to Emulate the Use of an External Contrast Agent in Cardiovascular 4D Flow MRI
- 2021
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In: Journal of Magnetic Resonance Imaging. - : Wiley. - 1053-1807 .- 1522-2586. ; 54:3, s. 777-786
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Journal article (peer-reviewed)abstract
- Background Although contrast agents would be beneficial, they are seldom used in four-dimensional (4D) flow magnetic resonance imaging (MRI) due to potential side effects and contraindications. Purpose To develop and evaluate a deep learning architecture to generate high blood-tissue contrast in noncontrast 4D flow MRI by emulating the use of an external contrast agent. Study Type Retrospective. Subjects Of 222 data sets, 141 were used for neural network (NN) training (69 with and 72 without contrast agent). Evaluation was performed on the remaining 81 noncontrast data sets. Field Strength/Sequences Gradient echo or echo-planar 4D flow MRI at 1.5 T and 3 T. Assessment A cyclic generative adversarial NN was trained to perform image translation between noncontrast and contrast data. Evaluation was performed quantitatively using contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR), structural similarity index (SSIM), mean squared error (MSE) of edges, and Dice coefficient of segmentations. Three observers performed a qualitative assessment of blood-tissue contrast, noise, presence of artifacts, and image structure visualization. Statistical Tests The Wilcoxon rank-sum test evaluated statistical significance. Kendalls concordance coefficient assessed interobserver agreement. Results Contrast in the regions of interest (ROIs) in the NN enhanced images increased by 88%, CNR increased by 63%, and SNR improved by 48% (all P < 0.001). The SSIM was 0.82 +/- 0.01, and the MSE of edges was 0.09 +/- 0.01 (range [0,1]). Segmentations based on the generated images resulted in a Dice similarity increase of 15.25%. The observers managed to differentiate between contrast MR images and our results; however, they preferred the NN enhanced images in 76.7% of cases. This percentage increased to 93.3% for phase-contrast MR angiograms created from the NN enhanced data. Visual grading scores were blood-tissue contrast = 4.30 +/- 0.74, noise = 3.12 +/- 0.98, and presence of artifacts = 3.63 +/- 0.76. Image structures within and without the ROIs resulted in scores of 3.42 +/- 0.59 and 3.07 +/- 0.71, respectively (P < 0.001). Data Conclusion The proposed approach improves blood-tissue contrast in MR images and could be used to improve data quality, visualization, and postprocessing of cardiovascular 4D flow data. Evidence Level 3 Technical Efficacy Stage 1
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| 9. |
- Bäck, Sophia, et al.
(author)
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Assessment of transmitral and left atrial appendage flow rate from cardiac 4D-CT
- 2023
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In: Communications Medicine. - : Springer Nature. - 2730-664X. ; 3:1
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Journal article (peer-reviewed)abstract
- Plain language summaryAssessing the blood flow inside the heart is important in diagnosis and treatment of various cardiovascular diseases, such as atrial fibrillation or heart failure. We developed a method to accurately track the motion of the heart walls over the course of a heartbeat in three-dimensional Computed Tomography (CT) images. Based on the motion, we calculated the amount of blood passing through the mitral valve and the left atrial appendage orifice, which are markers used in the diagnostic of heart failure and assessment of stroke risk in atrial fibrillation. The results agreed well with measurements from 4D flow MRI, an imaging technique that measures blood velocities. Our method could broaden the use of CT and make additional exams redundant. It can even be used to calculate the blood flow inside the heart. BackgroundCardiac time-resolved CT (4D-CT) acquisitions provide high quality anatomical images of the heart. However, some cardiac diseases require assessment of blood flow in the heart. Diastolic dysfunction, for instance, is diagnosed by measuring the flow through the mitral valve (MV), while in atrial fibrillation, the flow through the left atrial appendage (LAA) indicates the risk for thrombus formation. Accurate validated techniques to extract this information from 4D-CT have been lacking, however.MethodsTo measure the flow rate though the MV and the LAA from 4D-CT, we developed a motion tracking algorithm that performs a nonrigid deformation of the surface separating the blood pool from the myocardium. To improve the tracking of the LAA, this region was deformed separately from the left atrium and left ventricle. We compared the CT based flow with 4D flow and short axis MRI data from the same individual in 9 patients.ResultsFor the mitral valve flow, good agreement was found for the time span between the early and late diastolic peak flow (bias: <0.1 s). The ventricular stroke volume is similar compared to short-axis MRI (bias 3 ml). There are larger differences in the diastolic peak flow rates, with a larger bias for the early flow rate than the late flow rate. The peak LAA outflow rate measured with both modalities matches well (bias: -6 ml/s).ConclusionsOverall, the developed algorithm provides accurate tracking of dynamic cardiac geometries resulting in similar flow rates at the MV and LAA compared to 4D flow MRI. Back et al. describe a motion tracking algorithm to measure the flow rate through the mitral valve (MV) and the left atrial appendage (LAA) from 4D-CT data. The developed algorithm provided accurate tracking of dynamic cardiac geometries resulting in similar flow rates at the MV and LAA to those measured by 4D flow MRI.
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| 10. |
- Bäck, Sophia, et al.
(author)
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Comprehensive left atrial flow component analysis reveals abnormal flow patterns in paroxysmal atrial fibrillation
- 2024
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In: American Journal of Physiology. Heart and Circulatory Physiology. - : AMER PHYSIOLOGICAL SOC. - 0363-6135 .- 1522-1539. ; 326:3, s. H511-H521
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Journal article (peer-reviewed)abstract
- Left atrial (LA) blood flow plays an important role in diseases such as atrial fibrillation (AF) and atrial cardiomyopathy since alterations in the blood flow might lead to thrombus formation and stroke. Using traditional techniques, such as echocardiography, atrial flow velocities can be measured at the pulmonary veins and the mitral valve, but a comprehensive understanding of the three-dimensional atrial flow field is missing. Previously, ventricular flow has been analyzed using flow component analysis, revealing new insights into ventricular flow and function. Thus, the aim of this project was to develop a comprehensive flow component analysis method for the LA and explore its utility in 21 patients with paroxysmal atrial fibrillation compared with a control group of 8 participants. The flow field was derived from time-resolved CT acquired during sinus rhythm using computational fluid dynamics. Flow components were computed from particle tracking. We identified six atrial flow components: conduit, reservoir, delayed ejection, retained inflow, residual volume, and pulmonary vein backflow. It was shown that conduit flow, defined as blood entering and leaving the LA within the same diastolic phase, exists in most subjects. Although the volume of conduit and reservoir is similar in patients with paroxysmal AF in sinus rhythm and controls, the volume of the other components is increased in paroxysmal AF. Comprehensive quantification of LA flow using flow component analysis makes atrial blood flow quantifiable, thus facilitating investigation of mechanisms underlying atrial dysfunction and can increase understanding of atrial blood flow in disease progression and stroke risk. NEW & NOTEWORTHY We developed a new comprehensive approach to atrial blood component analysis that includes both conduit flow and residual volume and compared the flow components of atrial fibrillation (AF) patients in sinus rhythm with controls. Conduit and reservoir flow were similar between the groups, whereas components with longer residence time in the left atrium were increased in the AF group. This could add to the pathophysiological understanding of atrial diseases and possibly clinical management.
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| 11. |
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| 12. |
- Bäck, Sophia, et al.
(author)
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Elevated atrial blood stasis in paroxysmal atrial fibrillation during sinus rhythm: a patient-specific computational fluid dynamics study
- 2023
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In: Frontiers in Cardiovascular Medicine. - : FRONTIERS MEDIA SA. - 2297-055X. ; 10
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Journal article (peer-reviewed)abstract
- Introduction: Atrial fibrillation (AF) is associated with an increased risk of stroke, often caused by thrombi that form in the left atrium (LA), and especially in the left atrial appendage (LAA). The underlying mechanism is not fully understood but is thought to be related to stagnant blood flow, which might be present despite sinus rhythm. However, measuring blood flow and stasis in the LAA is challenging due to its small size and low velocities. We aimed to compare the blood flow and stasis in the left atrium of paroxysmal AF patients with controls using computational fluid dynamics (CFD) simulations.Methods : The CFD simulations were based on time-resolved computed tomography including the patient-specific cardiac motion. The pipeline allowed for analysis of 21 patients with paroxysmal AF and 8 controls. Stasis was estimated by computing the blood residence time.Results and Discussion: Residence time was elevated in the AF group (p < 0.001). Linear regression analysis revealed that stasis was strongest associated with LA ejection ratio (p < 0.001, R-2 = 0.68) and the ratio of LA volume and left ventricular stroke volume (p < 0.001, R-2 = 0.81). Stroke risk due to LA thrombi could already be elevated in AF patients during sinus rhythm. In the future, patient specific CFD simulations may add to the assessment of this risk and support diagnosis and treatment.
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| 13. |
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| 14. |
- Feng, Fan, et al.
(author)
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FM-Net: A Fully Automatic Deep Learning Pipeline for Epicardial Adipose Tissue Segmentation
- 2024
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In: STATISTICAL ATLASES AND COMPUTATIONAL MODELS OF THE HEART. REGULAR AND CMRXRECON CHALLENGE PAPERS, STACOM 2023. - : SPRINGER INTERNATIONAL PUBLISHING AG. - 9783031524479 - 9783031524486 ; , s. 88-97
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Conference paper (peer-reviewed)abstract
- Epicardial adipose tissue (EAT) has been recognized as a risk factor and independent predictor for cardiovascular diseases (CVDs), due to its intimate relationship with the myocardium and coronary arteries. Dixon MRI is widely used to depict adipose tissue by deriving fat and water signals. The purpose of this study was to automatically segment and quantify EAT from Dixon MRI data using a fully automated deep learning pipeline based on fat maps (FM-Net). Data used in this study was from a sub-study (HEALTH) of the Swedish CArdioPulmonarybiolmage Study (SCAPIS), with 6504 Dixon MRI 2D images from 90 participants (45 each for type 2 diabetes and controls). FM-Net was comprised of a double Res-UNet CNN architecture, designed to compensate for the severe class imbalance and complex geometry of EAT. The first network accurately detected the region of interest (ROI) containing fat, and the second network performed targeted regional segmentation of the ROI. Performance of fat segmentation was improved by using fatmaps as input of FM-Net, to enhance fat features by combining out-of-phase, water, and fat phase images. Performance was evaluated using dice similarity coefficient (DSC) and 95% Hausdorff distance (HD95). Overall, FM-Net obtained a promising DSC of 86.3%, and a low HD95 of 3.11 mm, outperforming existing state-of-the-art methods. The proposed method enables automatic and accurate quantification of EAT from Dixon MRI data, which could enhance the understanding of the role of EAT in CVDs.
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| 15. |
- Firouznia, Marjan, et al.
(author)
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FK-means: automatic atrial fibrosis segmentation using fractal-guided K-means clustering with Voronoi-clipping feature extraction of anatomical structures
- 2023
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In: Interface Focus. - : ROYAL SOC. - 2042-8898 .- 2042-8901. ; 13:6
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Journal article (peer-reviewed)abstract
- Assessment of left atrial (LA) fibrosis from late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) adds to the management of patients with atrial fibrillation. However, accurate assessment of fibrosis in the LA wall remains challenging. Excluding anatomical structures in the LA proximity using clipping techniques can reduce misclassification of LA fibrosis. A novel FK-means approach for combined automatic clipping and automatic fibrosis segmentation was developed. This approach combines a feature-based Voronoi diagram with a hierarchical 3D K-means fractal-based method. The proposed automatic Voronoi clipping method was applied on LGE-MRI data and achieved a Dice score of 0.75, similar to the score obtained by a deep learning method (3D UNet) for clipping (0.74). The automatic fibrosis segmentation method, which uses the Voronoi clipping method, achieved a Dice score of 0.76. This outperformed a 3D UNet method for clipping and fibrosis classification, which had a Dice score of 0.69. Moreover, the proposed automatic fibrosis segmentation method achieved a Dice score of 0.90, using manual clipping of anatomical structures. The findings suggest that the automatic FK-means analysis approach enables reliable LA fibrosis segmentation and that clipping of anatomical structures in the atrial proximity can add to the assessment of atrial fibrosis.
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| 16. |
- Garg, Pankaj, et al.
(author)
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Assessment of mitral valve regurgitation by cardiovascular magnetic resonance imaging
- 2020
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In: Nature Reviews Cardiology. - : Nature Publishing Group. - 1759-5002 .- 1759-5010. ; 17:5, s. 298-312
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Journal article (peer-reviewed)abstract
- Mitral regurgitation (MR) is a common valvular heart disease and is the second most frequent indication for heart valve surgery in Western countries. Echocardiography is the recommended first-line test for the assessment of valvular heart disease, but cardiovascular magnetic resonance imaging (CMR) provides complementary information, especially for assessing MR severity and to plan the timing of intervention. As new CMR techniques for the assessment of MR have arisen, standardizing CMR protocols for research and clinical studies has become important in order to optimize diagnostic utility and support the wider use of CMR for the clinical assessment of MR. In this Consensus Statement, we provide a detailed description of the current evidence on the use of CMR for MR assessment, highlight its current clinical utility, and recommend a standardized CMR protocol and report for MR assessment.
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| 17. |
- Henningsson, Markus, et al.
(author)
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Inflow artifact reduction using an adaptive flip-angle navigator restore pulse for late gadolinium enhancement of the left atrium
- 2020
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In: Magnetic Resonance in Medicine. - : WILEY. - 0740-3194 .- 1522-2594. ; 84:6, s. 3308-3315
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Journal article (peer-reviewed)abstract
- Purpose Late gadolinium enhancement (LGE) of the left atrium is susceptible to artifacts arising from the right pulmonary veins, caused by inflowing blood tagged by the navigator restore pulse. The purpose of this study was to evaluate a new method to reduce the inflow artifact using an adaptive flip-angle restore pulse. Methods A low-restore angle reduces the inflow artifact but may lead to a poor navigator SNR. The proposed approach aims to determine the patient-specific restore angle, which optimizes the trade-off between inflow artifacts and navigator SNR. Three-dimensional LGE with adaptive navigator restore (3D LGE(A)) was implemented by incrementing the flip angle of the restore pulse from a starting value of 0 degrees, based on the navigator normalized cross-correlation. Magnetic resonance imaging experiments were performed on a 1.5T scanner. The value of 3D LGE(A) was compared with 3D LGE with a constant 180 degrees restore pulse (3D LGE(180)) in 22 patients with heart diseases. The values of 3D LGE(A) and 3D LGE(180) were compared in terms of pulmonary vein blood signal relative to reference blood in the descending aorta (PVrel) and visual scoring to determine level of motion artifacts using a 4-point scale (1 = severe artifacts; 4 = no artifacts). Results The value of PVrel was significantly lower for 3D LGE(A) than for 3D LGE(180) (1.16 +/- 0.23 vs. 1.59 +/- 0.29, P < .001). Furthermore, visual scoring of the motion artifacts yielded no difference (P = .78). Conclusion Adaptively adjusting the navigator restore flip angle based on the navigator normalized cross-correlation reduces the 3D LGE inflow artifact without affecting image quality or the scan time.
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| 18. |
- Henningsson, Markus, et al.
(author)
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Myocardial arterial spin labeling in systole and diastole using flow-sensitive alternating inversion recovery with parallel imaging and compressed sensing
- 2021
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In: NMR in Biomedicine. - : WILEY. - 0952-3480 .- 1099-1492. ; 34:2
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Journal article (peer-reviewed)abstract
- Quantitative myocardial perfusion can be achieved without contrast agents using flow-sensitive alternating inversion recovery (FAIR) arterial spin labeling. However, FAIR has an intrinsically low sensitivity, which may be improved by mitigating the effects of physiological noise or by increasing the area of artifact-free myocardium. The aim of this study was to investigate if systolic FAIR may increase the amount of analyzable myocardium compared with diastolic FAIR and its effect on physiological noise. Furthermore, we compare parallel imaging acceleration with a factor of 2 with compressed sensing acceleration with a factor of 3 for systolic FAIR. Twelve healthy subjects were scanned during rest on a 3 T scanner using diastolic FAIR with parallel imaging factor 2 (FAIR-PI2(D)), systolic FAIR with the same acceleration (FAIR-PI2(S)) and systolic FAIR with compressed sensing factor 3 (FAIR-CS3(S)). The number of analyzable pixels in the myocardium, temporal signal-to-noise ratio (TSNR) and mean myocardial blood flow (MBF) were calculated for all methods. The number of analyzable pixels using FAIR-CS3(S) (663 +/- 55) and FAIR-PI2(S) (671 +/- 58) was significantly higher than for FAIR-PI2(D) (507 +/- 82; P = .001 for both), while there was no significant difference between FAIR-PI2(S) and FAIR-CS3(S). The mean TSNR of the midventricular slice for FAIR-PI2(D) was 11.4 +/- 3.9, similar to that of FAIR-CS3(S,) which was 11.0 +/- 3.3, both considerably higher than for FAIR-PI2(S,) which was 8.4 +/- 3.1 (P < .05 for both). Mean MBF was similar for all three methods. The use of compressed sensing accelerated systolic FAIR benefits from an increased number of analyzable myocardial pixels compared with diastolic FAIR without suffering from a TSNR penalty, unlike systolic FAIR with parallel imaging acceleration.
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| 19. |
- Henningsson, Markus, et al.
(author)
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Non-contrast myocardial perfusion in rest and exercise stress using systolic flow-sensitive alternating inversion recovery
- 2022
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In: Magnetic Resonance Materials in Physics, Biology and Medicine. - : Springer. - 0968-5243 .- 1352-8661. ; 35:5, s. 711-718
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Journal article (peer-reviewed)abstract
- Objective To evaluate systolic flow-sensitive alternating inversion recovery (FAIR) during rest and exercise stress using 2RR (two cardiac cycles) or 1RR intervals between inversion pulse and imaging. Materials and methods 1RR and 2RR FAIR was implemented on a 3T scanner. Ten healthy subjects were scanned during rest and stress. Stress was performed using an in-bore ergometer. Heart rate, mean myocardial blood flow (MBF) and temporal signal-to-noise ratio (TSNR) were compared using paired t tests. Results Mean heart rate during stress was higher than rest for 1RR FAIR (85.8 +/- 13.7 bpm vs 63.3 +/- 11.1 bpm; p < 0.01) and 2RR FAIR (83.8 +/- 14.2 bpm vs 63.1 +/- 10.6 bpm; p < 0.01). Mean stress MBF was higher than rest for 1RR FAIR (2.97 +/- 0.76 ml/g/min vs 1.43 +/- 0.6 ml/g/min; p < 0.01) and 2RR FAIR (2.8 +/- 0.96 ml/g/min vs 1.22 +/- 0.59 ml/g/min; p < 0.01). Resting mean MBF was higher for 1RR FAIR than 2RR FAIR (p < 0.05), but not during stress. TSNR was lower for stress compared to rest for 1RR FAIR (4.52 +/- 2.54 vs 10.12 +/- 3.69; p < 0.01) and 2RR FAIR (7.36 +/- 3.78 vs 12.41 +/- 5.12; p < 0.01). 2RR FAIR TSNR was higher than 1RR FAIR for rest (p < 0.05) and stress (p < 0.001). Discussion We have demonstrated feasibility of systolic FAIR in rest and exercise stress. 2RR delay systolic FAIR enables non-contrast perfusion assessment during stress with relatively high TSNR.
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| 20. |
- Henningsson, Markus, et al.
(author)
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Quantification of epicardial fat using 3D cine Dixon MRI
- 2020
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In: BMC Medical Imaging. - : BMC. - 1471-2342. ; 20:1
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Journal article (peer-reviewed)abstract
- Background There is an increased interest in quantifying and characterizing epicardial fat which has been linked to various cardiovascular diseases such as coronary artery disease and atrial fibrillation. Recently, three-dimensional single-phase Dixon techniques have been used to depict the heart and to quantify the surrounding fat. The purpose of this study was to investigate the merits of a new high-resolution cine 3D Dixon technique for quantification of epicardial adipose tissue and compare it to single-phase 3D Dixon in patients with cardiovascular disease. Methods Fifteen patients referred for clinical CMR examination of known or suspected heart disease were scanned on a 1.5 T scanner using single-phase Dixon and cine Dixon. Epicardial fat was segmented by three readers and intra- and inter-observer variability was calculated per slice. Cine Dixon segmentation was performed in the same cardiac phase as single-phase Dixon. Subjective image quality assessment of water and fat images were performed by three readers using a 4-point Likert scale (1 = severe; 2 = significant; 3 = mild; 4 = no blurring of cardiac structures). Results Intra-observer variability was excellent for cine Dixon images (ICC = 0.96), and higher than single-phase Dixon (ICC = 0.92). Inter-observer variability was good for cine Dixon (ICC = 0.76) and moderate for single-phase Dixon (ICC = 0.63). The intra-observer measurement error (mean +/- standard deviation) per slice for cine was - 0.02 +/- 0.51 ml (- 0.08 +/- 0.4%), and for single-phase 0.39 +/- 0.72 ml (0.18 +/- 0.41%). Inter-observer measurement error for cine was 0.46 +/- 0.98 ml (0.11 +/- 0.46%) and for single-phase 0.42 +/- 1.53 ml (0.17 +/- 0.47%). Visual scoring of the water image yielded median of 2 (interquartile range = [Q3-Q1] 2-2) for cine and median of 3 (interquartile range = 3-2) for single-phase (P < 0.05) while no significant difference was found for the fat images, both techniques yielding a median of 3 and interquartile range of 3-2. Conclusion Cine Dixon can be used to quantify epicardial fat with lower intra- and inter-observer variability compared to standard single-phase Dixon. The time-resolved information provided by the cine acquisition appears to support the delineation of the epicardial adipose tissue depot.
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| 21. |
- Jarkman, Charlotta, et al.
(author)
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Clinical evaluation of the Multimapping technique for simultaneous myocardial T-1 and T-2 mapping
- 2022
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In: Frontiers in Cardiovascular Medicine. - : Frontiers Media SA. - 2297-055X. ; 9
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Journal article (peer-reviewed)abstract
- The Multimapping technique was recently proposed for simultaneous myocardial T-1 and T-2 mapping. In this study, we evaluate its correlation with clinical reference mapping techniques in patients with a range of cardiovascular diseases (CVDs) and compare image quality and inter- and intra-observer repeatability. Multimapping consists of an ECG-triggered, 2D single-shot bSSFP readout with inversion recovery and T-2 preparation modules, acquired across 10 cardiac cycles. The sequence was implemented at 1.5T and compared to clinical reference mapping techniques, modified Look-Locker inversion recovery (MOLLI) and T-2 prepared bSSFP with four echo times (T(2)bSSFP), and compared in 47 patients with CVD (of which 44 were analyzed). In diseased myocardial segments (defined as the presence of late gadolinium enhancement), there was a high correlation between Multimapping and MOLLI for native myocardium T-1 (r(2) = 0.73), ECV (r(2) = 0.91), and blood T-1 (r(2) = 0.88), and Multimapping and T(2)bSSFP for native myocardial T-2 (r(2) = 0.80). In healthy myocardial segments, a bias for native T-1 (Multimapping = 1,116 +/- 21 ms, MOLLI = 1,002 +/- 21, P < 0.001), post-contrast T-1 (Multimapping = 479 +/- 31 ms, MOLLI = 426 +/- 27 ms, 0.001), ECV (Multimapping = 21.5 +/- 1.9%, MOLLI = 23.7 +/- 2.3%, P = 0.001), and native T-2 (Multimapping = 48.0 +/- 3.0 ms, T(2)bSSFP = 53.9 +/- 3.5 ms, P < 0.001) was observed. The image quality for Multimapping was scored as higher for all mapping techniques (native T-1, post-contrast T-1, ECV, and T(2)bSSFP) compared to the clinical reference techniques. The inter- and intra-observer agreements were excellent (intraclass correlation coefficient, ICC > 0.9) for most measurements, except for inter-observer repeatability of Multimapping native T-1 (ICC = 0.87), post-contrast T-1 (ICC = 0.73), and T(2)bSSFP native T-2 (ICC = 0.88). Multimapping shows high correlations with clinical reference mapping techniques for T-1, T-2, and ECV in a diverse cohort of patients with different cardiovascular diseases. Multimapping enables simultaneous T-1 and T-2 mapping and can be performed in a short breath-hold, with image quality superior to that of the clinical reference techniques.
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| 22. |
- Krynska, Aleksandra, et al.
(author)
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Three-dimensional echocardiography to identify right ventricular dilatation in patients with corrected Fallot anomaly or pulmonary stenosis
- 2021
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In: Clinical Physiology and Functional Imaging. - : Wiley-Blackwell Publishing Inc.. - 1475-0961 .- 1475-097X. ; 41:1, s. 51-61
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Journal article (peer-reviewed)abstract
- Background 3-Dimensional Echocardiography allows measuring volumes and parameters of myocardial deformation (strain). Myocardial strain has been suggested to be superior to conventional echo parameters in the assessment of right ventricular (RV) function. Myocardial strain can be assessed by cardiac magnetic resonance (CMR) or two- and three-dimensional echocardiography (2D and 3DEcho). We performed a comprehensive assessment of the RV based on 3DEcho and compared the results with those based on CMR and 2DEcho. Methods 36 patients with corrected heart defects underwent CMR and 3DEcho to assess RV volume, strain and cardio pulmonary exercise testing with peak VO2 measurement. 2DEcho was used for reference. Results There was a moderate correlation between 3DEcho and CMR for measuring RV end-diastolic and end-systolic volumes (r = .82 and .72). 3DEcho tended to underestimate the RV volumes, mean difference EDV 8.5 +/- 33 ml (CI -2.8; 19.7 ml) and ESV 13.2 +/- 29 ml (CI 3.3; 23 ml). According to method-specific reference values for RVEDV, 34/35 (3DEcho) and 29/36 (CMR) were dilated. Among those dilated according to CMR, all were identified by 3DEcho. The coefficient of correlation between RV atrioventricular plane displacement measured by CMR and tricuspid annular plane systolic excursion measured by 3D and 2DEcho was r = .6 for both. 2DEcho measured lower LV volumes than CMR. LVEF and GLS were similar in 2DEcho, 3DEcho and CMR. Patients with CMR-determined RV free wall strain <= -14% tended to have lower peak VO2. Conclusions Although 3DEcho underestimated RV volumes, it successfully identified all patients with RV dilatation based on method-specific reference values.
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| 23. |
- Lantz, Jonas, 1982-, et al.
(author)
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Impact of prosthetic mitral valve orientation on the ventricular flow field : Comparison using patient-specific computational fluid dynamics
- 2021
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In: Journal of Biomechanics. - : Elsevier Science Ltd. - 0021-9290 .- 1873-2380. ; 116
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Journal article (peer-reviewed)abstract
- Significant mitral valve regurgitation creates progressive adverse remodeling of the left ventricle (LV). Replacement of the failing valve with a prosthesis generally improves patient outcomes but leaves the patient with non-physiological intracardiac flow patterns that might contribute to their future risk of thrombus formation and embolism. It has been suggested that the angular orientation of the implanted valve might modify the postoperative distortion of the intraventricular flow field. In this study, we investigated the effect of prosthetic valve orientation on LV flow patterns by using heart geometry from a patient with LV dysfunction and a competent native mitral valve to calculate intracardiac flow fields with computational fluid dynamics (CFD). Results were validated using in vivo 4D Flow MRI. The computed flow fields were compared to calculations following virtual implantation of a mechanical heart valve oriented in four different angles to assess the effect of leaflet position. Flow patterns were visualized in longand short-axes and quantified with flow component analysis. In comparison to a native valve, valve implantation increased the proportion of the mitral inflow remaining in the basal region and further increased the residual volume in the apical area. Only slight changes due to valve orientation were observed. Using our numerical framework, we demonstrated quantitative changes in left ventricular blood flow due to prosthetic mitral replacement. This framework may be used to improve design of prosthetic heart valves and implantation procedures to minimize the potential for apical flow stasis, and potentially assist personalized treatment planning. (c) 2020 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
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| 24. |
- Nasr, Patrik, et al.
(author)
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Evaluating the prevalence and severity of NAFLD in primary care: the EPSONIP study protocol
- 2021
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In: BMC Gastroenterology. - : BMC. - 1471-230X. ; 21:1
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Journal article (peer-reviewed)abstract
- BackgroundNon-alcoholic fatty liver disease (NAFLD) affects 20-30% of the general adult population. NAFLD patients with type 2 diabetes mellitus (T2DM) are at an increased risk of advanced fibrosis, which puts them at risk of cardiovascular complications, hepatocellular carcinoma, or liver failure. Liver biopsy is the gold standard for assessing hepatic fibrosis. However, its utility is inherently limited. Consequently, the prevalence and characteristics of T2DM patients with advanced fibrosis are unknown. Therefore, the purpose of the current study is to evaluate the prevalence and severity of NAFLD in patients with T2DM by recruiting participants from primary care, using the latest imaging modalities, to collect a cohort of well phenotyped patients.MethodsWe will prospectively recruit 400 patients with T2DM using biomarkers to assess their status. Specifically, we will evaluate liver fat content using magnetic resonance imaging (MRI); hepatic fibrosis using MR elastography and vibration-controlled transient elastography; muscle composition and body fat distribution using water-fat separated whole body MRI; and cardiac function, structure, and tissue characteristics, using cardiovascular MRI.DiscussionWe expect that the study will uncover potential mechanisms of advanced hepatic fibrosis in NAFLD and T2DM and equip the clinician with better diagnostic tools for the care of T2DM patients with NAFLD.Trial registration: Clinicaltrials.gov, identifier NCT03864510. Registered 6 March 2019, https://clinicaltrials.gov/ct2/show/NCT03864510.
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| 25. |
- Ohlsson, Linus, et al.
(author)
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Enhancing students understanding of cardiac physiology by using 4D visualization
- 2023
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In: Clinical anatomy (New York, N.Y. Print). - : WILEY. - 0897-3806 .- 1098-2353. ; 36:3, s. 542-549
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Journal article (peer-reviewed)abstract
- Difficulties in achieving knowledge about physiology and anatomy of the beating heart highlight the challenges with more traditional pedagogical methods. Recent research regarding anatomy education has mainly focused on digital three-dimensional models. However, these pedagogical improvements may not be entirely applicable to cardiac anatomy and physiology due to the multidimensional complexity with moving anatomy and complex blood flow. The aim of this study was therefore to evaluate whether high quality time-resolved anatomical images combined with realistic blood flow simulations improve the understanding of cardiac structures and function. Three time-resolved datasets were acquired using time-resolved computed tomography and blood flow was computed using Computational Fluid Dynamics. The anatomical and blood flow information was combined and interactively visualized using volume rendering on an advanced stereo projection system. The setup was tested in interactive lectures for medical students. Ninety-seven students participated. Summative assessment of examinations showed significantly improved mean score (18.1 +/- 4.5 vs 20.3 +/- 4.9, p = 0.002). This improvement was driven by knowledge regarding myocardial hypertrophy and pressure-velocity differences over a stenotic valve. Additionally, a supplementary formative assessment showed significantly more agreeing answers than disagreeing answers (p < 0.001) when the participants subjectively evaluated the contribution of the visualizations to their education and knowledge. In conclusion, the use of simultaneous visualization of time-resolved anatomy data and simulated blood flow improved medical students results, with a particular effect on understanding of cardiac physiology and these simulations may be useful educational tools for teaching complex anatomical and physiological concepts.
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| 26. |
- Riva, Alessandra, et al.
(author)
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Impact of dobutamine stress on diastolic energetic efficiency of healthy left ventricle: an in vivo kinetic energy analysis
- 2023
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In: Frontiers in Cardiovascular Medicine. - : FRONTIERS MEDIA SA. - 2297-055X. ; 10
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Journal article (peer-reviewed)abstract
- The total kinetic energy (KE) of blood can be decomposed into mean KE (MKE) and turbulent KE (TKE), which are associated with the phase-averaged fluid velocity field and the instantaneous velocity fluctuations, respectively. The aim of this study was to explore the effects of pharmacologically induced stress on MKE and TKE in the left ventricle (LV) in a cohort of healthy volunteers. 4D Flow MRI data were acquired in eleven subjects at rest and after dobutamine infusion, at a heart rate that was similar to 60% higher than the one in rest conditions. MKE and TKE were computed as volume integrals over the whole LV and as data mapped to functional LV flow components, i.e., direct flow, retained inflow, delayed ejection flow and residual volume. Diastolic MKE and TKE increased under stress, in particular at peak early filling and peak atrial contraction. Augmented LV inotropy and cardiac frequency also caused an increase in direct flow and retained inflow MKE and TKE. However, the TKE/KE ratio remained comparable between rest and stress conditions, suggesting that LV intracavitary fluid dynamics can adapt to stress conditions without altering the TKE to KE balance of the normal left ventricle at rest.
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| 27. |
- Skoda, Iulia, et al.
(author)
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Simultaneous Assessment of Left Atrial Fibrosis and Epicardial Adipose Tissue Using 3D Late Gadolinium Enhanced Dixon MRI
- 2022
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In: Journal of Magnetic Resonance Imaging. - : Wiley. - 1053-1807 .- 1522-2586. ; 56:5, s. 1393-1403
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Journal article (peer-reviewed)abstract
- Background Epicardial adipose tissue (EAT) may induce left atrium (LA) wall inflammation and promote LA fibrosis. Therefore, simultaneous assessment of these two important atrial fibrillation (AF) risk factors would be desirable. Purpose To perform a comprehensive evaluation of 3D Dixon water-fat separated late gadolinium enhancement (LGE-Dixon) MRI by analysis of repeatability and systematic comparison with reference methods for assessment of fibrosis and fat. Study Type Prospective. Population Twenty-eight, 10, and 7 patients, respectively, with clinical indications for cardiac MRI. Field Strength/Sequence A 1.5-T scanner, inversion recovery multiecho spoiled gradient echo. Assessment Twenty-eight patients (age 58 +/- 19 years, 15 males) were scanned using LGE-Dixon. A 5-point Likert-type scale was used to grade the image quality. Another 10 patients (age 46 +/- 19 years, 9 males) were scanned using LGE-Dixon and 3D proton density Dixon (PD-Dixon). Finally, seven patients (age 62 +/- 14 years, 4 males) were scanned using LGE-Dixon and conventional LGE. The scan time, intraobserver and interobserver variability, and levels of agreement were assessed. Statistical Tests Students t-test, one-way ANOVA, and Mann-Whitney U-test were used; P < 0.05 was considered significant, intraclass correlation coefficient (ICC). Results The scan time (minutes:seconds) for LGE-Dixon (n = 28) was 5:01 +/- 1:40. ICC values for intraobserver and interobserver measurements of LA wall fibrosis percentage were 0.98 (95% CI, 0.97-0.99) and 0.97 (95% CI, 0.94-0.99) while of EAT were 0.92 (95% CI, 0.82-0.97) and 0.90 (95% CI, 0.80-0.95). The agreement for LA fibrosis percentage between the LGE-Dixon and the conventional LGE was 0.92 (95% CI, 0.66-0.99) and for EAT volume between the LGE-Dixon and the PD-Dixon was 0.93 (95% CI, 0.72-0.98). Conclusion LA fibrosis and EAT can be assessed simultaneously using LGE-Dixon. This method allows a high level of intraobserver and interobserver repeatability as well as agreement with reference methods and can be performed in a clinically feasible scan time. Evidence Level 2 Technical Efficacy Stage 3
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| 28. |
- Sundin, Jonathan, et al.
(author)
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Improved Efficiency of Intraventricular Blood Flow Transit Under Cardiac Stress: A 4D Flow Dobutamine CMR Study
- 2020
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In: Frontiers in cardiovascular medicine. - : Frontiers Media S.A.. - 2297-055X. ; 7
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Journal article (peer-reviewed)abstract
- Introduction: The effects of heart rate, inotropy, and lusitropy on multidimensional flow patterns and energetics within the human heart remain undefined. Recently, reduced volume and end-diastolic kinetic energy (KE) of the portion of left ventricular (LV) inflow passing directly to outflow, Direct flow (DF), have been shown to reflect inefficient LV pumping and to be a marker of LV dysfunction in heart failure patients. In this study, we hypothesized that increasing heart rate, inotropy, and lusitropy would result in an increased efficiency of intraventricular blood flow transit. Therefore, we sought to investigate LV 4D blood flow patterns and energetics with dobutamine infusion. Methods: 4D flow and morphological cardiovascular magnetic resonance (CMR) data were acquired in twelve healthy subjects: at rest and with dobutamine infusion to achieve a target heart rate similar to 60% higher than the resting heart rate. A previously validated method was used for flow analysis: pathlines were emitted from the end-diastolic (ED) LV blood volume and traced forward and backward in time to separate four functional LV flow components. For each flow component, KE/mL blood volume at ED was calculated. Results: With dobutamine infusion there was an increase in heart rate (64%, p < 0.001), systolic blood pressure (p = 0.02) and stroke volume (p = 0.01). Of the 4D flow parameters, the most efficient flow component (DF), increased its proportion of EDV (p < 0.001). The EDV proportion of Residual volume, the blood residing in the ventricle over at least two cardiac cycles, decreased (p < 0.001). The KE/mL at ED for all flow components increased (p < 0.001). DF had the largest absolute and relative increase while Residual volume had the smallest absolute and relative increase. Conclusions: This study demonstrates that it is feasible to compare 4D flow patterns within the normal human heart at rest and with stress. At higher heart rate, inotropy and lusitropy, elicited by dobutamine infusion, the efficiency of intraventricular blood flow transit improves, as quantified by an increased relative volume and pre-systolic KE of the most efficient DF component of the LV volume. The change in these markers may allow a novel assessment of LV function and LV dysfunction over a range of stress.
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| 29. |
- Sundin, Jonathan, et al.
(author)
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Turbulent Intensity of Blood Flow in the Healthy Aorta Increases With Dobutamine Stress and is Related to Cardiac Output
- 2022
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In: Frontiers in Physiology. - : FRONTIERS MEDIA SA. - 1664-042X. ; 13
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Journal article (peer-reviewed)abstract
- Introduction: The blood flow in the normal cardiovascular system is predominately laminar but operates close to the threshold to turbulence. Morphological distortions such as vascular and valvular stenosis can cause transition into turbulent blood flow, which in turn may cause damage to tissues in the cardiovascular system. A growing number of studies have used magnetic resonance imaging (MRI) to estimate the extent and degree of turbulent flow in different cardiovascular diseases. However, the way in which heart rate and inotropy affect turbulent flow has not been investigated. In this study we hypothesized that dobutamine stress would result in higher turbulence intensity in the healthy thoracic aorta.Method: 4D flow MRI data were acquired in twelve healthy subjects at rest and with dobutamine, which was infused until the heart rate increased by 60% when compared to rest. A semi-automatic segmentation method was used to segment the thoracic aorta in the 4D flow MR images. Subsequently, flow velocity and several turbulent kinetic energy (TKE) parameters were calculated in the ascending aorta, aortic arch, descending aorta and whole thoracic aorta.Results: With dobutamine infusion there was an increase in heart rate (66 +/- 9 vs. 108 +/- 13 bpm, p < 0.001) and stroke volume (88 +/- 13 vs. 102 +/- 25 ml, p < 0.01). Additionally, there was an increase in Peak Average velocity (0.7 +/- 0.1 vs. 1.2 +/- 0.2 m/s, p < 0.001, Peak Max velocity (1.3 +/- 0.1 vs. 2.0 +/- 0.2 m/s, p < 0.001), Peak Total TKE (2.9 +/- 0.7 vs. 8.0 +/- 2.2 mJ, p < 0.001), Peak Median TKE (36 +/- 7 vs. 93 +/- 24 J/m3, p = 0.002) and Peak Max TKE (176 +/- 33 vs. 334 +/- 69 J/m3, p < 0.001). The relation between cardiac output and Peak Total TKE in the whole thoracic aorta was very strong (R-2 = 0.90, p < 0.001).Conclusion: TKE of blood flow in the healthy thoracic aorta increases with dobutamine stress and is strongly related to cardiac output. Quantification of such turbulence intensity parameters with cardiac stress may serve as a risk assessment of aortic disease development.
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| 30. |
- Tunedal, Kajsa, et al.
(author)
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Haemodynamic effects of hypertension and type 2 diabetes: Insights from a 4D flow MRI-based personalized cardiovascular mathematical model
- 2023
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In: Journal of Physiology. - : Wiley-Blackwell. - 0022-3751 .- 1469-7793. ; 601:17, s. 3765-3787
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Journal article (peer-reviewed)abstract
- Type 2 diabetes (T2D) and hypertension increase the risk of cardiovascular diseases mediated by whole-body changes to metabolism, cardiovascular structure and haemodynamics. The haemodynamic changes related to hypertension and T2D are complex and subject-specific, however, and not fully understood. We aimed to investigate the haemodynamic mechanisms in T2D and hypertension by comparing the haemodynamics between healthy controls and subjects with T2D, hypertension, or both. For all subjects, we combined 4D flow magnetic resonance imaging data, brachial blood pressure and a cardiovascular mathematical model to create a comprehensive subject-specific analysis of central haemodynamics. When comparing the subject-specific haemodynamic parameters between the four groups, the predominant haemodynamic difference is impaired left ventricular relaxation in subjects with both T2D and hypertension compared to subjects with only T2D, only hypertension and controls. The impaired relaxation indicates that, in this cohort, the long-term changes in haemodynamic load of co-existing T2D and hypertension cause diastolic dysfunction demonstrable at rest, whereas either disease on its own does not. However, through subject-specific predictions of impaired relaxation, we show that altered relaxation alone is not enough to explain the subject-specific and group-related differences; instead, a combination of parameters is affected in T2D and hypertension. These results confirm previous studies that reported more adverse effects from the combination of T2D and hypertension compared to either disease on its own. Furthermore, this shows the potential of personalized cardiovascular models in providing haemodynamic mechanistic insights and subject-specific predictions that could aid in the understanding and treatment planning of patients with T2D and hypertension.
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| 31. |
- Viola, Federica, et al.
(author)
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Data Quality and Optimal Background Correction Order of Respiratory-Gated k-Space Segmented Spoiled Gradient Echo (SGRE) and Echo Planar Imaging (EPI)-Based 4D Flow MRI
- 2020
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In: Journal of Magnetic Resonance Imaging. - : WILEY. - 1053-1807 .- 1522-2586. ; 51:3, s. 885-896
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Journal article (peer-reviewed)abstract
- Background A reduction in scan time of 4D Flow MRI would facilitate clinical application. A recent study indicates that echo-planar imaging (EPI) 4D Flow MRI allows for a reduction in scan time and better data quality than the recommended k-space segmented spoiled gradient echo (SGRE) sequence. It was argued that the poor data quality of SGRE was related to the nonrecommended absence of respiratory motion compensation. However, data quality can also be affected by the background offset compensation. Purpose To compare the data quality of respiratory motion-compensated SGRE and EPI 4D Flow MRI and their dependence on background correction (BC) order. Study Type Retrospective. Subjects Eighteen healthy subjects (eight female, mean age 32 +/- 5 years). Field Strength and Sequence 5T. SGRE and EPI-based 4D Flow MRI. Assessment Data quality was investigated visually and by comparing flows through the cardiac valves and aorta. Measurements were obtained from transvalvular flow and pathline analysis. Statistical Tests Linear regression and Bland-Altman analysis were used. Wilcoxon test was used for comparison of visual scoring. Students t-test was used for comparison of flow volumes. Results No significant difference was found by visual inspection (P = 0.08). Left ventricular (LV) flows were strongly and very strongly associated with SGRE and EPI, respectively (R-2 = 0.86-0.94 SGRE; 0.71-0.79 EPI, BC0-4). LV and right ventricular (RV) outflows and LV pathline flows were very strongly associated (R-2 = 0.93-0.95 SGRE; 0.88-0.91 EPI, R-2 = 0.91-0.95 SGRE; 0.91-0.93 EPI, BC1-4). EPI LV outflow was lower than the short-axis-based stroke volume. EPI RV outflow and proximal descending aortic flow were lower than SGREs. Data Conclusion Both sequences yielded good internal data consistency when an adequate background correction was applied. Second and first BC order were considered sufficient for transvalvular flow analysis in SGRE and EPI, respectively. Higher BC orders were preferred for particle tracing. Technical Efficacy Stage 1 J. Magn. Reson. Imaging 2019.
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