Background Advances in four-dimensional fow cardiovascular magnetic resonance (4D fow CMR) have allowed quantifcation of left ventricular (LV) and right ventricular (RV) blood fow. We aimed to (1)... Show moreBackground Advances in four-dimensional fow cardiovascular magnetic resonance (4D fow CMR) have allowed quantifcation of left ventricular (LV) and right ventricular (RV) blood fow. We aimed to (1) investigate age and sex diferences of 4D fow CMR-derived LV and RV relative fow components and kinetic energy (KE) parameters indexed to end-diastolic volume (KEiEDV) in healthy subjects; and (2) assess the efects of age and sex on these parameters. Methods We performed 4D fow analysis in 163 healthy participants (42% female; mean age 43±13 years) of a pro‑ spective registry study (NCT03217240) who were free of cardiovascular diseases. Relative fow components (direct fow, retained infow, delayed ejection fow, residual volume) and multiple phasic KEiEDV (global, peak systolic, average systolic, average diastolic, peak E-wave, peak A-wave) for both LV and RV were analysed. Results Compared with men, women had lower median LV and RV residual volume, and LV peak and average systolic KEiEDV, and higher median values of RV direct fow, RV global KEiEDV, RV average diastolic KEiEDV, and RV peak E-wave KEiEDV. ANOVA analysis found there were no diferences in fow components, peak and average systolic, average diastolic and global KEiEDV for both LV and RV across age groups. Peak A-wave KEiEDV increased signifcantly (r=0.458 for LV and 0.341 for RV), whereas peak E-wave KEiEDV (r=− 0.355 for LV and − 0.318 for RV), and KEiEDV E/A ratio (r=− 0.475 for LV and − 0.504 for RV) decreased signifcantly, with age. Conclusion These data using state-of-the-art 4D fow CMR show that biventricular fow components and kinetic energy parameters vary signifcantly by age and sex. Age and sex trends should be considered in the interpretation of quantitative measures of biventricular fow. Show less
Sun, X.W.; Cheng, L.H.; Plein, S.; Garg, P.; Geest, R.J. van der 2024
Background: 4D flow MRI enables assessment of cardiac function and intra-cardiac blood flow dynamics from a single acquisition. However, due to the poor contrast between the chambers and... Show moreBackground: 4D flow MRI enables assessment of cardiac function and intra-cardiac blood flow dynamics from a single acquisition. However, due to the poor contrast between the chambers and surrounding tissue, quantitative analysis relies on the segmentation derived from a registered cine MRI acquisition. This requires an additional acquisition and is prone to imperfect spatial and temporal inter-scan alignment. Therefore, in this work we developed and evaluated deep learning-based methods to segment the left ventricle (LV) from 4D flow MRI directly. Methods: We compared five deep learning-based approaches with different network structures, data pre-processing and feature fusion methods. For the data pre-processing, the 4D flow MRI data was reformatted into a stack of short-axis view slices. Two feature fusion approaches were proposed to integrate the features from magnitude and velocity images. The networks were trained and evaluated on an in-house dataset of 101 subjects with 67,567 2D images and 3030 3D volumes. The performance was evaluated using various metrics including Dice, average surface distance (ASD), end-diastolic volume (EDV), end-systolic volume (ESV), LV ejection fraction (LVEF), LV blood flow kinetic energy (KE) and LV flow components. The Monte Carlo dropout method was used to assess the confidence and to describe the uncertainty area in the segmentation results. Results: Among the five models, the model combining 2D U-Net with late fusion method operating on short-axis reformatted 4D flow volumes achieved the best results with Dice of 84.52% and ASD of 3.14 mm. The best averaged absolute and relative error between manual and automated segmentation for EDV, ESV, LVEF and KE was 19.93 ml (10.39%), 17.38 ml (22.22%), 7.37% (13.93%) and 0.07 mJ (5.61%), respectively. Flow component results derived from automated segmentation showed high correlation and small average error compared to results derived from manual segmentation. Conclusions: Deep learning-based methods can achieve accurate automated LV segmentation and subsequent quantification of volumetric and hemodynamic LV parameters from 4D flow MRI without requiring an additional cine MRI acquisition. Show less
Sun, X.W.; Cheng, L.H.; Plein, S.; Garg, P.; Moghari, M.H.; Geest, R.J. van der 2023
Purpose: We aimed to design and evaluate a deep learning-based method to automatically predict the time-varying in-plane blood flow velocity within the cardiac cavities in long-axis cine MRI,... Show morePurpose: We aimed to design and evaluate a deep learning-based method to automatically predict the time-varying in-plane blood flow velocity within the cardiac cavities in long-axis cine MRI, validated against 4D flow. Methods: A convolutional neural network (CNN) was implemented, taking cine MRI as the input and the in-plane velocity derived from the 4D flow acquisition as the ground truth. The method was evaluated using velocity vector end-point error (EPE) and angle error. Additionally, the E/A ratio and diastolic function classification derived from the predicted velocities were compared to those derived from 4D flow. Results: For intra-cardiac pixels with a velocity > 5 cm/s, our method achieved an EPE of 8.65 cm/s and angle error of 41.27 degrees. For pixels with a velocity > 25 cm/s, the angle error significantly degraded to 19.26 degrees. Although the averaged blood flow velocity prediction was under-estimated by 26.69%, the high correlation (PCC = 0.95) of global time-varying velocity and the visual evaluation demonstrate a good agreement between our prediction and 4D flow data. The E/A ratio was derived with minimal bias, but with considerable mean absolute error of 0.39 and wide limits of agreement. The diastolic function classification showed a high accuracy of 86.9%. Conclusion: Using a deep learning-based algorithm, intra-cardiac blood flow velocities can be predicted from long-axis cine MRI with high correlation with 4D flow derived velocities. Visualization of the derived velocities provides adjunct functional information and may potentially be used to derive the E/A ratio from conventional CMR exams. Show less
A. das; Kelly, C.; Ben-Arzi, H.; Geest, R.J. van der; Plein, S.; Dall'Armellina, E. 2022
Background: Despite advancements in percutaneous coronary intervention, a significant proportion of ST-elevation myocardial infarction (STEMI) survivors develop long-term adverse left ventricular ... Show moreBackground: Despite advancements in percutaneous coronary intervention, a significant proportion of ST-elevation myocardial infarction (STEMI) survivors develop long-term adverse left ventricular (LV) remodelling, which is associated with poor prognosis. Adverse remodelling is difficult to predict, however four-dimensional (4D) flow cardiovascular magnetic resonance (CMR) can measure various aspects of LV intra-cavity flow beyond LV ejection fraction and is well equipped for exploring the underlying mechanical processes driving remodelling. The aim for this study was to compare acute 4D flow CMR parameters between patients who develop adverse remodelling with patients who do not. Methods: Fifty prospective 'first-event' STEMI patients underwent CMR 5 days post-reperfusion, which included cine-imaging, and 4D flow for assessing in-plane kinetic energy (KE), residual volume, peak-E and peak-A wave KE (indexed for LV end-diastolic volume [LVEDV]). All subjects underwent follow-up cine CMR imaging at 12 months to identify adverse remodelling (defined as 20% increase in LVEDV from baseline). Quantitative variables were compared using unpaired student's t-test. Tests were deemed statistically significant when p < 0.05. Results: Patients who developed adverse LV remodelling by 12 months had significantly higher in-plane KE (54 +/- 12 vs 42 +/- 10%, p = 0.02), decreased proportion of direct flow (27 +/- 9% vs 11 +/- 4%, p < 0.01), increased proportion of delayed ejection flow (22 +/- 9% vs 12 +/- 2, p < 0.01) and increased proportion of residual volume after 2 consecutive cardiac cycles (64 +/- 14 vs 34 +/- 14%, p < 0.01), in their acute scan. Conclusion: Following STEMI, increased in-plane KE, reduced direct flow and increased residual volume in the acute scan were all associated with adverse LV remodelling at 12 months. Our results highlight the clinical utility of acute 4D flow in prognostic stratification in patients following myocardial infarction. Show less
Demirkiran, A.; Geest, R.J. van der; Hopman, L.H.G.A.; Robbers, L.F.H.J.; Handoko, M.L.; Nijveldt, R.; ... ; Garg, P. 2022
Background: Myocardial infarction leads to complex changes in left ventricular (LV) hemodynamics. It remains unknown how four-dimensional acute changes in LV-cavity blood flow kinetic energy... Show moreBackground: Myocardial infarction leads to complex changes in left ventricular (LV) hemodynamics. It remains unknown how four-dimensional acute changes in LV-cavity blood flow kinetic energy affects LV-remodeling.Methods and results: In total, 69 revascularised ST-segment elevation myocardial infarction (STEMI) patients were enrolled. All patients underwent cardiovascular magnetic resonance (CMR) examination within 2 days of the index event and at 3-month. CMR examination included cine, late gadolinium enhancement, and whole-heart four-dimensional flow acquisitions. LV volume-function, infarct size (indexed to body surface area), microvas-cular obstruction, mitral inflow, and blood flow KEi (kinetic energy indexed to end-diastolic volume) charac-teristics were obtained. Adverse LV-remodeling was defined and categorized according to increase in LV end -diastolic volume of at least 10%, 15%, and 20%. Twenty-four patients (35%) developed at least 10%, 17 pa-tients (25%) at least 15%, 11 patients (16%) at least 20% LV-remodeling. Demographics and clinical history were comparable between patients with/without LV-remodeling. In univariable regression-analysis, A-wave KEi was associated with at least 10%, 15%, and 20% LV-remodeling (p = 0.03, p = 0.02, p = 0.02, respectively), whereas infarct size only with at least 10% LV-remodeling (p = 0.02). In multivariable regression-analysis, A-wave KEi was identified as an independent marker for at least 10%, 15%, and 20% LV-remodeling (p = 0.09, p < 0.01, p < 0.01, respectively), yet infarct size only for at least 10% LV-remodeling (p = 0.03).Conclusion: In patients with STEMI, LV hemodynamic assessment by LV blood flow kinetic energetics demon-strates a significant inverse association with adverse LV-remodeling. Late-diastolic LV blood flow kinetic ener-getics early after acute MI was independently associated with adverse LV-remodeling. Show less
Objectives: Mitral regurgitation (MR) and microvascular obstruction (MVO) are common complications of myocardial infarction (MI). This study aimed to investigate the association between MR in ST... Show moreObjectives: Mitral regurgitation (MR) and microvascular obstruction (MVO) are common complications of myocardial infarction (MI). This study aimed to investigate the association between MR in ST-elevation MI (STEMI) subjects with MVO post-reperfusion. STEMI subjects undergoing primary percutaneous intervention were enrolled. Cardiovascular magnetic resonance (CMR) imaging was performed within 48-hours of initial presentation. 4D flow images of CMR were analysed using a retrospective valve tracking technique to quantify MR volume, and late gadolinium enhancement images of CMR to assess MVO. Results: Among 69 patients in the study cohort, 41 had MVO (59%). Patients with MVO had lower left ventricular (LV) ejection fraction (EF) (42 +/- 10% vs. 52 +/- 8%, P < 0.01), higher end-systolic volume (98 +/- 49 ml vs. 73 +/- 28 ml, P < 0.001) and larger scar volume (26 +/- 19% vs. 11 +/- 9%, P < 0.001). Extent of MVO was associated with the degree of MR quantified by 4D flow (R = 0.54, P = 0.0003). In uni-variate regression analysis, investigating the association of CMR variables to the degree of acute MR, only the extent of MVO was associated (coefficient = 0.27, P = 0.001). The area under the curve for the presence of MVO was 0.66 (P = 0.01) for MR > 2.5 ml. We conclude that in patients with reperfused STEMI, the degree of acute MR is associated with the degree of MVO. Show less
Background: Left ventricular thrombus (LVT) formation is a frequent and serious complication of myocardial infarction (MI). How global LV flow characteristics are related to this phenomenon is yet... Show moreBackground: Left ventricular thrombus (LVT) formation is a frequent and serious complication of myocardial infarction (MI). How global LV flow characteristics are related to this phenomenon is yet uncertain. In this study, we investigated LV flow differences using 4D flow cardiovascular magnetic resonance (CMR) between chronic MI patients with LVT [MI-LVT(+)] and without LVT [MI-LVT(-)], and healthy controls. Methods: In this prospective cohort study, the 4D flow CMR data were acquired in 19 chronic MI patients (MI-LVT (+), n = 9 and MI-LVT(-), n = 10) and 9 age-matched controls. All included subjects were in sinus rhythm. The following LV flow parameters were obtained: LV flow components (direct, retained, delayed, residual), mean and peak kinetic energy (KE) values (indexed to instantaneous LV volume), mean and peak vorticity values, and diastolic vortex ring properties (position, orientation, shape). Results: The MI patients demonstrated a significantly larger amount of delayed and residual flow, and a smaller amount of direct flow compared to controls (p = 0.02, p = 0.03, and p < 0.001, respectively). The MI-LVT(+) patients demonstrated numerically increased residual flow and reduced retained and direct flow in comparison to MI-LVT(-) patients. Systolic mean and peak LV blood flow KE values were significantly lower in MI patients compared to controls (p = 0.04, p = 0.03, respectively). Overall, the mean and peak LV vorticity values were significantly lower in MI patients compared to controls. The mean and peak systolic vorticity at the basal level were significantly higher in MI-LVT(+) than in MI-LVT(-) patients (p < 0.01, for both). The vortex ring core during E-wave in MI-LVT(+) group was located in a less tilted orientation to the LV compared to MI-LVT(-) group (p < 0.01). Conclusions: Chronic MI patients with LVT express a different distribution of LV flow components, irregular vorticity vector fields, and altered diastolic vortex ring geometric properties as assessed by 4D flow CMR. Larger prospective studies are warranted to further evaluate the significance of these initial observations. Show less
Background Right atrial (RA) area predicts mortality in patients with pulmonary hypertension, and is recommended by the European Society of Cardiology/European Respiratory Society pulmonary... Show moreBackground Right atrial (RA) area predicts mortality in patients with pulmonary hypertension, and is recommended by the European Society of Cardiology/European Respiratory Society pulmonary hypertension guidelines. The advent of deep learning may allow more reliable measurement of RA areas to improve clinical assessments. The aim of this study was to automate cardiovascular magnetic resonance (CMR) RA area measurements and evaluate the clinical utility by assessing repeatability, correlation with invasive haemodynamics and prognostic value. Methods A deep learning RA area CMR contouring model was trained in a multicentre cohort of 365 patients with pulmonary hypertension, left ventricular pathology and healthy subjects. Inter-study repeatability (intraclass correlation coefficient (ICC)) and agreement of contours (DICE similarity coefficient (DSC)) were assessed in a prospective cohort (n = 36). Clinical testing and mortality prediction was performed in n = 400 patients that were not used in the training nor prospective cohort, and the correlation of automatic and manual RA measurements with invasive haemodynamics assessed in n = 212/400. Radiologist quality control (QC) was performed in the ASPIRE registry, n = 3795 patients. The primary QC observer evaluated all the segmentations and recorded them as satisfactory, suboptimal or failure. A second QC observer analysed a random subcohort to assess QC agreement (n = 1018). Results All deep learning RA measurements showed higher interstudy repeatability (ICC 0.91 to 0.95) compared to manual RA measurements (1st observer ICC 0.82 to 0.88, 2nd observer ICC 0.88 to 0.91). DSC showed high agreement comparing automatic artificial intelligence and manual CMR readers. Maximal RA area mean and standard deviation (SD) DSC metric for observer 1 vs observer 2, automatic measurements vs observer 1 and automatic measurements vs observer 2 is 92.4 +/- 3.5 cm(2), 91.2 +/- 4.5 cm(2) and 93.2 +/- 3.2 cm(2), respectively. Minimal RA area mean and SD DSC metric for observer 1 vs observer 2, automatic measurements vs observer 1 and automatic measurements vs observer 2 was 89.8 +/- 3.9 cm(2), 87.0 +/- 5.8 cm(2) and 91.8 +/- 4.8 cm(2). Automatic RA area measurements all showed moderate correlation with invasive parameters (r = 0.45 to 0.66), manual (r = 0.36 to 0.57). Maximal RA area could accurately predict elevated mean RA pressure low and high-risk thresholds (area under the receiver operating characteristic curve artificial intelligence = 0.82/0.87 vs manual = 0.78/0.83), and predicted mortality similar to manual measurements, both p < 0.01. In the QC evaluation, artificial intelligence segmentations were suboptimal at 108/3795 and a low failure rate of 16/3795. In a subcohort (n = 1018), agreement by two QC observers was excellent, kappa 0.84. Conclusion Automatic artificial intelligence CMR derived RA size and function are accurate, have excellent repeatability, moderate associations with invasive haemodynamics and predict mortality. Show less
Heart failure (HF) is among the most important and frequent complications of diabetes mellitus (DM). The detection of subclinical dysfunction is a marker of HF risk and presents a potential target... Show moreHeart failure (HF) is among the most important and frequent complications of diabetes mellitus (DM). The detection of subclinical dysfunction is a marker of HF risk and presents a potential target for reducing incident HF in DM. Left ventricular (LV) dysfunction secondary to DM is heterogeneous, with phenotypes including predominantly systolic, predominantly diastolic, and mixed dysfunction. Indeed, the pathogenesis of HF in this setting is heterogeneous. Effective management of this problem will require detailed phenotyping of the contributions of fibrosis, microcirculatory disturbance, abnormal metabolism, and sympathetic innervation, among other mechanisms. For this reason, an imaging strategy for the detection of HF risk needs to not only detect subclinical LV dysfunction (LVD) but also characterize its pathogenesis. At present, it is possible to identify individuals with DM at increased risk HF, and there is evidence that cardioprotection may be of benefit. However, there is insufficient justification for HF screening, because we need stronger evidence of the links between the detection of LVD, treatment, and improved outcome. This review discusses the options for screening for LVD, the potential means of identifying the underlying mechanisms, and the pathways to treatment. Show less
Ben-Arzi, H.; A. das; Kelly, C.; Geest, R.J. van der; Plein, S.; Dall'Armellina, E. 2021
Background Four-dimensional (4D) flow cardiac magnetic resonance (cardiac MR) imaging provides quantification of intracavity left ventricular (LV) flow kinetic energy (KE) parameters in three... Show moreBackground Four-dimensional (4D) flow cardiac magnetic resonance (cardiac MR) imaging provides quantification of intracavity left ventricular (LV) flow kinetic energy (KE) parameters in three dimensions. ST-elevation myocardial infarction (STEMI) patients have been shown to have altered intracardiac blood flow compared to controls; however, how 4D flow parameters change over time has not been explored previously. Purpose Measure longitudinal changes in intraventricular flow post-STEMI and ascertain its predictive relevance of long-term cardiac remodeling. Study Type Prospective. Population Thirty-five STEMI patients (M:F = 26:9, aged 56 +/- 9 years). Field Strength/Sequence A 3 T/3D EPI-based, fast field echo (FFE) free-breathing 4D-flow sequence with retrospective cardiac gating. Assessment Serial imaging at 3-7 days (V1), 3-months (V2), and 12-months (V3) post-STEMI, including the following protocol: functional imaging for measuring volumes and 4D-flow for calculating parameters including systolic and peakE-wave LVKE, normalized to end-diastolic volume (iEDV) and stroke volume (iSV). Data were analyzed by H.B. (3 years experience). Patients were categorized into two groups: preserved ejection fraction (pEF, if EF > 50%) and reduced EF (rEF, if EF < 50%). Statistical Tests Independent sample t-tests were used to detect the statistical significance between any two cohorts. P < 0.05 was considered statistically significant. Results Across the cohort, systolic KEi(sv) was highest at V1 (28.0 +/- 4.4 mu J/mL). Patients with rEF retained significantly higher systolic KEi(sv) than patients with pEF at V2 (18.2 +/- 3.4 mu J/mL vs. 6.9 +/- 0.6 mu J/mL, P < 0.001) and V3 (21.6 +/- 5.1 mu J/mL vs. 7.4 +/- 0.9 mu J/mL, P < 0.001). Patients with pEF had significantly higher peakE-wave KEi(EDV) than rEF patients throughout the study (V1: 25.4 +/- 11.6 mu J/mL vs. 18.1 +/- 9.9 mu J/mL, P < 0.03, V2: 24.0 +/- 10.2 mu J/mL vs. 17.2 +/- 12.2 mu J/mL, P < 0.05, V3: 27.7 +/- 14.8 mu J/mL vs. 15.8 +/- 7.6 mu J/mL, P < 0.04). Data Conclusion Systolic KE increased acutely following MI; in patients with pEF, this decreased over 12 months, while patients with rEF, this remained raised. Compared to patients with pEF, persistently lower peakE-wave KE in rEF patients is suggestive of early and fixed impairment in diastolic function. Evidence Level 1 Technical Efficacy Stage 3 Show less
Background: Four-dimensional flow cardiovascular magnetic resonance (4D flow CMR) allows quantification of left ventricular (LV) blood flow. We aimed to 1) establish reference ranges for 4D flow... Show moreBackground: Four-dimensional flow cardiovascular magnetic resonance (4D flow CMR) allows quantification of left ventricular (LV) blood flow. We aimed to 1) establish reference ranges for 4D flow CMR-derived LV relative flow components and kinetic energy parameters indexed to end-diastolic volume (KEiEDV) among healthy Asian subjects, 2) assess effects of age and sex on these parameters, and 3) compare these parameters between Asian and Caucasian subjects.Methods: 74 healthy Asian subjects underwent cine and 4D flow CMR. Relative flow components (direct flow, retained inflow, delayed ejection flow, residual volume) and multiple phasic KEiEDV (LV global, peak systolic, systolic, diastolic, peak E-wave, peak A-wave) were analyzed. Sex-and age-specific reference ranges were reported.Results: Relative flow components and systolic phase KEiEDV did not vary with age. Women had higher retained inflow and peak E-wave KEiEDV, lower residual volume, peak systolic and systolic KEiEDV than men. Peak A-wave KEiEDV increased significantly (r = 0.474) whereas peak E-wave KEiEDV (r = -0.458) and E-wave/A-wave ratio (r = -0.528) decreased with age. A sub-population (n = 44) was compared with 44 sex-and age-matched Caucasian subjects: no significant group differences were observed for all 4D flow CMR parameters.Conclusion: Asian sex-and age-specific 4D flow CMR reference ranges were established. Sex differences in retained inflow, residual volume, peak systolic, systolic KEiEDV and peak E-wave KEiEDV were observed. Ageing influenced diastolic KEiEDV but not systolic phase KEiEDV or relative flow components. All studied parameters were similar between sex-and age-matched Asian and Caucasian subjects, implying generalizability of the ranges. (C) 2021 Elsevier B.V. All rights reserved. Show less
Grafton-Clarke, C.; Crandon, S.; Westenberg, J.J.M.; Swoboda, P.P.; Greenwood, J.P.; Geest, R.J. van der; ... ; Garg, P. 2021
Objectives Four-dimensional flow CMR allows for a comprehensive assessment of the blood flow kinetic energy of the ventricles of the heart. In comparison to standard two-dimensional image... Show moreObjectives Four-dimensional flow CMR allows for a comprehensive assessment of the blood flow kinetic energy of the ventricles of the heart. In comparison to standard two-dimensional image acquisition, 4D flow CMR is felt to offer superior reproducibility, which is important when repeated examinations may be required. The objective was to evaluate the inter-observer and intra-observer reproducibility of blood flow kinetic energy assessment using 4D flow of the left ventricle in 20 healthy volunteers across two centres in the United Kingdom and the Netherlands. Data description This dataset contains 4D flow CMR blood flow kinetic energy data for 20 healthy volunteers with no known cardiovascular disease. Presented is kinetic energy data for the entire cardiac cycle (global), the systolic and diastolic components, in addition to blood flow kinetic energy for both early and late diastolic filling. This data is available for reuse and would be valuable in supporting other research, such as allowing for larger sample sizes with more statistical power for further analysis of these variables. Show less
Background: There are several methods to quantify mitral regurgitation (MR) by cardiovascular magnetic resonance (CMR). The interoperability of these methods and their reproducibility remains... Show moreBackground: There are several methods to quantify mitral regurgitation (MR) by cardiovascular magnetic resonance (CMR). The interoperability of these methods and their reproducibility remains undetermined.Objective: To determine the agreement and reproducibility of different MR quantification methods by CMR across all aetiologies.Methods: Thirty-five patients with MR were recruited (primary MR = 12, secondary MR = 10 and MVR = 13). Patients underwent CMR, including cines and four-dimensional flow (4D flow). Four methods were evaluated: MRStandard (left ventricular stroke volume-aortic forward flow by phase contrast), MRLVRV (left ventricular stroke volume - right ventricular stroke volume), MRJet (direct jet quantification by 4D flow) and MRMVAV (mitral forward flow by 4D flow - aortic forward flow by 4D flow). For all cases and MR types, 520 MR volumes were recorded by these 4 methods for intra-/inter-observer tests.Results: In primary MR, MRMVAV and MRLVRV were comparable to MRStandard (P > 0.05). MRJet resulted in significantly higher MR volumes when compared to MRStandard (P < 0.05) In secondary MR and MVR cases, all methods were comparable. In intra-observer tests, MRMVAV demonstrated least bias with best limits of agreement (bias = -0.1 ml,-8 ml to 7.8 ml, P = 0.9) and best concordance correlation coefficient (CCC = 0.96, P < 0.01). In inter-observer tests, for primary MR and MVR, least bias and highest CCC were observed for MRMVAV. For secondary MR, bias was lowest for MRJet (-0.1 ml, P=NS).Conclusion: CMR methods of MR quantification demonstrate agreement in secondary MR and MVR. In primary MR, this was not observed. Across all types of MR, MRMVAV quantification demonstrated the highest reproducibility and consistency. (C) 2021 The Author(s). Published by Elsevier B.V. Show less
Sun, X.W.; Garg, P.; Plein, S.; Geest, R.J. van der 2021
Purpose Quantification of left ventricular (LV) volume, ejection fraction and myocardial mass from multi-slice multi-phase cine MRI requires accurate segmentation of the LV in many images. We... Show morePurpose Quantification of left ventricular (LV) volume, ejection fraction and myocardial mass from multi-slice multi-phase cine MRI requires accurate segmentation of the LV in many images. We propose a stack attention-based convolutional neural network (CNN) approach for fully automatic segmentation from short-axis cine MR images.Methods To extract the relevant spatiotemporal image features, we introduce two kinds of stack methods, spatial stack model and temporal stack model, combining the target image with its neighboring images as the input of a CNN. A stack attention mechanism is proposed to weigh neighboring image slices in order to extract the relevant features using the target image as a guide. Based on stack attention and standard U-Net, a novel Stack Attention U-Net (SAUN) is proposed and trained to perform the semantic segmentation task. A loss function combining cross-entropy and Dice is used to train SAUN. The performance of the proposed method was evaluated on an internal and a public dataset using technical metrics including Dice, Hausdorff distance (HD), and mean contour distance (MCD), as well as clinical parameters, including left ventricular ejection fraction (LVEF) and myocardial mass (LVM). In addition, the results of SAUN were compared to previously presented CNN methods, including U-Net and SegNet.Results The spatial stack attention model resulted in better segmentation results than the temporal stack model. On the internal dataset comprising of 167 post-myocardial infarction patients and 57 healthy volunteers, our method achieved a mean Dice of 0.91, HD of 3.37 mm, and MCD of 1.08 mm. Evaluation on the publicly available ACDC dataset demonstrated good generalization performance, yielding a Dice of 0.92, HD of 9.4 mm, and MCD of 0.74 mm on end-diastolic images, and a Dice of 0.89, HD of 7.1 mm and MCD of 1.03 mm on end-systolic images. The Pearson correlation coefficient of LVEF and LVM between automatically and manually derived results were higher than 0.98 in both datasets.Conclusion We developed a CNN with a stack attention mechanism to automatically segment the LV chamber and myocardium from the multi-slice short-axis cine MRI. The experimental results demonstrate that the proposed approach exceeds existing state-of-the-art segmentation methods and verify its potential clinical applicability. Show less
Assessment of right ventricular (RV) diastolic function is not routinely carried out. This is due to standard two-dimensional imaging techniques being unreliable. Four-dimensional flow (4D flow)... Show moreAssessment of right ventricular (RV) diastolic function is not routinely carried out. This is due to standard two-dimensional imaging techniques being unreliable. Four-dimensional flow (4D flow) derived right ventricular blood flow kinetic energy assessment could circumvent the issues of the current imaging modalities. It also remains unknown whether there is an association between right ventricular blood flow kinetic energy (KE) and healthy ageing. We hypothesise that healthy ageing requires maintaining normal RV intra-cavity blood flow as quantified using KE method. The main objective of this study was to investigate the effect of healthy ageing on tricuspid through-plane flow and right ventricular blood flow kinetic energy. In this study, fifty-three healthy participants received a 4D flow cardiovascular magnetic resonance (CMR) scan on 1.5T Philips Ingenia. Cine segmentation and 4D flow analysis were performed using dedicated software. Standard statistical methods were carried out to investigate the associations. Both RV E-wave KEi(EDV) (r=-0.3, P=0.04) and A-wave KEi(EDV) (r=0.42, P<0.01) showed an association with healthy ageing. Additionally, the right ventricular blood flow KEi(EDV) E/A ratio demonstrated the strongest association with healthy ageing (r=-0.53, P<0.01) when compared to all RV functional and haemodynamic parameters. Furthermore, in a multivariate regression model, KEi(EDV) E/A ratio and 4D flow derived tricuspid valve stroke volume demonstrated independent association to healthy ageing (beta -0.02 and 0.68 respectively, P<0.01). Ageing is independently associated with 4D flow derived tricuspid stroke volume and RV blood flow KE E/A ratio. These novel 4D flow CMR derived imaging markers have future potential for RV diastolic assessment. Show less
Background The T-1 Mapping and Extracellular volume (ECV) Standardization (T1MES) program explored T-1 mapping quality assurance using a purpose-developed phantom with Food and Drug Administration ... Show moreBackground The T-1 Mapping and Extracellular volume (ECV) Standardization (T1MES) program explored T-1 mapping quality assurance using a purpose-developed phantom with Food and Drug Administration (FDA) and Conformite Europeenne (CE) regulatory clearance. We report T-1 measurement repeatability across centers describing sequence, magnet, and vendor performance. Methods Phantoms batch-manufactured in August 2015 underwent 2 years of structural imaging, B-0 and B-1, and "reference" slow T-1 testing. Temperature dependency was evaluated by the United States National Institute of Standards and Technology and by the German Physikalisch-Technische Bundesanstalt. Center-specific T-1 mapping repeatability (maximum one scan per week to minimum one per quarter year) was assessed over mean 358 (maximum 1161) days on 34 1.5 T and 22 3 T magnets using multiple T-1 mapping sequences. Image and temperature data were analyzed semi-automatically. Repeatability of serial T-1 was evaluated in terms of coefficient of variation (CoV), and linear mixed models were constructed to study the interplay of some of the known sources of T-1 variation. Results Over 2 years, phantom gel integrity remained intact (no rips/tears), B-0 and B-1 homogenous, and "reference" T-1 stable compared to baseline (% change at 1.5 T, 1.95 +/- 1.39%; 3 T, 2.22 +/- 1.44%). Per degrees Celsius, 1.5 T, T-1 (MOLLI 5s(3s)3s) increased by 11.4 ms in long native blood tubes and decreased by 1.2 ms in short post-contrast myocardium tubes. Agreement of estimated T-1 times with "reference" T-1 was similar across Siemens and Philips CMR systems at both field strengths (adjusted R-2 ranges for both field strengths, 0.99-1.00). Over 1 year, many 1.5 T and 3 T sequences/magnets were repeatable with mean CoVs < 1 and 2% respectively. Repeatability was narrower for 1.5 T over 3 T. Within T1MES repeatability for native T-1 was narrow for several sequences, for example, at 1.5 T, Siemens MOLLI 5s(3s)3s prototype number 448B (mean CoV = 0.27%) and Philips modified Look-Locker inversion recovery (MOLLI) 3s(3s)5s (CoV 0.54%), and at 3 T, Philips MOLLI 3b(3s)5b (CoV 0.33%) and Siemens shortened MOLLI (ShMOLLI) prototype 780C (CoV 0.69%). After adjusting for temperature and field strength, it was found that the T-1 mapping sequence and scanner software version (both P < 0.001 at 1.5 T and 3 T), and to a lesser extent the scanner model (P = 0.011, 1.5 T only), had the greatest influence on T-1 across multiple centers. Conclusion The T1MES CE/FDA approved phantom is a robust quality assurance device. In a multi-center setting, T-1 mapping had performance differences between field strengths, sequences, scanner software versions, and manufacturers. However, several specific combinations of field strength, sequence, and scanner are highly repeatable, and thus, have potential to provide standardized assessment of T-1 times for clinical use, although temperature correction is required for native T-1 tubes at least. Show less
