Mediation of the association between obesity and osteoarthritis by blood pressure, vessel wall stiffness and subclinical atherosclerosis

Objective

We investigated the role of blood pressure, vessel wall stiffness [pulse wave velocity (PWV)] and subclinical atherosclerosis markers [carotid intima-media thickness (cIMT), popliteal vessel wall thickness (pVWT)] as mediators of the association of obesity with OA.

Methods

We used cross-sectional data from a subset of the population-based NEO study (n = 6334). We classified clinical hand and knee OA by the ACR criteria, and structural knee OA, effusion and bone marrow lesions on MRI (n = 1285). cIMT was assessed with ultrasonography. pVWT was estimated on knee MRI (n = 1285), and PWV by abdominal velocity-encoded MRIs (n = 2580), in subpopulations. Associations between BMI and OA were assessed with logistic regression analyses, adjusted for age, sex and education. Blood pressure, cIMT, pVWT and PWV were added to the model to estimate mediation.

Results

The population consisted of 55% women, with a mean (s.d.) age of 56(6) years. Clinical hand OA was present in 8%, clinical knee OA in 10%, and structural knee OA in 12% of participants. BMI was positively associated with all OA outcomes. cIMT partially mediated the association of BMI with clinical hand OA [10.6 (6.2; 30.5)%], structural knee OA [3.1 (1.9; 7.3)%] and effusion [10.8 (6.0; 37.6)%]. Diastolic blood pressure [2.1 (1.6; 3.0)%] minimally mediated the association between BMI and clinical knee OA. PWV and pVWT did not mediate the association between BMI and OA.

Conclusions

cIMT and diastolic blood pressure minimally mediated the association of BMI with OA. This suggests that such mediation is trivial in the middle-aged population.

Impact of age, sex and ethnicity on intra-cardiac flow components and left ventricular kinetic energy derived from 4D flow CMR

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 CMR-derived LV relative flow components and kinetic energy parameters indexed to end-diastolic volume (KEi_EDV) 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 KEi_EDV (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 KEi_EDV did not vary with age. Women had higher retained inflow and peak E-wave KEi_EDV, lower residual volume, peak systolic and systolic KEi_EDV than men. Peak A-wave KEi_EDV increased significantly (r = 0.474) whereas peak E-wave KEi_EDV (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 KEi_EDV and peak E-wave KEi_EDV were observed. Ageing influenced diastolic KEi_EDV but not systolic phase KEi_EDV or relative flow components. All studied parameters were similar between sex- and age-matched Asian and Caucasian subjects, implying generalizability of the ranges.

Feasibility and validation of trans-valvular flow derived by four-dimensional flow cardiovascular magnetic resonance imaging in patients with atrial fibrillation

Background: Four-dimensional (4D) flow cardiovascular magnetic resonance imaging (MRI) is an emerging technique used for intra-cardiac blood flow assessment. The role of 4D flow cardiovascular MRI in the assessment of trans-valvular flow in patients with atrial fibrillation (AF) has not previously been assessed. The purpose of this study was to assess the feasibility, image quality, and internal validity of 4D flow cardiovascular MRI in the quantification of trans-valvular flow in patients with AF. Methods: Patients with AF and healthy controls in sinus rhythm underwent cardiovascular MRI, including 4D flow studies. Quality assurance checks were done on the raw data and streamlines. Consistency was investigated by trans-valvular flow assessment between the mitral valve (MV) and the aortic valve (AV). Results: Eight patients with AF (88% male, mean age 62±13 years, mean heart rate (HR) 83±16 beats per minute (bpm)) were included and compared with ten healthy controls (70% male, mean age 41±20 years, mean HR 68.5±9 bpm). All scans were of either good quality with minimal blurring artefacts, or excellent quality with no artefacts. No significant bias was observed between the AV and MV stroke volumes in either healthy controls (-4.8, 95% CI -15.64 to 6.04; P=0.34) or in patients with AF (1.64, 95% CI -4.7 to 7.94; P=0.56). A significant correlation was demonstrated between MV and AV stroke volumes in both healthy controls (r=0.87, 95% CI 0.52 to 0.97; P=0.001) and in AF patients (r=0.82, 95% CI 0.26 to 0.97; P=0.01). Conclusions: In patients with AF, 4D flow cardiovascular MRI is feasible with good image quality, allowing for quantification of trans-valvular flow.

Left ventricular blood flow kinetic energy is associated with the six-minute walk test and left ventricular remodelling post valvular intervention in aortic stenosis

Background

Left ventricular (LV) kinetic energy (KE) assessment by four-dimensional flow cardiovascular magnetic resonance (4D flow CMR) may offer incremental value over routine assessment in aortic stenosis (AS). The main objective of this study is to investigate the LV KE in patients with AS before and after the valve intervention. In addition, this study aimed to investigate if LV KE offers incremental value for its association to the six-minute walk test (6MWT) or LV remodelling post-intervention.

Methods

We recruited 18 patients with severe AS. All patients underwent transthoracic echocardiography for mean pressure gradient (mPG), CMR including 4D flow and 6MWT. Patients were invited for post-valve intervention follow-up CMR at 3 months and twelve patients returned for follow-up CMR. KE assessment of LV blood flow and the components (direct, delayed, retained and residual) were carried out for all cases. LV KE parameters were normalised to LV end-diastolic volume (LVEDV).

Results

For LV blood flow KE assessment, the metrics including time delay (TD) for peak E-wave from base to mid-ventricle (14±48 vs. 2.5±9.75 ms, P=0.04), direct (4.91±5.07 vs. 1.86±1.72 µJ, P=0.01) and delayed (2.46±3.13 vs. 1.38±1.15 µJ, P=0.03) components of LV blood flow demonstrated a significant change between pre- and post-valve intervention. Only LV KEi_EDV (r=-0.53, P<0.01), diastolic KEi_EDV (r=-0.53, P<0.01) and E_wave KEi_EDV (r=-0.38, P=0.04) demonstrated association to the 6MWT. However, Pre-operative LV KEi_EDV (r=0.67, P=0.02) demonstrated association to LV remodelling post valve intervention.

Conclusions

LV blood flow KE is associated with 6MWT and LV remodelling in patients with AS. LV KE assessment provides incremental value over routine LV function and pressure gradient (PG) assessment in AS.

SAUN: Stack attention U-Net for left ventricle segmentation from cardiac cine magnetic resonance imaging

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 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.

Feasibility and validation of trans-valvular flow derived by four-dimensional flow cardiovascular magnetic resonance imaging in patients with atrial fibrillation

Background: Four-dimensional (4D) flow cardiovascular magnetic resonance imaging (MRI) is an emerging technique used for intra-cardiac blood flow assessment. The role of 4D flow cardiovascular MRI in the assessment of trans-valvular flow in patients with atrial fibrillation (AF) has not previously been assessed. The purpose of this study was to assess the feasibility, image quality, and internal validity of 4D flow cardiovascular MRI in the quantification of trans-valvular flow in patients with AF. Methods: Patients with AF and healthy controls in sinus rhythm underwent cardiovascular MRI, including 4D flow studies. Quality assurance checks were done on the raw data and streamlines. Consistency was investigated by trans-valvular flow assessment between the mitral valve (MV) and the aortic valve (AV). Results: Eight patients with AF (88% male, mean age 62±13 years, mean heart rate (HR) 83±16 beats per minute (bpm)) were included and compared with ten healthy controls (70% male, mean age 41±20 years, mean HR 68.5±9 bpm). All scans were of either good quality with minimal blurring artefacts, or excellent quality with no artefacts. No significant bias was observed between the AV and MV stroke volumes in either healthy controls (-4.8, 95% CI -15.64 to 6.04; P=0.34) or in patients with AF (1.64, 95% CI -4.7 to 7.94; P=0.56). A significant correlation was demonstrated between MV and AV stroke volumes in both healthy controls (r=0.87, 95% CI 0.52 to 0.97; P=0.001) and in AF patients (r=0.82, 95% CI 0.26 to 0.97; P=0.01). Conclusions: In patients with AF, 4D flow cardiovascular MRI is feasible with good image quality, allowing for quantification of trans-valvular flow.

Altered left atrial 4D flow characteristics in patients with paroxysmal atrial fibrillation in the absence of apparent remodeling

The pathophysiology behind thrombus formation in paroxysmal atrial fibrillation (AF) patients is very complex. This can be due to left atrial (LA) flow changes, remodeling, or both. We investigated differences for cardiovascular magnetic resonance (CMR)-derived LA 4D flow and remodeling characteristics between paroxysmal AF patients and patients without cardiac disease. In this proof-of-concept study, the 4D flow data were acquired in 10 patients with paroxysmal AF (age = 61 ± 8 years) and 5 age/gender matched controls (age = 56 ± 1 years) during sinus rhythm. The following LA and LA appendage flow parameters were obtained: flow velocity (mean, peak), stasis defined as the relative volume with velocities < 10 cm/s, and kinetic energy (KE). Furthermore, LA global strain values were derived from b-SSFP cine images using dedicated CMR feature-tracking software. Even in sinus rhythm, LA mean and peak flow velocities over the entire cardiac cycle were significantly lower in paroxysmal AF patients compared to controls [(13.1 ± 2.4 cm/s vs. 16.7 ± 2.1 cm/s, p = 0.01) and (19.3 ± 4.7 cm/s vs. 26.8 ± 5.5 cm/s, p = 0.02), respectively]. Moreover, paroxysmal AF patients expressed more stasis of blood than controls both in the LA (43.2 ± 10.8% vs. 27.8 ± 7.9%, p = 0.01) and in the LA appendage (73.3 ± 5.7% vs. 52.8 ± 16.2%, p = 0.04). With respect to energetics, paroxysmal AF patients demonstrated lower mean and peak KE values (indexed to maximum LA volume) than controls. No significant differences were observed for LA volume, function, and strain parameters between the groups. Global LA flow dynamics in paroxysmal AF patients appear to be impaired including mean/peak flow velocity, stasis fraction, and KE, partly independent of LA remodeling. This pathophysiological flow pattern may be of clinical value to explain the increased incidence of thromboembolic events in paroxysmal AF patients, in the absence of actual AF or LA remodeling.

Posterior Left Atrial Adipose Tissue Attenuation Assessed by Computed Tomography and Recurrence of Atrial Fibrillation After Catheter Ablation

[Figure: see text].

Standard and emerging CMR methods for mitral regurgitation quantification

BACKGROUND

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: MR_Standard (left ventricular stroke volume - aortic forward flow by phase contrast), MR_LVRV (left ventricular stroke volume - right ventricular stroke volume), MR_Jet (direct jet quantification by 4D flow) and MR_MVAV (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, MR_MVAV and MR_LVRV were comparable to MR_Standard (P > 0.05). MR_Jet resulted in significantly higher MR volumes when compared to MR_Standard (P < 0.05) In secondary MR and MVR cases, all methods were comparable. In intra-observer tests, MR_MVAV 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 MR_MVAV. For secondary MR, bias was lowest for MR_Jet (-0.1 ml, PNS).

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, MR_MVAV quantification demonstrated the highest reproducibility and consistency.

Reference ranges ("normal values") for cardiovascular magnetic resonance (CMR) in adults and children: 2020 update

Cardiovascular magnetic resonance (CMR) enables assessment and quantification of morphological and functional parameters of the heart, including chamber size and function, diameters of the aorta and pulmonary arteries, flow and myocardial relaxation times. Knowledge of reference ranges ("normal values") for quantitative CMR is crucial to interpretation of results and to distinguish normal from disease. Compared to the previous version of this review published in 2015, we present updated and expanded reference values for morphological and functional CMR parameters of the cardiovascular system based on the peer-reviewed literature and current CMR techniques. Further, databases and references for deep learning methods are included.

Cardiac magnetic resonance using fused 3D cine and 4D flow sequences:Validation of ventricular and blood flow measurements

PURPOSE

Current cardiovascular magnetic resonance (CMR) examinations require expert planning, multiple breath holds, and 2D imaging. To address this, we sought to develop and validate a comprehensive free-breathing 3D cine function and flow CMR examination using a steady-state free precession (SSFP) sequence to depict anatomy fused with a spatially registered phase contrast (PC) sequence for blood flow analysis.

METHODS

In a prospective study, 25 patients underwent a CMR examination which included a 3D cine SSFP sequence and a 3D cine PC (also known as 4D flow) sequence acquired during free-breathing and after the administration of a gadolinium-based contrast agent. Both 3D sequences covered the heart and mediastinum, and used retrospective vectorcardiogram gating (20 phases/beat interpolated to 30 phases/beat) and prospective respiratory motion compensation confining data acquisition to end-expiration. Cardiovascular measurements derived from the 3D cine SSFP and PC images were then compared with those from standard 2D imaging.

RESULTS

All 3D cine SSFP and PC acquisitions were completed successfully. The mean time for the 3D cine sequences including prescription was shorter than that for the corresponding 2D sequences (21 min vs. 36 min, P-value <0.001). Left and right ventricular end-diastolic volumes and stroke volumes by 3D cine SSFP were slightly smaller than those from 2D cine SSFP (all biases ≤5%). The blood flow measurements from the 3D and 2D sequences had close agreement in the ascending aorta (bias -2.6%) but main pulmonary artery flow was lower with the 3D cine sequence (bias -11.2%).

CONCLUSION

Compared to the conventional 2D cine approach, a comprehensive 3D cine function and flow examination was faster and yielded slightly lower left and right end-diastolic volumes, stroke volumes, and main pulmonary artery blood flow. This free-breathing 3D cine approach allows flexible post-examination data analysis and has the potential to make examinations more comfortable for patients and easier to perform for the operator.

Hypertensive Exposure Markers by MRI in Relation to Cerebral Small Vessel Disease and Cognitive Impairment

OBJECTIVES

This study sought to investigate the extent of hypertensive exposure as assessed by cardiovascular magnetic resonance imaging (MRI) in relation to cerebral small vessel disease (CSVD) and cognitive impairment, with the aim of understanding the role of hypertension in the early stages of deteriorating brain health.

BACKGROUND

Preserving brain health into advanced age is one of the great challenges of modern medicine. Hypertension is thought to induce vascular brain injury through exposure of the cerebral microcirculation to increased pressure/pulsatility. Cardiovascular MRI provides markers of (subclinical) hypertensive exposure, such as aortic stiffness by pulse wave velocity (PWV), left ventricular (LV) mass index (LVMi), and concentricity by mass-to-volume ratio.

METHODS

A total of 559 participants from the Heart-Brain Connection Study (431 patients with manifest cardiovascular disease and 128 control participants), age 67.8 ± 8.8 years, underwent 3.0-T heart-brain MRI and extensive neuropsychological testing. Aortic PWV, LVMi, and LV mass-to-volume ratio were evaluated in relation to presence of CSVD and cognitive impairment. Effect modification by patient group was investigated by interaction terms; results are reported pooled or stratified accordingly.

RESULTS

Aortic PWV (odds ratio [OR]: 1.17; 95% confidence interval [CI]: 1.05 to 1.30 in patient groups only), LVMi (in carotid occlusive disease, OR: 5.69; 95% CI: 1.63 to 19.87; in other groups, OR: 1.30; 95% CI: 1.05 to 1.62]) and LV mass-to-volume ratio (OR: 1.81; 95% CI: 1.46 to 2.24) were associated with CSVD. Aortic PWV (OR: 1.07; 95% CI: 1.02 to 1.13) and LV mass-to-volume ratio (OR: 1.27; 95% CI: 1.07 to 1.51) were also associated with cognitive impairment. Relations were independent of sociodemographic and cardiac index and mostly persisted after correction for systolic blood pressure or medical history of hypertension. Causal mediation analysis showed significant mediation by presence of CSVD in the relation between hypertensive exposure markers and cognitive impairment.

CONCLUSIONS

The extent of hypertensive exposure is associated with CSVD and cognitive impairment beyond clinical blood pressure or medical history. The mediating role of CSVD suggests that hypertension may lead to cognitive impairment through the occurrence of CSVD.

RV Tissue Heterogeneity on CT: A Novel Tool to Identify the VT Substrate in ARVC

OBJECTIVES

This study sought to evaluate whether right ventricular (RV) tissue heterogeneity on computed tomography (CT): 1) is associated with conduction delay in arrhythmogenic right ventricular cardiomyopathy (ARVC); and 2) distinguishes patients with ARVC from those with exercise-induced arrhythmogenic remodeling (EIAR) and control individuals.

BACKGROUND

ARVC is characterized by fibrofatty replacement, related to conduction delay and ventricular tachycardias. Distinguishing ARVC from acquired, EIAR is challenging.

METHODS

Patients with ARVC or EIAR and combined endocardial-epicardial electroanatomic voltage mapping for VT ablation with CT integration were enrolled. Patients without structural heart disease served as control individuals. Tissue heterogeneity on CT (CT heterogeneity) was automatically quantified within the 2-mm subepicardium of the entire RV free wall at normal sites and low voltage sites harboring late potentials (LP+) in ARVC/EIAR.

RESULTS

Seventeen patients with ARVC (15 males; age: 50 ± 17 years), 9 patients with EIAR (7 males; age: 45 ± 14 years) and 17 control individuals (14 males; age: 50 ± 15 years) were enrolled. Of 5,215 ARVC mapping points, 560 (11%) showed LP+. CT heterogeneity was higher at sites with LP+ compared to normal sites (median: 31 HU/mm; IQR: 23 to 46 HU/mm vs. median: 16 HU/mm; IQR: 13 to 21 HU/mm; p < 0.001). The optimal CT heterogeneity cutoff for detection of LP+ was 25 HU/mm (area under the curve [AUC]: 0.80; sensitivity: 72%; specificity: 78%). Overall CT heterogeneity allowed highly accurate differentiation between patients with ARVC and control individuals (AUC: 0.97; sensitivity: 100%; specificity: 82%) and between ARVC and EIAR (AUC: 0.78; sensitivity: 65%; specificity: 89%).

CONCLUSIONS

In patients with ARVC, tissue heterogeneity on CT can be used to identify LP+ as a surrogate for ventricular tachycardia substrate. The overall tissue heterogeneity on CT allows the distinguishing of patients with ARVC from those with EIAR and control individuals.

The clinical impact of phase offset errors and different correction methods in cardiovascular magnetic resonance phase contrast imaging: a multi-scanner study

BACKGROUND

Cardiovascular magnetic resonance (CMR) phase contrast (PC) flow measurements suffer from phase offset errors. Background subtraction based on stationary phantom measurements can most reliably be used to overcome this inaccuracy. Stationary tissue correction is an alternative and does not require additional phantom scanning. The aim of this study was 1) to compare measurements with and without stationary tissue correction to phantom corrected measurements on different GE Healthcare CMR scanners using different software packages and 2) to evaluate the clinical implications of these methods.

METHODS

CMR PC imaging of both the aortic and pulmonary artery flow was performed in patients on three different 1.5 T CMR scanners (GE Healthcare) using identical scan parameters. Uncorrected, first, second and third order stationary tissue corrected flow measurement were compared to phantom corrected flow measurements, our reference method, using Medis QFlow, Circle cvi42 and MASS software. The optimal (optimized) stationary tissue order was determined per scanner and software program. Velocity offsets, net flow, clinically significant difference (deviation > 10% net flow), and regurgitation severity were assessed.

RESULTS

Data from 175 patients (28 (17-38) years) were included, of which 84% had congenital heart disease. First, second and third order and optimized stationary tissue correction did not improve the velocity offsets and net flow measurements. Uncorrected measurements resulted in the least clinically significant differences in net flow compared to phantom corrected data. Optimized stationary tissue correction per scanner and software program resulted in net flow differences (> 10%) in 19% (MASS) and 30% (Circle cvi42) of all measurements compared to 18% (MASS) and 23% (Circle cvi42) with no correction. Compared to phantom correction, regurgitation reclassification was the least common using uncorrected data. One CMR scanner performed worse and significant net flow differences of > 10% were present both with and without stationary tissue correction in more than 30% of all measurements.

CONCLUSION

Phase offset errors had a significant impact on net flow quantification, regurgitation assessment and varied greatly between CMR scanners. Background phase correction using stationary tissue correction worsened accuracy compared to no correction on three GE Healthcare CMR scanners. Therefore, careful assessment of phase offset errors at each individual scanner is essential to determine whether routine use of phantom correction is necessary.

TRIAL REGISTRATION

Observational Study.

Association of scar distribution with epicardial electrograms and surface ventricular tachycardia QRS duration in nonischemic cardiomyopathy

INTRODUCTION

The association of late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) with epicardial and surface ventricular tachycardia (VT) electrogram features, in nonischemic cardiomyopathy (NICM), is unknown. We sought to define the association of LGE and viable wall thickness with epicardial electrogram features and exit site paced QRS duration in patients with NICM.

METHODS

A total of 19 patients (age 53.5 ± 11.5 years) with NICM (ejection fraction 40.2 ± 13.2%) underwent CMR before VT ablation. LGE transmurality was quantified on CMR and coregistered with 2294 endocardial and 2724 epicardial map points.

RESULTS

Both bipolar and unipolar voltage were associated with transmural signal intensity on CMR. Longer electrogram duration and fractionated potentials were associated with increased LGE transmurality, but late potentials or local abnormal ventricular activity were more prevalent in nontransmural versus transmural LGE regions (p < .05). Of all critical VT sites, 19% were located adjacent to regions with LGE but normal bipolar and unipolar voltage. Exit site QRS duration was affected by LGE transmurality and intramural scar location, but not by wall thickness, at the impulse origin.

CONCLUSIONS

In patients with NICM and VT, LGE is associated with epicardial electrogram features and may predict critical VT sites. Additionally, exit site QRS duration is affected by LGE transmurality and intramural location at the impulse origin or exit.

Comparison between quantitative cardiac magnetic resonance perfusion imaging and [15O]H2O positron emission tomography

Purpose

To compare cardiac magnetic resonance imaging (CMR) with [¹⁵O]H₂O positron emission tomography (PET) for quantification of absolute myocardial blood flow (MBF) and myocardial flow reserve (MFR) in patients with coronary artery disease (CAD).

Methods

Fifty-nine patients with stable CAD underwent CMR and [¹⁵O]H₂O PET. The CMR imaging protocol included late gadolinium enhancement to rule out presence of scar tissue and perfusion imaging using a dual sequence, single bolus technique. Absolute MBF was determined for the three main vascular territories at rest and during vasodilator stress.

Results

CMR measurements of regional stress MBF and MFR showed only moderate correlation to those obtained using PET (r = 0.39; P < 0.001 for stress MBF and r = 0.36; P < 0.001 for MFR). Bland-Altman analysis revealed a significant bias of 0.2 ± 1.0 mL/min/g for stress MBF and − 0.5 ± 1.2 for MFR. CMR-derived stress MBF and MFR demonstrated area under the curves of respectively 0.72 (95% CI: 0.65 to 0.79) and 0.76 (95% CI: 0.69 to 0.83) and had optimal cutoff values of 2.35 mL/min/g and 2.25 for detecting abnormal myocardial perfusion, defined as [¹⁵O]H₂O PET-derived stress MBF ≤ 2.3 mL/min/g and MFR ≤ 2.5. Using these cutoff values, CMR and PET were concordant in 137 (77%) vascular territories for stress MBF and 135 (80%) vascular territories for MFR.

Conclusion

CMR measurements of stress MBF and MFR showed modest agreement to those obtained with [¹⁵O]H₂O PET. Nevertheless, stress MBF and MFR were concordant between CMR and [¹⁵O]H₂O PET in 77% and 80% of vascular territories, respectively.

Effect of Liraglutide on Cardiovascular Function and Myocardial Tissue Characteristics in Type 2 Diabetes Patients of South Asian Descent Living in the Netherlands: A Double-Blind, Randomized, Placebo-Controlled Trial

Background

The glucagon‐like peptide‐1 (GLP‐1) receptor agonist liraglutide may be beneficial in the regression of diabetic cardiomyopathy. South Asian ethnic groups in particular are at risk of developing type 2 diabetes.

Purpose

To assess the effects of liraglutide on left ventricular (LV) diastolic and systolic function in South Asian type 2 diabetes patients.

Study Type

Prospective, double‐blind, randomized, placebo‐controlled trial.

Population

Forty‐seven type 2 diabetes patients of South Asian ancestry living in the Netherlands, with or without ischemic heart disease, who were randomly assigned to 26‐week treatment with liraglutide (1.8 mg/day) or placebo.

Field Strength/Sequence

3T (balanced steady‐state free precession cine MRI, 2D and 4D velocity‐encoded MRI, ¹H‐MRS, T₁ mapping).

Assessment

Primary endpoints were changes in LV diastolic function (early deceleration peak [Edec], ratio of early and late peak filling rate [E/A], estimated LV filling pressure [E/Ea]) and LV systolic function (ejection fraction). Secondary endpoints were changes in aortic stiffness (aortic pulse wave velocity [PWV]), myocardial steatosis (myocardial triglyceride content), and diffuse fibrosis (extracellular volume [ECV]).

Statistical Tests

Data were analyzed according to intention‐to‐treat. Between‐group differences were reported as mean (95% confidence interval [CI]) and were assessed using analysis of covariance (ANCOVA).

Results

Liraglutide (n = 22) compared with placebo (n = 25) did not change Edec (+0.2 mL/s² × 10^‐3 (–0.3;0.6)), E/A (–0.09 (–0.23;0.05)), E/Ea (+0.1 (–1.2;1.3)) and ejection fraction (0% (–3;2)), but decreased stroke volume (–9 mL (–14;–5)) and increased heart rate (+10 bpm (4;15)). Aortic PWV (+0.5 m/s (–0.6;1.6)), myocardial triglyceride content (+0.21% (–0.09;0.51)), and ECV (–0.2% (–1.4;1.0)) were unaltered.

Data Conclusion

Liraglutide did not affect LV diastolic and systolic function, aortic stiffness, myocardial triglyceride content, or extracellular volume in Dutch South Asian type 2 diabetes patients with or without coronary artery disease.

Level of Evidence: 1

Technical Efficacy Stage: 4

J. Magn. Reson. Imaging 2020;51:1679–1688.

Impact of Epicardial Adipose Tissue, Left Ventricular Myocardial Fat Content, and Interstitial Fibrosis on Myocardial Contractile Function

Background Current understanding of metabolic heart disease consists of a myriad of different pathophysiological mechanisms. Epicardial adipose tissue (EAT) is increasingly recognized as metabolically active and associated with adverse cardiovascular outcomes. The present study aimed to investigate the effect of increased EAT volume index on left ventricular (LV) myocardial fat content and burden of interstitial myocardial fibrosis and their subsequent effects on LV myocardial contractile function. Methods and Results A total of 40 volunteers (mean age, 35±10 years; 26 males) of varying body mass index (25.0±4.1 kg/m²; range, 19.3-36.3 kg/m²) and without diabetes mellitus or hypertension were prospectively recruited. EAT volume index, LV myocardial fat content, and extracellular volume were quantified by magnetic resonance imaging. LV myocardial contractile function was quantified by speckle tracking echocardiography global longitudinal strain on the same day as magnetic resonance imaging examination. Mean total EAT volume index, LV myocardial fat content, and extracellular volume were 30.0±19.6 cm³/m², 5.06%±1.18%, and 27.5%±0.5%, respectively. On multivariable analyses, increased EAT volume index and insulin resistance were independently associated with both increased LV myocardial fat content content and higher burden of interstitial myocardial fibrosis. Furthermore, increased EAT volume index was independently associated with LV global longitudinal strain. Conclusions Increased EAT volume index and insulin resistance were independently associated with increased myocardial fat accumulation and interstitial myocardial fibrosis. Increased EAT volume index was associated with detrimental effects on myocardial contractile function as evidenced by a reduction in LV global longitudinal strain.

Fetal and infant growth patterns and left and right ventricular measures in childhood assessed by cardiac MRI

OBJECTIVES

Early life is critical for cardiac development. We examined the associations of longitudinal fetal and childhood growth patterns with childhood right and left ventricular structures measured by cardiac magnetic resonance imaging.

METHODS

In a population-based prospective cohort study among 2827 children, we measured growth at 20 and 30 weeks of pregnancy, at birth, 0.5, 1, 2, 6 and 10 years. At 10 years, we measured right ventricular end-diastolic volume, left ventricular end-diastolic volume, left ventricular mass and left ventricular mass-to-volume ratio by cardiac magnetic resonance imaging.

RESULTS

Small size for gestational age at birth was associated with smaller right and left ventricular end-diastolic volume relative to current body surface area, but with larger left ventricular mass-to-volume ratio (P < 0.05). Children in the upper 25% of right and left ventricular end-diastolic volume and left ventricular mass at age 10 years were larger at birth and became taller and leaner in childhood (P < 0.05). In contrast, children in the lower 25% of right and left ventricular end-diastolic volume and left ventricular mass were smaller at birth and became shorter and heavier in childhood (P < 0.05). Both fetal and childhood growth were independently of each other associated with childhood right and left ventricular end-diastolic volume and left ventricular mass.

CONCLUSION

Children who are larger at birth and grow taller and leaner in childhood have larger hearts relative to body surface area. Small size at birth children, who grow shorter and heavier in childhood, have relatively smaller hearts with larger left ventricular mass-to-volume ratio. Both fetal and childhood growth are important for the development of cardiac dimensions.

Cine MRI analysis by deep learning of optical flow: Adding the temporal dimension

Accurate segmentation of the left ventricle (LV) from cine magnetic resonance imaging (MRI) is an important step in the reliable assessment of cardiac function in cardiovascular disease patients. Several deep learning convolutional neural network (CNN) models have achieved state-of-the-art performances for LV segmentation from cine MRI. However, most published deep learning methods use individual cine frames as input and process each frame separately. This approach entirely ignores an important visual clue-the dynamic cardiac motion along the temporal axis, which radiologists observe closely when viewing cine MRI. To imitate the approach of experts, we propose a novel U-net-based method (OF-net) that integrates temporal information from cine MRI into LV segmentation. Our proposed network adds the temporal dimension by incorporating an optical flow (OF) field to capture the cardiac motion. In addition, we introduce two additional modules, a LV localization module and an attention module, that provide improved LV detection and segmentation accuracy, respectively. We evaluated OF-net on the public Cardiac Atlas database with multicenter cine MRI data. The results showed that OF-net achieves an average perpendicular distance (APD) of 0.90±0.08 pixels and a Dice index of 0.95±0.03 for LV segmentation in the middle slices, outperforming the classical U-net model (APD 0.92±0.04 pixels, Dice 0.94±0.16, p < 0.05). Specifically, the proposed method enhances the temporal continuity of segmentation at the apical and basal slices, which are typically more difficult to segment than middle slices. Our work exemplifies the ability of CNN to "learn" from expert experience when applied to specific analysis tasks.