Journal of Cardiovascular Magnetic Resonance最新文献

Background: Secondary pulmonary lymphangiectasia (PL) is a recognised complication of hypoplastic left heart syndrome (HLHS) with an intact or restrictive atrial septum, associated with poor postnatal outcomes. Fetal MRI has been increasingly used to assess pulmonary abnormalities in HLHS, but the prognostic significance of subtle PL-like changes remains unclear. In this study, we evaluate the relationship between fetal MRI lung findings, echocardiographic markers of pulmonary venous obstruction, and postnatal outcomes.

Methods: A retrospective analysis of all fetuses with HLHS who underwent fetal MRI between July 2019 and December 2022 was performed. MRI images were reviewed for features of PL and categorised as "normal," "suspicious," or "diagnostic" of PL. Pulmonary venous Doppler velocity-time integral (VTI) ratios from the most recent fetal echocardiogram were then compared to MRI findings. Postnatal outcomes, including early ventilation, need for intervention, and survival at 28 days and 1 year, were assessed.

Results: Of 20 fetuses with HLHS who underwent MRI, 6/20 (30%) showed features suspicious or diagnostic of PL (5 "suspicious" and 1 "diagnostic"), and 6/20 (30%) showed some evidence of pulmonary venous obstruction (PVO) on echo. While echo markers of PVO were significantly associated with some degree of PL on MRI (p=0.006), neither PL nor PVO predicted the need for early support/intervention or survival in fetuses who underwent active postnatal management.

Conclusion: Fetuses with HLHS may exhibit a spectrum of lung changes on fetal MRI related to pulmonary venous obstruction. Whilst technical factors may also play a role, a degree of caution is advisable when interpreting more subtle forms of PL in fetal life, particularly in the absence of echocardiographic markers of severe atrial restriction. Larger, multi-centre prospective studies are needed to refine diagnostic criteria for PL in HLHS and better understand its prognostic significance in terms of both early and long-term outcome.

Background: Image reconstruction from highly undersampled four-dimensional (4D) flow magnetic resonance imaging (MRI) data can be very time-consuming and may result in significant underestimation of velocities depending on regularization, thereby limiting the applicability of the method. The objective of the present work was to develop a generalizable self-supervised deep learning-based framework for fast and accurate reconstruction of highly undersampled 4D flow MRI and to demonstrate the utility of the framework for aortic and cerebrovascular applications.

Methods: The proposed deep-learning-based framework, called FlowMRI-Net, employs physics-driven unrolled optimization using a complex-valued convolutional recurrent neural network and is trained in a self-supervised manner. The generalizability of the framework is evaluated using aortic and cerebrovascular 4D flow MRI acquisitions acquired on systems from two different vendors for various undersampling factors (R = 8, 16, 24) and compared to compressed sensing locally low rank (CS-LLR) reconstructions. Evaluation includes an ablation study and a qualitative and quantitative analysis of image and velocity magnitudes.

Results: FlowMRI-Net outperforms CS-LLR for aortic 4D flow MRI reconstruction, resulting in significantly lower vectorial normalized root mean square error and mean directional errors for velocities in the thoracic aorta. Furthermore, the feasibility of FlowMRI-Net's generalizability is demonstrated for cerebrovascular 4D flow MRI reconstruction. Reconstruction times ranged from 3 to 7 min on commodity central processing unit/graphical processing unit hardware.

Conclusion: FlowMRI-Net enables fast and accurate reconstruction of highly undersampled aortic and cerebrovascular 4D flow MRI, with possible applications to other vascular territories.

Background: Cardiac cine imaging is routinely used in patient with suspected or known cardiac dysfunction. Water and fat (W/F) separated cardiovascular magnetic resonance (CMR) will be helpful to distinguish adipose tissue, blood, and myocardium. Inclusion of a multi-echo acquisition in the conventional balanced steady-state free precession (bSSFP) cine sequence can introduce artifacts and reduce temporal resolution. Spiral MRI is known for its signal-to-noise ratio (SNR) efficiency and has the potential to improve temporal efficiency for W/F separated cine imaging. The present work implements a spoiled gradient echo sequence (SPGR) with spiral trajectory to obtain W/F separated cine images simultaneously.

Methods: Three different sequences were performed for comparison, a Cartesian 2-TE bSSFP sequence, a Cartesian 3-TE bSSFP sequence, and the proposed spiral SPGR sequence. Five volunteers were recruited for the scans on a 1.5T scanner with spatial resolution 1.7×1.7×8.0mm³ over a 400×400mm² FOV. In addition to qualitative comparisons, a quantitative measurement is performed in terms of the contrast-to-noise ratio (CNR).

Results: The proposed method to obtain W/F separated cine images provides better temporal efficiency and fewer artifacts compared to conventional Cartesian bSSFP sequences. The 2-TE bSSFP features the highest artifact level, including susceptibility artifacts and fat/water swaps. The proposed method reduces scan time by approximately 50% with similar spatial and temporal resolution with lower specific absorption rate (SAR). The contrast between the blood pool and myocardium is higher when using the spiral readout (p≤0.05). The results suggest that the presented sequence has potential to facilitate simultaneous imaging for water and fat components in a cine scan while shortening exam time and lowering SAR.

Background: Cardiomyopathy (CMP) is the leading cause of death in Duchenne muscular dystrophy (DMD). Characterization of disease trajectory can be challenging, especially in early stages of CMP, where onset and progression may vary. Traditional metrics from cardiovascular magnetic resonance (CMR) imaging, such as left ventricular ejection fraction (LVEF) (left ventricular ejection fraction) and late gadolinium enhancement (LGE) are often insufficient for assessing the pace of disease progression. We hypothesized that strain patterns from a novel four-dimensional (4D) (three-dimensional [3D]+time) CMR regional strain analysis method can be used to predict DMD CMP progression.

Methods: We compiled 190 short-axis cine CMR image stacks for n=66 pediatric DMD patients (age: 13.3 [10.8-16.5] years; median [interquartile range]) imaged for 3 consecutive years and computed regional strain metrics using custom-built feature-tracking software. We measured regional strain parameters from the generated 4D endocardial surface mesh.

Results: Using LVEF decrease, measured two years following the initial scan, we classified patients into slow (ΔLVEF%<5; n=35) or fast (ΔLVEF%≥5; n=30) progressing groups. There was no statistical difference between the slow and fast-progressing groups in terms of standard metrics such as age, LVEF, or LGE status. However, peak basal circumferential strain (E_cc) and surface area strain (E_a) magnitudes were decreased in fast progressors (p<0.01 for all). Basal E_cc late diastolic strain rate and basal E_a late diastolic strain rate magnitude were also significantly decreased in fast progressors (p<0.01 for all).

Conclusion: Regional strain metrics from 4D CMR can be used to differentiate between slow or fast CMP progression in a longitudinal DMD cohort.

Background: Fetal cardiovascular magnetic resonance (CMR) is a valuable tool for assessing fetal blood flow; however, its use has primarily been focused on near-term pregnancies. This study aimed to evaluate the feasibility of Doppler ultrasound-gated two-dimensional (2D) phase-contrast CMR of the human fetus in the early, mid, and late third trimester.

Methods: A total of 100 fetal MRI scans were performed at gestational age (GA) 28, 32, and 38 weeks in 38 fetuses with (n = 13) and without (n = 25) congenital heart defects. Combined ventricular output was measured by Doppler ultrasound-gated 2D phase-contrast CMR in the ascending aorta and main pulmonary artery. Success rate of acquisition, repeatability of phase-contrast measurements, and intra-/interobserver agreement were assessed at each GA.

Results: Combined ventricular output was obtained in 76/100 (76%) scans. The success rate of acquisition improved with increasing GA from 15/34 (44%) at GA 28 weeks to 31/35 (89%) at GA 32 weeks (p < 0.001 compared to 28 weeks) and 30/31 (97%) at GA 38 weeks (p < 0.001 compared to 28 weeks). Repeatability of phase-contrast measurements demonstrated a moderate to strong correlation (r = 0.63-0.82, p = 0.002), with no significant bias but wide limits of agreement. The mean difference ±95% limits of agreement were 7.3 ± 245 mL/min, -13.0 ± 260 mL/min, and -3.9 ± 326 mL/min at 28, 32, and 38 weeks, respectively.

Conclusion: Feasibility of fetal CMR improves with increasing GA. While Doppler-gated 2D phase-contrast CMR can effectively assess fetal combined ventricular output and allows for in-group comparisons, the precision may still be insufficient for clinical application.

Background: Structural and functional abnormalities of the left atrium (LA) predict adverse outcomes such as heart failure and mortality in many patients with heart disease. However, the effect of anthracyclines on LA structural and functional abnormalities remains incompletely characterized. Further, atorvastatin prevented the anthracycline-associated decline in the left ventricular ejection fraction; however, whether atorvastatin protects against anthracycline-associated impairment of LA structure and function is currently unknown.

Methods: In the STOP-CA randomized clinical trial, participants with lymphoma treated with anthracyclines were randomized to placebo (n=150) or atorvastatin (n=150) for 12 months. In post hoc analyses, CMR-derived LA volumetric and functional measurements (reservoir [GLS], conduit, and booster strain) were measured at baseline and 12 months using feature tracking (FT). The primary endpoint was the difference in the proportion of participants with a ≥1 SD decrease in LA GLS between the atorvastatin and placebo groups. The secondary endpoint was a ≥20% relative decrease in LA GLS. Other exploratory endpoints included volume indices and emptying fractions.

Results: Of 300 participants, 158 (mean age 51±16years, 48% female, 83 with atorvastatin) had paired CMR-derived LA strain and volumetric data at baseline and follow-up. Both groups had similar baseline characteristics and cancer treatment. All LA strain and volumetric measures were similar between the two groups at baseline. Among the placebo group, LA GLS decreased from baseline to follow-up (35.5±8.8 vs 32.4±8.2%, p=0.007). A ≥1 SD absolute decrease in LA GLS (8.8% units) was observed among 24% with atorvastatin and 28% with placebo (p=0.59). Similarly, a ≥20% relative decrease in GLS was observed in 25% vs 31% (p=0.48). Participants over 50 had an almost 10% (9.9%, 95% confidence interval: -18.75, -1.12) greater relative decrease in LA GLS with anthracyclines. There were no differences between cardiac hospitalization rates with a ≥1 SD absolute decrease (5% vs 8%, p=0.72) in LA GLS at 24 months. Among other indices of LA structure and function, the LA total emptying fraction also decreased from baseline to follow-up, with no differences between groups at follow-up.

Conclusion: Atorvastatin did not attenuate the decline in CMR-derived LA GLS among lymphoma patients undergoing anthracycline-based chemotherapy.

Clinical trial registration: NCT02943590; https://clinicaltrials.gov/study/NCT02943590.

Background: Cardiac diffusion tensor imaging (cDTI) is an emerging technique for microstructural characterization of the heart and has shown clinical potential in a range of cardiomyopathies. However, there is substantial variation reported for in vivo cDTI results across the literature, and sensitivity of cDTI to differences in imaging sites, scanners, acquisition protocols, and post-processing methods remains incompletely understood.

Methods: SIGNET is a prospective multi-center, observational study in traveling and non-traveling healthy volunteers. The study was initiated by the executive board of the Society of Cardiovascular Magnetic Resonance (SCMR) Cardiac Diffusion Special Interest Group (SIG) as a follow-up to a previous multi-center study on phantom validation of cardiac DTI and a recently published SCMR consensus statement on cardiac diffusion MRI. The study has been developed by the Project Management Committee in consultation with the SCMR cardiac diffusion SIG, which includes international experts in cardiac diffusion MRI. To date, more than 20 international institutions have engaged with the study, including sites that are new to cardiac DTI, making this the largest collaborative effort in the field.

Discussion: SIGNET will provide important information about the key sources of variation in cardiac DTI. This will help rationalize strategies for addressing and minimizing such variation. Harmonization of protocols in this and future studies will underpin efforts to translate cardiac DTI for clinical application.

Background: Identifying the cause of dyspnea (i.e., cardiac vs. non-cardiac) can be challenging in the absence of significant resting cardiac abnormalities. Exercise cardiovascular magnetic resonance (Ex-CMR) enables quantification of cardiac volumetric indices under physiological stress. Using Ex-CMR, we sought to develop a non-invasive imaging marker, referred to as the myocardial dynamic index (MDI), and to demonstrate its potential for evaluating cardiac dyspnea.

Methods: MDI is a metric derived from Ex-CMR work-volume loop model that integrates rest and stress left ventricular (LV) end-diastolic and end-systolic volumes with workload measured during supine exercise, while accounting for body size and LV mass. To evaluate MDI as a marker of cardiac dyspnea, we retrospectively analyzed data from a prospective multicenter study measuring MDI in patients with cardiac or non-cardiac dyspnea. All had invasive exercise testing before Ex-CMR. Cardiac dyspnea was defined by established invasive and non-invasive criteria, including HFpEF (early to advanced) and HFmrEF. Non-cardiac dyspnea patients had normal invasive hemodynamics and cardiac function. Univariable and multivariable logistic regression identified clinical and imaging predictors of cardiac dyspnea. A base model incorporating clinical and rest CMR variables was compared to a model that included the base model plus MDI. Diagnostic performance was assessed using receiver operating characteristic analysis and compared using the DeLong test. MDI scan/re-scan reproducibility over one year, inter- and intra-observer reproducibility, and correlation with VO₂ max were evaluated.

Results: Among 93 patients (66 with cardiac dyspnea, 27 with non-cardiac dyspnea), MDI was lower in patients with cardiac dyspnea (25.9±9.5 vs. 45.1±10.7 mL·W/g/m², p<0.0001). The base model included age, body mass index, NYHA class, and left atrial strain. In multivariable analysis, MDI emerged as the only independent predictor of cardiac dyspnea when added to the base model. Inclusion of MDI improved the AUC from 0.86 to 0.93 (p=0.012), while MDI alone yielded an AUC of 0.91. A strong correlation was observed between MDI and the VO₂ max index (r=0.84, p<0.0001). Reproducibility was excellent.

Conclusion: Ex-CMR MDI is independently associated with cardiac dyspnea and strongly correlates with the VO₂ max index. It aids in differentiating cardiac from non-cardiac dyspnea and provides incremental diagnostic value beyond conventional clinical and resting imaging parameters.

Background: Serial perfusion cardiovascular magnetic resonance (CMR) in symptomatic patients undergoing coronary artery bypass grafting (CABG) may provide mechanistic insight into dynamic abnormalities of the myocardium.

Objectives: To assess how changes in cardiac reperfusion and remodeling associate with symptom improvement in patients undergoing CABG METHODS: Patients awaiting elective CABG completed serial quality of life questionnaires and detailed CMR at baseline and at 6-12 months post-CABG as per protocol. Automated fully quantitative stress and rest myocardial blood flow was calculated, alongside assessment of the visual ischemic burden. Findings were correlated with changes in symptomatology.

Results: Of 40 patients who underwent serial evaluation with CMR (mean age 62.1±9.3, median LVEF 68% [IQR: 62-73%]), there was improvement in the median visual ischemic burden (42% [IQR: 27-51] vs 18% [IQR: 11-21], P<0.001), mean global stress myocardial blood flow (1.34±0.5 mL/min/g vs 1.59±0.5 mL/min/g, P=0.002) and median global myocardial perfusion reserve (1.85±0.6 vs 2.4±0.9, P<0.001) following CABG. Greater improvement in the SAQ-7 summary score was associated with a greater decrease in the visual ischemic burden following CABG (ρ=-0.38, P=0.02). Quantitative MBF metrics did not associate with baseline or change in SAQ-7 summary score.

Conclusion: Serial perfusion CMR identifies dynamic changes in markers of myocardial perfusion in patients following CABG. Greater reduction of visually assessed ischemia associated with improvement in SAQ-7 score. Quantitative perfusion indices were not associated with symptom improvement in this study. The results also suggest residual inducible ischemia post-CABG, requiring further studies to elucidate its clinical relevance.