Aug 2026· Journal of Cardiovascular Magnetic Resonance· pp.
102792
· 0 citations· 52 references
Medicine
TL;DR
Volumetric real-time MRI is feasible for the guidance of invasive procedures such as right-heart catheterization at 0.55T and offers flexible real-time re-slicing, volumetric 3D visualization, and the potential for improved device monitoring.
Abstract
Background
Interventional cardiovascular MRI (iCMR) uses rapid high-contrast images to guide invasive procedures, such as right-heart catheterization (RHC), an important diagnostic tool for characterizing pulmonary hypertension and heart failure. Current iCMR uses interleaved multi-planar 2D acquisitions (1-3 planes) with balanced steady-state free precession (bSSFP) contrast. A common challenge is tracking devices as they move out of plane and the operational burden of updating views in real-time. We propose a volumetric method that images the heart and great vessels in their entirety, and offers flexible real-time re-slicing, volumetric 3D visualization, and the potential for improved device monitoring.
Methods
Volumetric real-time MRI (3DRT) was implemented at 0.55T using a stack-of-spirals bSSFP acquisition paired with a low-latency online spatiotemporally constrained image reconstruction, to achieve 3.5 mm3 isotropic spatial resolution and ~500 ms/volume temporal resolution. Numerical simulations were performed to evaluate tracking capability of gadolinium balloons as a function of device speed, and to verify image quality. Six healthy volunteers were imaged without catheterization to test performance on human subjects. Six naïve pigs were imaged during RHC, with gadolinium-filled polymer balloon wedge end-hole catheters.
Results
Simulation experiments demonstrated that 3DRT imaging with low-latency spatiotemporally constrained reconstruction can resolve moving catheters at ~2.0cm/s. 3DRT with bSSFP contrast was successfully demonstrated for right-heart catheterization procedures in porcine models, providing adequate blood-myocardium contrast, and balloon-blood contrast to track the catheter tip. 3DRT images provided adequate image quality and resolved respiratory motion in healthy volunteers. Volumes were re-sliced live and re-sliced planes could be flexibly manipulated during the scan in real-time before the next volume was acquired.
Conclusion
Volumetric real-time MRI is feasible for the guidance of invasive procedures such as right-heart catheterization at 0.55T. 3DRT imaging has been demonstrated in model pig experiments with ~500 ms temporal resolution and 3.5 mm3 isotropic spatial resolution, providing improved balloon tracking.
BACKGROUND
Cardiovascular magnetic resonance (CMR) is the reference standard for assessing cardiac function, yet its widespread clinical use remains challenged by time-intensive workflows requiring ECG gating, repetitive breath-holding, and expert planning. The free-running framework (FRF) addresses these barriers by enabling respiratory and cardiac motion resolved (5D) whole-heart imaging without ECG, breath-holds, or expert scan plane planning. Its fast interrupted steady-state (FISS) variant further enables high quality clinical imaging with gadolinium-based or ferumoxytol contrast agents by providing balanced steady-state free precession (bSSFP)-like contrast with intrinsic fat suppression. The combined 5D FISS-FRF approach, therefore, enables 3D, motion-resolved, free-breathing whole-heart imaging with efficient fat suppression. Early single-center studies have demonstrated feasibility and high concordance with conventional 2D cine imaging, but its generalizability and clinical utility in a multi-center, multi-vendor setting is not yet established.
METHODS/DESIGN
FAST-CMR (Assessment and validation of the established free-running framework for cardiac function by magnetic resonance imaging) is a prospective, observational, intra-individually controlled, pragmatic multi-center study enrolling 300 patients with cardiac disease across 21 international sites from 6 continents using 1.5T MR systems of both Siemens Healthineers and Philips Healthcare. Patients will undergo conventional 2D cine bSSFP CMR in both short-axis and long-axis orientations and a post-contrast 5D FISS-FRF acquisition of six minutes in length. Stratification will include equal representation across three disease cohorts: patients with congenital heart disease (CHD), patients unable to breath-hold, and patients who are able to breath-hold. 5D FISS-FRF raw image acquisition data will undergo centralized reconstruction at the coordinating center (CHUV) before blinded analysis at the core laboratory (Mayo Clinic). The primary endpoint is the precision of the mean paired difference in left ventricular ejection fraction (LVEF) between 5D FISS-FRF and conventional 2D cine CMR, assessed on a within-subject basis. Agreement will be further characterized using confidence intervals for the mean difference and Bland-Altman analysis. Secondary endpoints include detection of regional wall-motion abnormalities, image quality, scan efficiency, patient comfort, LV mass, left and right atrial volumes, and feasibility of automated post-processing and artificial intelligence (AI)-based reconstruction.
DISCUSSION/CONCLUSION
FAST-CMR will provide the first prospective international multi-center, multi-vendor evaluation of 5D FISS-FRF. By combining standardized acquisition, centralized reconstruction, and harmonized analysis across 21 international sites and two vendor systems, the study will assess the generalizability and robustness of ventricular functional measurements obtained with 5D FISS-FRF. Using a pre-specified precision-based framework for global ventricular function and complementary agreement analyses, FAST-CMR will evaluate whether 5D FISS-FRF can provide measurements that are comparable to conventional 2D cine across diverse clinical settings, while potentially offering improvements in workflow, scan efficiency and patient experience. These results will inform future studies assessing clinical interchangeability with conventional 2D cine imaging and implementation in routine CMR practice.
K. Eyre, Kenan Kaya, T. Coudert et al.· Journal of Cardiovascular Ma...· 0 citations
BACKGROUND
Conventional cardiovascular magnetic resonance (CMR) in pediatric and congenital heart disease uses 2D, breath-hold (BH), balanced steady state free precession (bSSFP) cine imaging for assessment of function, in addition to cardiac-gated, respiratory-navigated, static 3D bSSFP whole-heart imaging for anatomical assessment. Our aim is to concatenate a stack of 2D free-breathing real-time cines and use Deep Learning (DL) to create an isotropic fully segmented 'pseudo' 3D-cine dataset from these images.
METHODS
Four DL models were trained on open-source data that performed: a) Interslice signal-correction; b) Interslice respiratory-correction; c) Super-resolution in the slice direction; and d) Segmentation of right and left atria and ventricles (RA, LA, RV, and LV), thoracic aorta (Ao) and pulmonary arteries (PA). Our method was validated in 20 patients undergoing routine cardiovascular examination, by converting prospectively acquired sagittal stacks of real-time cine images to segmented, isotropic pseudo 3D-cine data. Quantitative metrics (ventricular volumes and vessel diameters) and image quality of the DL pseudo-3D-cines were compared to reference-standard breath-hold cine and whole-heart imaging.
RESULTS
All real-time data were successfully transformed into pseudo 3D-cines with a total offline reconstruction and post-processing time of <1min in all cases. There were no significant biases in any left ventricular (LV) or right ventricular (RV) metrics (bias ± standard deviation in ml, LV end diastolic volume (EDV): 0.7 ± 8.8, LV end systolic volume (ESV): -1.7 ± 7.1, RV EDV: 1.9 ± 12.4, RV ESV: -1.5 ± 10.7) with reasonable limits of agreement and correlation. There is also reasonable agreement for all vessel diameters, although there was a small but significant overestimation (p<0.05) of right PA (RPA) and main PA (MPA) diameter (RPA: bias = -1.0mm. MPA: bias = -1.1mm). The DL pseudo-3D-cine data were assessed to be of adequate diagnostic quality unlike the unprocessed 2D real-time data.
CONCLUSION
We have demonstrated the potential of creating a pseudo 3D-cine data from concatenated 2D real-time cine images using a series of DL models. Our method has short acquisition and reconstruction times with fully segmented data being available in less than one minute. Our models are trained from fully open-source datasets, allowing our technique to be easily shared with other clinical centers. The agreement with reference-standard imaging suggests that our method could help to significantly speed up CMR in clinical practice.
Mark Wrobel, T. Yao, Ruaraidh Campbell et al.· Journal of Cardiovascular Ma...· 0 citations
Abstract Objectives To evaluate the feasibility and clinical utility of cardiovascular four-dimensional flow magnetic resonance imaging (4D Flow MRI) for multidirectional hemodynamic visualization and quantitative assessment. Methods This single-centre observational study included 30 cardiovascular MRI cases acquired at Huaqiao University Affiliated Strait Hospital using a Siemens MAGNETOM Skyra 3.0-T system with an 18-channel phased-array coil. Time-resolved three-dimensional velocity-encoded 4D Flow MRI was performed with retrospective electrocardiographic gating, respiratory compensation, and region-adjusted velocity encoding. Acquisition parameters included TR/TE 38.88/6.88 ms, flip angle 8°, matrix 256 × 256, field of view 300 mm, in-plane spatial resolution 1.4 × 1.4 mm, slice thickness 3 mm, and slice gap 0.6 mm. Preprocessing corrected background phase offsets, Maxwell terms, velocity aliasing, and noise artefacts. Results 4D Flow MRI enabled assessment of intracardiac shunting, pulmonary regurgitation, Fontan circulation, bicuspid aortic valve hemodynamics, aortic regurgitation, and atrioventricular valve dysfunction. Quantified parameters included pulmonary-to-systemic flow ratio, shunt volume, regurgitant fraction, peak velocity, pressure gradient, wall shear stress, vorticity, helicity, kinetic energy, turbulent kinetic energy, oscillatory shear index, and energy loss. Conclusions Cardiovascular 4D Flow MRI supports patient-specific hemodynamic assessment across complex cardiovascular conditions within a practical single-centre clinical workflow with retrospective quantification.
Yuguang Ye, Taisheng Zeng, Yusi Chen et al.· Biomedizinische Technik. Bio...· 0 citations
PURPOSE
4D cardiac cine is a powerful tool for comprehensive cardiac function assessment; however, current methods rely on regular breathing and are sensitive to bulk motion and arrhythmia. We aim to develop a 4D cardiac cine approach that requires no patient cooperation and is robust to irregular breathing, bulk motion, and cardiac arrhythmia.
METHODS
2D real-time (RT) spiral bSSFP with synchronized ECG was acquired in 4 cardiac orientations. In each orientation, the 2D slice was "swept" across the heart to provide volume coverage. Retrospectively gated slice-to-volume reconstruction (SVR) was then performed to reconstruct 4D cine with 1 mm3 voxel size and 25 cardiac phases. RT-SVR and clinical standard breath-hold short-axis cine were acquired in 19 subjects, including 4 arrhythmia and 2 myocardial infarction patients. Biventricular volumes were measured, and blood-myocardium contrast and boundary sharpness scores were compared.
RESULTS
The RT-SVR approach successfully provided 4D cardiac cine for all subjects. Acquisition time was 8:33 ± 1:01 min and 8:27 ± 2:06 min (p = 0.85), blood-myocardium contrast ratio was 2.30 ± 0.58 and 2.38 ± 0.59 (p = 0.33), boundary sharpness was 1.11 ± 0.46 and 1.18 ± 0.53 (p = 0.04), for RT-SVR and breath-hold cine, respectively. Bi-ventricular volumes had good agreement, with an ejection fraction bias of -4.02% (p < 0.05) and -2.30% (p = 0.10) for left and right ventricles, respectively.
CONCLUSION
The RT-SVR approach enables 4D cardiac cine with comparable bi-ventricular volumes, contrast, sharpness, and acquisition time compared to standard breath-hold cine while providing additional motion robustness. This approach may be beneficial in patients that are non-cooperative, children, and those with irregular breathing and/or arrhythmia.
Ye Tian, Anand A Joshi, Jon A. Detterich et al.· Magnetic Resonance in Medici...· 0 citations
AIMS
Cardiac MRI is central to evaluating ventricular function and hemodynamics in pediatric congenital heart disease (CHD). Conventional two-dimensional phase-contrast (2D-PC) imaging is challenged by fixed planes, operator dependence, and multiple breath-holds, where four-dimensional flow (4DF) MRI overcomes these challenges. This study compares accelerated whole heart 4D Flow (WH-4DF) MRI with 2D-PC and volumetric measurements in routine clinical follow up of pediatric CHD and highlights its applicability.
METHODS AND RESULTS
For this prospective study seventy-one consecutive pediatric patients (median age 14 ± 2.4 years; 49 male) with surgically corrected CHD underwent both 2D-PC and accelerated WH-4DF MRI. Planning and acquisition times and overall success rate were recorded. Flow, velocity and volumetric measurements were compared using Bland-Altman analysis, orthogonal regression, and intraclass correlation coefficients. WH-4DF showed excellent agreement with 2D-PC and short-axis volumetry for aortic, pulmonary, and ventricular stroke volumes (mean differences <5%). Mean planning and acquisition time for WH-4DF was 10.3minutes (SD 1.1), where planning and acquisition time of 2D-PC was 11.2minutes (SD 6.25). Aliasing was observed in 11% of the WH-4DF acquisitions but did not compromise interpretability.
CONCLUSIONS
Accelerated WH-4DF MRI is clinically robust and broadly applicable across CHD, including complex postoperative anatomies. It provides comparable numbers to 2D-PC, reproducible, and time-efficient flow quantification with superior coverage and reduced operator dependence. A single WH-4DF scan can replace multiple 2D-PC acquisitions with comparable results and may enhance assessment of regurgitant flow. These features underscore its potential role in routine clinical practice and in advancing our understanding of disease processes.
J. van Schuppen, A. E. van der Hulst, R. A. P. Takx et al.· Journal of Cardiovascular Ma...· 0 citations
Fetal cardiac MRI (fCMR) provides valuable diagnostic information complementary to echocardiography, particularly for complex congenital heart disease (CHD). Dynamic cine imaging captures cardiac motion essential for assessment of cardiac function; however, the reconstruction of 3D+time cine volumes from 2D+time acquired slices remains challenging due to unpredictable fetal motion and the absence of automated and robust processing tools suitable for clinical deployment. We present the SPARC pipeline (Slice-to-volume Pipeline for Automated Reconstruction of gated 3D+time fetal Cardiac MRI) which combines physics-informed slice-to-volume reconstruction (SVR) of Doppler ultrasound (DUS) gated stacks of slices, assisted by deep learning (DL) models for thoracic segmentation and anatomical reorientation. The proposed SVR algorithm achieves a tenfold reduction in reconstruction time relative to existing frame-wise approaches ($4.8 \pm 1.0$ vs $49.0 \pm 14.1$ min, $p<0.0001$) while improving the reconstruction quality. Thoracic segmentation performance using ensemble aggregation exceeded inter-rater agreement (Dice $84.7 \pm 3.9\%$ vs $81.4 \pm 7.7\%$, $p<0.05$), while anatomical reorientation achieved a success rate of $90.1\%$. End-to-end evaluation on a large held-out clinical cohort ($n = 121$) demonstrated fully automatic processing in $82.6\%$ of cases with a mean runtime of $7.1 \pm 1.3$ min, compatible with clinical deployment. The complete SPARC pipeline is publicly available as a Docker container https://hub.docker.com/r/aboutill/sparc and is currently deployed at our institution as a clinical research tool.
Arnaud Boutillon, Naomi Clarke, Tomás Woodgate et al.· 0 citations