Visualization of coronary arteries in paediatric patients using whole-heart coronary magnetic resonance angiography: comparison of image-navigation and the standard approach for respiratory motion compensation

Aims: To investigate the use of respiratory motion compensation using image-based navigation (iNAV) with constant respiratory efficiency using single end-expiratory thresholding (CRUISE) for coronary magnetic resonance angiography (CMRA), and compare it to the conventional diaphragmatic navigator (dNAV) in paediatric patients with congenital or suspected heart disease. Methods: iNAV allowed direct tracking of the respiratory heart motion and was generated using balanced steady state free precession startup echoes. Respiratory gating was achieved using CRUISE with a fixed 50% efficiency. Whole-heart CMRA was acquired with 1.3mm isotropic resolution. For comparison, CMRA with identical imaging parameters were acquired using dNAV. Scan time, visualization of coronary artery origins and mid-course, imaging quality and sharpness was compared between the two sequences. Results: Forty patients (13 females; median weight: 44 kg; median age: 12.6, range: 3 months–17 years) were enrolled. 25 scans were performed in awake patients. A contrast agent was used in 22 patients. The scan time was significantly reduced using iNAV for awake patients (iNAV 7:48 ± 1:26 vs dNAV 9:48 ± 3:11, P = 0.01) but not for patients under general anaesthesia (iNAV = 6:55 ± 1:50 versus dNAV = 6:32 ± 2:16; P = 0.32). In 98% of the cases, iNAV image quality had an equal or higher score than dNAV. The visual score analysis showed a clear difference, favouring iNAV (P = 0.002). The right coronary artery and the left anterior descending vessel sharpness was significantly improved (iNAV: 56.8% ± 10.1% vs dNAV: 53.7% ± 9.9%, P < 0.002 and iNAV: 55.8% ± 8.6% vs dNAV: 53% ± 9.2%, P = 0.001, respectively). Conclusion: iNAV allows for a higher success-rate and clearer depiction of the mid-course of coronary arteries in paediatric patients. Its acquisition time is shorter in awake patients and image quality score is equal or superior to the conventional method in most cases.Medical Engineering at King’s College London WT 088641/Z/09/ZBHF Centre of Excellence RE/08/0

Single centre experience of the application of self navigated 3D whole heart cardiovascular magnetic resonance for the assessment of cardiac anatomy in congenital heart disease.

BACKGROUND: For free-breathing cardiovascular magnetic resonance (CMR), the self-navigation technique recently emerged, which is expected to deliver high-quality data with a high success rate. The purpose of this study was to test the hypothesis that self-navigated 3D-CMR enables the reliable assessment of cardiovascular anatomy in patients with congenital heart disease (CHD) and to define factors that affect image quality. METHODS: CHD patients ≥2 years-old and referred for CMR for initial assessment or for a follow-up study were included to undergo a free-breathing self-navigated 3D CMR at 1.5T. Performance criteria were: correct description of cardiac segmental anatomy, overall image quality, coronary artery visibility, and reproducibility of great vessels diameter measurements. Factors associated with insufficient image quality were identified using multivariate logistic regression. RESULTS: Self-navigated CMR was performed in 105 patients (55% male, 23 ± 12y). Correct segmental description was achieved in 93% and 96% for observer 1 and 2, respectively. Diagnostic quality was obtained in 90% of examinations, and it increased to 94% if contrast-enhanced. Left anterior descending, circumflex, and right coronary arteries were visualized in 93%, 87% and 98%, respectively. Younger age, higher heart rate, lower ejection fraction, and lack of contrast medium were independently associated with reduced image quality. However, a similar rate of diagnostic image quality was obtained in children and adults. CONCLUSION: In patients with CHD, self-navigated free-breathing CMR provides high-resolution 3D visualization of the heart and great vessels with excellent robustness

4D Flow cardiovascular magnetic resonance consensus statement: 2023 update

Hemodynamic assessment is an integral part of the diagnosis and management of cardiovascular disease. Four-dimensional cardiovascular magnetic resonance flow imaging (4D Flow CMR) allows comprehensive and accurate assessment of flow in a single acquisition. This consensus paper is an update from the 2015 '4D Flow CMR Consensus Statement'. We elaborate on 4D Flow CMR sequence options and imaging considerations. The document aims to assist centers starting out with 4D Flow CMR of the heart and great vessels with advice on acquisition parameters, post-processing workflows and integration into clinical practice. Furthermore, we define minimum quality assurance and validation standards for clinical centers. We also address the challenges faced in quality assurance and validation in the research setting. We also include a checklist for recommended publication standards, specifically for 4D Flow CMR. Finally, we discuss the current limitations and the future of 4D Flow CMR. This updated consensus paper will further facilitate widespread adoption of 4D Flow CMR in the clinical workflow across the globe and aid consistently high-quality publication standards

4D Flow cardiovascular magnetic resonance consensus statement: 2023 update

4D Flow MRI; Hemodynamics; RecommendationsRessonància magnètica de flux 4D; Hemodinàmica; RecomanacionsResonancia magnética de flujo 4D; Hemodinámica; RecomendacionesHemodynamic assessment is an integral part of the diagnosis and management of cardiovascular disease. Four-dimensional cardiovascular magnetic resonance flow imaging (4D Flow CMR) allows comprehensive and accurate assessment of flow in a single acquisition. This consensus paper is an update from the 2015 ‘4D Flow CMR Consensus Statement’. We elaborate on 4D Flow CMR sequence options and imaging considerations. The document aims to assist centers starting out with 4D Flow CMR of the heart and great vessels with advice on acquisition parameters, post-processing workflows and integration into clinical practice. Furthermore, we define minimum quality assurance and validation standards for clinical centers. We also address the challenges faced in quality assurance and validation in the research setting. We also include a checklist for recommended publication standards, specifically for 4D Flow CMR. Finally, we discuss the current limitations and the future of 4D Flow CMR. This updated consensus paper will further facilitate widespread adoption of 4D Flow CMR in the clinical workflow across the globe and aid consistently high-quality publication standards.1R01HL149787-01A1 (S. Schnell, M. Markl), 1R21NS122511-01 (S. Schnell), 1R01CA233878-01 (J.Collins) J.Sotelo thanks to ANID–Millennium Science Initiative Program–ICN2021_004 and FONDECYT de iniciación en investigación #11200481. Dr. Oechtering receives funding from the German Research Foundation (OE 746/1-1)

Improved 3D MR Image Acquisition and Processing in Congenital Heart Disease

Congenital heart disease (CHD) is the most common type of birth defect, affecting about 1% of the population. MRI is an essential tool in the assessment of CHD, including diagnosis, intervention planning and follow-up. Three-dimensional MRI can provide particularly rich visualization and information. However, it is often complicated by long scan times, cardiorespiratory motion, injection of contrast agents, and complex and time-consuming postprocessing. This thesis comprises four pieces of work that attempt to respond to some of these challenges. The first piece of work aims to enable fast acquisition of 3D time-resolved cardiac imaging during free breathing. Rapid imaging was achieved using an efficient spiral sequence and a sparse parallel imaging reconstruction. The feasibility of this approach was demonstrated on a population of 10 patients with CHD, and areas of improvement were identified. The second piece of work is an integrated software tool designed to simplify and accelerate the development of machine learning (ML) applications in MRI research. It also exploits the strengths of recently developed ML libraries for efficient MR image reconstruction and processing. The third piece of work aims to reduce contrast dose in contrast-enhanced MR angiography (MRA). This would reduce risks and costs associated with contrast agents. A deep learning-based contrast enhancement technique was developed and shown to improve image quality in real low-dose MRA in a population of 40 children and adults with CHD. The fourth and final piece of work aims to simplify the creation of computational models for hemodynamic assessment of the great arteries. A deep learning technique for 3D segmentation of the aorta and the pulmonary arteries was developed and shown to enable accurate calculation of clinically relevant biomarkers in a population of 10 patients with CHD

Improved coronary magnetic resonance angiography using gadobenate dimeglumine in pediatric congenital heart disease

Background: CMRA in pediatrics remains challenging due to the smaller vessel size, high heart rates (HR), potential image degradation caused by limited patient cooperation and long acquisition times. High-relaxivity contrast agents have been shown to improve coronary imaging in adults, but limited data is available in children. We sought to investigate whether gadobenate dimeglumine (Gd-BOPTA) together with self-navigated inversion-prepared coronary magnetic resonance angiography (CMRA) sequence design improves coronary image quality in pediatric patients. Methods: Forty consecutive patients (mean age 6 ± 2.8 years; 73% males) were prospectively recruited for a 1.5-T MRI study under general anesthesia. Two electrocardiographic-triggered free breathing steady-state free precession (SSFP) angiography sequences (A and B) with isotropic spatial resolution (1.3 mm3) were acquired using a recently developed image-based self-navigation technique. Sequence A was acquired prior to contrast administration using T2 magnetization preparation (T2prep). Sequence B was acquired 5–8 min after a bolus of Gd-BOPTA with the T2prep replaced by an inversion recovery (IR) pulse to null the signal from the myocardium. Scan time, signal-to noise and contrast-to-noise ratios (SNR and CNR), vessel wall sharpness (VWS) and qualitative visual score for each sequence were compared. Results: Scan time was similar for both sequences (5.3 ± 1.8 vs 5.2 ± 1.5 min, p = .532) and average heart rate (78 ± 14.7 vs 78 ± 14.5 bpm, p = .443) remained constant throughout both acquisitions. Sequence B resulted in higher SNR (12.6 ± 4.4 vs 31.1 ± 7.4, p < .001) and CNR (9.0 ± 1.8 vs 13.5 ± 3.7, p < .001) and provided improved coronary visualization in all coronary territories (VWS A = 0.53 ± 0.07 vs B = 0.56 ± 0.07, p = .001; and visual scoring A = 3.8 ± 0.59 vs B = 4.1 ± 0.53, p < .001). The number of non-diagnostic coronary segments was lower for sequence B [A = 42 (13.1%) segments vs B = 33 (10.3%) segments; p = .002], and contrary to the pre-contrast sequence, never involved a proximal segment. These results were independent of the patients' age, body surface area and HR. Conclusions: The use of Gd-BOPTA with a 3D IR SSFP CMRA sequence results in improved coronary visualization in small infants and young children with high HR within a clinically acceptable scan time