Keywords: Valves, Valves, SPEEDI, sub-millisecond, high temporal resolution

Motivation: get-SPEEDI, a recently published pulse sequence, offers a promising MRI technique for imaging the rapid dynamics of the aortic valve (AV) opening and closing with sub-millisecond temporal resolution.

Goal(s): This study aims to assess the accuracy of measuring the AV dynamics with get-SPEEDI by comparing its performance with transthoracic ultrasound, which is the gold standard clinically.

Approach: Ultrasound echocardiograms and get-SPEEDI MR images of AV were acquired in healthy human subjects with 0.6- and 0.8-ms temporal resolution, respectively.

Results: There were no statistically significant differences between get-SPEEDI and ultrasound in the measurements of AV opening and closing dynamics and the maximum AV area.

Impact: The dynamic characteristics of the aortic valve measured with get-SPEEDI MRI agree well with the ultrasound measurements. get-SPEEDI MRI provides a new imaging tool for diagnosis of aortic valve diseases.

Keywords: Flow, Low-Field MRI

Motivation: Aortic flow imaging at 0.55T has limited SNR, especially in diastolic phases, which can limit the accuracy of flow and regurgitant fraction measurements.

Goal(s): Our goal was to improve the SNR of phase contrast images at 0.55T using a bSSFP readout and maintain accurate flow quantification.

Approach: We developed a through-plane phase contrast sequence with bSSFP readout and tested it in phantoms and healthy volunteers.

Results: Significantly improved SNR (25.5±9.6 vs 8.2±2.9, p<0.001) and accuracy of velocities measurement were demonstrated in phantom. Accurate flow and constant high SNR were measured using our method in 8 subjects, for both breath-hold and free-breathing cases.

Impact: Our proposed phase contrast with bSSFP readout can reliably evaluate aortic flow at 0.55T with higher SNR and VNR leading to more accurate quantification compared to conventional GRE based phase contrast method.

Keywords: Valves, Velocity & Flow

Motivation: The Ross Procedure is a complex cardiac surgery that utilizes the pulmonary valve to replace a diseased aortic valve. More work is needed to improve preoperative candidacy.

Goal(s): To develop and validate an ex-vivo model of the aortic valve in combination with a mock circulatory system.

Approach: The left ventricle was mounted on a circulatory loop with preservation of aortic valve anatomy and application of hemodynamic flow to assess valve characteristics.  

Results: A successful system was built and 4D Flow MRI performed with resultant functional  quantification and representative curves mimicking ventricular inflow and aortic outflow.

Impact: 4D Flow MRI, in combination with an ex-vivo left ventricular mock circulatory system, provides a method to study aortic flow and assess valvular abnormalities or preoperative candidacy in cardiac surgery.

Keywords: Vessel Wall, Low-Field MRI, bright- and black-blood whole heart, vessel lumen,vessel wall

Motivation: Bright-blood and black-blood MRI is fundamental for the comprehensive assessment of cardiac disease.Low field MRI promises high quality imaging at lower cost and improved patient accessibility.3D bright-blood and black-blood whole-heart imaging applications at low-field are limited.
 

Goal(s): To implement and evaluate the diagnostic quality of a novel framework for simultaneous 3D whole-heart bright-and black-blood(BOOST) imaging at 0.55T.

Approach: 3D whole-heart BOOST including image-based navigation, motion corrected reconstruction and patch-based denoising was evaluated at 0.55T.Diagnostic capabilities of 3D BOOST was evaluated versus its counterpart at 1.5T.

Results: 3D whole-heart BOOST at 0.55T offers good quality imaging, that is comparable to its counterpart at 1.5T. 

Impact: This study demonstrates that high-quality bright- and black-blood 3D whole-heart imaging can be achieved at 0.55T CMR, showing comparable image and diagnostic quality to the current clinical standard in ­both healthy subjects and clinical patients. 

Keywords: Flow, Heart, Whole-heart, UTE, Congenital Heart Disease

Motivation: Free-running phase-contrast whole-heart MRI, despite its ease of use and efficiency may suffer from artifacts and inaccuracy in the presence of non-laminar flow and high velocities due to prolonged echo times.

Goal(s): Our goal was to reduce the echo time in free-running radial 4D flow (radial 4D flow).

Approach: We incorporated ultra-short echo time (UTE) imaging techniques into our radial 4D flow framework.

Results: Net flow and peak flow measurements that correlate well with reference values were obtained in a cohort of healthy volunteers with the modified sequence and enabled qualitative evaluation of turbulent flow in patients with congenital heart disease.

Impact: The combination of UTE and radial 4D flow MRI marks a step towards a more precise and robust quantification of hemodynamics under complex conditions, in an effort to improve both diagnosis and patient outcomes. 

Keywords: Myocardium, Cardiovascular, Congenital heart disease, Free-running, whole-heart

Motivation: There is a need for simplified and time-efficient dynamic whole-heart imaging in the evaluation of congenital heart disease patients. 

Goal(s): To demonstrate the feasibility of Gadolinium enhanced 5D FISS CMR and compare it to established 2D and 3D CMR methods in a cohort of congenital heart disease patients.

Approach: Ejection fraction and vessel sharpness measurements derived from established 2D and 3D CMR are quantitatively compared to those obtained from the proposed 5D sequence.

Results: 5D FISS CMR is feasible for the evaluation of cardiac function and anatomy building towards an easy-to-use and time-efficient method for evaluating congenital heart disease.

Impact: Free-running 5D whole-heart MRI using a Gadolinium enhanced FISS sequence enables both measurements of cardiac function and evaluation of morphology in patients with congenital heart disease with a fixed six-minute scan time.

Keywords: Myocardium, Cardiovascular, Statistical shape modeling, biomechanical modeling, myocardial contractility, biventricular interaction, biomarkers

Motivation: In patients with repaired tetralogy of Fallot prolonged exposure to the right ventricular (RV) pressure and/or volume overload can affect the function of both RV and left ventricle (LV).

Goal(s): We aimed to investigate the link between RV function and RV and LV shape variation. 

Approach: We combined biomechanical modeling (i.e., provides RV contractility) with statistical shape modeling to quantify function and shape interaction. 

Results: Higher values of RV contractility were associated with a compressed LV cavity with associated septal flattening. No meaningful relationship was identified between RV function and RV endocardial shape. 

Impact: The link between anatomy and function can be studied with unprecedented detail in rTOF by combining biomechanical and statistical modeling frameworks from MRI. Such an approach facilitates the discovery of new disease mechanisms.

Keywords: Vascular, Blood vessels, Marfan

Motivation: New biomarkers are needed to guide aortic surgery to prevent aortic dissection in Marfan syndrome (MFS).

Goal(s): To investigate differences in aortic motion between healthy volunteers and (subgroups of) MFS patients. 

Approach: We apply a recently published novel non-contrast enhanced, free breathing, time-resolved 3D balanced steady free precession CMR scan with a machine learning based algorithm for automatic aortic segmentations to evaluate 4D aortic motion. 

Results: We found significant differences in aortic motion between patients with- and without a history of aortic root surgery and healthy volunteers. Thus, aortic motion might be a novel marker for aortic disease severity in MFS. 

Impact: The differences in 4D aortic motion measured using 3D CINE balanced steady state free precession CMR  between healthy volunteers and (subgroups of) Marfan syndrome patients might provide a new marker for disease severity in Marfan syndrome.

Keywords: Heart Failure, Modelling, Congenital Heart Disease

Motivation: The complexity of Fontan palliation in single-ventricle physiology prompts the need to understand the associated cardiovascular adaptations and their impact on ventricular function.

Goal(s): The research aims to quantify the relationship between single-ventricle contractile function and flow dynamic efficiency within the total cavopulmonary connection.

Approach: Utilizing Interventional Cardiac MR and a biomechanical heart model, this study analysed hemodynamic data from 11 post-Fontan procedure patients, correlating myocardial contractility with energy loss (EL) and clinical metrics.

Results: The analysis showed that EL significantly predicts myocardial contractility and the max(dP/dt), offering insights into the mechanical implications of Fontan circulation, with potential applications in patient-specific intervention strategies. 

Impact: This study exemplifies the integration of patient-specific biomechanical modelling with clinical cardiac MRI and hemodynamic data to understand Fontan circulation, potentially providing a quantitative framework for personalized treatment strategies and improving the cardiovascular health of patients with congenital heart disease.