Keywords: Vascular, Cardiovascular, low-field, congenital heart disease

Motivation: Low-field MRI is promising to enhance equity in medical care and accessibility for obese, claustrophobic patients and patients with implanted electronic devices. The investigation of the performance of 3D whole-heart imaging at low-field is still limited.

Goal(s): To implement and evaluate a free-breathing image-navigator based framework for 3D whole-heart imaging with isotropic resolution at 0.55T.

Approach: A 3D whole-heart free-breathing framework including image-based navigation, respiratory motion-correction reconstruction and patch-based denoising was implemented at 0.55T. The diagnostic performance of 3D whole-heart imaging was evaluated versus its counterpart at 1.5T.

Results: 3D whole-heart imaging at 0.55T offers good image and diagnostic quality, comparable to 1.5T.

Impact: This study demonstrates that high-quality 3D whole-heart imaging can be achieved at 0.55T showing comparable image and diagnostic quality to the current clinical standard in ­both healthy subjects and clinical patients, paving the pathway for affordable and accessible MRI.

Keywords: Vascular, Cardiovascular, Rapid MRI

Motivation: Angiography using ferumoxytol-enhanced free-running MRI can be obtained within an acquisition window of 6 minutes, which could be further reduced for faster clinical workflows. 

Goal(s): To determine the lower bounds of scan time for fast free-running whole-heart MRI using a data-driven reconstruction (SIMBA).

Approach: Fifteen datasets were retrospectively undersampled and image quality metrics were determined as a function of scan time reduction. 

Results: A 3-minute acquisition provides comparable image quality to that of its original 6-minute counterpart, and when applying compressed sensing we can confidently further reduce the acquisition time of 3D MR angiography with high resolution to 2 minutes. 

Impact: Free-running whole-heart MRI acquisitions can be greatly sped-up by exploiting ferumoxytol contrast enhancement, in conjunction with a data-driven reconstruction, which facilitates fast whole-heart angiography in congenital heart disease patients.

Keywords: Myocardium, Myocardium, Relaxometry,Novel Contrast Mechanisms,Ex-Vivo Applications

Motivation: Rotating frame relaxation mapping can detect fibrotic tissue and may offer contrast agent-free method for imaging the sinoatrial node (SAN). 

Goal(s): To identify SAN from the surrounding myocardium using RAFF2 and T_1ρ maps.

Approach: RAFF2, T_1ρ, T₁ and T₂ maps, and MT imaging were performed on ex vivo swine hearths at 7T and 3T. SAN location was validated with Masson’s trichrome histology sections. 

Results: Relaxation time differences between SAN and myocardium were found in all imaging methods. T_RAFF2 and T_1ρ demonstrated higher contrast than other methods. SAN can be distinguished as area with elevated relaxation times in T_RAFF2 maps.

Impact: Detection and visualization of 3D SAN structure can be done using RAFF2 and T_1ρ relaxation time maps without contrast agents.

Keywords: Flow, Cardiovascular

Motivation: Estimating pressure gradients due to valvular disease using 4D flow MRI in repaired TOF

Goal(s): Identify the location and extent of the pressure gradient

Approach: new 4D flow MRI software for pressure gradient measurement

Results: In right heart catheter-defined pulmonary hypertension, this software showed a right ventricular outflow tract to pulmonary artery pressure gradient.

Impact: Whereas pressure gradients used to require invasive catheterization, our method is a noninvasive test that does not use contrast media. It also has the advantage of being able to locate the site of the pressure gradient.

Keywords: Vascular, Cardiovascular, Congenital Heart Disease (CHD)

Motivation: 3-Dimensional Whole Heart balanced Steady-State-Free-Precession (3D bSSFP) MR imaging is reliable for congenital heart disease (CHD) assessment, but field inhomogeneity-induced banding artifacts limit its utility.

Goal(s): This study assesses a 3D Whole Heart approach utilizing a modified REACT technology to enhance image quality for cardiac cardiovascular anatomy compared to conventional 3D bSSFP imaging.

Approach: Eleven patients were compared for image quality, vessel diameters and contrast-to-noise ratios.

Results: Modified REACT improves cardiovascular imaging in CHD particularly of the pulmonary veins and the aorta compared to traditional 3D bSSFP imaging 

Impact: Visualizing cardiovascular structures like pulmonary veins in CHD patients can be challenging due to off-resonance effects.  A modified REACT sequence with triggering overcomes these imaging difficulties providing improved image quality compared to 3D bSSFP.

Keywords: Myocardium, fMRI

Motivation: Chemotherapy-related cardiotoxicity has garnered more attention,  an early assessment of cardiac injury to delay or prevent the occurrence and development of irreversible cardiac injury is vitally important.

Goal(s): T2 mapping and T2* mapping are expected to be used for evaluating early anthracycline-induced cardiotoxicity (AIC) and anthracycline-induced liver injury (AILI).

Approach: We established a rabbit model of anthracycline-induced cardiotoxicity and dynamically observed the occurrence and progression of AIC and AILI using T2 and T2* mapping.

Results: Preliminary results show T2 and T2* mapping showed value one-stop assessment of AIC and AILI.

Impact: Anthracycline-induced cardiotoxicity could be detected by T2 mapping as earlier as the second week, mainly focusing on the 7th, 11th and 12th segments of left ventricle. Combined with T2* mapping, hepatoxicity and supplementary cardiotoxicity were assessed by one-stop scan.

Keywords: Flow, Vessels

Motivation: There is currently limited data examining longitudinal changes in hemodynamics and vascular properties in Fontan patients living at altitude.

Goal(s): We aimed to assess hemodynamic parameters and vessel morphology in Fontan patients at a single high-altitude surgical center and assess correlations between these parameters and post-Fontan outcomes.

Approach: We retrospectively reviewed patients undergoing Fontan operation from 1999 to 2021. We analyzed data from cardiac magnetic resonance imaging and cardiac catheterization.

Results: Our findings highlight post-Fontan changes in flow, pressure, and area. The changes in systemic and caval flow, along with pressure variations, offer insights into the effects of Fontan circulation.

Impact: This study advances our understanding of Fontan circulation at high-altitude, paving the way for improved prognostic information and long-term outcomes in this patient population.

Keywords: Myocardium, Radiomics

Motivation: Right ventricular (RV) dilation and exercise intolerance are important prognostic indicators in repaired Tetralogy of Fallot (rTOF) patients. The conventional native T1 value may ignore subtle changes of myocardial fibrosis patterns in rTOF patients. Radiomics uncovers concealed insights regarding cardiomyopathy.

Goal(s): To establish a radiomics model using native T1 mapping for identifying rTOF patients with severe RV dilation and exercise intolerance.

Approach: We extracted 623 radiomic features from native T1 mapping and employed machine learning for feature selection and classification that enhance diagnostic accuracy in identifying cardiac involvements.

Results: Optimal performance was achieved in the segmental mid-slice T1 mapping model.

Impact: The radiomic analysis of myocardial native T1 can reveal the different myocardial T1 distribution patterns between different severity of RV dilation and exercise intolerance before substantial changes of conventional native T1 values.

Keywords: Heart Failure, Parkinson's Disease, Cardiac magnetic resonance, feature tracking, left heart

Motivation: To evaluate the changes of cardiac structure and function in patients with Parkinson's disease (PD).

Goal(s): To evaluate the structural and functional changes of left heart in PD patients by cardiac magnetic resonance feature tracking (CMR-FT), and to explore the influencing factors of left heart structure and function.

Approach: Cardiac function and strain parameters of left heart were obtained, and the correlation between CMR parameters and motor dysfunction and autonomic dysfunction was evaluated.

Results: Left atrium reserve and conduction function are related to the severity of motor dysfunction and autonomic dysfunction. CMR-FT can detect the early changes of cardiac function in PD patients.

Impact: The prevalence of heart failure has been twice among Parkinson's Disease patients compared with overall population. Cardiac magnetic resonance feature tracking technology  can be used as an effective tool for early diagnosis of cardiac dysfunction in Parkinson's Disease patients.

Keywords: Heart Failure, Heart, Right Heart Failure, Cardiac Perfusion

Motivation: Little is known about the right ventricular (RV) perfusion reserve in patients with chronic thromboembolic pulmonary hypertension (CTEPH) and whether pulmonary thromboendarterectomy (PTE) surgery improves RV perfusion. 

Goal(s): This study sought to assess whether PTE improves RV perfusion in CTEPH patients and whether RV perfusion reserve correlates with invasive pulmonary hemodynamics.

Approach: We prospectively enrolled 6 CTEPH subjects undergoing PTE, performed stress-rest MRI and right heart catheterization, and calculated RV myocardial perfusion reserve pre and post PTE.

Results: RV perfusion reserve is improved in CTEPH with PTE, correlates with invasive pulmonary hemodynamics, and may serve as a non-invasive marker for monitoring treatment efficacy.

Impact: This study demonstrates feasibility of utilizing right ventricular perfusion reserve as an imaging marker for evaluation of pulmonary thromboendarterectomy (PTE) in chronic thromboembolic pulmonary hypertension (CTEPH) patients.

Keywords: Flow, Kidney, Arterial stiffness

Motivation: Arterial stiffness is a key predictor of mortality in chronic kidney disease (CKD) patients.

Goal(s): Use 4D-Flow MRI to noninvasively evaluate the abdominal aortic compliance in CKD patients.

Approach: Thirteen healthy controls and seventy-three CKD patients were enrolled to evaluate the hemodynamic parameters including pulse wave velocity (PWV), peak velocity, and maximum wall shear stress (WSS) for healthy controls and different CKD groups.

Results: CKD patients tend to have an increased PWV and a decreased maximum WSS in the abdominal aorta, compared to healthy controls. Correlations between PWV/WSS and estimated glomerular filtration rate (eGFR) were found.

Impact: Our study shows that PWV tends to increase while WSS tends to decrease for CKD patients compared to healthy controls. Indicating that 4D Flow imaging can be used to assess changes in abdominal aortic compliance in CKD patients.

Keywords: Myocardium, Cardiovascular

Motivation: Early detection of hypertensive heart disease (HHD) in the compensatory stage is clinically challenging, necessitating novel evaluative parameters for cardiac function alterations due to HHD.

Goal(s): This research aimed to ascertain the diagnostic value of multiparametric cardiac magnetic resonance (CMR) imaging in this phase.

Approach: We compared cardiac functional parameters, T1 mapping, extracellular volume fraction (ECV), and myocardial strain metrics obtained via CMR among compensatory HHD, decompensated HHD, and a normotensive control group.

Results: Findings reveal that both circumferential and longitudinal strains in the compensatory HHD cohort were significantly reduced compared to the control group (P<0.05).

Impact: Employing quantitative CMR parameters facilitates the assessment of myocardial functional impairments in hypertensive heart disease, potentially unmasking subclinical cardiac dysfunction and providing prognostic value for disease progression.