Keywords: Myocardium, Susceptibility

Motivation: T₂*-contrast is not-specific to iron in the heart, with edema having a competing and contradictory effect to iron. Quantitative susceptibility mapping (QSM) may improve identification of intra-myocardial haemorrhage (IMH), through greater specificity to iron.

Goal(s): To present our initial experience of using QSM for the assessment of IMH.

Approach: 10 patients were scanned with QSM, 5 without myocardial infarcts to perform AHA-segmental analysis and 5 with scar to demonstrate the identification of IMH with QSM.

Results: The mean AHA-segment susceptibility was 0.00±0.02ppm and precision 0.05±0.03ppm in the non-infarct-group. Four of the patients with scar had IMH, which was successfully identified with QSM.

Impact: Cardiac quantitative susceptibility mapping successfully visualized intra-myocardial haemorrhage in four patients, and found no haemorrhage in one further patient, in agreement with the gold standard T₂/T₂* techniques.

Keywords: Myocardium, Cardiomyopathy, microstructure, diffusion, strain.

Motivation: Although functional integrity is preserved in most hypertrophic cardiomyopathy (HCM) patients, the microstructure is continuously and silently changing. 

Goal(s): To better comprehend the myocardial response, we need to characterize diffusion changes between healthy and disease state.  

Approach: We quantitatively investigate the relationship between myocardial strain and diffusion tensor imaging (DTI)-derived metrics in HCM. We assessed diffusion and strain in HCM and healthy patients using a new investigational MR system with ultra-high-performance gradients.

Results: HCM subjects exhibited lower anisotropy values that correlated with strain analysis indicative of early microstructural disarray.

Impact: Our results highlight the contribution of microstructural anisotropy in HCM development. Even in the absence of detectable mechanical deficiencies, diffusion myocardial mapping is an adjunct tool for managing the disease, aiding treatment planning, and bridging clinical outcomes with research findings.

Keywords: Myocardium, Heart, Cardiac diffusion MRI, time-dependent diffusion, free-gradient waveforms, tensor-valued diffusion encoding

Motivation: Oscillating gradient spin-echo (OGSE) diffusion MRI provides information about the cardiac microstructure that is complementary to conventional pulsed gradient spin echo (PGSE).

Goal(s): Using gradient waveforms with different frequencies enables the assessment of diffusion at sub-cellular length scales. 

Approach: OGSE diffusion tensor imaging (DTI) was applied in the ex vivo mouse heart to investigate the ability of OGSE to disentangle hypertrophic from healthy hearts.

Results: Our results show that hypertrophic hearts exhibited significantly different OGSE parameters (8 of 10) compared to control hearts. These and DTI observations are in agreement with expected microstructural changes.

Impact: Gradient waveforms with different frequencies enable the assessment of diffusion at sub-cellular length scales. OGSE may potentially serve as an imaging biomarker, to enhance the specificity of measurements with DTI. 

Keywords: Heart Failure, Cardiovascular

Motivation: The evaluation of surrogate markers of cardiopulmonary status may provide risk stratification and prognostication in patients with dilated cardiomyopathy.

Goal(s): To investigate the prognostic value of the dark right ventricular blood pool (RVBP) sign on T2 mapping by CMR.

Approach: T2 mapping was used to measure T2 values of septum, RV and LV blood pool images in DCM patients and healthy controls.All patients were followed to record major adverse cardiac events (MACEs).

Results: The sign of dark-RVBP on T2 mapping was found in 31.3% (42/134) of DCM patients. The ratio of T2RV/T2LV seemed to be an independent predictor for MACEs in DCM patients.

Impact: The sign of dark-RVBP on T2 mapping by CMR was associated with hard clinical events with prognostic information independent of and incremental to myocardial strain parameters.

Keywords: Myocardium, Animals, Relaxometry, T2*, Motion-resolved, Low-rank-tensor, Multi-echo

Motivation: To explore various stages of myocardial pathophysiology and improve prediction and interception of disease progression by capturing myocardial T₂* variations across cardiac cycle.

Goal(s): To establish a framework that operates independently of ECG- and respiratory-gating, enabling cinematic, whole-heart myocardial T₂*-mapping in mouse models.

Approach: A tailored framework was developed using modified Multi-Gradient-Echo (MGE) sequence and Low-Rank-Tensor (LRT) reconstruction technique. In vivo study was performed.

Results: Our preliminary findings demonstrate the feasibility of flow-compensated, free breathing, fully ungated, cardiac motion-resolved, whole heart and whole cardiac cycle coverage CINE imaging and T₂* mapping in healthy and diseased mice heart. 

Impact: The differences in myocardial T₂* obtained for wild-type mice and HCM model provide a new metric ΔT₂*_,rel for myocardial tissue characterization, and springboard to inform on the different stages of myocardial pathophysiology and improve prediction and interception of disease progression.

Keywords: Myocardium, Cardiomyopathy

Motivation: Dilated cardiomyopathy (DCM) patients with severely reduced left ventricular ejection fraction of≤35% face a high risk of sudden cardiac death and heart failure events. 

Goal(s): We aimed to refine a risk stratification model based on cardiac magnetic resonance imaging for DCM patients with LVEF≤35%, and to enhance clinical decision-making and ultimately, patient outcomes.

Approach: A retrospective analysis was conducted on 1272 DCM patients divided into a development cohort and an internal validation cohort, as well as a prospective validation cohort (n=301).

Results: Both LGE and LAVi are independently risk factors for predicting survival in a large cohort of patients with DCM and LVEF≤35%.

Impact: Our novel risk stratification may assist in timely interventions such as implantation of implantable cardioverter-defibrillator, heart transplantation, implementation of left ventricular assist devices, or referral for HF specialty care, ultimately leading to improved outcomes for DCM patients with LVEF≤35%.

Keywords: Inflammation, Infiltration, Heart

Motivation: The prognostic value of T1 mapping and extracellular volume fraction (ECV) in acute myocarditis has not yet been supported by high-quality, evidence-based medicine.

Goal(s): To investigate the prognostic value of T1 mapping and ECV in patients with acute suspected myocarditis.

Approach: Patients meeting the recommended clinical criteria for suspected myocarditis were enrolled.  The potential value for predicting MACE was explored using Cox proportional hazards models.  

Results: Patients with MACE showed higher global native T1 and ECV z scores and were more likely to have tissue changes in interventricular septum. Quantitative mapping parameters have incremental prognostic value beyond clinical variables and conventional CMR parameters.

Impact: Our study reveals the prognostic predictive ability of native T1 and ECV in myocarditis. The application of mapping techniques will further contribute to the understanding of the pathophysiology of heart disease and will guide the development of effective therapeutic approaches.

Keywords: Myocardium, Cardiovascular, Quantitative Imaging

Motivation: Chronic kidney disease (CKD) leads to significantly increased risk of cardiovascular death, highlighting the need for a non-contrast and non-invasive method to detect potential cardiomyopathy.

Goal(s): To evaluate the performance of cardiac multi-parametric mapping in assessing cardiomyopathy in CKD patients.

Approach: A recently proposed free-breathing multi-parametric mapping (FB-MultiMap) technique was employed to obtain myocardial T1, T2 and T1ρ maps of CKD patients. The parametric values were compared between healthy controls, stage 2, and stage 3-5 CKD patients.

Results: Myocardial T1, T2 and T1ρ exhibit significant differences between early-stage and moderate-to-end-stage CKD patients, indicating their potential for assessing the progression of cardiomyopathy in CKD.

Impact: FB-MultiMap may serve as an effective and easy-to-use tool for early diagnosis and monitoring of cardiomyopathy in CKD, potentially improving the outcome of CKD patients.

Keywords: Myocardium, Cardiovascular

Motivation: Explore relationship between cardiac image and duration of dialysis.

Goal(s): To evaluate myocardial damage using CMR in end-stage renal disease (ESRD) patients undergoing hemodialysis and further explore its relationship with duration of dialysis.

Approach: Patients with long- and short-term dialysis were included. CMR parameters (native T1 value and ECV) and two biochemical results (brain pro-natriuretic peptide and troponin T) were compared.

Results: Native T1 value, ECV, brain pro-natriuretic peptide and troponin T were significant different in two groups. Multiple linear regression analysis showed that native T1 value and ECV were independently associated with duration of dialysis and troponin T.

Impact: Quantification of myocardial fibrosis in ESRD is challenging. CMR imaging is useful in the detection of cardiac damage. Longer durations of dialysis may lead to poor outcomes. Our purpose was to explore relationship between cardiac image and duration of dialysis.