Native T1 and T2 provide distinctive signatures in hypertrophic cardiac conditions - Comparison of uremic, hypertensive and hypertrophic cardiomyopathy

Temporal progression of replacement and interstitial fibrosis in optimally managed dilated cardiomyopathy patients: A prospective study

BACKGROUND

To prospectively examine the dynamic evolution of fibrotic processes within a one-year in patients with dilated cardiomyopathy (DCM).

METHODS

Between May 2019 and September 2020, 102 DCM patients (mean age 45.2 ± 11.8 years, EF 29.9 ± 11.6%) underwent cardiac magnetic resonance (CMR-1). After 13.9 ± 2.9 months, 92 of these patients underwent a follow-up CMR (CMR-2). Replacement fibrosis was assessed via late gadolinium enhancement (LGE), quantified in terms of LGE mass and extent. Interstitial fibrosis was evaluated via T1-mapping and expressed as extracellular volume fraction (ECV). This data, along with left ventricular (LV) mass, facilitated the calculation of LV matrix and cellular volumes.

RESULTS

At CMR-1, LGE was present in 45 patients (48.9%), whereas at CMR-2 LGE was detected in 46 (50%) (p = 0.88). Although LGE mass remained stable, LGE extent increased from 2.18 ± 4.1% to 2.7 ± 4.6% (p < 0.01). Conversely, ECV remained unchanged [27.7% (25.5-31.3) vs. 26.7% (24.5-29.9); p = 0.19]; however, LV matrix and cell volumes exhibited a noteworthy regression. During a subsequent follow-up of 19.2 ± 9 months (spanning from CMR-2 to April 30th, 2023), the composite primary outcome (all-cause mortality, HTX, LVAD or heart failure worsening) was evident in 18 patients. Only the LV matrix volume index at follow-up was an independent predictor of outcome (OR 1.094; 95%CI 1.004-1.192; p < 0.05).

CONCLUSIONS

In optimally managed DCM patients, both replacement and interstitial fibrosis remained stable over the course of one year. In contrast, LV matrix and cell volumes displayed significant regression. LV matrix volume index at 12-month follow-up was found to be an independent predictor of outcome in DCM.

Cardiovascular Magnetic Resonance-Based Tissue Characterization in Patients With Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a common hereditable cardiomyopathy that affects between 1:200 to 1:500 of the general population. The role of cardiovascular magnetic resonance (CMR) imaging in the management of HCM has expanded over the past 2 decades to become a key informant of risk in this patient population, delivering unique insights into tissue health and its influence on future outcomes. Numerous mature CMR-based techniques are clinically available for the interrogation of tissue health in patients with HCM, inclusive of contrast and noncontrast methods. Late gadolinium enhancement imaging remains a cornerstone technique for the identification and quantification of myocardial fibrosis with large cumulative evidence supporting value for the prediction of arrhythmic outcomes. T1 mapping delivers improved fidelity for fibrosis quantification through direct estimations of extracellular volume fraction but also offers potential for noncontrast surrogate assessments of tissue health. Water-sensitive imaging, inclusive of T2-weighted dark blood imaging and T2 mapping, have also shown preliminary potential for assisting in risk discrimination. Finally, emerging techniques, inclusive of innovative multiparametric methods, are expanding the utility of CMR to assist in the delivery of comprehensive tissue characterization toward the delivery of personalized HCM care. In this narrative review we summarize the contemporary landscape of CMR techniques aimed at characterizing tissue health in patients with HCM. The value of these respective techniques to identify patients at elevated risk of future cardiovascular outcomes are highlighted.

Deep Learning for Discrimination of Hypertrophic Cardiomyopathy and Hypertensive Heart Disease on MRI Native T1 Maps

BACKGROUND

Native T1 and radiomics were used for hypertrophic cardiomyopathy (HCM) and hypertensive heart disease (HHD) differentiation previously. The current problem is that global native T1 remains modest discrimination performance and radiomics requires feature extraction beforehand. Deep learning (DL) is a promising technique in differential diagnosis. However, its feasibility for discriminating HCM and HHD has not been investigated.

PURPOSE

To examine the feasibility of DL in differentiating HCM and HHD based on T1 images and compare its diagnostic performance with other methods.

STUDY TYPE

Retrospective.

POPULATION

128 HCM patients (men, 75; age, 50 years ± 16) and 59 HHD patients (men, 40; age, 45 years ± 17).

FIELD STRENGTH/SEQUENCE

3.0T; Balanced steady-state free precession, phase-sensitive inversion recovery (PSIR) and multislice native T1 mapping.

ASSESSMENT

Compare HCM and HHD patients baseline data. Myocardial T1 values were extracted from native T1 images. Radiomics was implemented through feature extraction and Extra Trees Classifier. The DL network is ResNet32. Different input including myocardial ring (DL-myo), myocardial ring bounding box (DL-box) and the surrounding tissue without myocardial ring (DL-nomyo) were tested. We evaluate diagnostic performance through AUC of ROC curve.

STATISTICAL TESTS

Accuracy, sensitivity, specificity, ROC, and AUC were calculated. Independent t test, Mann-Whitney U-test and Chi-square test were adopted for HCM and HHD comparison. P < 0.05 was considered statistically significant.

RESULTS

DL-myo, DL-box, and DL-nomyo models showed an AUC (95% confidential interval) of 0.830 (0.702-0.959), 0.766 (0.617-0.915), 0.795 (0.654-0.936) in the testing set. AUC of native T1 and radiomics were 0.545 (0.352-0.738) and 0.800 (0.655-0.944) in the testing set.

DATA CONCLUSION

The DL method based on T1 mapping seems capable of discriminating HCM and HHD. Considering diagnostic performance, the DL network outperformed the native T1 method. Compared with radiomics, DL won an advantage for its high specificity and automated working mode.

LEVEL OF EVIDENCE

4 TECHNICAL EFFICACY STAGE: 2.

Single-nuclear transcriptome profiling identifies persistent fibroblast activation in hypertrophic and failing human hearts of patients with longstanding disease

AIMS

Cardiac fibrosis drives the progression of heart failure in ischaemic and hypertrophic cardiomyopathy. Therefore, the development of specific anti-fibrotic treatment regimens to counteract cardiac fibrosis is of high clinical relevance. Hence, this study examined the presence of persistent fibroblast activation during longstanding human heart disease at a single-cell resolution to identify putative therapeutic targets to counteract pathological cardiac fibrosis in patients.

METHODS AND RESULTS

We used single-nuclei RNA sequencing with human tissues from two samples of one healthy donor, and five hypertrophic and two failing hearts. Unsupervised sub-clustering of 7110 nuclei led to the identification of 7 distinct fibroblast clusters. De-convolution of cardiac fibroblast heterogeneity revealed a distinct population of human cardiac fibroblasts with a molecular signature of persistent fibroblast activation and a transcriptional switch towards a pro-fibrotic extra-cellular matrix composition in patients with established cardiac hypertrophy and heart failure. This sub-cluster was characterized by high expression of POSTN, RUNX1, CILP, and a target gene adipocyte enhancer-binding protein 1 (AEBP1) (all P < 0.001). Strikingly, elevated circulating AEBP1 blood level were also detected in a validation cohort of patients with confirmed cardiac fibrosis and hypertrophic cardiomyopathy by cardiac magnetic resonance imaging (P < 0.01). Since endogenous AEBP1 expression was increased in patients with established cardiac hypertrophy and heart failure, we assessed the functional consequence of siRNA-mediated AEBP1 silencing in human cardiac fibroblasts. Indeed, AEBP1 silencing reduced proliferation, migration, and fibroblast contractile capacity and α-SMA gene expression, which is a hallmark of fibroblast activation (all P < 0.05). Mechanistically, the anti-fibrotic effects of AEBP1 silencing were linked to transforming growth factor-beta pathway modulation.

CONCLUSION

Together, this study identifies persistent fibroblast activation in patients with longstanding heart disease, which might be detected by circulating AEBP1 and therapeutically modulated by its targeted silencing in human cardiac fibroblasts.

Myocardial Tissue Characterization in Patients with Hypertensive Crisis, Positive Troponin, and Unobstructed Coronary Arteries: A Cardiovascular Magnetic Resonance-Based Study

Hypertensive crisis can present with cardiac troponin elevation and unobstructed coronary arteries. We used cardiac magnetic resonance (CMR) imaging to characterize the myocardial tissue in patients with hypertensive crisis, elevated cardiac troponin, and unobstructed coronary arteries. Patients with hypertensive crisis and elevated cardiac troponin with coronary artery stenosis <50% were enrolled. Patients with troponin-negative hypertensive crisis served as controls. All participants underwent CMR imaging at 1.5 Tesla. Imaging biomarkers and tissue characteristics were compared between the groups. There were 19 patients (63% male) with elevated troponin and 24 (33% male) troponin-negative controls. The troponin-positive group was older (57 ± 11 years vs. 47 ± 14 years, p = 0.015). The groups had similar T2-weighted signal intensity ratios and native T1 times. T2 relaxation times were longer in the troponin-positive group, and the difference remained significant after excluding infarct-pattern late gadolinium enhancement (LGE) from the analysis. Extracellular volume (ECV) was higher in the troponin-positive group (25 ± 4 ms vs. 22 ± 3 ms, p = 0.008) and correlated strongly with T2 relaxation time (rs = 0.701, p = 0.022). Late gadolinium enhancement was 32% more prevalent in the troponin-positive group (82% vs. 50%, p = 0.050), with 29% having infarct-pattern LGE. T2 relaxation time was independently associated with troponin positivity (OR 2.1, p = 0.043), and both T2 relaxation time and ECV predicted troponin positivity (C-statistics: 0.71, p = 0.009; and 0.77, p = 0.006). Left ventricular end-diastolic and left atrial volumes were the strongest predictors of troponin positivity (C-statistics: 0.80, p = 0.001; and 0.82, p < 0.001). The increased T2 relaxation time and ECV and their significant correlation in the troponin-positive group suggest myocardial injury with oedema, while the non-ischaemic LGE could be due to myocardial fibrosis or acute necrosis. These CMR imaging biomarkers provide important clinical indices for risk stratification and prognostication in patients with hypertensive crisis.

Left Ventricular Function in Patients on Maintenance Hemodialysis: A Three-Dimensional Speckle-Tracking Imaging Study

INTRODUCTION

Although maintenance hemodialysis (MHD) in end-stage renal disease (ESRD) appears to induce some risk factors and strengthen cardiac function, the morbidity of ESRD patients receiving hemodialysis remains high. This study aimed to identify left ventricular (LV) structural and functional abnormalities in ESRD patients on MHD using three-dimensional speckle-tracking imaging (3D-STI).

METHODS

Eighty-five ESRD patients with normal LV ejection fraction (LVEF >50%) participated in this study, including 55 MHD patients comprising the chronic kidney disease (CKD) V-D group and 30 nondialysis patients comprising the CKD V-ND group. Thirty age- and sex-matched control participants who had normal kidney function were enrolled as the N group. Conventional echocardiography and 3D-STI were conducted, and global longitudinal strain (GLS), global circumferential strain (GCS), global area strain (GAS), and global radial strain (GRS) values were measured.

RESULTS

No substantial differences in two-dimensional LVEF were observed among the three groups, and LV hypertrophy was the most common abnormality in patients with ESRD, irrespective of whether they had received or not received MHD. There were no significant differences in the 3D LV mass index between the CKD V-ND and N groups (p > 0.05). Conversely, the 3D LV mass index was considerably higher in the CKD V-D group than in both the N and CKD V-ND groups. The GLS, GAS, and GRS values were significantly lower in the CKD V-ND group than in the N group (p < 0.05). Furthermore, the CKD V-D group had significantly lower GLS, GCS, GAS, and GRS values than the N and CKD V-ND groups (p < 0.05). The interventricular septal thickness and E/e' ratio were independently associated with LV strain values in all patients with ESRD.

CONCLUSIONS

MHD can exacerbate LV deformation and dysfunction in ESRD patients with preserved LVEF, and 3D-STI can be potentially useful for detecting these asymptomatic preclinical abnormalities.

Cardiac Magnetic Resonance in HCM Phenocopies: From Diagnosis to Risk Stratification and Therapeutic Management

Hypertrophic cardiomyopathy (HCM) is a genetic heart disease characterized by the thickening of the heart muscle, which can lead to symptoms such as chest pain, shortness of breath, and an increased risk of sudden cardiac death. However, not all patients with HCM have the same underlying genetic mutations, and some have conditions that resemble HCM but have different genetic or pathophysiological mechanisms, referred to as phenocopies. Cardiac magnetic resonance (CMR) imaging has emerged as a powerful tool for the non-invasive assessment of HCM and its phenocopies. CMR can accurately quantify the extent and distribution of hypertrophy, assess the presence and severity of myocardial fibrosis, and detect associated abnormalities. In the context of phenocopies, CMR can aid in the differentiation between HCM and other diseases that present with HCM-like features, such as cardiac amyloidosis (CA), Anderson-Fabry disease (AFD), and mitochondrial cardiomyopathies. CMR can provide important diagnostic and prognostic information that can guide clinical decision-making and management strategies. This review aims to describe the available evidence of the role of CMR in the assessment of hypertrophic phenotype and its diagnostic and prognostic implications.

Implications of uremic cardiomyopathy for the practicing clinician: an educational review

Studies over recent years have redeveloped our understanding of uremic cardiomyopathy, defined as left ventricular hypertrophy, congestive heart failure, and associated cardiac hypertrophy plus other abnormalities that result from chronic kidney disease and are often the cause of death in affected patients. Definitions of uremic cardiomyopathy have conflicted and overlapped over the decades, complicating the body of published evidence, and making comparison difficult. New and continuing research into potential risk factors, including uremic toxins, anemia, hypervolemia, oxidative stress, inflammation, and insulin resistance, indicates the increasing interest in illuminating the pathways that lead to UC and thereby identifying potential targets for intervention. Indeed, our developing understanding of the mechanisms of UC has opened new frontiers in research, promising novel approaches to diagnosis, prognosis, treatment, and management. This educational review highlights advances in the field of uremic cardiomyopathy and how they may become applicable in practice by clinicians. Pathways to optimal treatment with current modalities (with hemodialysis and angiotensin-converting enzyme inhibitors) will be described, along with proposed steps to be taken in research to allow evidence-based integration of developing investigational therapies.

Cardiac Imaging Biomarkers in Chronic Kidney Disease

Uremic cardiomyopathy (UC), the peculiar cardiac remodeling secondary to the systemic effects of renal dysfunction, is characterized by left ventricular (LV) diffuse fibrosis with hypertrophy (LVH) and stiffness and the development of heart failure and increased rates of cardiovascular mortality. Several imaging modalities can be used to obtain a non-invasive assessment of UC by different imaging biomarkers, which is the focus of the present review. Echocardiography has been largely employed in recent decades, especially for the determination of LVH by 2-dimensional imaging and diastolic dysfunction by pulsed-wave and tissue Doppler, where it retains a robust prognostic value; more recent techniques include parametric assessment of cardiac deformation by speckle tracking echocardiography and the use of 3D-imaging. Cardiac magnetic resonance (CMR) imaging allows a more accurate assessment of cardiac dimensions, including the right heart, and deformation by feature-tracking imaging; however, the most evident added value of CMR remains tissue characterization. T1 mapping demonstrated diffuse fibrosis in CKD patients, increasing with the worsening of renal disease and evident even in early stages of the disease, with few, but emerging, prognostic data. Some studies using T2 mapping highlighted the presence of subtle, diffuse myocardial edema. Finally, computed tomography, though rarely used to specifically assess UC, might provide incidental findings carrying prognostic relevance, including information on cardiac and vascular calcification. In summary, non-invasive cardiovascular imaging provides a wealth of imaging biomarkers for the characterization and risk-stratification of UC; integrating results from different imaging techniques can aid a better understanding of the physiopathology of UC and improve the clinical management of patients with CKD.

Incident Clinical and Mortality Associations of Myocardial Native T1 in the UK Biobank

BACKGROUND

Cardiac magnetic resonance native T1-mapping provides noninvasive, quantitative, and contrast-free myocardial characterization. However, its predictive value in population cohorts has not been studied.

OBJECTIVES

The associations of native T1 with incident events were evaluated in 42,308 UK Biobank participants over 3.17 ± 1.53 years of prospective follow-up.

METHODS

Native T1-mapping was performed in 1 midventricular short-axis slice using the Shortened Modified Look-Locker Inversion recovery technique (WIP780B) in 1.5-T scanners (Siemens Healthcare). Global myocardial T1 was calculated using an automated tool. Associations of T1 with: 1) prevalent risk factors (eg, diabetes, hypertension, and high cholesterol); 2) prevalent and incident diseases (eg, any cardiovascular disease [CVD], any brain disease, valvular heart disease, heart failure, nonischemic cardiomyopathies, cardiac arrhythmias, atrial fibrillation [AF], myocardial infarction, ischemic heart disease [IHD], and stroke); and 3) mortality (eg, all-cause, CVD, and IHD) were examined. Results are reported as odds ratios (ORs) or HRs per SD increment of T1 value with 95% CIs and corrected P values, from logistic and Cox proportional hazards regression models.

RESULTS

Higher myocardial T1 was associated with greater odds of a range of prevalent conditions (eg, any CVD, brain disease, heart failure, nonischemic cardiomyopathies, AF, stroke, and diabetes). The strongest relationships were with heart failure (OR: 1.41 [95% CI: 1.26-1.57]; P = 1.60 × 10-9) and nonischemic cardiomyopathies (OR: 1.40 [95% CI: 1.16-1.66]; P = 2.42 × 10-4). Native T1 was positively associated with incident AF (HR: 1.25 [95% CI: 1.10-1.43]; P = 9.19 × 10-4), incident heart failure (HR: 1.47 [95% CI: 1.31-1.65]; P = 4.79 × 10-11), all-cause mortality (HR: 1.24 [95% CI: 1.12-1.36]; P = 1.51 × 10-5), CVD mortality (HR: 1.40 [95% CI: 1.14-1.73]; P = 0.0014), and IHD mortality (HR: 1.36 [95% CI: 1.03-1.80]; P = 0.0310).

CONCLUSIONS

This large population study demonstrates the utility of myocardial native T1-mapping for disease discrimination and outcome prediction.

Quantitative MRI in cardiometabolic disease: From conventional cardiac and liver tissue mapping techniques to multi-parametric approaches

Cardiometabolic disease refers to the spectrum of chronic conditions that include diabetes, hypertension, atheromatosis, non-alcoholic fatty liver disease, and their long-term impact on cardiovascular health. Histological studies have confirmed several modifications at the tissue level in cardiometabolic disease. Recently, quantitative MR methods have enabled non-invasive myocardial and liver tissue characterization. MR relaxation mapping techniques such as T₁, T_1ρ, T₂ and T₂* provide a pixel-by-pixel representation of the corresponding tissue specific relaxation times, which have been shown to correlate with fibrosis, altered tissue perfusion, oedema and iron levels. Proton density fat fraction mapping approaches allow measurement of lipid tissue in the organ of interest. Several studies have demonstrated their utility as early diagnostic biomarkers and their potential to bear prognostic implications. Conventionally, the quantification of these parameters by MRI relies on the acquisition of sequential scans, encoding and mapping only one parameter per scan. However, this methodology is time inefficient and suffers from the confounding effects of the relaxation parameters in each single map, limiting wider clinical and research applications. To address these limitations, several novel approaches have been proposed that encode multiple tissue parameters simultaneously, providing co-registered multiparametric information of the tissues of interest. This review aims to describe the multi-faceted myocardial and hepatic tissue alterations in cardiometabolic disease and to motivate the application of relaxometry and proton-density cardiac and liver tissue mapping techniques. Current approaches in myocardial and liver tissue characterization as well as latest technical developments in multiparametric quantitative MRI are included. Limitations and challenges of these novel approaches, and recommendations to facilitate clinical validation are also discussed.

Cardiac magnetic resonance imaging parameters show association between myocardial abnormalities and severity of chronic kidney disease

BACKGROUND

Chronic kidney disease patients have increased risk of cardiovascular abnormalities. This study investigated the relationship between cardiovascular abnormalities and the severity of chronic kidney disease using cardiac magnetic resonance imaging.

METHODS

We enrolled 84 participants with various stages of chronic kidney disease (group I: stages 1-3, n = 23; group II: stages 4-5, n = 20; group III: hemodialysis patients, n = 41) and 32 healthy subjects. The demographics and biochemical parameters of the study subjects were evaluated. All subjects underwent non-contrast cardiac magnetic resonance scans. Myocardial strain, native T1, and T2 values were calculated from the scanning results. Analysis of covariance was used to compare the imaging parameters between group I-III and the controls.

RESULTS

The left ventricular ejection fraction (49 vs. 56%, p = 0.021), global radial strain (29 vs. 37, p = 0.019) and global circumferential strain (-17.4 vs. -20.6, p < 0.001) were significantly worse in group III patients compared with the controls. Furthermore, the global longitudinal strain had a significant decline in group II and III patients compared with the controls (-13.7 and -12.9 vs. -16.2, p < 0.05). Compared with the controls, the native T1 values were significantly higher in group II and III patients (1,041 ± 7 and 1,053 ± 6 vs. 1,009 ± 6, p < 0.05), and T2 values were obviously higher in group I-III patients (49.9 ± 0.6 and 53.2 ± 0.7 and 50.1 ± 0.5 vs. 46.6 ± 0.5, p < 0.001). The advanced chronic kidney disease stage showed significant positive correlation with global radial strain (r = 0.436, p < 0.001), global circumferential strain (r = 0.386, p < 0.001), native T1 (r = 0.5, p < 0.001) and T2 (r = 0.467, p < 0.001) values. In comparison with the group II patients, hemodialysis patients showed significantly lower T2 values (53.2 ± 0.7 vs. 50.1 ± 0.5, p = 0.002), but no significant difference in T1 values (1,041 ± 7 vs. 1,053 ± 6).

CONCLUSIONS

Our study showed that myocardial strain, native T1, and T2 values progressively got worse with advancing chronic kidney disease stage. The increased T1 values and decreased T2 values of hemodialysis patients might be due to increasing myocardial fibrosis but with reduction in oedema following effective fluid management.

TRIAL REGISTRATION NUMBER

ChiCTR2100053561 (http://www.chictr.org.cn/edit.aspx?pid=139737&htm=4).

Cardiovascular Magnetic Resonance Imaging Patterns in Rare Cardiovascular Diseases

Rare cardiovascular diseases (RCDs) have low incidence but major clinical impact. RCDs' classification includes Class I-systemic circulation, Class II-pulmonary circulation, Class III-cardiomyopathies, Class IV-congenital cardiovascular diseases (CVD), Class V-cardiac tumors and CVD in malignancy, Class VI-cardiac arrhythmogenic disorders, Class VII-CVD in pregnancy, Class VIII-unclassified rare CVD. Cardiovascular Magnetic Resonance (CMR) is useful in the diagnosis/management of RCDs, as it performs angiography, function, perfusion, and tissue characterization in the same examination. Edema expressed as a high signal in STIRT2 or increased T2 mapping is common in acute/active inflammatory states. Diffuse subendocardial fibrosis, expressed as diffuse late gadolinium enhancement (LGE), is characteristic of microvascular disease as in systemic sclerosis, small vessel vasculitis, cardiac amyloidosis, and metabolic disorders. Replacement fibrosis, expressed as LGE, in the inferolateral wall of the left ventricle (LV) is typical of neuromuscular disorders. Patchy LGE with concurrent edema is typical of myocarditis, irrespective of the cause. Cardiac hypertrophy is characteristic in hypertrophic cardiomyopathy (HCM), cardiac amyloidosis (CA) and Anderson-Fabry Disease (AFD), but LGE is located in the IVS, subendocardium and lateral wall in HCM, CA and AFD, respectively. Native T1 mapping is increased in HCM and CA and reduced in AFD. Magnetic resonance angiography provides information on aortopathies, such as Marfan, Turner syndrome and Takayasu vasculitis. LGE in the right ventricle is the typical finding of ARVC, but it may involve LV, leading to the diagnosis of arrhythmogenic cardiomyopathy. Tissue changes in RCDs may be detected only through parametric imaging indices.

T2 and T2⁎ mapping and weighted imaging in cardiac MRI

Cardiac imaging is progressing from simple imaging of heart structure and function to techniques visualizing and measuring underlying tissue biological changes that can potentially define disease and therapeutic options. These techniques exploit underlying tissue magnetic relaxation times: T₁, T₂ and T₂*. Initial weighting methods showed myocardial heterogeneity, detecting regional disease. Current methods are now fully quantitative generating intuitive color maps that do not only expose regionality, but also diffuse changes - meaning that between-scan comparisons can be made to define disease (compared to normal) and to monitor interval change (compared to old scans). T₁ is now familiar and used clinically in multiple scenarios, yet some technical challenges remain. T₂ is elevated with increased tissue water - oedema. Should there also be blood troponin elevation, this oedema likely reflects inflammation, a key biological process. T₂* falls in the presence of magnetic/paramagnetic materials - practically, this means it measures tissue iron, either after myocardial hemorrhage or in myocardial iron overload. This review discusses how T₂ and T₂^⁎ imaging work (underlying physics, innovations, dependencies, performance), current and emerging use cases, quality assurance processes for global delivery and future research directions.

T2 mapping in myocardial disease: a comprehensive review

Cardiovascular magnetic resonance (CMR) is considered the gold standard imaging modality for myocardial tissue characterization. Elevated transverse relaxation time (T2) is specific for increased myocardial water content, increased free water, and is used as an index of myocardial edema. The strengths of quantitative T2 mapping lie in the accurate characterization of myocardial edema, and the early detection of reversible myocardial disease without the use of contrast agents or ionizing radiation. Quantitative T2 mapping overcomes the limitations of T2-weighted imaging for reliable assessment of diffuse myocardial edema and can be used to diagnose, stage, and monitor myocardial injury. Strong evidence supports the clinical use of T2 mapping in acute myocardial infarction, myocarditis, heart transplant rejection, and dilated cardiomyopathy. Accumulating data support the utility of T2 mapping for the assessment of other cardiomyopathies, rheumatologic conditions with cardiac involvement, and monitoring for cancer therapy-related cardiac injury. Importantly, elevated T2 relaxation time may be the first sign of myocardial injury in many diseases and oftentimes precedes symptoms, changes in ejection fraction, and irreversible myocardial remodeling. This comprehensive review discusses the technical considerations and clinical roles of myocardial T2 mapping with an emphasis on expanding the impact of this unique, noninvasive tissue parameter.

Cardiac Remodeling in Hypertension: Clinical Impact on Brain, Heart, and Kidney Function

Hypertension is the most common causative factor of cardiac remodeling, which, in turn, has been associated with changes in brain and kidney function. Currently, the role of blood biomarkers as indices of cardiac remodeling remains unclear. In contrast, cardiac imaging, including echocardiography and cardiovascular magnetic resonance (CMR), has been a valuable noninvasive tool to assess cardiac remodeling. Cardiac remodeling during the course of systemic hypertension is not the sole effect of the latter. "Remodeling" of other vital organs, such as brain and kidney, also takes place. Therefore, it will be more accurate if we discuss about "hypertensive remodeling" involving the heart, the brain, and the kidneys, rather than isolated cardiac remodeling. This supports the idea of their simultaneous assessment to identify the early, silent lesions of total "hypertensive remodeling". In this context, magnetic resonance imaging is the ideal modality to provide useful information about these organs in a noninvasive fashion and without radiation. For this purpose, we propose a combined protocol to employ MRI in the simultaneous assessment of the heart, brain and kidneys. This protocol should include all necessary indices for the evaluation of "hypertensive remodeling" in these 3 organs, and could be performed within a reasonable time, not exceeding one hour, so that it remains patient-friendly. Furthermore, a combined protocol may offer "all in one examination" and save time. Finally, the amount of contrast agent used will be limited granted that post-contrast evaluations of the three organs will be performed after 1 injection.

Cardiac Magnetic Resonance Imaging in Immune Check-Point Inhibitor Myocarditis: A Systematic Review

Immune checkpoint inhibitors (ICIs) are a family of anticancer drugs in which the immune response elicited against the tumor may involve other organs, including the heart. Cardiac magnetic resonance (CMR) imaging is increasingly used in the diagnostic work-up of myocardial inflammation; recently, several studies investigated the use of CMR in patients with ICI-myocarditis (ICI-M). The aim of the present systematic review is to summarize the available evidence on CMR findings in ICI-M. We searched electronic databases for relevant publications; after screening, six studies were selected, including 166 patients from five cohorts, and further 86 patients from a sub-analysis that were targeted for a tissue mapping assessment. CMR revealed mostly preserved left ventricular ejection fraction; edema prevalence ranged from 9% to 60%; late gadolinium enhancement (LGE) prevalence ranged from 23% to 83%. T1 and T2 mapping assessment were performed in 108 and 104 patients, respectively. When available, the comparison of CMR with endomyocardial biopsy revealed partial agreement between techniques and was higher for native T1 mapping amongst imaging biomarkers. The prognostic assessment was inconsistently assessed; CMR variables independently associated with the outcome included decreasing LVEF and increasing native T1. In conclusion, CMR findings in ICI-M include myocardial dysfunction, edema and fibrosis, though less evident than in more classic forms of myocarditis; native T1 mapping retained the higher concordance with EMB and significant prognostic value.

BUDA-MESMERISE: Rapid acquisition and unsupervised parameter estimation for T1 , T2 , M0 , B0 , and B1 maps

PURPOSE

Rapid acquisition scheme and parameter estimation method are proposed to acquire distortion-free spin- and stimulated-echo signals and combine the signals with a physics-driven unsupervised network to estimate T₁ , T₂ , and proton density (M₀ ) parameter maps, along with B₀ and B₁ information from the acquired signals.

THEORY AND METHODS

An imaging sequence with three 90° RF pulses is utilized to acquire spin- and stimulated-echo signals. We utilize blip-up/-down acquisition to eliminate geometric distortion incurred by the effects of B₀ inhomogeneity on rapid EPI acquisitions. For multislice imaging, echo-shifting is applied to utilize dead time between the second and third RF pulses to encode information from additional slice positions. To estimate parameter maps from the spin- and stimulated-echo signals with high fidelity, 2 estimation methods, analytic fitting and a novel unsupervised deep neural network method, are developed.

RESULTS

The proposed acquisition provided distortion-free T₁ , T₂ , relative proton density (M0), B₀ , and B₁ maps with high fidelity both in phantom and in vivo brain experiments. From the rapidly acquired spin- and stimulated-echo signals, analytic fitting and the network-based method were able to estimate T₁ , T₂ , M₀ , B₀ , and B₁ maps with high accuracy. Network estimates demonstrated noise robustness owing to the fact that the convolutional layers take information into account from spatially adjacent voxels.

CONCLUSION

The proposed acquisition/reconstruction technique enabled whole-brain acquisition of coregistered, distortion-free, T₁ , T₂ , M₀ , B₀ , and B₁ maps at 1 × 1 × 5 mm³ resolution in 50 s. The proposed unsupervised neural network provided noise-robust parameter estimates from this rapid acquisition.

Cardiac Alterations on 3T MRI in Young Adults With Sedentary Lifestyle-Related Risk Factors

Background

Young adult populations with the sedentary lifestyle-related risk factors overweight, hypertension, and type 2 diabetes (T2D) are growing, and associated cardiac alterations could overlap early findings in non-ischemic cardiomyopathy on cardiovascular MRI. We aimed to investigate cardiac morphology, function, and tissue characteristics for these cardiovascular risk factors.

Methods

Non-athletic non-smoking asymptomatic adults aged 18-45 years were prospectively recruited and underwent 3Tesla cardiac MRI. Multivariate linear regression was performed to investigate independent associations of risk factor-related parameters with cardiac MRI values.

Results

We included 311 adults (age, 32 ± 7 years; men, 49%). Of them, 220 subjects had one or multiple risk factors, while 91 subjects were free of risk factors. For overweight, increased body mass index (per SD = 5.3 kg/m2) was associated with increased left ventricular (LV) mass (+7.3 g), biventricular higher end-diastolic (LV, +8.6 ml), and stroke volumes (SV; +5.0 ml), higher native T1 (+7.3 ms), and lower extracellular volume (ECV, -0.38%), whereas the higher waist-hip ratio was associated with lower biventricular volumes. Regarding hypertension, increased systolic blood pressure (per SD = 14 mmHg) was associated with increased LV mass (+6.9 g), higher LV ejection fraction (EF; +1.0%), and lower ECV (-0.48%), whereas increased diastolic blood pressure was associated with lower LV EF. In T2D, increased HbA1c (per SD = 9.0 mmol/mol) was associated with increased LV mass (+2.2 g), higher right ventricular end-diastolic volume (+3.2 ml), and higher ECV (+0.27%). Increased heart rate was linked with decreased LV mass, lower biventricular volumes, and lower T2 values.

Conclusions

Young asymptomatic adults with overweight, hypertension, and T2D show subclinical alterations in cardiac morphology, function, and tissue characteristics. These alterations should be considered in cardiac MRI-based clinical decision making.

The Role of Cardiovascular Magnetic Resonance Imaging in the Evaluation of Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiac disorder, affecting 1 out of 500 adults globally. It is a widely heterogeneous disorder characterized by a range of phenotypic expressions, and is most often identified by non-invasive imaging that includes echocardiography and cardiovascular magnetic resonance imaging (CMR). Within the last two decades, cardiac magnetic resonance imaging (MRI) has emerged as the defining tool for the characterization and prognostication of cardiomyopathies. With a higher image quality, spatial resolution, and the identification of morphological variants of HCM, CMR has become the gold standard imaging modality in the assessment of HCM. Moreover, it has been crucial in its management, as well as adding prognostic information that clinical history nor other imaging modalities may not provide. This literature review addresses the role and current applications of CMR, its capacity in evaluating HCM, and its limitations.

Multimodality Cardiac Imaging in Cardiomyopathies: From Diagnosis to Prognosis

Cardiomyopathies are a group of structural and/or functional myocardial disorders which encompasses hypertrophic, dilated, arrhythmogenic, restrictive, and other cardiomyopathies. Multimodality cardiac imaging techniques are the cornerstone of cardiomyopathy diagnosis; transthoracic echocardiography should be the first-line imaging modality due to its availability, and diagnosis should be confirmed by cardiovascular magnetic resonance, which will provide more accurate morphologic and functional information, as well as extensive tissue characterization. Multimodality cardiac imaging techniques are also essential in assessing the prognosis of patients with cardiomyopathies; left ventricular ejection fraction and late gadolinium enhancement are two of the main variables used for risk stratification, and they are incorporated into clinical practice guidelines. Finally, periodic testing with cardiac imaging techniques should also be performed due to the evolving and progressive natural history of most cardiomyopathies.

T1 and T2 Mapping in Uremic Cardiomyopathy: An Update

Uremic cardiomyopathy (UC) is the cardiac remodelling that occurs in patients with chronic kidney disease (CKD). It is characterised by a left ventricular (LV) hypertrophy phenotype, diastolic dysfunction and generally preserved LV ejection fraction. UC has a major role mediating the increased rate of cardiovascular events, especially heart failure related, observed in patients with CKD. Recently, the use of T1 and T2 mapping techniques on cardiac MRI has expanded the ability to characterise cardiac involvement in CKD. Native T1 mapping effectively tracks the progression of interstitial fibrosis in UC, whereas T2 mapping analysis suggests the contribution of myocardial oedema, at least in a subgroup of patients. Both T1 and T2 increased values were related to worsening clinical status, myocardial injury and B-type natriuretic peptide release. Studies investigating the prognostic relevance and histology validation of mapping techniques in CKD are awaited.

Tranilast inhibits angiotensin II-induced myocardial fibrosis through S100A11/ transforming growth factor-β (TGF-β1)/Smad axis

Tranilast has an ameliorative effect on myocardial fibrosis (MF), but the specific mechanism has not been studied. S100A11 is a key regulator of collagen expression in MF. In this paper, we will study the regulatory roles of Tranilast and S100A11 in MF. After the introduction of angiotensin II (AngII) to Human cardiac fibroblasts (HCF), Tranilast was administered. CCK-8 kit was used to detect cell viability. Wound Healing assay detected cell migration, and Western blot was used to detect the expression of migration-related proteins and proteins related to extracellular matrix synthesis. The expression of α-SMA was detected by immunofluorescence (IF). The expression of S100A11 was detected by qPCR and Western blot, and then S100A11 was overexpressed by cell transfection technology, so as to explore the mechanism by which Tranilast regulated MF. In addition, the expression of TGF-β1/Smad pathway related proteins was detected by Western blot. Tranilast inhibited Ang II–induced over-proliferation, migration and fibrosis of human cardiac fibroblasts (HCF), and simultaneously significantly decreased S100A11 expression was observed. Overexpression of S100A11 reversed the inhibition of Tranilast on AngII–induced over-proliferation, migration, and fibrosis in HCF, accompanied by activation of the TGF-β1/Smad pathway. Overall, Tranilast inhibits angiotensin II-induced myocardial fibrosis through S100A11/TGF-β1/Smad axis.

Novel Imaging and Genetic Risk Markers in Takotsubo Syndrome

Takotsubo syndrome (TTS) is an increasingly recognized condition burdened by significant acute and long-term adverse events. The availability of novel techniques expanded the knowledge on TTS and allowed a more accurate risk-stratification, potentially guiding clinical management. The present review aims to summarize the recent advances in TTS prognostic evaluation with a specific focus on novel imaging and genetic markers. Parametric deformation analysis by speckle-tracking echocardiography, as well as tissue characterization by cardiac magnetic resonance imaging T1 and T2 mapping techniques, currently appear the most clinically valuable applications. Notwithstanding, computed tomography and nuclear imaging studies provided limited but promising data. A genetic predisposition to TTS has been hypothesized, though available evidence is still not sufficient. Although a genetic predisposition appears likely, further studies are needed to fully characterize the genetic background of TTS, in order to identify genetic markers that could assist in predicting disease recurrences and help in familial screening.

Incremental Values of T1 Mapping in the Prediction of Sudden Cardiac Death Risk in Hypertrophic Cardiomyopathy: A Comparison With Two Guidelines

Background: MRI native T1 mapping and extracellular volume fraction (ECV) are quantitative values that could reflect various myocardial tissue characterization. The role of these parameters in predicting the risk of sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM) is still poorly understood.

Aim: This study aims to investigate the ability of native T1 mapping and ECV values to predict major adverse cardiovascular events (MACE) in HCM, and its incremental values over the 2014 European Society of Cardiology (ESC) and enhanced American College of Cardiology/American Heart Association (ACC/AHA) guidelines.

Methods: Between July 2016 and October 2020, HCM patients and healthy individuals with sex and age matched who underwent cardiac MRI were prospectively enrolled. The native T1 and ECV parameters were measured. The SCD risk was evaluated by the 2014 ESC guidelines and enhanced ACC/AHA guidelines. MACE included cardiac death, transplantation, heart failure admission, and implantable cardioverter-defibrillator implantation.

Results: A total of 203 HCM patients (54.2 ± 14.9 years) and 101 healthy individuals (53.2 ± 14.7 years) were evaluated. During a median follow-up of 15 months, 25 patients (12.3%) had MACE. In multivariate Cox regression analysis, global native T1 mapping (hazard ratio (HR): 1.446; 95% confidence interval (CI): 1.195–1.749; P < 0.001) and non-sustained ventricular tachycardia (NSVT) (HR: 4.949; 95% CI, 2.033–12.047; P < 0.001) were independently associated with MACE. Ten of 86 patients (11.6%) with low SCD risk assessed by the two guidelines had MACE. In this subgroup of patients, multivariate Cox regression analysis showed that global native T1 mapping was independently associated with MACE (HR: 1.532; 95% CI: 1.221–1.922; P < 0.001). In 85 patients with conflicting results assessed by the two guidelines, end-stage systolic dysfunction was independently associated with MACE (HR: 7.942, 95% CI: 1.322–47.707, P = 0.023). In 32 patients with high SCD risk assessed by the two guidelines, NSVT was independently associated with MACE (HR: 9.779, 95% CI: 1.953–48.964, P = 0.006).

Conclusion: The global native T1 mapping could provide incremental values and serve as potential supplements to the current guidelines in the prediction of MACE.

Cardiac biomarkers in chronic kidney disease are independently associated with myocardial edema and diffuse fibrosis by cardiovascular magnetic resonance

BACKGROUND

High sensitivity cardiac troponin T (hs-cTnT) and NT-pro-brain natriuretic peptide (NT-pro BNP) are often elevated in chronic kidney disease (CKD) and associated with both cardiovascular remodeling and outcome. Relationship between these biomarkers and quantitative imaging measures of myocardial fibrosis and edema by T1 and T2 mapping remains unknown.

METHODS

Consecutive patients with established CKD and estimated glomerular filtration rate (eGFR) < 59 ml/min/1.73 m2 (n = 276) were compared to age/sex matched patients with eGFR ≥ 60 ml/min/1.73 m2 (n = 242) and healthy controls (n = 38). Comprehensive cardiovascular magnetic resonance (CMR) with native T1 and T2 mapping, myocardial ischemia and scar imaging was performed with venous sampling immediately prior to CMR.

RESULTS

Patients with CKD showed significant cardiac remodeling in comparison with both healthy individuals and non-CKD patients, including a stepwise increase of native T1 and T2 (p < 0.001 between all CKD stages). Native T1 and T2 were the sole imaging markers independently associated with worsening CKD in patients [B = 0.125 (95% CI 0.022-0.235) and B = 0.272 (95% CI 0.164-0.374) with p = 0.019 and < 0.001 respectively]. At univariable analysis, both hs-cTnT and NT-pro BNP significantly correlated with native T1 and T2 in groups with eGFR 30-59 ml/min/1.73 m2 and eGFR < 29 ml/min/1.73 m2 groups, with associations being stronger at lower eGFR (NT-pro BNP (log transformed, lg10): native T1 r = 0.43 and r = 0.57, native T2 r = 0.39 and r = 0.48 respectively; log-transformed hs-cTnT(lg10): native T1 r = 0.23 and r = 0.43, native T2 r = 0.38 and r = 0.58 respectively, p < 0.001 for all, p < 0.05 for interaction). On multivariable analyses, we found independent associations of native T1 with NT-pro BNP [(B = 0.308 (95% CI 0.129-0.407), p < 0.001 and B = 0.334 (95% CI 0.154-0.660), p = 0.002 for eGFR 30-59 ml/min/1.73 m2 and eGFR < 29 ml/min/1.73 m2, respectively] and of T2 with hs-cTnT [B = 0.417 (95% CI 0.219-0.650), p < 0.001 for eGFR < 29 ml/min/1.73 m2].

CONCLUSIONS

We demonstrate independent associations between cardiac biomarkers with imaging markers of interstitial expansion, which are CKD-group specific. Our findings indicate the role of diffuse non-ischemic tissue processes, including excess of myocardial fluid in addition to diffuse fibrosis in CKD-related adverse remodeling.

Uraemic Cardiomyopathy: A Review of Current Literature

Uraemic Cardiomyopathy (UC) is recognised as an intricate and multifactorial disease which portends a significant burden in patients with End-Stage Renal Disease (ESRD). The cardiovascular morbidity and mortality associated with UC is significant and can be associated with the development of arrythmias, cardiac failure and sudden cardiac death (SCD). The pathophysiology of UC involves a complex interplay of traditional implicative factors such as haemodynamic overload and circulating uraemic toxins as well as our evolving understanding of the Chronic Kidney Disease-Mineral Bone Disease pathway. There is an instrumental role for multi-modality imaging in the diagnostic process; including transthoracic echocardiography and cardiac magnetic resonance imaging in identifying the hallmarks of left ventricular hypertrophy and myocardial fibrosis that characterise UC. The appropriate utilisation of the aforementioned diagnostics in the ESRD population may help guide therapeutic approaches, such as pharmacotherapy including beta-blockers and aldosterone-antagonists as well as haemodialysis and renal transplantation. Despite this, there remains limitations in effective therapeutic interventions for UC and ongoing research on a cellular level is vital in establishing further therapies.

Role of CMR Mapping Techniques in Cardiac Hypertrophic Phenotype

Non-ischemic cardiomyopathies represent a heterogeneous group of myocardial diseases potentially leading to heart failure, life-threatening arrhythmias, and eventually death. Myocardial dysfunction is associated with different underlying pathological processes, ultimately inducing changes in morphological appearance. Thus, classification based on presenting morphological phenotypes has been proposed, i.e., dilated, hypertrophic, restrictive, and right ventricular cardiomyopathies. In light of the key diagnostic and prognostic role of morphological and functional features, cardiovascular imaging has emerged as key element in the clinical workflow of suspected cardiomyopathies, and above all, cardiovascular magnetic resonance (CMR) represents the ideal technique to be used: thanks to its physical principles, besides optimal spatial and temporal resolutions, incomparable contrast resolution allows to assess myocardial tissue abnormalities in detail. Traditionally, weighted images and late enhancement images after gadolinium-based contrast agent administration have been used to perform tissue characterization, but in the last decade quantitative assessment of pre-contrast longitudinal relaxation time (native T1), post-contrast longitudinal relaxation time (post-contrast T1) and transversal relaxation time (T2), all displayed with dedicated pixel-wise color-coded maps (mapping), has contributed to give precious knowledge insight, with positive influence of diagnostic accuracy and prognosis assessment, mostly in the setting of the hypertrophic phenotype. This review aims to describe the available evidence of the role of mapping techniques in the assessment of hypertrophic phenotype, and to suggest their integration in the routine CMR evaluation of newly diagnosed cardiomyopathies with increased wall thickness.

Longitudinal changes of left and right cardiac structure and function in patients with end-stage renal disease on replacement therapy

BACKGROUND

Few data are available regarding longitudinal changes of cardiac structure and function in end-stage chronic kidney disease (CKD). Aim of the present study is to describe serial echocardiographic findings in a cohort of dialyzed CKD patients.

METHODS

In this retrospective longitudinal study, we included n = 120 dialyzed CKD patients who underwent at least 2 echocardiograms either 1, 2 or 3 years apart. After baseline echocardiogram, n = 112 had a further examination at year 1, n = 76 at year 2 and n = 45 at year 3. Echocardiographic examination included Tissue Doppler Imaging of both left (LV) and right (RV) ventricle.

RESULTS

LV geometry and LV mass index did not significantly change over time. RV progressively dilated (mean change +1.3 mm, +1.1 mm and +3.1 mm at year 1, 2 and 3 respectively, p = 0.002, adjusted p = 0.003). Tissue Doppler parameters showed significant changes with regard to both LV (mean change of E/E' +0.7, +1.3, +1.7 at year 1, 2 and 3 respectively p<0.001, adjusted p = 0.079) and RV (mean change of S wave (cm/sec) -1, -1.7, -2 at year 1, 2 and 3 respectively, p <0.001, adjusted p = 0.041). Decrease of RV S wave negatively correlated with E/E' changes (r=-0.303, p = 0.002; r=-0.246, p = 0.049; r=-0.265, p = 0.089; at year 1, 2 and 3 respectively). LV ejection fraction (LVEF) progressively declined (p = 0.034, adjusted p = 0.140), albeit being significant lower against baseline only at year 3 (mean change -4.3%, p<0.05).

CONCLUSIONS

In dialyzed CKD patients we observed parallel worsening of LV diastolic and RV systolic function accompanied by RV dilation. LVEF decreased less sharply.

Contemporary Cardiac MRI in Chronic Coronary Artery Disease

Chronic coronary artery disease remains an unconquered clinical problem, affecting an increasing number of people worldwide. Despite the improved understanding of the disease development, the implementation of the many advances in diagnosis and therapy is lacking. Many clinicians continue to rely on patient’s symptoms and diagnostic methods, which do not enable optimal clinical decisions. For example, echocardiography and invasive coronary catheterisation remain the mainstay investigations for stable angina patients in many places, despite the evidence on their limitations and availability of better diagnostic options. Cardiac MRI is a powerful diagnostic method, supporting robust measurements of crucial markers of cardiac structure and function, myocardial perfusion and scar, as well as providing detailed insight into myocardial tissue. Accurate and informative diagnostic readouts can help with guiding therapy, monitoring disease progress and tailoring the response to treatment. In this article, the authors outline the evidence supporting the state-of-art applications based on cardiovascular magnetic resonance, allowing the clinician optimal use of this insightful diagnostic method in everyday clinical practice.

Aortic Stiffness and Heart Failure in Chronic Kidney Disease

Purpose of Review

To provide an update on the recent findings in the field of aortic stiffness and heart failure in patients with chronic kidney disease (CKD).

Recent Findings

Stratification of cardiovascular risk in CKD remains an open question. Recent reports suggest that aortic stiffness, an independent predictor of cardiovascular events in many patient populations, is also an important prognostic factor in CKD. Also, novel measures of myocardial tissue characterization, native T1 and T2 mapping techniques, have potential as diagnostic and prognostic factors in CKD.

Summary

Cardiovascular magnetic resonance has the ability to thoroughly evaluate novel imaging markers: aortic stiffness, native T1, and native T2. Novel imaging markers can be used for diagnostic and prognostic purposes as well as potential therapeutic targets in CKD population.