Role of T1 Mapping in Inherited Cardiomyopathies

The Significance of Parametric Mapping in Advanced Cardiac Imaging

Cardiac magnetic resonance imaging has witnessed a transformative shift with the integration of parametric mapping techniques, such as T1 and T2 mapping and extracellular volume fraction. These techniques play a crucial role in advancing our understanding of cardiac function and structure, providing unique insights into myocardial tissue properties. Native T1 mapping is particularly valuable, correlating with histopathological fibrosis and serving as a marker for various cardiac pathologies. Extracellular volume fraction, an early indicator of myocardial remodeling, predicts adverse outcomes in heart failure. Elevated T2 relaxation time in cardiac MRI indicates myocardial edema, enabling noninvasive and early detection in conditions like myocarditis. These techniques offer precise insights into myocardial properties, enhancing the accuracy of diagnosis and prognosis across a spectrum of cardiac conditions, including myocardial infarction, autoimmune diseases, myocarditis, and sarcoidosis. Emphasizing the significance of these techniques in myocardial tissue analysis, the review provides a comprehensive overview of their applications and contributions to our understanding of cardiac diseases.

Regional extracellular volume within late gadolinium enhancement-positive myocardium to differentiate cardiac sarcoidosis from myocarditis of other etiology: a cardiovascular magnetic resonance study

BACKGROUND

Cardiovascular magnetic resonance (CMR) plays a pivotal role in diagnosing myocardial inflammation. In addition to late gadolinium enhancement (LGE), native T1 and T2 mapping as well as extracellular volume (ECV) are essential tools for tissue characterization. However, the differentiation of cardiac sarcoidosis (CS) from myocarditis of other etiology can be challenging. Positron-emission tomography-computed tomography (PET-CT) regularly shows the highest Fluordesoxyglucose (FDG) uptake in LGE positive regions. It was therefore the aim of this study to investigate, whether native T1, T2, and ECV measurements within LGE regions can improve the differentiation of CS and myocarditis compared with using global native T1, T2, and ECV values alone.

METHODS

PET/CT confirmed CS patients and myocarditis patients (both acute and chronic) from a prospective registry were compared with respect to regional native T1, T2, and ECV. Acute and chronic myocarditis were defined based on the 2013 European Society of Cardiology position paper on myocarditis. All parametric measures and ECV were acquired in standard fashion on three short-axis slices according to the ConSept study for global values and within PET-CT positive regions of LGE.

RESULTS

Between 2017 and 2020, 33 patients with CS and 73 chronic and 35 acute myocarditis patients were identified. The mean ECV (± SD) in LGE regions of CS patients was higher than in myocarditis patients (CS vs. acute and chronic, respectively: 0.65 ± 0.12 vs. 0.45 ± 0.13 and 0.47 ± 0.1; p < 0.001). Acute and chronic myocarditis patients had higher global native T1 values (1157 ± 54 ms vs. 1196 ± 63 ms vs. 1215 ± 74 ms; p = 0.001). There was no difference in global T2 and ECV values between CS and acute or chronic myocarditis patients.

CONCLUSION

This is the first study to show that the calculation of regional ECV within LGE-positive regions may help to differentiate CS from myocarditis. Further studies are warranted to corroborate these findings.

Cardiac MR fingerprinting with a short acquisition window in consecutive patients referred for clinical CMR and healthy volunteers

Cardiac Magnetic Resonance Fingerprinting (cMRF) has been demonstrated to enable robust and accurate T₁ and T₂ mapping for the detection of myocardial fibrosis and edema. However, the relatively long acquisition window (250 ms) used in previous cMRF studies might leave it vulnerable to motion artifacts in patients with high heart rates. The goal of this study was therefore to compare cMRF with a short acquisition window (154 ms) and low-rank reconstruction to routine cardiac T₁ and T₂ mapping at 1.5 T. Phantom studies showed that the proposed cMRF had a high T₁ and T₂ accuracy over a wider range than routine mapping techniques. In 9 healthy volunteers, the proposed cMRF showed small but significant myocardial T₁ and T₂ differences compared to routine mapping (ΔT₁ = 1.5%, P = 0.031 and ΔT₂ = - 7.1%, P < 0.001). In 61 consecutive patients referred for CMR, the native T₁ values were slightly lower (ΔT₁ = 1.6%; P = 0.02), while T₂ values did not show statistical difference (ΔT₂ = 4.3%; P = 0.11). However, the difference was higher in post-contrast myocardial T₁ values (ΔT₁ = 12.3%; P < 0.001), which was reflected in the extracellular volume (ΔECV = 2.4%; P < 0.001). Across all subjects, the proposed cMRF had a lower precision when compared to routine techniques, although its higher spatial resolution enabled the visualization of smaller details.

Phenotyping the hypertensive heart

Arterial hypertension remains the most frequent cardiovascular (CV) risk factor, and is responsible for a huge global burden of disease. Echocardiography is the first-line imaging method for the evaluation of cardiac damage in hypertensive patients and novel techniques, such as 2D and D speckle tracking and myocardial work, provide insight in subclinical left ventricular (LV) impairment that would not be possible to detect with conventional echocardiography. The structural, functional, and mechanical cardiac remodelling that are detected with imaging are intermediate stages in the genesis of CV events, and initiation or intensification of antihypertensive therapy in response to these findings may prevent or delay progressive remodelling and CV events. However, LV remodelling—especially LV hypertrophy—is not specific to hypertensive heart disease (HHD) and there are circumstances when other causes of hypertrophy such as athlete heart, aortic stenosis, or different cardiomyopathies need exclusion. Tissue characterization obtained by LV strain, cardiac magnetic resonance, or computed tomography might significantly help in the distinction of different LV phenotypes, as well as being sensitive to subclinical disease. Selective use of multimodality imaging may therefore improve the detection of HHD and guide treatment to avoid disease progression. The current review summarizes the advanced imaging tests that provide morphological and functional data about the hypertensive cardiac injury.

Early diagnosis of cardiomyopathies by cardiac magnetic resonance. Overview of the main criteria

Cardiomyopathies (CMPs) are diseases of the heart muscle. They include a variety of myocardial disorders that manifest with various structural and functional phenotypes and are frequently genetic. Myocardial disease caused by known cardiovascular causes (such as hypertension, ischemic heart disease, or valvular disease) should be distinguished from CMPs for classification and management purposes. Identification of various CMP phenotypes relies primarily upon echocardiographic evaluation. In selected cases, cardiac magnetic resonance imaging (CMR) or computed tomography may be useful to identify and localize fatty infiltration, inflammation, scar/fibrosis, focal hypertrophy, and better visualize the left ventricular apex and right ventricle.  CMR imaging has emerged as a comprehensive tool for the diagnosis and follow-up of patients with CMPs. The accuracy and reproducibility in evaluating cardiac structures, the unique ability of non-invasive tissue characterization and the lack of ionizing radiation, make CMR very attractive as a potential "all-in-one technique". Indeed, it provides valuable data to confirm or establish the diagnosis, screen subclinical cases, identify aetiology, establish the prognosis. Additionally, it provides information for setting a risk stratification (based on evaluation of proved independent prognostic factors as ejection fraction, end-systolic-volume, myocardial fibrosis) and follow-up. Last, it helps to monitor the response to the therapy. In this review, the pivotal role of CMR in the comprehensive evaluation of patients with CMP is discussed, highlighting the key features guiding differential diagnosis and the assessment of prognosis.

Right and left ventricle native T1 mapping in systolic phase in patients with congenital heart disease

BACKGROUND

T1 mapping is emerging as a powerful tool in cardiac magnetic resonance (CMR) to evaluate diffuse fibrosis. However, right ventricular (RV) T1 mapping proves difficult due to the limited wall thickness in diastolic phase. Several studies focused on systolic T1 mapping, albeit only on the left ventricle (LV).

PURPOSE

To estimate intra- and inter-observer variability of native T1 (nT1) mapping of the RV, and its correlations with biventricular and pulmonary function in patients with congenital heart disease (CHD).

MATERIAL AND METHODS

In this retrospective, observational, cross-sectional study we evaluated 36 patients with CHD, having undergone CMR on a 1.5-T scanner. LV and RV functional evaluations were performed. A native modified look-locker inversion recovery short-axis sequence was acquired in the systolic phase. Intra- and inter-reader reproducibility were reported as complement to 100% of the ratio between coefficient of reproducibility and mean. Spearman ρ and Mann-Whitney U-test were used to compare distributions.

RESULTS

Intra- and inter-reader reproducibility was 84% and 82%, respectively. Median nT1 was 1022 ms (interquartile range [IQR] 1108-972) for the RV and 947 ms (IQR 986-914) for the LV. Median RV-nT1 was 1016 ms (IQR 1090-1016) in patients with EDVI ≤100 mL/m² and 1100 ms (IQR 1113-1100) in patients with EDVI >100 mL/m² (P = 0.049). A significant negative correlation was found between RV ejection fraction and RV-nT1 (ρ = -0.284, P = 0.046).

CONCLUSION

Systolic RV-nT1 showed a high reproducibility and a negative correlation with RV ejection fraction, potentially reflecting an adaptation of the RV myocardium to pulmonary valve/conduit (dys)-function.

Manganese-enhanced magnetic resonance imaging in dilated cardiomyopathy and hypertrophic cardiomyopathy

AIMS

The aim of this study is to quantify altered myocardial calcium handling in non-ischaemic cardiomyopathy using magnetic resonance imaging.

METHODS AND RESULTS

Patients with dilated cardiomyopathy (n = 10) or hypertrophic cardiomyopathy (n = 17) underwent both gadolinium and manganese contrast-enhanced magnetic resonance imaging and were compared with healthy volunteers (n = 20). Differential manganese uptake (Ki) was assessed using a two-compartment Patlak model. Compared with healthy volunteers, reduction in T1 with manganese-enhanced magnetic resonance imaging was lower in patients with dilated cardiomyopathy [mean reduction 257 ± 45 (21%) vs. 288 ± 34 (26%) ms, P < 0.001], with higher T1 at 40 min (948 ± 57 vs. 834 ± 28 ms, P < 0.0001). In patients with hypertrophic cardiomyopathy, reductions in T1 were less than healthy volunteers [mean reduction 251 ± 86 (18%) and 277 ± 34 (23%) vs. 288 ± 34 (26%) ms, with and without fibrosis respectively, P < 0.001]. Myocardial manganese uptake was modelled, rate of uptake was reduced in both dilated and hypertrophic cardiomyopathy in comparison with healthy volunteers (mean Ki 19 ± 4, 19 ± 3, and 23 ± 4 mL/100 g/min, respectively; P = 0.0068). In patients with dilated cardiomyopathy, manganese uptake rate correlated with left ventricular ejection fraction (r2 = 0.61, P = 0.009). Rate of myocardial manganese uptake demonstrated stepwise reductions across healthy myocardium, hypertrophic cardiomyopathy without fibrosis and hypertrophic cardiomyopathy with fibrosis providing absolute discrimination between the healthy myocardium and fibrosed myocardium (mean Ki 23 ± 4, 19 ± 3, and 13 ± 4 mL/100 g/min, respectively; P < 0.0001).

CONCLUSION

The rate of manganese uptake in both dilated and hypertrophic cardiomyopathy provides a measure of altered myocardial calcium handling. This holds major promise for the detection and monitoring of dysfunctional myocardium, with the potential for early intervention and prognostication.

Elevated serum YKL40 level is a predictor of MACE during the long-term follow up in hypertensive patients

Background: YKL-40 (human cartilage glycoprotein 39, chitinase-3-like protein 1) is an inflammatory marker secreted mainly by macrophages and has distinctive roles on extracellular matrix remodeling, macrophage maturation, adhesion, and migration. Despite the presence of robust data suggesting the association of YKL-40 with variety of cardiovascular diseases (CV), there is no study up to date evaluating the role of YKL-40 on the long-term prognosis in patients with hypertension (HT).Methods: A single center, prospective, observational cohort study that included 327 consecutive hypertensive patients which were presented to a cardiology outpatient clinic. Patients were followed up for 7.89 ± 0.12 years. Primary outcome of the study was the occurrence of major cardiovascular outcomes (MACE) defined as all-cause mortality, new onset heart failure (HF), and coronary artery disease (CAD) requiring revascularization.Results: A total of 135 patients constituted the final study population [mean age: 52.4 ± 10.2, female: 63 (46%)]. A total of 28 (20.7%) patients had MACE during the follow up. Cox regression analysis revealed that age (HR: 1.046, 1.016-1.093 CI 95%, p = .026), diabetes (HR: 2.278, 1.026-5.057 CI 95%, p = .043), and YKL-40 level (HR: 1.019, 1.013-1.026 CI 95%, p = .005) significantly predicted MACE. We found that sensitivity and specificity of YKL-40 > 93.5 for predicting MACE was 71.4% and 65%, respectively with an area under curve (AUC) 0.723 (0.617-0.828 CI 95%, p < .001)Conclusion: Elevated serum YKL-40 level predicted MACE in hypertensive patients during a long-term follow up.

Cardiovascular magnetic resonance T2* mapping for structural alterations in hypertrophic cardiomyopathy

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HCM patients exhibited significantly decreased T2* values compared to controls.

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Within HCM patients, those with myocardial fibrosis presented with decreased T2* values.

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T2* provided good diagnostic accuracy to diagnose HCM with fibrosis.

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T2* may add information for identifying a higher risk sub-group of HCM patients.

Purpose

Hypertrophic cardiomyopathy (HCM) is characterized by a heterogeneous morphology and variable prognosis. A mismatch between left ventricular mass (LVM) and microvascular circulation with corresponding relative ischemia has been implicated to cause myocardial replacement fibrosis that deteriorates prognosis. Besides parametric T1 mapping, Cardiovascular Magnetic Resonance (CMR) T2* mapping is able to identify ischemia as well as fibrosis in cardiac and extracardiac diseases. Therefore, we aimed to investigate the value of T2* mapping to characterize structural alterations in patients with HCM.

Methods

CMR was performed on a 1.5 T MR imaging system (Achieva, Philips, Best, Netherlands) using a 5-channel coil in patients with HCM (n = 103, 50.6 ± 16.4 years) and in age- and gender-matched controls (n = 20, 44.8 ± 16.9 years). T2* mapping (1 midventricular short axis slice) was acquired in addition to late gadolinium enhancement (LGE). T2* values were compared between patients with HCM and controls as well as between HCM patients with- and without fibrosis.

Results

HCM patients showed significantly decreased T2* values compared to controls (26.2 ± 4.6 vs. 31.3 ± 4.3 ms, p < 0.001). Especially patients with myocardial fibrosis presented with decreased T2* values in comparison to those without fibrosis (25.2 ± 4.0 vs. 28.7 ± 5.3 ms, p = 0.003). A regression model including maximum wall thickness, LVM and T2* values provided good overall diagnostic accuracy of 80% to diagnose HCM with and without fibrosis.

Conclusion

In this study, parametric mapping identified lower T2* values in HCM patients compared to controls, especially in a sub-group of patients with myocardial fibrosis. As myocardial fibrosis has been suggested to influence prognosis of patients with HCM, T2* mapping may add information for identifying a higher risk sub-group of HCM patients.

Use of Myocardial T1 Mapping at 3.0 T to Differentiate Anderson-Fabry Disease from Hypertrophic Cardiomyopathy

Purpose To compare left ventricular (LV) and right ventricular (RV) 3.0-T cardiac magnetic resonance (MR) imaging T1 values in Anderson-Fabry disease (AFD) and hypertrophic cardiomyopathy (HCM) and evaluate the diagnostic value of native T1 values beyond age, sex, and conventional imaging features. Materials and Methods For this prospective study, 30 patients with gene-positive AFD (37% male; mean age ± standard deviation, 45.0 years ± 14.1) and 30 patients with HCM (57% male; mean age, 49.3 years ± 13.5) were prospectively recruited between June 2016 and September 2017 to undergo cardiac MR imaging T1 mapping with a modified Look-Locker inversion recovery (MOLLI) acquisition scheme at 3.0 T (repetition time msec/echo time msec, 280/1.12; section thickness, 8 mm). LV and RV T1 values were evaluated. Statistical analysis included independent samples t test, receiver operating characteristic curve analysis, multivariable logistic regression, and likelihood ratio test. Results Septal LV, global LV, and RV native T1 values were significantly lower in AFD compared with those in HCM (1161 msec ± 47 vs 1296 msec ± 55, respectively [P < .001]; 1192 msec ± 52 vs 1268 msec ± 55 [P < .001]; and 1221 msec ± 54 vs 1271 msec ± 37 [P = .001], respectively). A septal LV native T1 cutoff point of 1220 msec or lower distinguished AFD from HCM with sensitivity of 97%, specificity of 93%, and accuracy of 95%. Septal LV native T1 values differentiated AFD from HCM after adjustment for age, sex, and conventional imaging features (odds ratio, 0.94; 95% confidence interval: 0.91, 0.98; P = < .001). In a nested logistic regression model with age, sex, and conventional imaging features, model fit was significantly improved by the addition of septal LV native T1 values (χ² [df = 1] = 33.4; P < .001). Conclusion Cardiac MR imaging native T1 values at 3.0 T are significantly lower in patients with AFD compared with those with HCM and provide independent and incremental diagnostic value beyond age, sex, and conventional imaging features. ^© RSNA, 2018.