Aims:Left atrial (LA) myopathy is a key driver of atrial fibrillation (AF) development and progression. Late gadolinium enhancement (LGE) cardiovascular magnetic resonance enables non-invasive quantification of LA fibrosis, a hallmark of atrial myopathy. However, conventional LGE sequences lack sufficient spatial resolution to accurately depict the thin atrial wall, and reference data in healthy cohorts are scarce. This study aimed to evaluate a high-resolution isotropic 3D LGE Dixon sequence for assessing LA fibrosis in healthy controls and AF patients. Methods and results:In this prospective study, 40 ablation-naïve AF patients (21 paroxysmal, 19 persistent) and 20 healthy controls underwent isotropic (1.3 mm3) 3D whole-heart LGE imaging. Segmentation was successfully performed using CemrgApp in all participants. A setup-specific threshold for fibrosis detection was defined as an image-intensity ratio (IIR) > 1.34 (mean + 2SD of healthy controls) and validated against pre-procedural electroanatomical mapping (EAM) and follow-up imaging at six months post ablation. At baseline, total LA enhancement was higher in persistent than paroxysmal AF (3.65% [1.84-7.16] vs. 1.16% [0.43-2.27]; P = 0.044) and controls (1.25% [0.65-1.75]; P = 0.041). No significant correlation was observed between total LGE-derived fibrosis and bipolar low-voltage area (ρ = -0.03, P = 0.87), though point-by-point analysis showed a weak negative correlation (ρ = -0.05, P < 0.001). In patients with sinus rhythm at follow-up, total fibrosis increased from 1.68% [0.64-6.51] to 6.30% [2.53-12.28]; P < 0.001, driven by peri-ablational scar formation, with no change in remote myocardium. Intra-reader correlation for LA-LGE was excellent: ICC 0.99 (95% CI 0.95-0.99). Conclusion:High resolution isotropic 3D LA-LGE enables robust detection of ablation-induced scarring and biologically plausible fibrosis differences between AF stages. However, its correlation with bipolar voltage mapping remains limited, suggesting that LGE and EAM provide complementary information on atrial myopathy.

Purpose4D flow magnetic resonance imaging (4D‐MRI) allows time‐resolved visualization of blood flow patterns, quantification of volumes, velocities, and advanced parameters, such as wall shear stress (WSS). As 4D‐MRI enters the clinical arena, standardization and awareness of confounders are important. Our aim was to evaluate the equivalence of 4D flow‐derived aortic hemodynamics in healthy volunteers using different sequences and field strengths.Methods4D‐MRI was acquired in 10 healthy volunteers at 1.5T using three different prototype sequences, at 3T and at 7T (Siemens Healthineers). After evaluation of diagnostic quality in three segments (ascending‐, descending aorta, aortic arch), peak velocity, flow volumes, and WSS were investigated. Equivalence limits for comparison of field strengths/sequences were based on the limits of Bland‐Altman analyses of the intraobserver variability.ResultsNon‐diagnostic quality was found in 10/144 segments, 9/10 were obtained at 7T. Apart for the comparison of forward flow between sequence 1 and 3, the differences in measurements between field strengths/sequences exceeded the range of agreement. Significant differences were found between field strengths/sequences for forward flow (1.5T vs. 3T, 3T vs. 7T, sequence 1 vs. 3, 2 vs. 3 [P < .001]), WSS (1.5T vs. 3T [P < .05], sequence 1 vs. 2, 1 vs. 3, 2 vs. 3 [P < .001]), and peak velocity (1.5T vs. 7T, sequence 1 vs. 3 [P > .001]). All parameters at all field strengths/with all sequences correlated moderately to strongly (r ≥ 0.5).ConclusionData from all sequences could be acquired and resulting images showed sufficient quality for further analysis. However, the variability of the measurements of peak velocity, flow volumes, and WSS was higher when comparing field strengths/sequences as the equivalence limits defined by the intraobserver assessments.

Hypertrophic cardiomyopathy (HCM) is the most common genetic disease of the myocardium and bares the risk of progression to heart failure or sudden cardiac death. Identifying patients at risk remains an unmet need. Recognizing the dependence of microscopic susceptibility on tissue microstructure and on cardiac macromorphology we hypothesized that myocardial T2* might be altered in HCM patients compared to healthy controls. To test this hypothesis, myocardial T2*-mapping was conducted at 7.0 Tesla to enhance T2*-contrast. 2D CINE T2*-mapping was performed in healthy controls and HCM patients. To ensure that T2* is not dominated by macroscopic magnetic field inhomogeneities, volume selective B0 shimming was applied. T2* changes in the interventricular septum across the cardiac cycle were analyzed together with left ventricular radius and ventricular septal wall thickness. The results show that myocardial T2* is elevated throughout the cardiac cycle in HCM patients compared to healthy controls. A mean septal T2* = 13.7 ± 1.1 ms (end-systole: T2*,systole = 15.0 ± 2.1, end-diastole: T2*,diastole = 13.4 ± 1.3 ms, T2*,systole/T2*,diastole ratio = 1.12) was observed in healthy controls. For HCM patients a mean septal T2* = 17.4 ± 1.4 ms (end-systole: T2*,systole = 17.7 ± 1.2 ms, end-diastole: T2*,diastole = 16.2 ± 2.5 ms, T2*,systole/T2*,diastole ratio = 1.09) was found. Our preliminary results provide encouragement that assessment of T2* and its changes across the cardiac cycle may benefit myocardial tissue characterization in HCM.

Segmented phase-sensitive inversion recovery (PSIR) cardiovascular magnetic resonance (CMR) sequences are reference standard for non-invasive evaluation of myocardial fibrosis using late gadolinium enhancement (LGE). Several multi-slice LGE sequences have been introduced for faster acquisition in patients with arrhythmia and insufficient breathhold capability.

BACKGROUND:Continuous pressure overload may lead to subclinical myocardial tissue changes in patients with hypertensive heart disease (HHD) and aortic stenosis (AS). The study aim was to detect interstitial fibrosis using quantitative cardiovascular magnetic resonance.METHODS:Fifteen patients with HHD (arterial hypertension + septal wall thickness ≥13 mm), 33 with AS (eight mild, 15 moderate, 10 severe), and 60 healthy controls were enrolled. Native T1 maps (modified Look-Locker inversion recovery) were obtained in a basal, mid-ventricular, and apical shortaxis slice of the left ventricle to assess cardiac fibrosis. Focal fibrosis was assessed with late gadolinium enhancement (LGE).RESULTS:Patients with HHD and controls did not differ regarding the native myocardial T1 values, both per slice and per segment. In AS patients, apical native T1 values were lower than in controls, and there was a trend towards higher T1 values in the septum in severe AS (1172.6 ± 62.0 ms versus 1152.9 ± 43.9 ms). Five HHD patients and 11 AS patients had non-ischemic fibrosis in LGE images. Native T1 times did not differ between LGE-positive and LGEnegative groups (both with inclusion and exclusion of segments with LGE).CONCLUSIONS:T1 mapping did not reveal any evidence of abnormal interstitial fibrosis in HHD subjects with mild hypertrophy. In severe AS, a trend towards more interstitial fibrosis was present, but absolute differences were small for decision making.

Myocardial effective relaxation time T2* is commonly regarded as a surrogate for myocardial tissue oxygenation. However, it is legitimate to assume that there are multiple factors that influence T2* . To this end, this study investigates the relationship between T2* and cardiac macromorphology given by left ventricular (LV) wall thickness and left ventricular radius, and provides interpretation of the results in the physiological context.

Infiltrative cardiomyopathies are a heterogenous group of diseases that typically lead to restrictive cardiac dysfunction. Due to similar phenotypes, accurate diagnosis is challenging without invasive endomyocardial biopsy which has historically been considered mandatory. Cardiac magnetic resonance (CMR) has been well established in the diagnostic workup of patients with suspected cardiomyopathies due to its unique capability for tissue differentiation and its unsurpassed accuracy in defining cardiac morphology and function. The increasing variety of CMR techniques has generated both excitement and uncertainty with regard to their potential clinical use and its role vis-à-vis conventional noninvasive imaging techniques. The purpose of this review is to give an overview of established and emerging CMR techniques and typical image characteristics of the most commonly encountered infiltrative cardiomyopathies.

T1 mapping and extracellular volume (ECV) have the potential to guide patient care and serve as surrogate end-points in clinical trials, but measurements differ between cardiovascular magnetic resonance (CMR) scanners and pulse sequences. To help deliver T1 mapping to global clinical care, we developed a phantom-based quality assurance (QA) system for verification of measurement stability over time at individual sites, with further aims of generalization of results across sites, vendor systems, software versions and imaging sequences. We thus created T1MES: The T1 Mapping and ECV Standardization Program.

BACKGROUND:Studying T1- and T2-mapping for discrimination of acute from chronic myocardial infarction (AMI, CMI). METHODS:Eight patients with AMI underwent CMR at 3 T acutely and after >3 months. Imaging techniques included: T2-weighted imaging, late enhancement (LGE), T2-mapping, native and post-contrast T1-mapping. Myocardial T2- and T1-relaxation times were determined for every voxel. Abnormal voxels as defined by having T2- and T1-values beyond a predefined threshold (T2 > 50 ms, native T1 > 1250 ms and post-contrast T1 < 350 ms) were highlighted and compared with LGE as the reference. RESULTS:Abnormal T2-relaxation times were present in the voxels with AMI (=> delete acute infarction; unfortunately this is not possible in your web interface) acute infarction only in half of the subjects. Abnormal T2-values were also present in subjects with CMI, thereby matching the chronically infarcted territory in some. Abnormal native T1 times were present in voxels with AMI in 5/8 subjects, but also remote from the infarcted territory in four. In CMI, abnormal native T1 values corresponded with infarcted voxels, but were also abnormal remote from the infarcted territory. Voxels with abnormal post-contrast T1-relaxation times agreed well with LGE in AMI and CMI. CONCLUSIONS:In this pilot-study, T2- and T1-mapping with simple thresholds did not facilitate the discrimination of AMI and CMI.

Background Cardiovascular Magnetic Resonance (CMR) provides valuable information in patients with hypertrophic cardiomyopathy (HCM) based on myocardial tissue differentiation and the detection of small morphological details. CMR at 7.0T improves spatial resolution versus today’s clinical protocols. This capability is as yet untapped in HCM patients. We aimed to examine the feasibility of CMR at 7.0T in HCM patients and to demonstrate its capability for the visualization of subtle morphological details. Methods We screened 131 patients with HCM. 13 patients (9 males, 56 ±31 years) and 13 healthy age- and gender-matched subjects (9 males, 55 ±31years) underwent CMR at 7.0T and 3.0T (Siemens, Erlangen, Germany). For the assessment of cardiac function and morphology, 2D CINE imaging was performed (voxel size at 7.0T: (1.4x1.4x2.5) mm3 and (1.4x1.4x4.0) mm3; at 3.0T: (1.8x1.8x6.0) mm3). Late gadolinium enhancement (LGE) was performed at 3.0T for detection of fibrosis. Results All scans were successful and evaluable. At 3.0T, quantification of the left ventricle (LV) showed similar results in short axis view vs. the biplane approach (LVEDV, LVESV, LVMASS, LVEF) (p = 0.286; p = 0.534; p = 0.155; p = 0.131). The LV-parameters obtained at 7.0T where in accordance with the 3.0T data (pLVEDV = 0.110; pLVESV = 0.091; pLVMASS = 0.131; pLVEF = 0.182). LGE was detectable in 12/13 (92%) of the HCM patients. High spatial resolution CINE imaging at 7.0T revealed hyperintense regions, identifying myocardial crypts in 7/13 (54%) of the HCM patients. All crypts were located in the LGE-positive regions. The crypts were not detectable at 3.0T using a clinical protocol. Conclusions CMR at 7.0T is feasible in patients with HCM. High spatial resolution gradient echo 2D CINE imaging at 7.0T allowed the detection of subtle morphological details in regions of extended hypertrophy and LGE.

OBJECTIVES:Pectus excavatum (PE) is often regarded as a cosmetic disease, while its effect on cardiac function is under debate. Data regarding cardiac function before and after surgical correction of PE are limited. We aimed to assess the impact of surgical correction of PE on cardiac function by cardiovascular magnetic resonance (CMR).METHODS:CMR at 1.5 T was performed in 38 patients (mean age 21 ± 8.3; 31 men) before and after surgical correction to evaluate thoracic morphology, indices and its relation to three-dimensional left and right ventricular cardiac function.RESULTS:Surgery was successful in all patients as shown by the Haller Index ratio of maximum transverse diameter of the chest wall and minimum sternovertebral distance [pre: 9.64 (95% CI 8.18-11.11) vs post: 3.0 (2.84-3.16), P < 0.0001]. Right ventricular ejection fraction (RVEF) was reduced before surgery and improved significantly at the 1-year follow-up [pre: 45.7% (43.9-47.4%) vs 48.3% (46.9-49.5%), P = 0.0004]. Left ventricular ejection fraction was normal before surgery, but showed a further improvement after 1 year [pre: 61.0% (59.3-62.7%) vs 62.7% (61.3-64.2%), P = 0.0165]. Cardiac compression and the asymmetry index changed directly after surgery and were stable at the 1-year follow-up [3.93 (3.53-4.33) vs 2.08 (1.98-2.19) and 2.36 (2.12-2.59) vs 1.38 (1.33-1.44), respectively; P < 0.0001 for both]. None of the obtained thoracic indices were predictors of the improvement of cardiac function. A reduced preoperative RVEF was predictive of RVEF improvement.CONCLUSIONS:PE is associated with reduced RVEF, which improves after surgical correction. CMR has the capability of offering additional information prior to surgical correction.

Methods Eight male patients with acute ST-elevation myocardial infarction underwent CMR at 3T (Siemens Verio) acutely and after >3 months. Imaging techniques included: T2-weighted imaging, late enhancement (LGE) as well as T2-mapping (3 single-shot SSFP-images), native T1-mapping (MOLLI, 11 single-shot SSFPimages), and T1-mapping 10min after 0.2mmol gadobutrol using non-product sequences. Image analysis included: 1) Visual assessment: Five independent readers assessed the presence (yes/no) of an infarct-like myocardial lesion. 2) Quantitative assessment per segment: Myocardial T2and T1-relaxation times were determined for every segment and correlated to LGE. 3) Quantitative assessment per pixel: Based on reference T2and T1relaxation times, abnormal pixels were identified and correlated to LGE.