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Cardiac magnetic resonance imaging (MRI) is widely used for non-invasive assessment of cardiac morphology, function, and tissue characteristics due to its exquisite soft-tissue contrast. However, it remains time-consuming and requires proficiency, making it costly and limiting its widespread use. Traditional cardiac MRI is inefficient as signal acquisition is often limited to specific cardiac phases and requires complex view planning, parameter adjustments, and management of both respiratory and cardiac motion. Recent efforts have aimed to make cardiac MRI more efficient and accessible. Among these innovations, the free-running framework enables 5D whole-heart imaging without the need for an electrocardiogram signal, respiratory breath-holding, or complex planning. It uses a fully self-gated approach to extract cardiac and respiratory signals directly from the acquired image data, allowing for more efficient coverage in time and space without the need for electrocardiogram gating, triggering, navigators, or breath-holds. This review provides a comprehensive overview of the free-running framework, detailing its history, concepts, recent improvements, and clinical applications. [ABSTRACT FROM AUTHOR]

Background: The potential role of cardiac computed tomography (CT) has increasingly been demonstrated for the assessment of diffuse myocardial fibrosis through the quantification of extracellular volume (ECV). Photon-counting detector (PCD)-CT technology may deliver more accurate ECV quantification compared to energy-integrating detector CT. We evaluated the impact of reconstruction settings on the accuracy of ECV quantification using PCD-CT, with magnetic resonance imaging (MRI)-based ECV as reference. Methods: In this post hoc analysis, 27 patients (aged 53.1 ± 17.2 years (mean ± standard deviation); 14 women) underwent same-day cardiac PCD-CT and MRI. Late iodine CT scans were reconstructed with different quantum iterative reconstruction levels (QIR 1−4), slice thicknesses (0.4−8 mm), and virtual monoenergetic imaging levels (VMI, 40−90 keV); ECV was quantified for each reconstruction setting. Repeated measures ANOVA and t-test for pairwise comparisons, Bland–Altman plots, and Lin's concordance correlation coefficient (CCC) were used. Results: ECV values did not differ significantly among QIR levels (p = 1.000). A significant difference was observed throughout different slice thicknesses, with 0.4 mm yielding the highest agreement with MRI-based ECV (CCC = 0.944); 45-keV VMI reconstructions showed the lowest mean bias (0.6, 95% confidence interval 0.1–1.4) compared to MRI. Using the most optimal reconstruction settings (QIR4. slice thickness 0.4 mm, VMI 45 keV), a 63% reduction in mean bias and a 6% increase in concordance with MRI-based ECV were achieved compared to standard settings (QIR3, slice thickness 1.5 mm; VMI 65 keV). Conclusions: The selection of appropriate reconstruction parameters improved the agreement between PCD-CT and MRI-based ECV. Relevance statement: Tailoring PCD-CT reconstruction parameters optimizes ECV quantification compared to MRI, potentially improving its clinical utility. Key points: • CT is increasingly promising for myocardial tissue characterization, assessing focal and diffuse fibrosis via late iodine enhancement and ECV quantification, respectively. • PCD-CT offers superior performance over conventional CT, potentially improving ECV quantification and its agreement with MRI-based ECV. • Tailoring PCD-CT reconstruction parameters optimizes ECV quantification compared to MRI, potentially improving its clinical utility. [ABSTRACT FROM AUTHOR]

(1) Background and Objectives: Dark-blood late gadolinium enhancement has been shown to be a reliable cardiac magnetic resonance (CMR) method for assessing viability and depicting myocardial scarring in ischemic cardiomyopathy. The aim of this study was to evaluate dark-blood LGE imaging compared with conventional bright-blood LGE for the detection of myocardial scarring in non-ischemic cardiomyopathies. (2) Materials and Methods: Patients with suspected non-ischemic cardiomyopathy were prospectively enrolled in this single-centre study from January 2020 to March 2023. All patients underwent 1.5 T CMR with both dark-blood and conventional bright-blood LGE imaging. Corresponding short-axis stacks of both techniques were analysed for the presence, distribution, pattern, and localisation of LGE, as well as the quantitative scar size (%). (3) Results: 343 patients (age 44 ± 17 years; 124 women) with suspected non-ischemic cardiomyopathy were examined. LGE was detected in 123 of 343 cases (36%) with excellent inter-reader agreement (κ 0.97–0.99) for both LGE techniques. Dark-blood LGE showed a sensitivity of 99% (CI 98–100), specificity of 99% (CI 98–100), and an accuracy of 99% (CI 99–100) for the detection of non-ischemic scarring. No significant difference in total scar size (%) was observed. Dark-blood imaging with mean 5.35 ± 4.32% enhanced volume of total myocardial volume, bright-blood with 5.24 ± 4.28%, p = 0.84. (4) Conclusions: Dark-blood LGE imaging is non-inferior to conventional bright-blood LGE imaging in detecting non-ischemic scarring. Therefore, dark-blood LGE imaging may become an equivalent method for the detection of both ischemic and non-ischemic scars. [ABSTRACT FROM AUTHOR]

Background Delayed enhancement cardiac magnetic resonance (DE-CMR) is the reference standard for the non-invasive assessment of myocardial fibrosis. DE-CMR is able to distinguish ischaemic from non-ischaemic aetiologies based on differences in hyperenhancement distribution patterns. Hyperenhancement caused by ischaemic injury typically involves the endocardium, while hyperenhancement confined to the mid- and epicardial layers of the myocardium suggests a non-ischaemic aetiology. Case summary This is a case of a 20-year-old male with an unremarkable medical history with an acute ST-elevation myocardial infarction. DE-CMR revealed two distinct patterns of hyperenhancement: (i) a 'normal' wavefront-ischaemic pattern, and (ii) multiple atypical mid-wall and epicardial areas of focal hyperenhancement. Invasive coronary angiography (ICA) and coronary computed tomographic angiography (CCTA) showed multiple intracoronary thrombi and distal emboli in the left anterior descending, ramus circumflexus, and in smaller branches of the LCA. All hyperenhancement patterns observed on DE-CMR perfectly matched the distribution territories of the affected coronary arteries. Discussion This case with an acute myocardial infarction showed intracoronary thrombi and emboli on ICA and CCTA. Interestingly, DE-CMR showed two different patterns of hyperenhancement in the same territories of the coronary thrombi. This observation may challenge the concept that these non-endocardial areas of hyperenhancement on DE-CMR are always of non-ischaemic aetiology. It is hypothesized that occlusion of smaller distal branches of the coronary arteries may result in mid-wall or epicardial fibrosis as opposed to subendocardial fibrosis commonly found in patients with a large epicardial coronary occlusion. Clinicians should be aware of these atypical patterns to be able to initiate adequate medical therapy. [ABSTRACT FROM AUTHOR]

Background Surgical epicardial atrial fibrillation (AF) ablation can be performed as a stand-alone (thoracoscopic) procedure or concomitant to other cardiac surgery. In hybrid AF ablation thoracoscopic surgical epicardial ablation is combined with a percutaneous endocardial ablation. The Medtronic Gemini-S clamp is a surgical tool that uses irrigated bipolar biparietal radiofrequency (RF) energy applied with two clamp lesions that overlap to create one epicardial box lesion including the posterior left atrial wall and the pulmonary veins. Case summary We describe three patients with therapy-refractory persistent AF and different stages of atrial remodelling in whom the Medtronic Cardioblate Gemini-S Irrigated RF Surgical Ablation System was used for hybrid AF ablation. Acute endocardial validation at the end of the hybrid ablation revealed a complete box lesion in all three cases. At 2-year follow-up, two out of three patients had recurrence of atrial arrhythmias. Invasive electro-anatomical mapping confirmed the persistence of the box lesion, and the mechanism of arrhythmia recurrence in both patients was unrelated to posterior left atrium or the pulmonary veins. The third patient has been without arrhythmia symptoms since the ablation procedure. A three-dimensional late gadolinium enhancement magnetic resonance imaging illustrates the ablation scar non-invasively in two cases. Discussion Thoracoscopic biparietal RF AF ablation with the Medtronic Cardioblate Gemini-S Irrigated RF Surgical Ablation System results in permanent transmural scar formation, irrespective of the stage of atrial remodelling, as shown in this small population by means of multimodality scar evaluation. [ABSTRACT FROM AUTHOR]

Background: Conventional bright‐blood late gadolinium enhancement (LGE) cardiac magnetic resonance imaging (MRI) often suffers from poor scar‐to‐blood contrast due to the bright blood pool adjacent to the enhanced scar tissue. Recently, a dark‐blood LGE method was developed which increases scar‐to‐blood contrast without using additional magnetization preparation. Purpose We aim to histopathologically validate this dark‐blood LGE method in a porcine animal model with induced myocardial infarction (MI). Study Type: Prospective. Animal Model: Thirteen female Yorkshire pigs. Field Strength/Sequence: 1.5 T, two‐dimensional phase‐sensitive inversion‐recovery radiofrequency‐spoiled turbo field‐echo. Assessment MI was experimentally induced by transient coronary artery occlusion. At 1‐week and 7‐week post‐infarction, in‐vivo cardiac MRI was performed including conventional bright‐blood and novel dark‐blood LGE. Following the second MRI examination, the animals were sacrificed, and histopathology was obtained. Matching LGE slices and histopathology samples were selected based on anatomical landmarks. Independent observers, while blinded to other data, manually delineated the endocardial, epicardial, and infarct borders on either LGE images or histopathology samples. The percentage of infarcted left‐ventricular myocardium was calculated for both LGE methods on a per‐slice basis, and compared with histopathology as reference standard. Contrast‐to‐noise ratios were calculated for both LGE methods at 1‐week and 7‐week post‐infarction. Statistical Tests: Pearson's correlation coefficient and paired‐sample t‐tests were used. Significance was set at P < 0.05. Results: A combined total of 24 matched LGE and histopathology slices were available for histopathological validation. Dark‐blood LGE demonstrated a high level of agreement compared to histopathology with no significant bias (−0.03%, P = 0.75). In contrast, bright‐blood LGE showed a significant bias of −1.57% (P = 0.03) with larger 95% limits of agreement than dark‐blood LGE. Image analysis demonstrated significantly higher scar‐to‐blood contrast for dark‐blood LGE compared to bright‐blood LGE, at both 1‐week and 7‐weeks post‐infarction. Data Conclusion: Dark‐blood LGE without additional magnetization preparation provides superior visualization and quantification of ischemic scar compared to the current in vivo reference standard. Level of Evidence: 1 Technical Efficacy Stage: 2 [ABSTRACT FROM AUTHOR]