Background: Myocardial strain is a valuable biomarker for diagnosing and predicting cardiac conditions, offering additional prognostic information to traditional metrics like ejection fraction. While cardiovascular magnetic resonance (CMR) methods, particularly cine displacement encoding with stimulated echoes (DENSE), are the gold standard for strain estimation, evaluation of regional strain estimation requires precise ground truth. This study introduces DENSE-Sim, an open-source simulation pipeline for generating realistic cine DENSE images with high-resolution known ground truth strain, enabling evaluation of accuracy and precision in strain analysis pipelines.
Methods: This pipeline is a modular tool designed for simulating cine DENSE images and evaluating strain estimation performance. It comprises four main modules: 1) anatomy generation, for creating end-diastolic cardiac shapes; 2) motion generation, to produce myocardial deformations over time and Lagrangian strain; 3) DENSE image generation, using Bloch equation simulations with realistic noise, spiral sampling, and phase-cycling; and 4) strain evaluation. To illustrate the pipeline, a synthetic dataset of 180 short-axis slices was created, and analysed using the commonly-used DENSEanalysis tool. The impact of the spatial regularization parameter (k) in DENSEanalysis was evaluated against the ground-truth pixel strain, to particularly assess the resulting bias and variance characteristics.
Results: Simulated strain profiles were generated with a myocardial SNR ranging from 3.9 to 17.7. For end-systolic radial strain, DENSEanalysis average signed error (ASE) in Green strain ranged from 0.04 ± 0.09 (true-calculated, mean ± std) for a typical regularization (k=0.9), to - 0.01 ± 0.21 at low regularization (k=0.1). Circumferential strain ASE ranged from - 0.00 ± 0.04 at k=0.9 to - 0.01 ± 0.10 at k=0.1. This demonstrates that the circumferential strain closely matched the ground truth, while radial strain displayed more significant underestimations, particularly near the endocardium. A lower regularization parameter from 0.3 to 0.6 depending on the myocardial SNR, would be more appropriate to estimate the radial strain, as a compromise between noise compensation and global strain accuracy.
Conclusion: Generating realistic cine DENSE images with high-resolution ground-truth strain and myocardial segmentation enables accurate evaluation of strain analysis tools, while reproducing key in vivo acquisition features, and will facilitate the future development of deep-learning models for myocardial strain analysis, enhancing clinical CMR workflows.
Thoracic aortopathies result in aneurysmal expansion of the aorta that can lead to rapidly fatal aortic dissection or rupture. Despite the availability of abundant non-invasive imaging tools, the greatest contemporary challenge in the management of thoracic aortic aneurysm (TAA) is the lack of reliable metrics for risk stratification, with absolute aortic diameter, growth rate and syndromic factors remaining the primary determinants by which prophylactic surgical intervention is adjudged. Advanced MRI techniques present as a potential key to unlocking insights into TAA that could guide disease surveillance and surgical intervention. MRI has the capacity to encapsulate the aorta as a complex biomechanical structure, permitting the determination of aortic volume, morphology, composition, distensibility and fluid dynamics in a time-efficient manner. Nevertheless, current standard-of-care imaging protocols do not harness its full capacity. This state-of-the-art review explores the emerging role of MRI in the assessment of TAA and presents a blueprint for the required paradigm shift away from aortic size as the sole metric for risk stratifying TAA.
Background: Left ventricular (LV) reverse myocardial remodeling occurs following septal myectomy in hypertrophic obstructive cardiomyopathy (HOCM), but it remains unclear whether diffuse fibrosis is reversible during this period. Extracellular volume fraction (ECV) and indexed extracellular volume (iECV) are important surrogate markers of diffuse myocardial fibrosis. This study aimed to investigate whether diffuse myocardial fibrosis in HOCM can regress after myectomy.
Methods: A prospective cohort study was conducted among patients with HOCM. All subjects underwent clinical assessment (clinical history, 6-min walk test, biochemical analysis), echocardiography and cardiovascular magnetic resonance (CMR) preoperatively and 6 months after septal myectomy.
Results: A total of 43 patients (52±14 years, 23 female) were included in the analysis. At 6 months post-myectomy, there were significant within-person decreases in LV mass index (101.0[81.5-121.0] to 85.8[66.7-100.0] g/m2; p < 0.001), indexed cell volume (68.6[53.2-82.6] mL/m2 to 54.0[42.6-62.0] mL/m2; p < 0.001) and iECV (26.5[22.4-30.1] mL/m2 to 21.2[18.7-26.4] mL/m2; p < 0.001). Conversely, ECV (28.2±3.3% to 30.2±2.8%; p < 0.001) and late gadolinium enhancement mass (4.5[0.2-8.2] g to 8.7[2.1-12.8] g; p < 0.001) increased. These changes were accompanied by improvement of New York Heart Association functional class, 6-min walk test results, N-terminal pro-B-type natriuretic peptide, and high-sensitivity cardiac troponin T.
Conclusions: Six months after septal myectomy, both cellular hypertrophy and diffuse fibrosis are reversible in HOCM, while focal fibrosis does not regress. These are accompanied by improvement of exercise parameters and laboratory biomarkers, unfolding the plastic nature of diffuse fibrosis in HOCM and its potential as a therapeutic target.
Introduction: Cardiovascular magnetic resonance (CMR) is the gold standard for assessing cardiac volumes and function using 2D breath-held cine imaging. This technique, however, requires a reliable ECG signal, repetitive breath-holds, and the time-consuming and proficiency-demanding planning of cardiac views. Recently, a free-running framework has been developed for cardiac and respiratory motion-resolved 5D whole-heart imaging without the need for an ECG signal, repetitive breath-holds, and meticulous plan scanning. In this study, we investigate the impact of acquisition time on cardiac volumetric and functional measurements, when using free-running imaging, compared to reference standard 2D cine imaging.
Methods: Sixteen healthy adult volunteers underwent CMR at 1.5T, including standard 2D breath-held cine imaging and free-running imaging using acquisition durations ranging from 1 to 6min in randomized order. All datasets were anonymized and analysed for left-ventricular end-systolic and end-diastolic volumes, as well as ejection fraction. In a subset of data, intra- and inter-observer agreement was assessed. In addition, image quality and observer confidence were scored using a 4-point Likert scale. Finally, acquisition efficiency was reported for both imaging techniques, which was defined as the time required for data sampling divided by the total scan time.
Results: No significant differences in left-ventricular EDV and ESV were found between free-running imaging for 1, 2, 3, 5, and 6minutes and standard 2D breath-held cine imaging. Biases in EDV ranged from -2.4 to -7.4mL, while biases in ESV ranged from -3.8 to 2.1mL. No significant differences in ejection fraction were found between free-running imaging of any acquisition duration and standard 2D breath-held cine imaging. Biases in ejection fraction ranged from -2.8% to 0.94%. Both image quality and observer confidence in free-running imaging improved when the acquisition duration increased. However, they were always lower than standard 2D breath-held cine imaging. Acquisition efficiency improved from 13% for standard 2D cine imaging to 50% or higher for free-running imaging.
Discussion: Free-running CMR with an acquisition duration as short as one minute can provide left-ventricular cardiac volumes and ejection fraction comparable to standard 2D breath-held cine imaging, albeit at the expense of both image quality and observer confidence.
Background: The effects of endovascular therapeutic hypothermia (ETH) in ST-elevation myocardial infarction (STEMI) regional contractility are unknown, and its impact on segmental contractility has still not been evaluated. We sought to evaluate segmental myocardial strain after ETH adjuvant to percutaneous coronary intervention (PCI) in STEMI.
Methods: We included patients who underwent 1.5 T cardiac magnetic resonance exams 5 and 30 days after acute anterior or inferior STEMI in a previous randomized trial. Left ventricle (LV) strain was evaluated on infarcted, adjacent, and remote myocardium. Segmental circumferential (CS) and radial strains (RS) were measured using feature-tracking imaging. Repeated-measures of ANOVA was used for comparisons within time and treatment.
Results: Forty patients were divided into hypothermia (ETH, n=29) and control (n=11) groups, with 5210 LV segments. In ETH infarcted areas, RS (11.2±16 vs. 14.8±15.2, p=0.001) and CS (-5.4±11.1 vs. -8±11.1, p=0.001) showed recovery from 5 to 30 days compared to controls (11.4±14 vs. 13.1±16.8, p=0.09; -6.5±10.6 vs. -6.4±12.5, p=0.94). In control remote areas, RS (28±18 vs. 31.7±18.5, p=0.001) and CS (-15.5±10.7 vs. -17.1±9, p=0.001) improved from 5 to 30 days compared to ETH (28.6±18.6 vs. 29±20, p=0.44; -15.2±10.4 vs. -15.3±10.6, p=0.82). Transmural infarcted areas in ETH improved RS (11.8±13.2 vs. 8.17±14.7, p=0.001) and CS (-6.1±10.9 vs. -3.1±11.3, p=0.001) compared to controls, with better contractility at 30 days.
Conclusions: In anterior or inferior STEMI patients, ETH adjuvant to PCI is associated with significant improvement in RS and CS of infarcted areas, including transmural segments, but not in the remote area. This might further increase our pathophysiological knowledge on early LV remodeling and ultimately suggest potential clinical value.
Availability of data and materials: The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.
Background: Despite of being a common gating method for cardiovascular magnetic resonance (CMR), electrocardiogram (ECG) gating has its disadvantages and new gating strategies are desirable. An alternative CMR gating method is doppler ultrasound (DUS) gating, which detects blood flow and ventricular movement. The aim of this study was to prove the feasibility of DUS gating as a novel CMR gating method in a clinical patient population.
Methods: In this prospective study, patients underwent clinically indicated CMR. Balanced steady-state free precession two-dimensional (2D) cine sequences in short axis and 4-chamber views were acquired using ECG and DUS gating. DUS and ECG signal were recorded simultaneously. Time difference between R wave and DUS systolic trigger detection was defined as trigger delay, the standard deviation of trigger delays as trigger jitter. Left and right ventricular parameters were assessed: Left and right ventricular ejection fraction (LVEF, RVEF) and left and right ventricular end-diastolic volume index (LVEDVI, RVEDVI). Overall image quality was assessed using a 5-point Likert scale (5=excellent to 1=non-diagnostic). For statistical analysis, paired t-test, Wilcoxon test, Pearson Correlation and intraclass correlation coefficient (ICC) were employed.
Results: 21 patients (7 female) were included (age: 45.4±19.7 years; body mass index: 27.6±5.5kg/m2). DUS mean trigger delay was 128±28ms. DUS mean trigger jitter was 23±13ms. Overall image quality showed no difference between ECG and DUS gating (e.g., short axis: 5 [IQR 3-5] vs. 4 [IQR 3.5-5]; P=0.21). Quantitative analysis revealed no differences between ECG and DUS gating: LVEF (53.2±9.2% vs. 52.3±9.1%; P=0.18; ICC 0.97 [95% confidence interval [CI] 0.93-0.99]), LVEDVI (84.5±15.8ml/m2 vs. 83.3±15.8ml/m2; P=0.06; ICC 0.99 [95% CI 0.98-1.00]), RVEF (52.8±8.0% vs. 51.6±7.2%; P=0.06; ICC 0.96 [95% CI 0.89-0.99]) and RVEDVI (80.8±17.6ml/m2 vs. 80.9±16.5ml/m2; P=0.91; ICC 0.98 [95% CI 0.96-0.99]). In one patient with a prominent lingula of the lung image quality non-diagnostic with DUS gating.
Conclusion: CMR gating with DUS is feasible and can offer an equivalent performance to ECG regarding image quality and quantitative parameter assessment.
Background: There is currently a lack of evidence regarding the significance of late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) in predicting left ventricular (LV) reverse remodeling (RR) in pooled data. This study aimed to evaluate the predictive value of the presence and extent of LGE for LVRR in patients with dilated cardiomyopathy (DCM).
Methods: Systematic searches were conducted in PubMed, Embase, Cochrane Library, and ClinicalTrials.gov from database inception to May 21, 2024. We estimated the overall effect sizes using the Mantel-Haenszel random-effects model. Subgroup analyses, meta-regression, and sensitivity analyses were performed to investigate potential sources of heterogeneity among studies.
Results: A total of 1141 patients (LGE prevalence: 49.7%) from 13 studies (five prospective and eight retrospective) were included. After a median follow-up period of 15 months, 43.5% of patients achieved LVRR. The presence of LGE predicted LVRR with a pooled odds ratio (OR) of 0.23 (95% confidence interval [CI]: 0.14-0.38, P<0.01) with significant heterogeneity (I² = 68%). The pooled OR for LVRR per percent increase in the extent of LGE was 0.94 (95% CI: 0.90-0.98, P<0.01) with low heterogeneity (I² = 19%). Subgroup analysis based on follow-up duration demonstrated that the presence of LGE was more strongly inversely associated with LVRR in <12 months follow-up (OR 0.06, 95% CI: 0.03-0.13, P<0.01) compared to ≥ 12 months follow-up (OR 0.36, 95% CI: 0.24-0.54, P<0.01).
Conclusion: The presence and increase extent of LGE on CMR significantly diminish LVRR achievement in DCM patients, particularly in short-term follow-up (<12 months).
Objectives and background: Accurate diagnosis of transthyretin amyloidosis cardiomyopathy (ATTR-CM) and its differentiation from light-chain (AL) cardiac amyloidosis (CA) cases (AL-CM) is of paramount importance, since treatment strategies are totally different and obviously more successful in case of early disease detection. Surprisingly, comparative imaging data based on concurrent cardiovascular magnetic resonance (CMR) and bone scintigraphy in the same patients with biopsy-proven diagnosis of CA are still rare.
Methods: This was a real-world retrospective single-centre study based on a local clinical care pipeline and we carefully analysed clinical, laboratory, CMR, bone scintigraphy data (and if necessary additional endomyocardial biopsy (EMB) data) in patients with suspected CA. As a major inclusion criterion, we only looked at those patients who underwent both a CMR study and a bone scintigraphy - with a clear-cut imaging finding detected by at least one imaging method.
Results: N=123 patients in whom the final diagnosis was obtained either non-invasively based on combined findings from bone scintigraphy and monoclonal protein studies or invasively based on additional EMB findings were included. A positive CMR result indicating presence of CA was found in 121 patients - suggesting a CMR sensitivity of 98.4% for the diagnosis of any CA. Bone scintigraphy identified 18 patients with low to moderate uptake (Perugini-score = 0-1) and 105 patients with high uptake (Perugini-score ≥2) - resulting in a sensitivity for bone scintigraphy of 85.4% for the diagnosis of any CA. There was an agreement ("diagnostic match") between CMR and bone scintigraphy results in 103 patients (84%) of the total study cohort, while a discrepancy ("diagnostic mismatch") was observed in 20 patients (16%). In 18 out of these 20 diagnostic mismatch cases, CMR correctly diagnosed the presence of CA despite a negative or inconclusive result on bone scintigraphy (eight with AL-CM, eight with ATTR-CM, and two with EMB-proven but unspecified CA).
Conclusion: CMR shows a substantially higher diagnostic yield for the diagnosis of CA compared to bone scintigraphy, if a real-world cohort of patients comprising different subtypes of CA is looked at, since CMR does not only detect ATTR-CM but also depicts other CA subtypes such as AL. In case of a clear-cut positive CMR result unequivocally indicative of CA, there is no incremental diagnostic value of an additionally performed bone scintigraphy.
Relationship with industry policy: No financial support or influence of any pharmaceutical company.
Background: Deterioration of right ventricular (RV) function in repaired tetralogy of Fallot (rToF) is poorly understood. Cardiovascular magnetic resonance (CMR) is used for monitoring, but its analysis is user-dependent and time-consuming. We sought to automate the analysis of CMR using machine learning, and to identify imaging traits associated with adverse RV remodeling in the natural history of rToF.
Methods: A longitudinal cohort of rToF patients underwent CMR at the Children's Hospital of Philadelphia. The nnU-Net method was used to train a machine learning model to segment the left ventricular (LV) blood pool, LV myocardium, and RV blood pool from 2D short-axis CMR images. Conventional and novel measures were calculated and studied in association with remodeling rates using multivariable linear regression. Remodeling rates were calculated as ((Variablescan2 - Variablescan1)/years between scans) for the variables end-diastolic volume index (EDVi), end-systolic volume index (ESVi), stroke volume index (SVi), ejection fraction (EF), and Peak Systolic dV/dt.
Results: The cohort was comprised of 758 patients, of whom 152 had two analyzable scans. Thirty-six patients underwent PVR between scans. Compared to patients with no intervention (representing the natural history of rToF), patients with PVR had significantly lower remodeling rates for RVEDVi, RVESVi, RVSVi, and absolute peak systolic RV dV/dt, while RVEF and left-sided metrics did not differ between groups. In 116 patients without PVR between scans, RV remodeling rates were negatively associated with baseline LV mass index, LVEDVi, LVSVi, and absolute peak systolic LV dV/dt.
Conclusions: We demonstrated that rToF patients with two CMR scans and PVR have significant differences in and opposite directions of RV remodeling rates compared to those with no intervention. We also showed that several left-sided measures of structure and function were associated with RV remodeling rates, indicating the importance of baseline LV measurements in characterizing future risk of adverse RV remodeling.
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