Diagnostic Classification of Patients with Dilated Cardiomyopathy Using Ventricular Strain Analysis Algorithm.

Dilated cardiomyopathy (DCM) is a cardiomyopathy with left ventricle or double ventricle enlargement and systolic dysfunction. It is an important cause of sudden cardiac death and heart failure and is the leading indication for cardiac transplantation. Major heart diseases like heart muscle damage and valvular problems are diagnosed using cardiac MRI. However, it takes time for cardiologists to measure DCM-related parameters to decide whether patients have this disease. We have presented a method for automatic ventricular segmentation, parameter extraction, and diagnosing DCM. In this paper, left ventricle and right ventricle are segmented by parasternal short-axis cardiac MR image sequence; then, related parameters are extracted in the end-diastole and end-systole of the heart. Machine learning classifiers use extracted parameters as input to predict normal people and patients with DCM, among which Random forest classifier gives the highest accuracy. The results show that the proposed system can be effectively utilized to detect and diagnose DCM automatically. The experimental results suggest the capabilities and advantages of the proposed method to diagnose DCM. A small amount of sample input can generate results comparable to more complex methods.

Markers of Myocardial Damage Predict Mortality in Patients With Aortic Stenosis.

BACKGROUND: Cardiovascular magnetic resonance (CMR) is increasingly used for risk stratification in aortic stenosis (AS). However, the relative prognostic power of CMR markers and their respective thresholds remains undefined. OBJECTIVES: Using machine learning, the study aimed to identify prognostically important CMR markers in AS and their thresholds of mortality. METHODS: Patients with severe AS undergoing AVR (n = 440, derivation; n = 359, validation cohort) were prospectively enrolled across 13 international sites (median 3.8 years' follow-up). CMR was performed shortly before surgical or transcatheter AVR. A random survival forest model was built using 29 variables (13 CMR) with post-AVR death as the outcome. RESULTS: There were 52 deaths in the derivation cohort and 51 deaths in the validation cohort. The 4 most predictive CMR markers were extracellular volume fraction, late gadolinium enhancement, indexed left ventricular end-diastolic volume (LVEDVi), and right ventricular ejection fraction. Across the whole cohort and in asymptomatic patients, risk-adjusted predicted mortality increased strongly once extracellular volume fraction exceeded 27%, while late gadolinium enhancement >2% showed persistent high risk. Increased mortality was also observed with both large (LVEDVi >80 mL/m2) and small (LVEDVi ≤55 mL/m2) ventricles, and with high (>80%) and low (≤50%) right ventricular ejection fraction. The predictability was improved when these 4 markers were added to clinical factors (3-year C-index: 0.778 vs 0.739). The prognostic thresholds and risk stratification by CMR variables were reproduced in the validation cohort. CONCLUSIONS: Machine learning identified myocardial fibrosis and biventricular remodeling markers as the top predictors of survival in AS and highlighted their nonlinear association with mortality. These markers may have potential in optimizing the decision of AVR.

Association of immune cell subsets with cardiac mechanics in the Multi-Ethnic Study of Atherosclerosis.

BackgroundImmunomodulatory therapy may help prevent heart failure (HF). Data on immune cells and myocardial remodeling in older adults with cardiovascular risk factors are limited.MethodsIn the Multi-Ethnic Study of Atherosclerosis cohort, 869 adults had 19 peripheral immune cell subsets measured and underwent cardiac MRI during the baseline exam, of which 321 had assessment of left ventricular global circumferential strain (LV-GCS). We used linear regression with adjustment for demographics, cardiovascular risk factors, and cytomegalovirus serostatus to evaluate the cross-sectional association of immune cell subsets with left ventricular mass index (LVMI) and LV-GCS.ResultsThe average age of the cohort was 61.6 ± 10.0 years and 53% were women. Higher proportions of γ/δ T cells were associated with lower absolute (worse) LV-GCS (-0.105% [95% CI -0.164%, -0.046%] per 1 SD higher proportion of γ/δ T cells, P = 0.0006). This association remained significant after Bonferroni's correction. Higher proportions of classical monocytes were associated with worse absolute LV-GCS (-0.04% [95% CI -0.07%, 0.00%] per 1 SD higher proportion of classical monocytes, P = 0.04). This did not meet significance after Bonferroni's correction. There were no other significant associations with LV-GCS or LVMI.ConclusionPathways associated with γ/δ T cells may be potential targets for immunomodulatory therapy targeted at HF prevention in populations at risk.FundingContracts 75N92020D00001, HHSN268201500003I, N01-HC-95159, 75N92020D00005, N01-HC-95160, 75N92020D00002, N01-HC-95161, 75N92020D00003, N01-HC-95162, 75N92020D00006, N01-HC-95163, 75N92020D00004, N01-HC-95164, 75N92020D00007, N01-HC-95165, N01-HC-95166, N01-HC-95167, N01-HC-95168, and N01-HC-95169 and grant R01 HL98077 from the National Heart, Lung, and Blood Institute/NIH and grants KL2TR001424, UL1-TR-000040, UL1-TR-001079, and UL1-TR-001420 from the National Center for Advancing Translational Sciences/NIH.

CMMCSegNet: Cross-Modality Multicascade Indirect LGE Segmentation on Multimodal Cardiac MR.

Since Late-Gadolinium Enhancement (LGE) of cardiac magnetic resonance (CMR) visualizes myocardial infarction, and the balanced-Steady State Free Precession (bSSFP) cine sequence can capture cardiac motions and present clear boundaries; multimodal CMR segmentation has played an important role in the assessment of myocardial viability and clinical diagnosis, while automatic and accurate CMR segmentation still remains challenging due to a very small amount of labeled LGE data and the relatively low contrasts of LGE. The main purpose of our work is to learn the real/fake bSSFP modality with ground truths to indirectly segment the LGE modality of cardiac MR by using a proposed cross-modality multicascade framework: cross-modality translation network and automatic segmentation network, respectively. In the segmentation stage, a novel multicascade pix2pix network is designed to segment the fake bSSFP sequence obtained from a cross-modality translation network. Moreover, we propose perceptual loss measuring features between ground truth and prediction, which are extracted from the pretrained vgg network in the segmentation stage. We evaluate the performance of the proposed method on the multimodal CMR dataset and verify its superiority over other state-of-the-art approaches under different network structures and different types of adversarial losses in terms of dice accuracy in testing. Therefore, the proposed network is promising for Indirect Cardiac LGE Segmentation in clinical applications.

Synergistic multi-contrast cardiac magnetic resonance image reconstruction.

Cardiac magnetic resonance imaging (CMR) is an important tool for the non-invasive diagnosis of a variety of cardiovascular diseases. Parametric mapping with multi-contrast CMR is able to quantify tissue alterations in myocardial disease and promises to improve patient care. However, magnetic resonance imaging is an inherently slow imaging modality, resulting in long acquisition times for parametric mapping which acquires a series of cardiac images with different contrasts for signal fitting or dictionary matching. Furthermore, extra efforts to deal with respiratory and cardiac motion by triggering and gating further increase the scan time. Several techniques have been developed to speed up CMR acquisitions, which usually acquire less data than that required by the Nyquist-Shannon sampling theorem, followed by regularized reconstruction to mitigate undersampling artefacts. Recent advances in CMR parametric mapping speed up CMR by synergistically exploiting spatial-temporal and contrast redundancies. In this article, we will review the recent developments in multi-contrast CMR image reconstruction for parametric mapping with special focus on low-rank and model-based reconstructions. Deep learning-based multi-contrast reconstruction has recently been proposed in other magnetic resonance applications. These developments will be covered to introduce the general methodology. Current technical limitations and potential future directions are discussed. This article is part of the theme issue 'Synergistic tomographic image reconstruction: part 1'.

Utility of Fetal Cardiovascular Magnetic Resonance for Prenatal Diagnosis of Complex Congenital Heart Defects.

Importance: Prenatal diagnosis of complex congenital heart defects reduces mortality and morbidity in affected infants. However, fetal echocardiography can be limited by poor acoustic windows, and there is a need for improved diagnostic methods. Objective: To assess the clinical utility of fetal cardiovascular magnetic resonance imaging in cases in which fetal echocardiography could not visualize all relevant anatomy. Design, Setting, and Participants: This cohort study was conducted between January 20, 2017, and June 29, 2020, at Skåne University Hospital (Lund, Sweden), a tertiary center for pediatric cardiology and thoracic surgery. Participants were fetuses referred for fetal cardiovascular magnetic resonance examination by a pediatric cardiologist after an inconclusive echocardiograph. Exposures: Fetal cardiovascular magnetic resonance examination requested by the patient's pediatric cardiologist. Main Outcomes and Measures: Any change in patient management because of diagnostic information gained from fetal cardiovascular magnetic resonance imaging. Results: A total of 31 fetuses underwent cardiovascular magnetic resonance examination at a median gestational age of 36 weeks (range, 31-39 weeks). Overall, fetal cardiovascular magnetic resonance imaging had clinical utility, affecting patient management and/or parental counseling in 26 cases (84%). For aortic arch anatomy including signs of coarctation (20 fetuses), fetal cardiovascular magnetic resonance imaging added diagnostic information in 16 cases (80%). For assessment of univentricular vs biventricular outcome in borderline left ventricle, unbalanced atrioventricular septal defect, and pulmonary atresia with intact ventricular septum (15 fetuses), fetal cardiovascular magnetic resonance imaging visualized intracardiac anatomy and ventricular function, allowing assessment of outcome in 13 cases (87%). In 4 fetuses with hypoplastic left heart syndrome, fetal cardiovascular magnetic resonance imaging helped delivery planning in 3 cases (75%). Finally, fetal cardiovascular magnetic resonance imaging provided valuable information for parental counseling in 21 cases (68%). Conclusions and Relevance: In this cohort study, fetal cardiovascular magnetic resonance imaging added clinically useful information to what was available from echocardiography. These findings suggest that fetal CMR has the potential to affect clinical decision-making in challenging cases of congenital heart defects with inconclusive data from echocardiography. Fetal cardiovascular magnetic resonance imaging showed an association with clinical decision-making, including mode of delivery and early postnatal care, as well as with parental counseling.

Regional variation in cardiovascular magnetic resonance service delivery across the UK.

OBJECTIVES: To examine service provision in cardiovascular magnetic resonance (CMR) in the UK. Equitable access to diagnostic imaging is important in healthcare. CMR is widely available in the UK, but there may be regional variations. METHODS: An electronic survey was sent by the British Society of CMR to the service leads of all CMR units in the UK in 2019 requesting data from 2017 and 2018. Responses were analysed by region and interpreted alongside population statistics. RESULTS: The survey response rate was 100% (82 units). 100 386 clinical scans were performed in 2017 and 114 967 in 2018 (15% 1-year increase; 5-fold 10-year increase compared with 2008 data). In 2018, there were 1731 CMR scans/million population overall, with significant regional variation, for example, 4256 scans/million in London vs 396 scans/million in Wales. Median number of clinical scans per unit was 780, IQR 373-1951, range 98-10 000, with wide variation in mean waiting times (median 41 days, IQR 30-49, range 5-180); median 25 days in London vs 180 days in Northern Ireland). Twenty-five units (30%) reported mean elective waiting times in excess of 6 weeks, and 8 (10%) ≥3 months. There were 351 consultants reporting CMR, of whom 230 (66%) were cardiologists and 121 (34%) radiologists; 81% of units offered a CMR service for patients with pacemakers and defibrillators. CONCLUSIONS: This survey provides a unique, contemporary insight into national CMR delivery with 100% centre engagement. The 10-year growth in CMR usage at fivefold has been remarkable but heterogeneous across the UK, with some regions still reporting low usage or long waiting times which may be of clinical concern.

Predictors of Left Ventricular Scar Using Cardiac Magnetic Resonance in Athletes With Apparently Idiopathic Ventricular Arrhythmias.

Background In athletes with ventricular arrhythmias (VA) and otherwise unremarkable clinical findings, cardiac magnetic resonance (CMR) may reveal concealed pathological substrates. The aim of this multicenter study was to evaluate which VA characteristics predicted CMR abnormalities. Methods and Results We enrolled 251 consecutive competitive athletes (74% males, median age 25 [17-39] years) who underwent CMR for evaluation of VA. We included athletes with >100 premature ventricular beats/24 h or ≥1 repetitive VA (couplets, triplets, or nonsustained ventricular tachycardia) on 12-lead 24-hour ambulatory ECG monitoring and negative family history, ECG, and echocardiogram. Features of VA that were evaluated included number, morphology, repetitivity, and response to exercise testing. Left-ventricular late gadolinium-enhancement was documented by CMR in 28 (11%) athletes, mostly (n=25) with a subepicardial/midmyocardial stria pattern. On 24-hour ECG monitoring, premature ventricular beats with multiple morphologies or with right-bundle-branch-block and intermediate/superior axis configuration were documented in 25 (89%) athletes with versus 58 (26%) without late gadolinium-enhancement (P<0.001). More than 3300 premature ventricular beats were recorded in 4 (14%) athletes with versus 117 (53%) without positive CMR (P<0.001). At exercise testing, nonsustained ventricular tachycardia occurred at peak of exercise in 8 (29%) athletes with late gadolinium-enhancement (polymorphic in 6/8, 75%) versus 17 athletes (8%) without late gadolinium-enhancement (P=0.002), (P<0.0001). At multivariable analysis, all 3 parameters independently correlated with CMR abnormalities. Conclusions In athletes with apparently idiopathic VA, simple characteristics such as number and morphology of premature ventricular beats on 12-lead 24-hour ambulatory ECG monitoring and response to exercise testing predicted the presence of concealed myocardial abnormalities on CMR. These findings may help cost-effective CMR prescription.

Baseline and Dynamic Risk Predictors of Appropriate Implantable Cardioverter Defibrillator Therapy.

Background Current approaches fail to separate patients at high versus low risk for ventricular arrhythmias owing to overreliance on a snapshot left ventricular ejection fraction measure. We used statistical machine learning to identify important cardiac imaging and time-varying risk predictors. Methods and Results Three hundred eighty-two cardiomyopathy patients (left ventricular ejection fraction ≤35%) underwent cardiac magnetic resonance before primary prevention implantable cardioverter defibrillator insertion. The primary end point was appropriate implantable cardioverter defibrillator discharge or sudden death. Patient characteristics; serum biomarkers of inflammation, neurohormonal status, and injury; and cardiac magnetic resonance-measured left ventricle and left atrial indices and myocardial scar burden were assessed at baseline. Time-varying covariates comprised interval heart failure hospitalizations and left ventricular ejection fractions. A random forest statistical method for survival, longitudinal, and multivariable outcomes incorporating baseline and time-varying variables was compared with (1) Seattle Heart Failure model scores and (2) random forest survival and Cox regression models incorporating baseline characteristics with and without imaging variables. Age averaged 57±13 years with 28% women, 66% white, 51% ischemic, and follow-up time of 5.9±2.3 years. The primary end point (n=75) occurred at 3.3±2.4 years. Random forest statistical method for survival, longitudinal, and multivariable outcomes with baseline and time-varying predictors had the highest area under the receiver operating curve, median 0.88 (95% CI, 0.75-0.96). Top predictors comprised heart failure hospitalization, left ventricle scar, left ventricle and left atrial volumes, left atrial function, and interleukin-6 level; heart failure accounted for 67% of the variation explained by the prediction, imaging 27%, and interleukin-6 2%. Serial left ventricular ejection fraction was not a significant predictor. Conclusions Hospitalization for heart failure and baseline cardiac metrics substantially improve ventricular arrhythmic risk prediction.

Diagnostic accuracy of strain imaging in predicting myocardial viability after an ST-elevation myocardial infarction.

In the acute phase of ST-elevation myocardial infarction (STEMI) viability imaging techniques are not validated and/or not available.This study aimed to evaluate the ability of strain parameters assessed in the acute phase of STEMI, to predict myocardial viability after revascularization.Thirty-one STEMI patients whose culprit coronary artery was recanalized and in whom baseline echocardiogram showed an akinesia in the infarcted area, were prospectively included. Bidimensional left ventricular global longitudinal strain (GLS), and territorial longitudinal strain (TLS) in the territory of the infarct related artery were obtained within 24 hours from admission. Delayed enhancement (DE) cardiac magnetic resonance imaging (CMR) was used as a reference test to assess post-revascularization myocardial viability. DE-CMR was performed 3 months after percutaneous coronary intervention. According to myocardial viability, patients were divided into 2 groups; CMR viable myocardium patients with more than half of infarcted segments having a DE <50% (group V) and CMR nonviable myocardium patients with half or more of the infarcted segments having a DE >50% (group NV).GLS and TLS were lower in group V compared to group NV (respectively: -14.4% ±â€Š2.9% vs -10.9% ±â€Š2.4%, P = .002 and -11.0 ±â€Š4.1 vs -3.2 ±â€Š3.1, P = .001). GLS was correlated with DE-CMR (r = 0.54, P = .002) and a cut off value of -13.9% for GLS predicted viability with 86% sensitivity (Se) and 78% specificity (Sp). TLS showed the strongest correlation with DE-CMR (r = 0.69, P < .001). A cut off value of -9.4% for TLS yielded a Se of 78% and a Sp of 95% to predict myocardial viability.GLS and TLS measured in the acute phase of STEMI predicted myocardial viability assessed by 3 months DE-CMR. They are prognostic indicators and they can be used to guide the priority and usefulness of percutaneous coronary intervention in these patients.

Impact of infarct location and size on clinical outcome after ST-elevation myocardial infarction treated by primary percutaneous coronary intervention.

BACKGROUND: For patients suffering from acute ST-elevation myocardial infarction (STEMI), it is controversial whether infarct location predicts worse clinical outcome independently of infarct size. We therefore aimed to investigate the prognostic relevance of infarct location in relation to infarct size in STEMI patients treated with contemporary primary percutaneous coronary intervention (PCI). METHODS: Cardiac magnetic resonance was performed in 355 patients with acute STEMI 3 (interquartile range [IQR]: 2-4) days after primary PCI. Infarct location, infarct size, and microvascular obstruction were assessed by late gadolinium enhancement (LGE). Patients were followed for major adverse cardiac events (MACE) at a median follow-up of 35 (IQR: 12-52) months. RESULTS: One hundred and sixty five patients (47%) had anterior STEMI. These patients had a greater infarct size as compared to non-anterior STEMI patients (19 vs. 12% of left ventricular myocardial mass, p < .001), but no significant differences in microvascular obstruction occurrence and extent (p = .26 and p = .09, respectively). MACE occurred in 39 patients (11%). Patients with anterior STEMI had a higher risk of MACE (hazard ratio: 2.01; 95% confidence interval: 1.05-3.83; p = .03). In multivariable analysis, infarct severity by LGE imaging but not its location was independently associated with an increased risk of MACE (hazard ratio: 1.03; 95% confidence interval: 1.01-1.06; p = .01). CONCLUSIONS: The higher rate of medium-term MACE in anterior STEMI treated with contemporary primary PCI is explained by a larger extent of myocardial damage as determined by CMR imaging without any further contribution of infarct location.

Accelerated magnetic resonance imaging tissue phase mapping of the rat myocardium using compressed sensing with iterative soft-thresholding.

INTRODUCTION: Tissue Phase Mapping (TPM) MRI can accurately measure regional myocardial velocities and strain. The lengthy data acquisition, however, renders TPM prone to errors due to variations in physiological parameters, and reduces data yield and experimental throughput. The purpose of the present study is to examine the quality of functional measures (velocity and strain) obtained by highly undersampled TPM data using compressed sensing reconstruction in infarcted and non-infarcted rat hearts. METHODS: Three fully sampled left-ventricular short-axis TPM slices were acquired from 5 non-infarcted rat hearts and 12 infarcted rat hearts in vivo. The datasets were used to generate retrospectively (simulated) undersampled TPM datasets, with undersampling factors of 2, 4, 8 and 16. Myocardial velocities and circumferential strain were calculated from all datasets. The error introduced from undersampling was then measured and compared to the fully sampled data in order to validate the method. Finally, prospectively undersampled data were acquired and compared to the fully sampled datasets. RESULTS: Bland Altman analysis of the retrospectively undersampled and fully sampled data revealed narrow limits of agreement and little bias (global radial velocity: median bias = -0.01 cm/s, 95% limits of agreement = [-0.16, 0.20] cm/s, global circumferential strain: median bias = -0.01%strain, 95% limits of agreement = [-0.43, 0.51] %strain, all for 4x undersampled data at the mid-ventricular level). The prospectively undersampled TPM datasets successfully demonstrated the feasibility of method implementation. CONCLUSION: Through compressed sensing reconstruction, highly undersampled TPM data can be used to accurately measure the velocity and strain of the infarcted and non-infarcted rat myocardium in vivo, thereby increasing experimental throughput and simultaneously reducing error introduced by physiological variations over time.

Cardiovascular magnetic resonance imaging in patients with cardiac implantable electronic devices: best practice and real-world experience.

AIMS: Cardiovascular magnetic resonance (CMR) imaging has long been a contraindication for patients with a cardiac implantable electronic device (CIED). Recent studies support the feasibility and safety for non-thoracic magnetic resonance imaging, but data for CMR are sparse. The aim of the current study was to determine the safety in patients with magnetic resonance (MR)-conditional or non-MR-conditional CIED and to develop a best practice approach. METHODS AND RESULTS: All patients with a CIED undergoing CMR imaging (1.5 T) between April 2014 and April 2017 were included in the study. Devices were programmed according to the standardized protocol directly before and after the CMR examination. Follow-up interrogation was performed 6 months after CMR examination. Results were compared with a large, reference cohort of CIED patients not undergoing any MR examination. A total of 200 consecutive patients with a CIED (non-MR-conditional, n = 103) were included in the study. Directly after CMR imaging, one device failure (0.5%, battery status = end of service) was noted necessitating premature generator replacement. In three patients (2%) of pacemaker/implantable cardioverter-defibrillator (ICD) carriers a sustained ventricular tachycardia (VT) occurred during CMR imaging. Ten ICD showed a decrease in battery capacity immediately after CMR. Overall, the reference cohort showed comparable changes of CIED function during follow-up. CONCLUSION: With adherence to a standardized protocol and established exclusion criteria CMR imaging could safely be performed in patients with a CIED. The potential risks of device malfunction necessitate the presence of a device trained individual during the entire CMR examination. If there is a history of VT storm the attendance of an experienced cardiologist, should be mandatory.

A framework for constraining image SNR loss due to MR raw data compression.

INTRODUCTION: Computationally intensive image reconstruction algorithms can be used online during MRI exams by streaming data to remote high-performance computers. However, data acquisition rates often exceed the bandwidth of the available network resources creating a bottleneck. Data compression is, therefore, desired to ensure fast data transmission. METHODS: The added noise variance due to compression was determined through statistical analysis for two compression libraries (one custom and one generic) that were implemented in this framework. Limiting the compression error variance relative to the measured thermal noise allowed for image signal-to-noise ratio loss to be explicitly constrained. RESULTS: Achievable compression ratios are dependent on image SNR, user-defined SNR loss tolerance, and acquisition type. However, a 1% reduction in SNR yields approximately four to ninefold compression ratios across MRI acquisition strategies. For free-breathing cine data reconstructed in the cloud, the streaming bandwidth was reduced from 37 to 6.1 MB/s, alleviating the network transmission bottleneck. CONCLUSION: Our framework enabled data compression for online reconstructions and allowed SNR loss to be constrained based on a user-defined SNR tolerance. This practical tool will enable real-time data streaming and greater than fourfold faster cloud upload times.

The utility of cardiac magnetic resonance imaging in post-Fontan surveillance.

OBJECTIVE: Gated cardiac MRI offers the most detailed and accurate noninvasive method of assessing cardiac anatomy, particularly in patients with complex congenital heart disease. The proposed benefits of using cMRI as a routine screening tool in the Fontan population include early recognition of asymptomatic, postoperative anatomic and physiologic changes. In 2011, we therefore instituted at our center a recommended practice of cMRI screening in patients with Fontan physiology at 3 and 8 years post-Fontan operation. The purpose of this study was to determine the impact of this standardized practice of cMRI screening on the clinical management of a Fontan population. DESIGN: We retrospectively reviewed charts from our institutional Fontan database to determine which patients were eligible for cMRI under the current guidelines and who underwent imaging from November 2002 to June 2015. We reviewed the frequency of cMRI and number of changes in management based on the results. Statistical significance was determined using a chi-square test. RESULTS: There were 141 cMRIs performed on 121 patients who met inclusion criteria. The odds of a change in management were significantly greater after clinically indicated cMRI compared to screening cMRI (OR = 3.79, 95% CI: 1.48-9.66, P = .004). There were near significant odds of change in management if the cMRI occurred <8 years after Fontan regardless of whether it was for screening or clinically indicated purposes (OR = 2.43, 95% CI: 0.97-6.08, P = .052). The most frequent change in management was referral for catheterization with pulmonary artery angioplasty. CONCLUSIONS: There is an important role for cMRI in routine surveillance of post-Fontan patients. Screening cMRI performed less than 8 years after Fontan palliation offers increased utility compared to studies performed later. The optimal timing of such imaging after Fontan palliation remains unclear.

Early postoperative remodelling following repair of tetralogy of Fallot utilising unsedated cardiac magnetic resonance: a pilot study.

IntroductionThe right ventricular adaptations early after surgery in infants with tetralogy of Fallot are important to understand the changes that occur later on in life; this physiology has not been fully delineated. We sought to assess early postoperative right ventricular remodelling in patients with tetralogy of Fallot by cardiac MRI.Materials and methodSubjects with tetralogy of Fallot under 1 year of age were recruited following complete surgical repair for tetralogy of Fallot. Protocol-based cardiac MRI to assess anatomy, function, and flows was performed before hospital discharge using the feed and sleep technique, an unsedated imaging technique. RESULTS: MRI was completed in 16 subjects at a median age of 77 days (interquartile range 114). There was normal ventricular ejection fraction and indexed right ventricular end-diastolic volume (48±13 cc/m2), but elevated right ventricular mass (z score 6.2±2.4). Subjects requiring a transannular patch or right ventricle to pulmonary artery conduit had moderate pulmonary insufficiency (regurgitant fraction 27±16%).DiscussionEarly right ventricular remodelling after surgical repair for tetralogy of Fallot is characterised by significant pulmonary regurgitation, right ventricular hypertrophy, and lack of dilation. Performing cardiac MRI using the feed and sleep technique is feasible in infants younger than 5 months. These results might open new avenues to study longitudinal right ventricular changes in tetralogy of Fallot and to further explore the utility of unsedated MRI in patients with other types of CHDs.

The State of Cardiovascular Magnetic Resonance Imaging in Canada: Results from the CanSCMR Pan-Canadian Survey.

Over the past 25 years, cardiovascular magnetic resonance imaging (CMR) has developed into an increasingly valuable imaging modality. CMR is now a routine clinical tool for the evaluation of cardiovascular structure and function. However, current patterns in the utilization of CMR in Canada are unknown as are data on important issues such as wait times and appropriate use of this technology. To address these issues, we sought to perform a staged pan-Canadian Survey to initiate dialogue regarding the utilization and appropriate use of CMR in Canada. Two surveys were sent out to participants involved with the performance of CMR at tertiary care referral centres across Canada, one in 2015 and the other in 2017. Questions for both surveys were vetted by the executive committee of the Canadian Society for Cardiovascular Magnetic Resonance and were distributed to sites identified through Canadian Society for Cardiovascular Magnetic Resonance memberships. Descriptive statistics were used to summarize data. Twenty-one sites participated in the 2015 survey and 17 in the 2017 survey. Our results highlighted that most participants believe that CMR is an important component in the clinical decision-making process. They also exposed important issues such as excessive and seemingly worsening wait times for CMR and suggested potential drivers of this phenomenon. Finally, our results confirm ongoing challenges in the imaging community in meeting quality assurance guidelines aimed at documenting appropriate use criteria. Researchers and policy makers should focus on mechanisms aimed to reduce wait times as well as increase use of appropriate use criteria.

An 8-channel Tx/Rx dipole array combined with 16 Rx loops for high-resolution functional cardiac imaging at 7 T.

OBJECTIVE: To demonstrate imaging performance for cardiac MR imaging at 7 T using a coil array of 8 transmit/receive dipole antennas and 16 receive loops. MATERIALS AND METHODS: An 8-channel dipole array was extended by adding 16 receive-only loops. Average power constraints were determined by electromagnetic simulations. Cine imaging was performed on eight healthy subjects. Geometrical factor (g-factor) maps were calculated to assess acceleration performance. Signal-to-noise ratio (SNR)-scaled images were reconstructed for different combinations of receive channels, to demonstrate the SNR benefits of combining loops and dipoles. RESULTS: The overall image quality of the cardiac functional images was rated a 2.6 on a 4-point scale by two experienced radiologists. Imaging results at different acceleration factors demonstrate that acceleration factors up to 6 could be obtained while keeping the average g-factor below 1.27. SNR maps demonstrate that combining loops and dipoles provides a more than 50% enhancement of the SNR in the heart, compared to a situation where only loops or dipoles are used. CONCLUSION: This work demonstrates the performance of a combined loop/dipole array for cardiac imaging at 7 T. With this array, acceleration factors of 6 are possible without increasing the average g-factor in the heart beyond 1.27. Combining loops and dipoles in receive mode enhances the SNR compared to receiving with loops or dipoles only.

Fatty metaplasia quantification and impact on regional myocardial function as assessed by advanced cardiac MR imaging.

OBJECTIVE: This study aimed to investigate the advantages of recently developed cardiac imaging techniques of fat-water separation and feature tracking to characterize better individuals with chronic myocardial infarction (MI). MATERIALS AND METHODS: Twenty patients who had a previous MI underwent CMR imaging. The study protocol included routine cine and late gadolinium enhancement (LGE) technique. In addition, mDixon LGE imaging was performed in every patient. Left ventricular (LV) circumferential (EccLV) and radial (ErrLV) strain were calculated using dedicated software (CMR42, Circle, Calgary, Canada). The extent of global scar was measured in LGE and fat-water separated images to compare conventional and recent CMR imaging techniques. RESULTS: The infarct size derived from conventional LGE and fat-water separated images was similar. However, detection of lipomatous metaplasia was only possible with mDixon imaging. Subjects with fat deposition demonstrated a significantly smaller percentage of fibrosis than those without fat (10.68 ± 5.07% vs. 13.83 ± 6.30%; p = 0.005). There was no significant difference in EccLV or ErrLV between myocardial segments containing fibrosis only and fibrosis with fat. However, EccLV and ErrLV values were significantly higher in myocardial segments adjacent to fibrosis with fat deposition than in those adjacent to LGE only. CONCLUSIONS: Advanced CMR imaging ensures more detailed tissue characterization in patients with chronic MI without a relevant increase in imaging and post-processing time. Fatty metaplasia may influence regional myocardial deformation especially in the myocardial segments adjacent to scar tissue. A simplified and shortened myocardial viability CMR protocol might be useful to better characterize and stratify patients with chronic MI.

Single-breath-hold 3-D CINE imaging of the left ventricle using Cartesian sampling.

OBJECTIVES: Our objectives were to evaluate a single-breath-hold approach for Cartesian 3-D CINE imaging of the left ventricle with a nearly isotropic resolution of [Formula: see text] and a breath-hold duration of [Formula: see text]19 s against a standard stack of 2-D CINE slices acquired in multiple breath-holds. Validation is performed with data sets from ten healthy volunteers. MATERIALS AND METHODS: A Cartesian sampling pattern based on the spiral phyllotaxis and a compressed sensing reconstruction method are proposed to allow 3-D CINE imaging with high acceleration factors. The fully integrated reconstruction uses multiple graphics processing units to speed up the reconstruction. The 2-D CINE and 3-D CINE are compared based on ventricular function parameters, contrast-to-noise ratio and edge sharpness measurements. RESULTS: Visual comparisons of corresponding short-axis slices of 2-D and 3-D CINE show an excellent match, while 3-D CINE also allows reformatting to other orientations. Ventricular function parameters do not significantly differ from values based on 2-D CINE imaging. Reconstruction times are below 4 min. CONCLUSION: We demonstrate single-breath-hold 3-D CINE imaging in volunteers and three example patient cases, which features fast reconstruction and allows reformatting to arbitrary orientations.