The FAM13A Long Isoform Regulates Cilia Movement and Co-ordination in Airway Mucociliary Transport.

SNPs in the FAM13A locus are amongst the most commonly reported risk alleles associated with chronic obstructive pulmonary disease (COPD) and other respiratory diseases, however the physiological role of FAM13A is unclear. In humans, two major protein isoforms are expressed at the FAM13A locus: 'long' and 'short', but their functions remain unknown, partly due to a lack of isoform conservation in mice. We performed in-depth characterisation of organotypic primary human airway epithelial cell subsets and show that multiciliated cells predominantly express the FAM13A long isoform containing a putative N-terminal Rho GTPase activating protein (RhoGAP) domain. Using purified proteins, we directly demonstrate RhoGAP activity of this domain. In Xenopus laevis, which conserve the long isoform, Fam13a-deficiency impaired cilia-dependent embryo motility. In human primary epithelial cells, long isoform deficiency did not affect multiciliogenesis but reduced cilia co-ordination in mucociliary transport assays. This is the first demonstration that FAM13A isoforms are differentially expressed within the airway epithelium, with implications for the assessment and interpretation of SNP effects on FAM13A expression levels. We also show that the long FAM13A isoform co-ordinates cilia-driven movement, suggesting that FAM13A risk alleles may affect susceptibility to respiratory diseases through deficiencies in mucociliary clearance. This article is open access and distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/).

Mitral valve orifice area predicts outcome after biventricular repair in patients with hypoplastic left ventricles.

BACKGROUND: Identification of risk factors for biventricular (BiV) repair in children with hypoplastic left ventricles (HLV) has been challenging. We sought to identify preoperative cardiovascular magnetic resonance (CMR) predictors of outcome in patients with HLVs who underwent BiV repair, with a focus on the mitral valve (MV). METHODS: Single-center retrospective analysis of preoperative CMRs on patients with HLV (≤50 mL/m2) and no endocardial fibroelastosis who underwent BiV repair from 2005-2022. CMR measurements included MV orifice area in diastole. The primary composite outcome included time to death, transplant, BiV takedown, heart failure admission, left atrial decompression, or unexpected reoperation; and the secondary outcome included more than or equal to moderate mitral stenosis and/or regurgitation. RESULTS: Median follow-up was 0.7 (interquartile range 0.1, 2.2) years. Of 122 patients [59 atrioventricular canal (AVC) and 63 non-AVC] age 3 ± 2.8 years at the time of BiV repair, freedom from the primary outcome at 2 years was 53% for AVC and 69% for non-AVC (log rank p = 0.12), and freedom from the secondary outcome at 2 years was 49% for AVC and 79% for non-AVC (log rank p < 0.01). Independent predictors of primary outcome for AVC patients included MV orifice area z-score <-2 and transitional AVC; for non-AVC patients, predictors included MV orifice area z-score <-2, abnormal MV anatomy, and conal-septal ventricular septal defect. Independent predictors of secondary outcome for AVC patients included older age at surgery, transitional AVC, and transposition of the great arteries. CONCLUSION: In children with HLV, low MV orifice area and pre-existing MV pathology are risk factors for adverse outcome after BiV repair.

Design and implementation of multicenter pediatric and congenital studies with cardiovascular magnetic resonance: Big data in smaller bodies.

Cardiovascular magnetic resonance (CMR) has become the reference standard for quantitative and qualitative assessment of ventricular function, blood flow, and myocardial tissue characterization. There is a preponderance of large CMR studies and registries in adults; However, similarly powered studies are lacking for the pediatric and congenital heart disease (PCHD) population. To date, most CMR studies in children are limited to small single or multicenter studies, thereby limiting the conclusions that can be drawn. Within the PCHD CMR community, a collaborative effort has been successfully employed to recognize knowledge gaps with the aim to embolden the development and initiation of high-quality, large-scale multicenter research. In this publication, we highlight the underlying challenges and provide a practical guide toward the development of larger, multicenter initiatives focusing on PCHD populations, which can serve as a model for future multicenter efforts.

mRNA Display in Cell Lysates Enables Identification of Cyclic Peptides Targeting the BRD3 Extraterminal Domain.

mRNA display is a powerful technology to screen libraries of >1012 cyclic peptides against a protein target, enabling the rapid discovery of high affinity ligands. These cyclic peptides are particularly well suited to challenging protein targets that have been difficult to drug with small molecules. However, target choice can still be limited as screens are typically performed against purified proteins which often demands the use of isolated domains and precludes the use of aggregation-prone targets. Herein, we report a method to perform mRNA display selections in mammalian cell lysates without the need for prior target purification, vastly expanding the potential target scope of mRNA display. We have applied the methodology to identify low to sub-nanomolar peptide binders for two targets: a NanoLuc subunit (LgBiT) and full-length bromodomain-containing protein 3 (BRD3). Our cyclic peptides for BRD3 were found to bind to the extraterminal (ET) domain of BRD3 and the closely related BRD proteins, BRD2 and BRD4. While many chemical probes exist for the bromodomains of BRD proteins, the ET domain is relatively underexplored, making these peptides valuable additions to the BRD toolbox.

Cardiac magnetic resonance parameters associated with successful conversion from a single ventricular to a one-and-a-half or biventricular circulation in patients with a hypoplastic right ventricle.

BACKGROUND: Some patients with pulmonary atresia with an intact ventricular septum (PA/IVS) or a left ventricle dominant atrioventricular canal defect (LDAVC) with a hypoplastic right ventricle (RV) and univentricular (1 V) circulation may be candidates for conversion to either a complete biventricular (2 V) repair or a one-and-a-half ventricle repair (1.5 V). We sought to identify pre-operative cardiovascular magnetic resonance (CMR) findings associated with successful conversion from 1V to 1.5V or 2V circulation. METHODS: In this single center retrospective study, subjects with PA/IVS or LDAVC and no conotruncal abnormalities were included if they had a 1 V circulation at the time of CMR followed by a surgical intervention intended to convert them to a 1.5 V or 2 V circulation. Conversion failure was defined as any of the following: (1) oxygen saturation < 90% at the most recent follow-up, (2) conversion back to a 1.5 V or 1 V circulation, or (3) death. RESULTS: In the PA/IVS cohort (n = 15, median age 1.32 years), 10 patients underwent surgical conversion to a 1.5 V circulation and 5 to a 2 V circulation. In the attempted 1.5 V group, there were 2 failures, and these cases had a lower RV mass (p = 0.04). In the attempted 2 V group, there was 1 failure, and no CMR parameters were significantly different compared to the successes. Among the successful 2 V group patients, the minimum RV end-diastolic volume (EDV) was 27 ml/m2. In the LDAVC cohort (n = 15, median age 1.0 years), 1 patient underwent surgical conversion to a 1.5 V circulation and 14 patients to a 2 V circulation. In the attempted 1.5 V group, the 1 conversion was a failure and had an RV EDV of 15 ml/m2. In the attempted 2 V group, there were 2 failures, and these cases had a smaller RV:LV stroke volume ratio (p = 0.05) and a lower RV ejection fraction (p = 0.05) compared to the successes. Among the successful 2 V group patients, the minimum RV EDV was 22 ml/m2. CONCLUSIONS: We identified multiple CMR parameters associated with successful conversion from 1 V circulation to 1.5 V or 2 V circulation in patients with PA/IVS and LDAVC. This information may improve patient selection for conversion procedures and encourage larger studies to better define the role of CMR.

Magnetic resonance three-dimensional steady-state free precession imaging of the thoracic duct in patients with Fontan circulation and its relationship to outcomes.

BACKGROUND: Lymphatic complications are common in patients with Fontan circulation. Three-dimensional balanced steady-state free precession (3D bSSFP) angiography by cardiovascular magnetic resonance (CMR) is widely used for cardiovascular anatomical assessment. We sought to determine the frequency of thoracic duct (TD) visualization using 3D bSSFP images and assess whether TD characteristics are associated with clinical outcomes. METHODS: This was a retrospective, single-center study of patients with Fontan circulation who underwent CMR. Frequency matching of age at CMR was used to construct a comparison group of patients with repaired tetralogy of Fallot (rTOF). TD characteristics included maximum diameter and a qualitative assessment of tortuosity. Clinical outcomes included protein-losing enteropathy (PLE), plastic bronchitis, listing for heart transplantation, and death. A composite outcome was defined as presence of any of these events. RESULTS: The study included 189 Fontan patients (median age 16.1 years, IQR 11.0-23.2 years) and 36 rTOF patients (median age 15.7 years, IQR 11.1-23.7 years). The TD diameter was larger (median 2.50 vs. 1.95 mm, p = 0.002) and more often well visualized (65% vs. 22%, p < 0.001) in Fontan patients vs. rTOF patients. TD dimension increased mildly with age in Fontan patients, R = 0.19, p = 0.01. In Fontan patients, the TD diameter was larger in those with PLE vs. without PLE (age-adjusted mean 4.11 vs. 2.72, p = 0.005), and was more tortuous in those with NYHA class ≥ II vs. class I (moderate or greater tortuosity 75% vs. 28.5%, p = 0.02). Larger TD diameter was associated with a lower ventricular ejection fraction that was independent of age (partial correlation = - 0.22, p = 0.02). More tortuous TDs had a higher end-systolic volume (mean 70.0 mL/m2 vs. 57.3 mL/m2, p = 0.03), lower creatinine (mean 0.61 mg/dL vs. 0.70 mg/dL, p = 0.04), and a higher absolute lymphocyte count (mean 1.80 K cells/µL vs. 0.76 K cells/µL, p = 0.003). The composite outcome was present in 6% of Fontan patients and was not associated with TD diameter (p = 0.50) or tortuosity (p = 0.09). CONCLUSIONS: The TD is well visualized in two-thirds of patients with Fontan circulation on 3D-bSSFP images. Larger TD diameter is associated with PLE and increased TD tortuosity is associated with an NYHA class ≥ II.

The NHLBI Study on Long-terM OUtcomes after the Multisystem Inflammatory Syndrome In Children (MUSIC): Design and Objectives.

BACKGROUND: The Long-terM OUtcomes after the Multisystem Inflammatory Syndrome In Children (MUSIC) study aims to characterize the frequency and time course of acute and long-term cardiac and non-cardiac sequelae in multisystem inflammatory syndrome in children associated with COVID-19 (MIS-C), which are currently poorly understood. METHODS: This multicenter observational cohort study will enroll at least 600 patients <21 years old who meet the Centers for Disease Control and Prevention case definition of MIS-C across multiple North American centers over 2 years. The study will collect detailed hospital and follow-up data for up to 5 years, and optional genetic testing. Cardiac imaging at specific time points includes standardized echocardiographic assessment (all participants) and cardiac magnetic resonance imaging (CMR) in those with left ventricular ejection fraction (LVEF) <45% during the acute illness. The primary outcomes are the worst LVEF and the highest coronary artery z-score of the left anterior descending or right coronary artery. Other outcomes include occurrence and course of non-cardiac organ dysfunction, inflammation, and major medical events. Independent adjudication of cases will classify participants as definite, possible, or not MIS-C. Analysis of the outcomes will include descriptive statistics and regression analysis with stratification by definite or possible MIS-C. The MUSIC study will provide phenotypic data to support basic and translational research studies. CONCLUSION: The MUSIC study, with the largest cohort of MIS-C patients and the longest follow-up period to date, will make an important contribution to our understanding of the acute cardiac and non-cardiac manifestations of MIS-C and the long-term effects of this public health emergency.

Survey of centers performing cardiovascular magnetic resonance in pediatric and congenital heart disease: a report of the Society for Cardiovascular Magnetic Resonance.

BACKGROUND: There are few data on practice patterns and trends for cardiovascular magnetic resonance (CMR) in pediatric and congenital heart disease. The Society for Cardiovascular Magnetic Resonance (SCMR) sought to address this deficiency by performing an international survey of CMR centers. METHODS: Surveys consisting of 31 (2014) and 33 (2018) items were designed to collect data on the use of CMR for the evaluation of pediatric and congenital heart disease patients. They were sent to all SCMR members in 2014 and 2018. One response per center was collected. RESULTS: There were 93 centers that responded in 2014 and 83 in 2018. The results that follow show data from 2014 and 2018 separated by a dash. The median annual number of pediatric/congenital CMR cases per center was 183-209. The median number of scanners for CMR was 2-2 (range, 1-8) with 58-63% using only 1.5T scanners and 4-4% using only 3T scanners. The mean number of attending/staff reading CMRs was 3.7-2.6; among them, 52-61% were pediatric or adult cardiologists and 47-38% were pediatric or adult radiologists. The median annual case volume per attending was 54-86. The median number of technologists per center doing CMRs was 4-5. The median scanner time allocated for a non-sedated examination was 75-75 min (range, 45-120). Among the 21 centers responding to both surveys, the mean annual case volume increased from 320 in 2014 to 445 in 2018; 17 (81%) of the centers had an increase in annual case volume. For this subgroup, the median attending/staff per center was 4 in both 2014 and 2018. The median scanner time allotted per study was unchanged at 90 min. The mean time for an attending/staff physician to perform a typical CMR examination including reporting was 143-141 min. CONCLUSION: These survey data provide a novel comprehensive view of CMR practice in pediatric and congenital heart disease. This information is useful for internal benchmarking, resource allocation, addressing practice variation, quality improvement initiatives, and identifying unmet needs.

Longitudinal changes in ventricular size and function are associated with death and transplantation late after the Fontan operation.

BACKGROUND: Cross-sectional studies have reported that ventricular dilation and dysfunction are associated with adverse clinical outcome in Fontan patients; however, longitudinal changes and their relationship with outcome are not known. METHODS: This was a single-center retrospective analysis of Fontan patients with at least 2 cardiovascular magnetic resonance (CMR) scans without intervening interventions. Serial measures of end-diastolic volume index (EDVI), end-systolic volume index (ESVI), ejection fraction (EF), indexed mass (massi), mass-to-volume ratio, and end-systolic wall stress (ESWS) were used to estimate within-patient change over time. Changes were compared for those with and without a composite outcome (death, heart transplant, or transplant listing) as well as between patients with left (LV) and right ventricular (RV) dominance. RESULTS: Data from 156 patients were analyzed with a mean age at 1st CMR of 17.8 ± 9.6 years. 490 CMRs were included with median of 3 CMRs/patient (range 2-9). On regression analysis with mixed effects models, volumes and ESWS increased, while mass, mass-to-volume ratio, and EF decreased over time. With a median follow-up of 10.2 years, 14% met the composite outcome. Those with the composite outcome had a greater increase in EDVI compared to those without (4.7 vs. 0.8 ml/BSA1.3/year). Compared with LV dominance, RV dominance was associated with a greater increase in ESVI (1.4 vs. 0.5 ml/BSA1.3/year), a greater decrease in EF (- 0.61%/year vs. - 0.24%/year), and a higher rate of the composite outcome (21% vs. 8%). CONCLUSIONS: Ventricles in the Fontan circulation exhibit a steady decline in performance with an increase in EDVI, ESVI, and ESWS, and decrease in EF, mass index, and mass-to-volume ratio. Those with death or need for heart transplantation have a faster increase in EDVI. Patients with rapid increase in EDVI (> 5 ml/BSA1.3/year) may be at a higher risk of adverse outcomes and may benefit from closer surveillance. RV dominance is associated with worse clinical outcomes and remodeling compared to LV dominance.

Improving CPMG liver iron estimates with a T 1 -corrected proton density estimator.

PURPOSE: CPMG spin echo acquisitions are attractive for diagnosing and monitoring liver iron concentration in iron overload disorders due to their time efficiency and potential to reveal unique information about tissue iron distribution. Clinical adoption remains low due to the insensitivity of CPMG-based R 2 estimates to liver iron concentration (LIC) when common fitting techniques are applied. In this work, we demonstrate that the inclusion of a proton density estimator (PDE) derived from the CPMG acquisition increase the sensitivity of CPMG R 2 estimates to LIC in both simulated and in-vivo human data. THEORY AND METHODS: CPMG R 2 acquisitions from 50 clinically indicated MRI studies in patients with iron overload were analyzed with and without PDE constraints. Liver regions of interest were fit to monoexpontial and nonexponential signal decay equations. LIC by R 2 ∗ served as the reference standard. The observed calibration between CPMG R 2 values and LIC were compared to results predicted from a previously validated Monte Carlo model. RESULTS: The sensitivity of CPMG-derived R 2 triples when a proton density constraint is applied. When compared with R 2 ∗ -LIC estimates, both monoexponential and nonexponential models were unbiased but demonstrated broad 95% confidence intervals particularly for LIC values below 12 mg/g. Absolute error did not increase with LIC. CONCLUSION: A proton density constraint can increase the sensitivity of CPMG-based models to iron. CPMG acquisitions are time-efficient and could potentially improve the dynamic range of single spin echo techniques as well as providing insight into tissue iron distribution.

Impact of pulmonary valve replacement on left ventricular rotational mechanics in repaired tetralogy of Fallot.

BACKGROUND: In repaired tetralogy of Fallot (rTOF), abnormal left ventricular (LV) rotational mechanics are associated with adverse clinical outcomes. We performed a comprehensive analysis of LV rotational mechanics in rTOF patients using cardiac magnetic resonance (CMR) prior to and following surgical pulmonary valve replacement (PVR). METHODS: In this single center retrospective study, we identified rTOF patients who (1) had both a CMR ≤ 1 year before PVR and ≤ 5 years after PVR, (2) had no other intervening procedure between CMRs, (3) had a body surface area > 1.0 m2 at CMR, and (4) had images suitable for feature tracking analysis. These subjects were matched to healthy age- and sex-matched control subjects. CMR feature tracking analysis was performed on a ventricular short-axis stack of balanced steady-state free precession images. Measurements included LV basal and apical rotation, twist, torsion, peak systolic rates of rotation and torsion, and timing of events. Associations with LV torsion were assessed. RESULTS: A total of 60 rTOF patients (23.6 ± 7.9 years, 52% male) and 30 healthy control subjects (20.8 ± 3.1 years, 50% male) were included. Compared with healthy controls, rTOF patients had lower apical and basal rotation, twist, torsion, and systolic rotation rates, and these parameters peaked earlier in systole. The only parameters that were correlated with LV torsion were right ventricular (RV) end-systolic volume (r = - 0.28, p = 0.029) and RV ejection fraction (r = 0.26, p = 0.044). At a median of 1.0 year (IQR 0.5-1.7) following PVR, there was no significant change in LV rotational parameters versus pre-PVR despite reductions in RV volumes, RV mass, pulmonary regurgitation, and RV outflow tract obstruction. CONCLUSION: In this comprehensive study of CMR-derived LV rotational mechanics in rTOF patients, rotation, twist, and torsion were diminished compared to controls and did not improve at a median of 1 year after PVR despite favorable RV remodeling.

SCMR Position Paper (2020) on clinical indications for cardiovascular magnetic resonance.

The Society for Cardiovascular Magnetic Resonance (SCMR) last published its comprehensive expert panel report of clinical indications for CMR in 2004. This new Consensus Panel report brings those indications up to date for 2020 and includes the very substantial increase in scanning techniques, clinical applicability and adoption of CMR worldwide. We have used a nearly identical grading system for indications as in 2004 to ensure comparability with the previous report but have added the presence of randomized controlled trials as evidence for level 1 indications. In addition to the text, tables of the consensus indication levels are included for rapid assimilation and illustrative figures of some key techniques are provided.

Society for Cardiovascular Magnetic Resonance (SCMR) guidance for the practice of cardiovascular magnetic resonance during the COVID-19 pandemic.

The aim of this document is to provide general guidance and specific recommendations on the practice of cardiovascular magnetic resonance (CMR) in the era of the COVID-19 pandemic. There are two major considerations. First, continued urgent and semi-urgent care for the patients who have no known active COVID-19 should be provided in a safe manner for both patients and staff. Second, when necessary, CMR on patients with confirmed or suspected active COVID-19 should focus on the specific clinical question with an emphasis on myocardial function and tissue characterization while optimizing patient and staff safety.

Society for Cardiovascular Magnetic Resonance (SCMR) guidance for re-activation of cardiovascular magnetic resonance practice after peak phase of the COVID-19 pandemic.

During the peak phase of the COVID-19 pandemic, alterations of standard operating procedures were necessary for health systems to protect patients and healthcare workers and ensure access to vital hospital resources. As the peak phase passes, re-activation plans are required to safely manage increasing clinical volumes. In the context of cardiovascular magnetic resonance (CMR), re-activation objectives include continued performance of urgent CMR studies and resumption of CMR in patients with semi-urgent and elective indications in an environment that is safe for both patients and health care workers.

Preoperative Predictors of Death and Sustained Ventricular Tachycardia After Pulmonary Valve Replacement in Patients With Repaired Tetralogy of Fallot Enrolled in the INDICATOR Cohort.

BACKGROUND: Risk factors for adverse clinical outcomes have been identified in patients with repaired tetralogy of Fallot before pulmonary valve replacement (PVR). However, pre-PVR predictors for post-PVR sustained ventricular tachycardia and death have not been identified. METHODS: Patients with repaired tetralogy of Fallot enrolled in the INDICATOR cohort (International Multicenter TOF Registry), a 4-center international cohort study, who had a comprehensive preoperative evaluation and subsequently underwent PVR were included. Preprocedural clinical, ECG, cardiovascular magnetic resonance, and postoperative outcome data were analyzed. Cox proportional hazards multivariable regression analysis was used to evaluate factors associated with time from pre-PVR cardiovascular magnetic resonance until the primary outcome: death, aborted sudden cardiac death, or sustained ventricular tachycardia. RESULTS: Of the 452 eligible patients (median age at PVR, 25.8 years), 36 (8%) reached the primary outcome (27 deaths, 2 resuscitated death, and 7 sustained ventricular tachycardia) at a median time after PVR of 6.5 years. Cox proportional hazards regression identified pre-PVR right ventricular ejection fraction <40% (hazard ratio, 2.39; 95% CI, 1.18-4.85; P=0.02), right ventricular mass-to-volume ratio ≥0.45 g/mL (hazard ratio, 4.08; 95% CI, 1.57-10.6; P=0.004), and age at PVR ≥28 years (hazard ratio, 3.10; 95% CI, 1.42-6.78; P=0.005) as outcome predictors. In a subgroup analysis of 230 patients with Doppler data, predicted right ventricular systolic pressure ≥40 mm Hg was associated with the primary outcome (hazard ratio, 3.42; 95% CI, 1.09-10.7; P=0.04). Preoperative predictors of a composite secondary outcome, postoperative arrhythmias and heart failure, included older age at PVR, pre-PVR atrial tachyarrhythmias, and a higher left ventricular end-systolic volume index. CONCLUSIONS: In this observational investigation of patients with repaired tetralogy of Fallot, an older age at PVR and pre-PVR right ventricular hypertrophy and dysfunction were predictive of a shorter time to postoperative death and sustained ventricular tachycardia. These findings may inform the timing of PVR if confirmed by prospective clinical trials.

Myocardial Infarct After Marijuana Inhalation in a 16-year-old Adolescent Boy.

Many reports of marijuana-associated myocardial infarct (MI) are limited by incomplete evaluation of the toxicologic exposure, a lack of definitive anatomic findings, and the potential for comorbid coronary atherosclerosis inherent in an adult population. We report a 16-year-old adolescent boy who presented with chest pain after smoking marijuana and was found to have acute MI. Electrocardiogram showed diffuse ST-segment elevations. Exhaustive toxicologic testing confirmed the presence of Δ-9-tetrahydrocannabinol metabolite and ruled out other drugs of abuse. Echocardiography demonstrated moderate global left ventricular systolic dysfunction. Coronary angiography demonstrated no focal coronary lesions or obstruction. Right ventricular septal endomyocardial samples biopsied 36 hours after the onset of pain showed a subendocardial acute MI with a sparse neutrophilic infiltrate. One month after the event, magnetic resonance imaging showed a severely dilated left ventricle and moderately to severely depressed global systolic function. Late gadolinium enhancement consistent with myocardial fibrosis was seen in nearly all myocardial segments. Our unusually well-documented findings strengthen the potential association between marijuana and MI. Furthermore, we demonstrate a disease distribution supporting a process that affects the coronary circulation globally, likely at the distal, small-vessel level.

Accelerated whole-heart MR angiography using a variable-density poisson-disc undersampling pattern and compressed sensing reconstruction.

PURPOSE: To accelerate whole-heart three-dimension MR angiography (MRA) by using a variable-density Poisson-disc undersampling pattern and a compressed sensing (CS) reconstruction algorithm, and compare the results with sensitivity encoding (SENSE). METHODS: For whole-heart MRA, a prospective variable-density Poisson-disc k-space undersampling pattern was developed in which 1-2% of central part of k-space was fully sampled, and sampling in the remainder decreased exponentially toward the periphery. The undersampled data were then estimated using CS reconstruction. In patients, images using this sequence with an undersampling rate of ≈6 were compared with those using a SENSE rate of 2 (n = 15) and a SENSE rate of 6 (n = 13). RESULTS: Compared with SENSE rate 2, CS rate 6 images had similar objective border sharpness, significantly lower subjective image quality scores at all four locations (all P < 0.01), and shorter scan times (P < 0.05). Compared with SENSE rate 6, CS rate 6 had similar objective border sharpness at all four locations, significantly better subjective image quality scores at three of four locations (all P < 0.01), and similar scan times (P = 0.24). CONCLUSION: Compared with SENSE with a comparable acceleration rate, a variable-density Poisson-disc undersampling pattern and CS reconstruction achieved better subjective image quality and similar border sharpness. Magn Reson Med 79:761-769, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Free-breathing whole-heart 3D cine magnetic resonance imaging with prospective respiratory motion compensation.

PURPOSE: To develop and validate a new prospective respiratory motion compensation algorithm for free-breathing whole-heart 3D cine steady-state free precession (SSFP) imaging. METHODS: In a 3D cine SSFP sequence, 4 excitations per cardiac cycle are re-purposed to prospectively track heart position. Specifically, their 1D image is reconstructed and routed into the scanner's standard diaphragmatic navigator processing system. If all 4 signals are in end-expiration, cine image data from the entire cardiac cycle is accepted for image reconstruction. Prospective validation was carried out in patients (N = 17) by comparing in each a conventional breath-hold 2D cine ventricular short-axis stack and a free-breathing whole-heart 3D cine data set. RESULTS: All 3D cine SSFP acquisitions were successful and the mean scan time was 5.9 ± 2.7 min. Left and right ventricular end-diastolic, end-systolic, and stroke volumes by 3D cine SSFP were all larger than those from 2D cine SSFP. This bias was < 6% except for right ventricular end-systolic volume that was 12%. The 3D cine images had a lower ventricular blood-to-myocardium contrast ratio, contrast-to-noise ratio, mass, and subjective quality score. CONCLUSION: The novel prospective respiratory motion compensation method for 3D cine SSFP imaging was robust and efficient and yielded slightly larger ventricular volumes and lower mass compared to breath-hold 2D cine imaging. Magn Reson Med 80:181-189, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Impact of surgical pulmonary valve replacement on ventricular strain and synchrony in patients with repaired tetralogy of Fallot: a cardiovascular magnetic resonance feature tracking study.

BACKGROUND: In patients with repaired tetralogy of Fallot (TOF), a better understanding of the impact of surgical pulmonary valve replacement (PVR) on ventricular mechanics may lead to improved indications and outcomes. Therefore, we used cardiovascular magnetic resonance (CMR) feature tracking analysis to quantify ventricular strain and synchrony in repaired TOF patients before and after PVR. METHODS: Thirty-six repaired TOF patients (median age 22.4 years) prospectively underwent CMR a mean of 4.5 ± 3.8 months before PVR surgery and 7.3 ± 2.1 months after PVR surgery. Feature tracking analysis on cine steady-state free precession images was used to measure right ventricular (RV) and left ventricular (LV) circumferential strain from short-axis views at basal, mid-ventricular, and apical levels; and longitudinal strain from 4-chamber views. Intraventricular synchrony was quantified using the maximum difference in time-to-peak strain, the standard deviation of the time-to-peak, and cross correlation delay (CCD) metrics; interventricular synchrony was assessed using the CCD metric. RESULTS: Following PVR, RV end-diastolic volume, end-systolic volume, and ejection fraction declined, and LV end-diastolic volume and end-systolic volume both increased with no significant change in the LV ejection fraction. LV global basal and apical circumferential strains, and basal synchrony improved. RV global circumferential and longitudinal strains were unchanged, and there was a varied impact on synchrony across the locations. Interventricular synchrony worsened at the midventricular level but was unchanged at the base and apex, and on 4-chamber views. CONCLUSIONS: Surgical PVR in repaired TOF patients led to improved LV global strain and no change in RV global strain. LV and RV synchrony parameters improved or were unchanged, and interventricular synchrony worsened at the midventricular level.

Maldistribution of pulmonary blood flow in patients after the Fontan operation is associated with worse exercise capacity.

BACKGROUND: Maldistribution of pulmonary artery blood flow (MPBF) is a potential complication in patients who have undergone single ventricle palliation culminating in the Fontan procedure. Cardiovascular magnetic resonance (CMR) is the best modality that can evaluate MPBF in this population. The purpose of this study is to identify the prevalence and associations of MPBF and to determine the impact of MPBF on exercise capacity after the Fontan operation. METHODS: This retrospective single-center study included all patients after Fontan operation who had maximal cardiopulmonary exercise test (CPET) and CMR with flow measurements of the branch pulmonary arteries. MPBF was defined as > 20% difference in branch pulmonary artery flow. Exercise capacity was measured as percent of predicted oxygen consumption at peak exercise (% predicted VO2). Linear and logistic regression models were used to determine univariate and multivariable predictors of exercise capacity and correlates of MPBF, respectively. RESULTS: A total of 147 patients who had CMR between 1999 and 2017 were included (median age at CMR 21.8 years [interquartile range (IQR) 16.5-30.6]) and the median time between CMR and CPET was 2.8 months [IQR 0-13.8]. Fifty-three patients (36%) had MPBF (95% CI 29-45%). The mean % predicted VO2 was 63 ± 16%. Patients with MPBF had lower mean % predicted VO2 compared to patients without MPBF (60 ± 14% versus 65 ± 16%, p = 0.04). On multivariable analysis, a lower % predicted VO2 was independently associated with longer time since Fontan, higher ventricular mass-to-volume ratio, and MPBF. On multivariable analysis, only compression of the branch pulmonary arteries by the ascending aorta or aortic root was associated with MPBF (OR 6.5, 95% CI 5.6-7.4, p < 0.001). CONCLUSION: In patients after the Fontan operation, MPBF is common and is independently associated with lower exercise capacity. MPBF was most likely to be caused by pulmonary artery compression by the aortic root or the ascending aorta. This study identifies MPBF as an important risk factor and as a potential target for therapeutic interventions in this fragile patient population.