Vision-controlled jetting for composite systems and robots.

Recreating complex structures and functions of natural organisms in a synthetic form is a long-standing goal for humanity1. The aim is to create actuated systems with high spatial resolutions and complex material arrangements that range from elastic to rigid. Traditional manufacturing processes struggle to fabricate such complex systems2. It remains an open challenge to fabricate functional systems automatically and quickly with a wide range of elastic properties, resolutions, and integrated actuation and sensing channels2,3. We propose an inkjet deposition process called vision-controlled jetting that can create complex systems and robots. Hereby, a scanning system captures the three-dimensional print geometry and enables a digital feedback loop, which eliminates the need for mechanical planarizers. This contactless process allows us to use continuously curing chemistries and, therefore, print a broader range of material families and elastic moduli. The advances in material properties are characterized by standardized tests comparing our printed materials to the state-of-the-art. We directly fabricated a wide range of complex high-resolution composite systems and robots: tendon-driven hands, pneumatically actuated walking manipulators, pumps that mimic a heart and metamaterial structures. Our approach provides an automated, scalable, high-throughput process to manufacture high-resolution, functional multimaterial systems.

Feasibility of MRI assessment of maternal-fetal oxygen transport and consumption relative to maternal position in healthy late gestational pregnancies.

Late gestational supine positioning reduces maternal cardiac output due to inferior vena caval (IVC) compression, despite increased collateral venous return. However, little is known about the impact of maternal position on oxygen (O2 ) delivery and consumption of the gravid uterus, fetus, placenta and lower limbs. We studied the effects of maternal positioning on these parameters in 20 healthy pregnant subjects at 36 ± 2 weeks using magnetic resonance imaging (MRI); a follow-up MRI was performed 6-months postpartum (n = 16/20). MRI techniques included phase-contrast and T1/T2 relaxometry for blood flow and oximetry imaging, respectively. O2 transport was measured in the following vessels (bilateral where appropriate): maternal abdominal descending aorta (DAoabdo ), IVC, ovarian, paraspinal veins (PSV), uterine artery (UtA) and external iliacs, and umbilical. Maternal cardiac output was measured by summing DAothoracic and superior vena cava flows. Supine mothers (n = 6) had lower cardiac output and O2 delivery in the DAoabdo , UtA and external iliac arteries, and higher PSV flow than those in either the left (n = 8) or right (n = 6) lateral positions during MRI. However, O2 consumption in the gravid uterus, fetus, placenta and lower limbs was unaffected by maternal positioning. The ratio of IVC/PSV flow decreased in supine mothers while ovarian venous flow and O2 saturation were unaltered, suggesting a major route of pelvic venous return unaffected by maternal position. Placental-fetal O2 transport and consumption were similar between left and right lateral maternal positions. In comparison to non-pregnant findings, DAoabdo and UtA O2 delivery and pelvic O2 consumption increased, while lower-limb consumption remained constant , despite reduced external iliac artery O2 delivery in late gestation. KEY POINTS: Though sleeping supine during the third trimester is associated with an increased risk of antepartum stillbirth, the underlying biological mechanisms are not fully understood. Maternal cardiac output and uteroplacental flow are reduced in supine mothers due to inferior vena caval compression from the weight of the gravid uterus. This MRI study provides a comprehensive circulatory assessment, demonstrating reduced maternal cardiac output and O2 delivery (uteroplacental, lower body) in supine compared to lateral positioning; however, O2 consumption (gravid uterus, fetus, placenta, lower limbs) was preserved. Unlike other mammalian species, the ovarian veins conduct substantial venous return from the human pregnant uterus that is unaffected by maternal positioning. Lumbar paraspinal venous flow increased in supine mothers. These observations may have important considerations during major pelvic surgery in pregnancy (i.e. placenta percreta). Future studies should address the importance of maternal positioning as a potential tool to deliver improved perinatal outcomes in pregnancies with compromised uteroplacental O2 delivery.

Impact of fetal haemodynamics on surgical and neurodevelopmental outcomes in patients with Ebstein anomaly and tricuspid valve dysplasia.

OBJECTIVES: To evaluate the impact of fetal haemodynamics on surgical and neurodevelopmental outcomes in severe Ebstein anomaly and tricuspid valve dysplasia. METHODS: Thirty-four fetuses with Ebstein anomaly/tricuspid valve dysplasia were referred from 2013 to 2019 for fetal echocardiography and clinical management. Nineteen fetuses with Ebstein anomaly/tricuspid valve dysplasia and 30 controls underwent cardiovascular magnetic resonance to quantify the fetal blood flow and to calculate cerebral oxygen delivery (cDO2) and consumption (cVO2). The 3D steady-state free precession acquisition was used to measure fetal brain volume. Surgical outcome, brain MRI, and neurodevelopmental follow-up were reviewed. RESULTS: Twenty-six fetuses were live born (76%) and survival (65%) at a mean follow-up of 4 years. Nine fetuses had a brain MRI before discharge, and all had clinically silent injuries and volume loss. At 18 months, five single-ventricle patients had a neurodevelopmental delay in cognition and language (mean percentile: 11th), with gross-motor skills more affected than fine-motor skills (mean percentiles: 4th and 34th). Fetuses with Ebstein anomaly/tricuspid valve dysplasia had smaller brains, lower combined ventricular output, ascending aorta, superior caval vien and umbilical vein flows, lower oxygen saturation in ascending aorta and superior caval vien, lower cDO2 and cVO2 (p < 0.05). Superior caval vien/combined ventricular output and descending aorta/combined ventricular output ratios were lower in fetuses with circular shunt (p < 0.05). Fetuses requiring the Starnes procedure tended to have smaller brains, lower combined ventricular output, superior caval vien, descending aorta, and umbilical vein flows. CONCLUSIONS: All patients with Ebstein anomaly/tricuspid valve dysplasia are at high risk of neurodevelopmental delay and warrant follow-up. Fetal cardiovascular magnetic resonance revealed impaired brain growth with diminished cerebral blood flow and cDO2, the extenting dependent on the severity of the haemodynamic compromise.

An MRI approach to assess placental function in healthy humans and sheep.

KEY POINTS: Human placental function is evaluated using non-invasive Doppler ultrasound of umbilical and uterine artery pulsatility indices as measures of resistance in placental vascular beds, while measurement of placental oxygen consumption ( VO2 ) is only possible during Caesarean delivery. This study shows the feasibility of using magnetic resonance imaging (MRI) in utero to measure blood flow and oxygen content in uterine and umbilical vessels to calculate oxygen delivery to and VO2 by the gravid uterus, uteroplacenta and fetus. Normal late gestational human uteroplacental VO2 by MRI was ∼4 ml min-1  kg-1 fetal weight, which was similar to our MRI measurements in sheep and to those previously measured using invasive techniques. Our MRI approach can quantify uteroplacental VO2 , which involves the quantification of maternal- and fetal-placental blood flows, fetal oxygen delivery and VO2 , and the oxygen gradient between uterine- and umbilical-venous blood, providing a comprehensive assessment of placental function with clinical potential. ABSTRACT: It has not been feasible to perform routine clinical measurement of human placental oxygen consumption ( VO2 ) and in vitro studies do not reflect true metabolism in utero. Here we propose an MRI method to non-invasively quantify in utero placental and fetal oxygen delivery ( DO2 ) and VO2 in healthy humans and sheep. Women (n = 20) and Merino sheep (n = 10; 23 sets of measurements) with singleton pregnancies underwent an MRI in late gestation (36 ± 2 weeks and 128 ± 9 days, respectively; mean ± SD). Blood flow (phase-contrast) and oxygen content (T1 and T2 relaxometry) were measured in the major uterine- and umbilical-placental vessels, allowing calculation of uteroplacental and fetal DO2 and VO2 . Maternal DO2 (ml min-1  kg-1 fetus) to the gravid uterus was similar in humans and sheep (human = 54 ± 15, sheep = 53 ± 21, P = 0.854), while fetal DO2 (human = 25 ± 4, sheep = 22 ± 5, P = 0.049) was slightly lower in sheep. Uteroplacental and fetal VO2 (ml min-1  kg-1 fetus; uteroplacental: human = 4.1 ± 1.5, sheep = 3.5 ± 1.9, P = 0.281; fetus: human = 6.8 ± 1.3, sheep = 7.2 ± 1.7, P = 0.426) were similar between species. Late gestational uteroplacental:fetal VO2 ratio did not change with age (human, P = 0.256; sheep, P = 0.121). Human umbilical blood flow (ml min-1  kg-1 fetus) decreased with advancing age (P = 0.008), while fetal VO2 was preserved through an increase in oxygen extraction (P = 0.046). By contrast, sheep fetal VO2 was preserved through stable umbilical flow (ml min-1  kg-1 ; P = 0.443) and oxygen extraction (P = 0.582). MRI derived measurements of uteroplacental and fetal VO2 between humans and sheep were similar and in keeping with prior data obtained using invasive techniques. Taken together, these data confirm the reliability of our approach, which offers a novel clinical 'placental function test'.

Fetal Flow Quantification in Great Vessels Using Motion-Corrected Radial Phase Contrast MRI: Comparison With Cartesian.

BACKGROUND: Phase contrast MRI in the great vessels is a potential clinical tool for managing fetal pathologies. One challenge is the uncontrollable fetal motion, potentially corrupting flow quantifications. PURPOSE: To demonstrate improvements in fetal blood flow quantification in great vessels using retrospectively motion-corrected golden-angle radial phase contrast MRI relative to Cartesian phase contrast MRI. STUDY TYPE: Method comparison. PHANTOM/SUBJECTS: Computer simulation. Seventeen pregnant volunteers. FIELD STRENGTH/SEQUENCE: 1.5T and 3T. Cartesian and golden-angle radial phase contrast MRI. ASSESSMENT: Through computer simulations, radial (with and without retrospective motion correction) and Cartesian phase contrast MRI were compared using flow deviations. in vivo Cartesian and radial phase contrast MRI measurements and reconstruction qualities were compared in pregnancies. Cartesian data were reconstructed into gated reconstructions (CINEs) after cardiac gating with metric optimized gating (MOG). For radial data, real-time reconstructions were performed for motion correction and MOG followed by CINE reconstructions. STATISTICAL TESTS: Wilcoxon signed-rank test. Linear regression. Bland-Altman plots. Student's t-test. RESULTS: Simulations showed significant improvements (P < 0.05) in flow accuracy and reconstruction quality with motion correction ([mean/peak] flow errors with ±5 mm motion corruption: Cartesian [35 ± 1/115 ± 7] mL/s, motion uncorrected radial [25 ± 1/75 ± 2] mL/s and motion-corrected radial [1.0 ± 0.5/-5 ± 1] mL/s). in vivo Cartesian reconstructions without motion correction had lower quality than the motion-corrected radial reconstructions (P < 0.05). Across all fetal mean flow measurements, the bias [limits of agreement] between the two measurements were -0.2 [-76, 75] mL/min/kg, while the linear regression coefficients were (Mradial = 0.81 × MCartesian + 29.8 [mL/min/kg], r2 = 0.67). The corresponding measures for the peak fetal flows were -23 [-214, 167] mL/min/kg and (Pradial = 0.95 × PCartesian -1.2 [mL/min/kg], r2 = 0.80). Cartesian reconstructions of low quality showed significantly higher estimated mean and peak (P < 0.05) flows than the corresponding radial reconstructions. DATA CONCLUSION: Simulations showed that radial phase contrast MRI with motion compensation improved flow accuracy. For fetal measurements, motion-corrected radial reconstructions showed better image quality than, and different flow values from, Cartesian reconstructions. Level of Evidence 1. Technical Efficacy Stage 1. J. MAGN. RESON. IMAGING 2021;53:540-551.

Associations Between Age at Arterial Switch Operation, Brain Growth, and Development in Infants With Transposition of the Great Arteries.

BACKGROUND: Brain injury, impaired brain growth, and long-term neurodevelopmental problems are common in children with transposition of the great arteries. We sought to identify clinical risk factors for brain injury and poor brain growth in infants with transposition of the great arteries undergoing the arterial switch operation, and to examine their relationship with neurodevelopmental outcome. METHODS: The brains of 45 infants with transposition of the great arteries undergoing surgical repair were imaged pre- and postoperatively using magnetic resonance imaging. Brain weight z scores were calculated based on brain volume and autopsy reference data. Brain injury scores were determined as previously described. Neurodevelopment was assessed at 18 months using the Bayley-III scores of infant development. The relationships between clinical variables, brain injury, perioperative brain growth, and 18-month Bayley-III scores were analyzed. RESULTS: On preoperative imaging, moderate or severe white matter injury was present in 10 of 45 patients, whereas stroke was seen in 4 of 45. A similar prevalence of injury was seen on postoperative imaging, and we were unable to identify any clinical risk factors for brain injury. Brain weight z scores decreased perioperatively in 35 of 45 patients. The presence of a ventricular septal defect ( P=0.009) and older age at surgery ( P=0.007) were associated with impaired perioperative brain growth. When patients were divided into those undergoing surgery during the first 2 weeks of life (32/45) versus those being repaired later (13/45), infants repaired later had significantly worse perioperative brain growth (late repair postoperative brain weight z = -1.0±0.90 versus early repair z = -0.33±0.64; P=0.008). Bayley-III testing scores fell within the normal range for all patients, although age at repair ( P=0.03) and days of open chest ( P=0.03) were associated with a lower composite language score, and length of stay was associated with a lower composite cognitive score ( P=0.02). CONCLUSIONS: Surgery beyond 2 weeks of age is associated with impaired brain growth and slower language development in infants with transposition of the great arteries cared for at our center. Although the mechanisms underlying this association are still unclear, extended periods of cyanosis and pulmonary overcirculation may adversely impact brain growth and subsequent neurodevelopment.

Motion robust respiratory-resolved 3D radial flow MRI and its application in neonatal congenital heart disease.

PURPOSE: To test and implement a motion-robust and respiratory-resolved 3D Radial Flow framework that addresses the need for rapid, high resolution imaging in neonatal patients with congenital heart disease. METHODS: A 4-point velocity encoding and 3D radial trajectory with double-golden angle ordering was combined with bulk motion correction (from projection center of mass) and respiration phase detection (from principal component analysis of heartbeat-averaged data) to create motion-robust 3D velocity cardiac time-averaged data. This framework was tested in a whole-chest digital phantom with simulated bulk and realistic physiological motion. In vivo imaging was performed in 20 congenital heart disease infants under feed-and-sleep with submillimeter isotropic resolution in ~3 min. Flows were validated against clinical 2D PCMRI and whole-heart visualizations of blood flow were performed. RESULTS: The proposed framework resolved all simulated digital phantom motion states (mean ± standard error: rotation - azimuthal = 0.29 ± 0.02°; translation - Ty = 1.29 ± 0.12 mm, Tz = -0.27 ± 0.13 mm; rotation+translation - polar = 0.49 ± 0.16°, Tx = -2.47 ± 0.51 mm, Tz = 5.78 ± 1.33 mm). Measured timing errors of peak expiration across all signal-to-noise ratio values were 22% of the true respiratory period (range = [404-489 ± 298-334] ms). For in vivo imaging, motion correction improved 3D Radial Flow measurements (no correction: R2 = 0.62, root mean square error = 0.80 L/min/m2 , Bland-Altman bias [limits of agreement] = -0.21 [-1.40, 0.94] L/min/m2 ; motion corrected, expiration: R2 = 0.90, root mean square error = 0.46 L/min/m2 , bias [limits of agreement] = 0.06 [-0.49, 0.62] L/min/m2 ). Respiratory-resolved 3D velocity visualizations were achieved in various neonatal pathologies pre- and postsurgical correction. CONCLUSION: 3D cardiac flow may be visualized and accurately quantified in neonatal subjects using the proposed framework. This technique may enable more comprehensive hemodynamic studies in small infants.

MR imaging of the fetal heart.

In the last decade, technological advances have enabled the acquisition of high spatial and temporal resolution cardiac magnetic resonance imaging (MRI) in the fetus. Fetal cardiac MRI has emerged as an alternative to ultrasound, which may be helpful to confirm a diagnosis of congenital heart disease when ultrasound assessment is hampered, for example in late gestation or in the setting of oligohydramnios. MRI also provides unique physiologic information, including vessel blood flow, oxygen saturation and hematocrit, which may be helpful to investigate cardiac and placental diseases. In this review, we summarize some of the main techniques and significant advances in the field to date. Level of Evidence: 5 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2020;51:1030-1044.

The utility of MRI for measuring hematocrit in fetal anemia.

BACKGROUND: Doppler ultrasound measurements of the peak systolic velocity of the middle cerebral artery can be used to noninvasively diagnose fetal anemia but are less precise following fetal blood transfusion and in late gestation. We have previously demonstrated the feasibility of estimating fetal hematocrit in vitro using magnetic resonance imaging relaxation times. Here we report the use of magnetic resonance imaging as a noninvasive tool to accurately detect fetal anemia in vivo. OBJECTIVES: This study has 2 objectives: (1) to determine the feasibility and accuracy of magnetic resonance imaging in estimating hematocrit in anemic fetuses and (2) to compare magnetic resonance imaging and middle cerebral artery Doppler in detecting moderate to severe fetal anemia. STUDY DESIGN: Fetuses undergoing fetal blood sampling or transfusion underwent magnetic resonance imaging examinations prior to and following their procedures at 1.5 Tesla (Siemens Avanto). A modified Look-Locker inversion pulse sequence and T2 preparation sequence were applied for T1 and T2 mapping of the intrahepatic umbilical vein. Estimated fetal hematocrit was calculated using a combination of T1 and T2 values and compared with conventional hematocrit obtained from fetal blood samples and middle cerebral artery Doppler measurements. RESULTS: Twenty-three fetuses were assessed during 33 magnetic resonance imaging scans. The mean absolute difference between the laboratory and magnetic resonance imaging-estimated hematocrit was 0.06 ± 0.05 with a correlation of 0.77 (P < .001) determined by a multilevel, mixed-effects model adjusting for the repeated measurements from the same participants, multiple gestation pregnancies, and the scan type (ie, before or after transfusion scan). Bland-Altman analysis revealed a systematic bias of -0.03 between the magnetic resonance imaging and fetal blood sampling measurements. Magnetic resonance imaging and middle cerebral artery Doppler had similar sensitivities of approximately 90% to detect moderate to severe anemia. However, magnetic resonance imaging had a higher specificity (93% [13/14], 95% confidence interval, 66-100%) than Doppler (71% [10/14], 95% confidence interval, 42-92%). CONCLUSION: Moderate to severe fetal anemia can be detected noninvasively by magnetic resonance imaging with high sensitivity and specificity. Our results suggest an adjunct role for magnetic resonance imaging in fetuses with suspected anemia, particularly following previous transfusion and in late gestation.

Current and future role of fetal cardiovascular MRI in the setting of fetal cardiac interventions.

Over recent years, technical developments resulting in the feasibility of fetal cardiovascular magnetic resonance (CMR) have provided a new diagnostic tool for studying the human fetal heart and circulation. During the same period, we have witnessed the arrival of several minimally invasive fetal cardiac interventions (FCI) as a possible form of treatment in selected congenital heart diseases (CHDs). The role of fetal CMR in the planning and monitoring of FCI is not yet clear. Indeed, high-quality fetal CMR is not available or routinely offered at most centers caring for patients with prenatally detected CHD. However, in theory, fetal CMR could have much to offer in the setting of FCI by providing complementary anatomic and physiologic information relating to the specific intervention under consideration. Similarly, fetal CMR may be useful as an alternative imaging modality when ultrasound is hampered by technical limitations, for example, in the setting of oligohydramnios and in late gestation. In this review, we summarize current experience of the use of fetal CMR in the diagnosis and monitoring of fetuses with cardiopathies in the setting of a range of invasive in utero cardiac and vascular interventions and medical treatments and speculate about future directions for this versatile imaging medium.

Decreased Brain Volumes and Infants With Congenital Heart Disease Undergoing Venoarterial Extracorporeal Membrane Oxygenation.

OBJECTIVES: The aims of this study were to: i) determine the spectrum of brain injury and ii) compare brain volumes between pre- and postoperative brain MRI in the infants receiving extracorporeal membrane oxygenation compared with those who did not require extracorporeal membrane oxygenation. DESIGN: Cohort study of infants with D-transposition of the great arteries or single ventricle physiology. Brain volume (cm) was measured using a segmentation of a volumetric T1-weighted gradient echo sequence. Brain imaging findings (intraventricular hemorrhage, white matter injuries, and stroke) were analyzed with respect to known clinical risk factors for brain injury and adverse neurodevelopmental outcomes. Clinical factors were collected by retrospective chart review. The association between brain volume and extracorporeal membrane oxygenation was evaluated using generalized estimating equations to account for repeated measures. SETTING: Prospective and single-centered study. PATIENTS: One hundred nine infants (median gestational age, 39.1 wk) with D-transposition of the great arteries (n = 77) or single ventricle physiology (n = 32) were studied pre- and postoperatively with MRI as per clinical protocol. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Of the 28 infants (26%) receiving extracorporeal membrane oxygenation, 19 (68%) were supported with extracorporeal membrane oxygenation once, and nine (32%) were supported 2-4 times. On postoperative MRI, new white matter injury was found in only five (17%) of the extracorporeal membrane oxygenation infants versus 40 (49%) in the non-extracorporeal membrane oxygenation group (p = 0.073). The rate of stroke (9% vs 10%), intraventricular hemorrhage (24% vs 29%), and hypoxic ischemia (3% vs 14%) did not differ between the non-extracorporeal membrane oxygenation and extracorporeal membrane oxygenation groups (all p > 0.5). Accounting for D-transposition of the great arteries or single ventricle physiology diagnosis, infants requiring extracorporeal membrane oxygenation had slower brain volume with single (ß = -1.67) or multiple extracorporeal membrane oxygenation runs ([ß = -6.54]; overall interaction p = 0.012). CONCLUSIONS: Patients with d-transposition of the great arteries or single ventricle physiology undergoing extracorporeal membrane oxygenation at our center have a similar incidence of brain injury but more significant impairment of perioperative brain volumes than those not requiring extracorporeal membrane oxygenation.

Fetal cardiovascular magnetic resonance imaging.

Fetal cardiovascular MRI is showing promise as a clinical diagnostic tool in the setting of congenital heart disease when the cardiac anatomy is unresolved by US or when complementary quantitative data on blood flow, oxygen saturation and hematocrit are required to aid in management. Compared with postnatal cardiovascular MRI, prenatal cardiovascular MRI still has some technical limitations. However, ongoing technical advances continue to improve the robustness and usability of fetal cardiovascular MRI. In this review, we provide an overview of the state of the art of fetal cardiovascular MRI and summarize the current focus of clinical application for this versatile technique.

Understanding Fetal Hemodynamics Using Cardiovascular Magnetic Resonance Imaging.

Human fetal circulatory physiology has been investigated extensively using grey-scale ultrasound, which provides excellent visualization of cardiac anatomy and function, while velocity profiles in the heart and vessels can be interrogated using Doppler. Measures of cerebral and placental vascular resistance, as well as indirect measures of intracardiac pressure obtained from the velocity waveform in the ductus venosus are routinely used to guide the management of fetal cardiovascular and placental disease. However, the characterization of some key elements of cardiovascular physiology such as vessel blood flow and the oxygen content of blood in the arteries and veins, as well as fetal oxygen delivery and consumption are not readily measured using ultrasound. To study these parameters, we have historically relied on data obtained using invasive measurements made in animal models, which are not equivalent to the human in every respect. Over recent years, a number of technical advances have been made that have allowed us to examine the human fetal circulatory system using cardiovascular magnetic resonance (CMR). The combination of vessel blood flow measurements made using cine phase contrast magnetic resonance imaging and vessel blood oxygen saturation and hematocrit measurements made using T1 and T2 mapping have enabled us to emulate those classic fetal sheep experiments defining the distribution of blood flow and oxygen transport across the fetal circulation in the human fetus. In addition, we have applied these techniques to study the relationship between abnormal fetal cardiovascular physiology and fetal development in the setting of congenital heart disease and placental insufficiency. CMR has become an important diagnostic tool in the assessment of cardiovascular physiology in the setting of postnatal cardiovascular disease, and is now being applied to the fetus to enhance our understanding of normal and abnormal fetal circulatory physiology and its impact on fetal well-being.

Brain Injury in Infants with Critical Congenital Heart Disease: Insights from Two Clinical Cohorts with Different Practice Approaches.

OBJECTIVES: To determine prevalence and risk factors for brain injury in infants with critical congenital heart disease (CHD) from 2 sites with different practice approaches who were scanned clinically. STUDY DESIGN: Prospective, longitudinal cohort study (2016-2017) performed at Hospital for Sick Children Toronto (HSC) and Wilhelmina Children's Hospital Utrecht (WKZ), including 124 infants with cardiac surgery ≤60 days (HSC = 77; WKZ = 47). Magnetic resonance imaging was performed per clinical protocol, preoperatively (n = 100) and postoperatively (n = 120). Images were reviewed for multifocal (watershed, white matter injury) and focal ischemic injury (stroke, single white matter lesion). RESULTS: The prevalence of ischemic injury was 69% at HSC and 60% at WKZ (P = .20). Preoperative multifocal injury was associated with low cardiac output syndrome (OR, 4.6), which was equally present at HSC and WKZ (20% vs 28%; P = .38). Compared with WKZ, HSC had a higher prevalence of balloon-atrioseptostomy in transposition of the great arteries (83% vs 53%; P = .01) and more frequent preoperative focal injury (27% vs 6%; P = .06). Postoperatively, 30% of new multifocal injury could be attributed to postoperative low cardiac output syndrome, which was equally present at HSC and WKZ (38% vs 28%; P = .33). Postoperative focal injury was associated with intraoperative selective cerebral perfusion in CHD with arch obstruction at both sites (OR, 2.7). Compared with HSC, WKZ had more arch obstructions (62% vs 35%; P < .01) and a higher prevalence of new focal injury (36% vs 16%; P = .01). CONCLUSIONS: Brain injury is common in clinical cohorts of infants with critical CHD and related to practice approaches. This study confirms that the high prevalence of brain injury in critical CHD is a clinical concern and does not simply reflect the inclusion criteria of published research studies.

Fetal XCMR: a numerical phantom for fetal cardiovascular magnetic resonance imaging.

BACKGROUND: Validating new techniques for fetal cardiovascular magnetic resonance (CMR) is challenging due to random fetal movement that precludes repeat measurements. Consequently, fetal CMR development has been largely performed using physical phantoms or postnatal volunteers. In this work, we present an open-source simulation designed to aid in the development and validation of new approaches for fetal CMR. Our approach, fetal extended Cardiac-Torso cardiovascular magnetic resonance imaging (Fetal XCMR), builds on established methods for simulating CMR acquisitions but is tailored toward the dynamic physiology of the fetal heart and body. We present comparisons between the Fetal XCMR phantom and data acquired in utero, resulting in image quality, anatomy, tissue signals and contrast. METHODS: Existing extended Cardiac-Torso models are modified to create maternal and fetal anatomy, combined according to simulated motion, mapped to CMR contrast, and converted to CMR data. To provide a comparison between the proposed simulation and experimental fetal CMR images acquired in utero, images from a typical scan of a pregnant woman are included and simulated acquisitions were generated using matching CMR parameters, motion and noise levels. Three reconstruction (static, real-time, and CINE), and two motion estimation methods (translational motion, fetal heart rate) from data acquired in transverse, sagittal, coronal, and short-axis planes of the fetal heart were performed to compare to in utero acquisitions and demonstrate feasibility of the proposed simulation framework. RESULTS: Overall, CMR contrast, morphologies, and relative proportions of the maternal and fetal anatomy are well represented by the Fetal XCMR images when comparing the simulation to static images acquired in utero. Additionally, visualization of maternal respiratory and fetal cardiac motion is comparable between Fetal XCMR and in utero real-time images. Finally, high quality CINE image reconstructions provide excellent delineation of fetal cardiac anatomy and temporal dynamics for both data types. CONCLUSION: The fetal CMR phantom provides a new method for evaluating fetal CMR acquisition and reconstruction methods by simulating the underlying anatomy and physiology. As the field of fetal CMR continues to grow, new methods will become available and require careful validation. The fetal CMR phantom is therefore a powerful and convenient tool in the continued development of fetal cardiac imaging.

Multidimensional fetal flow imaging with cardiovascular magnetic resonance: a feasibility study.

PURPOSE: To image multidimensional flow in fetuses using golden-angle radial phase contrast cardiovascular magnetic resonance (PC-CMR) with motion correction and retrospective gating. METHODS: A novel PC-CMR method was developed using an ungated golden-angle radial acquisition with continuously incremented velocity encoding. Healthy subjects (n = 5, 27 ± 3 years, males) and pregnant females (n = 5, 34 ± 2 weeks gestation) were imaged at 3 T using the proposed sequence. Real-time reconstructions were first performed for retrospective motion correction and cardiac gating (using metric optimized gating, MOG). CINE reconstructions of multidimensional flow were then performed using the corrected and gated data. RESULTS: In adults, flows obtained using the proposed method agreed strongly with those obtained using a conventionally gated Cartesian acquisition. Across the five adults, bias and limits of agreement were - 1.0 cm/s and [- 5.1, 3.2] cm/s for mean velocities and - 1.1 cm/s and [- 6.5, 4.3] cm/s for peak velocities. Temporal correlation between corresponding waveforms was also high (R~ 0.98). Calculated timing errors between MOG and pulse-gating RR intervals were low (~ 20 ms). First insights into multidimensional fetal blood flows were achieved. Inter-subject consistency in fetal descending aortic flows (n = 3) was strong with an average velocity of 27.1 ± 0.4 cm/s, peak systolic velocity of 70.0 ± 1.8 cm/s and an intra-class correlation coefficient of 0.95 between the velocity waveforms. In one fetal case, high flow waveform reproducibility was demonstrated in the ascending aorta (R = 0.97) and main pulmonary artery (R = 0.99). CONCLUSION: Multidimensional PC-CMR of fetal flow was developed and validated, incorporating retrospective motion compensation and cardiac gating. Using this method, the first quantification and visualization of multidimensional fetal blood flow was achieved using CMR.

Protein-losing enteropathy in biventricular circulation precipitated by mild stenosis of the inferior caval vein in conjunction with total occlusion of the superior caval vein: a word of caution.

We report the case of a young boy with a history of total occlusion of the superior caval vein, diagnosed early after complex neonatal cardiac surgery, who developed severe protein-losing enteropathy. Protein-losing enteropathy was precipitated by a relatively mild stenosis at the junction of the inferior caval vein with the right atrium. Percutaneous stent dilation of the veno-atrial junction definitively relieved the stenosis, and the protein-losing enteropathy subsequently resolved.

Long-term outcome after percutaneous closure of persistent left superior caval vein draining into the left atrium: a contrast-enhanced CT study.

BACKGROUND: Data regarding long-term outcome after percutaneous closure of left superior caval vein draining into the left atrium are lacking. The aim of the present study was to report the long-term follow-up by using contrast-enhanced CT. METHODS: In all, three patients underwent percutaneous closure of left superior caval vein draining into the left atrium between 2005 and 2015. All of them were evaluated clinically and underwent contrast-enhanced CT. RESULTS: In one patient, the Amplatzer® Septal Occluder was used. In two patients, the Amplatzer® Vascular Plug type-1 was preferred: the device size/LSVC diameter ratio was 1.7 in the child and 1.2 in the adult. There were no early-onset or long-term onset complications. CT was performed 1, 2, and 10 years after the procedure, respectively. Complete occlusion of the vessel was documented in all. After 10 years since the procedure, CT revealed a persistent trivial residual shunt through the accessory hemiazygos vein in one patient, in whom the device was implanted above its drainage into the left superior caval vein. When an Amplatzer® Vascular Plug type-1 is oversized compared with the venous vessel diameter, it immediately assumes a dog-bone shape that disappears early to regain its shape memory and nominal size. CONCLUSIONS: Percutaneous occlusion of left superior caval vein draining into the left atrium has excellent early and long-term outcomes. The optimal implantation of the device is below the drainage of the accessory hemiazygos vein, when present. The device might be oversized compared with the left superior caval vein diameter according to the age of the patient.

Off-label use of the amplatzer ductal occluder II additional size for percutaneous closure of congenital and acquired coronary fistulae.

We report two cases in which congenital and acquired fistulae (CAFs) have been successfully closed by using the Amplatzer Ductal Occluder (ADO) II AS in children. Because of the flexibility, small profile and short length of ADO II AS, this device proved to be an excellent option in case of tortuous and short CAFs with coronary branches next to the fistulous orifice. © 2015 Wiley Periodicals, Inc.

Endomyocardial biopsy safety and clinical yield in pediatric myocarditis: An Italian perspective.

OBJECTIVES: The objective of this investigation is to evaluate the safety, the impact of endomyocardial biopsy (EMB) results in myocarditis management and the incidence of different etiologies of myocarditis in a pediatric population. BACKGROUND: Although EMB is an established diagnostic tool to evaluate suspected myocarditis, there is lack of clear diagnostic and management guidelines for myocarditis in pediatric patients, particularly in infants. METHODS: We performed a retrospective database review and subsequent outcomes analysis from five Italian pediatric cardiology centers to identify patients aged 0-18 years who underwent EMB for suspected myocarditis or inflammatory cardiomyopathy (ICMP) between 2009 and 2011. RESULTS: EMB was performed in 41 children, of which 16 were male. The population ranged between 16 days of age to 17 years (mean age at EMB = 5.2 ± 4.9 years). The overall incidence of EMB-related complications was 15.5% (31.2% in infants, and 6.8% in children > 1 year of age; P = 0.079) while the incidence of EMB-driven treatment changes was 29.2%. Histological examination together with PCR on heart biopsy specimens allowed an etiological diagnosis in 26/41 patients (63%). Among the 15 patients (36.5%) with diagnosis of dilated cardiomyopathy (DCM) 11 had idiopathic DCM. Finally, we found an overall incidence of death/cardiac transplantation of 24%. CONCLUSIONS: In a pediatric population with suspected myocarditis/ICMP, EMB was useful in confirming the diagnosis only in 41% of cases but showed an overall diagnostic power of 63%. As complications of EBM are not negligible, particularly in infants, the risk/benefit ratio should be taken into account in each patient.