Fetal Cardiovascular Magnetic Resonance Research Articles

Fetal Hemodynamics, Early Survival, and Neurodevelopment in Patients With Cyanotic Congenital Heart Disease

BackgroundFetuses with cyanotic congenital heart disease (CHD) exhibit profound fetal circulatory disturbances that may affect early outcomes. ObjectivesThis study sought to investigate the relationship between fetal hemodynamics and early survival and neurodevelopmental (ND) outcomes in patients with cyanotic CHD. MethodsIn this longitudinal observational study, fetuses with cyanotic CHD underwent late gestational fetal cardiovascular magnetic resonance (CMR) to measure vessel blood flow and oxygen content. Superior vena cava (SVC) flow was used as a proxy for cerebral blood flow. Primary outcomes were 18-month mortality and Bayley Scales of Infant Development-III assessment. ResultsA total of 144 fetuses with cyanotic CHD were assessed. By 18 months, 18 patients (12.5%) died. Early mortality was associated with reduced combined ventricular output (P = 0.01), descending aortic flow (P = 0.04), and umbilical vein flow (P = 0.03). Of the surviving patients, 71 had ND outcomes assessed. Cerebral oxygen delivery was the fetal hemodynamic variable most strongly associated with cognitive, language, and motor outcomes (P < 0.05). Fetal SVC flow was also associated with cognitive, language, and motor outcomes (P < 0.01), and it remained an independent predictor of cognitive (P = 0.002) and language (P = 0.04) outcomes after adjusting for diagnosis. Diminished SVC flow also performed better than other fetal CMR and echocardiographic predictors of cognitive ND delay (receiver-operating characteristic curve area: 0.85; SE 0.05). ConclusionsAmong fetuses with cyanotic CHD, diminished fetal combined ventricular output is associated with mortality, whereas cerebral blood flow and oxygen delivery are associated with early cognitive, language, and motor development at 18 months of age. These results support the inclusion of fetal CMR to help identify patients at risk of adverse ND outcomes.

Integration of Prenatal Cardiovascular Magnetic Resonance Imaging in Congenital Heart Disease.

Standard of care echocardiography can have limited diagnostic accuracy in certain cases of fetal congenital heart disease. Prenatal cardiovascular magnetic resonance (CMR) imaging has potential to provide additional anatomic imaging information, including excellent soft tissue images in multiple planes, improving prenatal diagnostics and in utero hemodynamic assessment. We conducted a literature review of fetal CMR, including its development and implementation into clinical practice, and compiled and analyzed the results. Our findings included the fact that technological and innovative approaches are required to overcome some of the challenges in fetal CMR, in part due to the dynamic nature of the fetal heart. A number of reconstruction algorithms and cardiac gating strategies have been developed over time to improve fetal CMR image quality, allowing unique investigations into fetal hemodynamics, oxygenation, and growth. Studies demonstrate that incorporating CMR in the prenatal arena influences postnatal clinical management. With further refinement and experience, fetal CMR in congenital heart disease continues to evolve and demonstrate ongoing potential as a complementary imaging modality to fetal echocardiography in the care of these patients.

Abstract 17366: Effects of Acute Maternal Supplemental Oxygen on the Fetal Circulation in Transposition of the Great Arteries

Introduction: The presence of a restrictive atrial septum in the setting of transposition of the great arteries (TGA) is associated with a high risk of hypoxic ischemic injury upon transition to postnatal circulation. Fetal cardiovascular magnetic resonance (CMR) measures of vessel flow and oxygen saturation provide a unique opportunity to study fetal TGA hemodynamics at baseline and during acute maternal hyperoxygenation. Methods: Thirty-one pregnant mothers with fetuses diagnosed with TGA and an intact ventricular septum (n=23) or small ventricular septal defect (n=8) were recruited and underwent fetal CMR in room air and during administration of 10L/min of oxygen by face mask for up to 45 minutes. Blood flow and oxygen saturations were measured in the major fetal vessels using cine phase contrast MRI and MR relaxometry at baseline and during hyperoxygenation. Results: Two patients exhibited severe restriction at the atrial septum, one undergoing fetal atrial septostomy at 37 weeks and one requiring cannulation onto ECMO shortly after birth. Both revealed reversal of the usual relationship of oxygen saturation between the aorta and the main pulmonary artery at baseline and during hyperoxygenation, i.e. in TGA with restrictive atrial septum the saturations are higher in the aorta than pulmonary. Acute maternal supplemental oxygen was associated with increased pulmonary blood flow (p=0.008) and reduced foramen ovale (p=0.01) and ductus arteriosus shunting (p=0.01). There were no significant changes in umbilical vein, descending aorta and superior vena cava flow. Fetal oxygen saturations increased throughout fetal circulation (p&lt;0.0001) with an associated increase in fetal oxygen delivery (p=0.007), but no increase in fetal cerebral oxygen delivery (p=0.58). Conclusions: This study characterized the effects of acute maternal supplemental oxygen on the fetal circulation in patients with TGA and confirmed the redistribution of flow toward the fetal pulmonary circulation. We observed higher oxygen saturations in the aorta than main pulmonary artery in fetuses with TGA with an intact or highly restrictive atrial septal communication. This finding could be helpful in selecting patients for prenatal or emergency neonatal balloon atrial septostomy.

Utility of fetal cardiovascular magnetic resonance imaging in assessing the fetuses with complete vascular ring.

This study aimed to report our experience in qualitative and quantitative evaluation of fetal complete vascular ring (CVR) using fetal cardiovascular magnetic resonance imaging (MRI) to improve prenatal diagnosis and make early postnatal management possible. A retrospective case-control study was performed on cases of CVR diagnosed using fetal cardiovascular MRI, and confirmed by postnatal imaging diagnosis. Associated abnormalities were recorded. The diameters of aortic arch isthmus (AoI) and ductus arteriosus (DA), and tracheal diameters in fetuses with tracheal compression were measured and compared with those of the control group. All fetal CVR cases in this study included right aortic arch (RAA) with aberrant left subclavian artery (ALSA) and left DA (n = 93), double aortic arch (DAA) (n = 29), RAA with mirror-image branching and retroesophageal left ductus arteriosus (RLDA) (n = 8). Compared with the control group, the diameters of AoI in fetuses with DAA were decreased (p < 0.001), and the diameters of DA in fetuses with RAA with ALSA and left DA were increased (p < 0.001). The diameters of AoI and DA were positively correlated with gestational age (GA) in the normal control group (both p < 0.001); The diameters of AoI and DA were also positively correlated with GA in RAA with ALSA and left DA subgroup (both p < 0.001) and RAA with mirror-image branching and RLDA subgroup (AoI: p = 0.003; DA: p = 0.002); The diameters of DA were positively associated with GA in DAA subgroup (p < 0.001), however, there was no linear tendency between the diameters of AoI and GA in the DAA subgroup (p = 0.074). There were CVR fetuses with associated intracardiac malformation (n = 13), especially ventricular septal defect rather than complex heart disease, and extracardiac malformation (n = 14). Sixteen fetuses were shown the airway compression whose tracheal diameters were smaller than the normal (p < 0.001). The altered diameters of AoI and DA can be detected and measured in CVR fetuses using fetal cardiovascular MRI. Fetal CVR can occur alone or with intracardiac and extracardiac malformation. Fetal CVR can be associated with prenatal airway compression.

Prenatal diagnosis of fetal ectopia cordis by fetal cardiovascular magnetic resonance imaging.

The purpose of this retrospective study was to report our cases of fetal ectopia cordis (EC) and to evaluate the utility of fetal cardiovascular magnetic resonance imaging (MRI) for the diagnosis of this rare anomaly. This retrospective study included 11 fetuses with EC. The multiplane steady-state free precession (SSFP) sequence, single-shot turbo spin-echo sequence and non-gated SSFP cine cardiovascular magnetic resonance were used to evaluate the fetal heart and abdomen. The 11 fetal cases with EC were examined by fetal cardiovascular MRI and confirmed by postnatal or post-mortem findings. Of these 11 cases, two were isolated thoracic EC, six had pentalogy of Cantrell, and three had an omphalocele and EC. Among all 11 fetuses, nine were associated with congenital heart defects. In four cases, fetal MRI added additional information compared to fetal ultrasound, however, in two cases, fetal MRI missed the diagnosis of a ventricular septal defect noted by echocardiography. Fetal MRI combined with prenatal echocardiography can improve the accuracy of the prenatal diagnosis of EC.

Fetal Cardiovascular MRI - A Systemic Review of the Literature: Challenges, New Technical Developments, and Perspectives.

Fetal magnetic resonance imaging (MRI) has become a valuable adjunct to ultrasound in the prenatal diagnosis of congenital pathologies of the central nervous system, thorax, and abdomen. Fetal cardiovascular magnetic resonance (CMR) was limited, mainly by the lack of cardiac gating, and has only recently evolved due to technical developments. A literature search was performed on PubMed, focusing on technical advancements to perform fetal CMR. In total, 20 publications on cardiac gating techniques in the human fetus were analyzed. Fetal MRI is a safe imaging method with no developmental impairments found to be associated with in utero exposure to MRI. Fetal CMR is challenging due to general drawbacks (e. g., fetal motion) and specific limitations such as the difficulty to generate a cardiac gating signal to achieve high spatiotemporal resolution. Promising technical advancements include new methods for fetal cardiac gating, based on novel post-processing approaches and an external hardware device, as well as motion compensation and acceleration techniques. Newly developed direct and indirect gating approaches were successfully applied to achieve high-quality morphologic and functional imaging as well as quantitative assessment of fetal hemodynamics in research settings. In cases when prenatal echocardiography is limited, e. g., by an unfavorable fetal position in utero, or when its results are inconclusive, fetal CMR could potentially serve as a valuable adjunct in the prenatal assessment of congenital cardiovascular malformations. However, sufficient data on the diagnostic performance and clinical benefit of new fetal CMR techniques is still lacking. · New fetal cardiac gating methods allow high-quality fetal CMR.. · Motion compensation and acceleration techniques allow for improvement of image quality.. · Fetal CMR could potentially serve as an adjunct to fetal echocardiography in the future.. · Knapp J, Tavares de Sousa M, Schönnagel BP. Fetal Cardiovascular MRI - A Systemic Review of the Literature: Challenges, New Technical Developments, and Perspectives. Fortschr Röntgenstr 2022; 194: 841 - 851.

Prenatal Diagnosis and Management of Single-Ventricle Heart Disease.

In the current era, most single-ventricle heart disease (SVHD) is diagnosed prenatally by means of fetal echocardiography. Disparities exist, however, by socioeconomic status and remote location, which require further attention. Prenatal diagnosis affords the opportunity to counsel expectant parents regarding the life-long course of children with SVHD, including the stages of single-ventricle palliation and challenges of the Fontan circulation; to discuss pregnancy management options; and to optimise delivery planning and perinatal care. Prognosis may be refined by specific features on the fetal echocardiogram, such as ventricular morphology, total anomalous pulmonary venous return, and atrioventricular valve regurgitation. Expectant mothers should be referred for evaluation of extracardiac anomalies and/or a genetic syndrome, which also significantly affect outcome. Fetuses with SVHD should be cared for by a multidisciplinary team and ideally delivered at term at or near a cardiac surgical center. Serial echocardiograms refine the anticipated postnatal physiology to optimise transitional care, including the need for prostaglandin or urgent atrial septal intervention in fetuses with hypoplastic left heart syndrome. In selected patients, there may be a role for fetal cardiac intervention to improve mortality or achieve a biventricular circulation after birth. Together, these strategies enhance the preoperative status of the neonate. Recent advances in fetal cardiovascular magnetic resonance imaging have focused on studying the relationships between cardiovascular physiology and fetal growth and development. These novel techniques allow for the exploration of the physiologic effects of SVHD on the brain and open avenues for the investigation of neuroprotective therapies.

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

To evaluate the impact of fetal haemodynamics on surgical and neurodevelopmental outcomes in severe Ebstein anomaly and tricuspid valve dysplasia. 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. 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. 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.

3D black blood cardiovascular magnetic resonance atlases of congenital aortic arch anomalies and the normal fetal heart: application to automated multi-label segmentation

BackgroundImage-domain motion correction of black-blood contrast T2-weighted fetal cardiovascular magnetic resonance imaging (CMR) using slice-to-volume registration (SVR) provides high-resolution three-dimensional (3D) images of the fetal heart providing excellent 3D visualisation of vascular anomalies [1]. However, 3D segmentation of these datasets, important for both clinical reporting and the application of advanced analysis techniques is currently a time-consuming process requiring manual input with potential for inter-user variability.MethodsIn this work, we present novel 3D fetal CMR population-averaged atlases of normal and abnormal fetal cardiovascular anatomy. The atlases are created using motion-corrected 3D reconstructed volumes of 86 third trimester fetuses (gestational age range 29-34 weeks) including: 28 healthy controls, 20 cases with postnatally confirmed neonatal coarctation of the aorta (CoA) and 38 vascular rings (21 right aortic arch (RAA), 17 double aortic arch (DAA)). We used only high image quality datasets with isolated anomalies and without any other deviations in the cardiovascular anatomy.In addition, we implemented and evaluated atlas-guided registration and deep learning (UNETR) methods for automated 3D multi-label segmentation of fetal cardiac vessels. We used images from CoA, RAA and DAA cohorts including: 42 cases for training (14 from each cohort), 3 for validation and 6 for testing. In addition, the potential limitations of the network were investigated on unseen datasets including 3 early gestational age (22 weeks) and 3 low SNR cases.ResultsWe created four atlases representing the average anatomy of the normal fetal heart, postnatally confirmed neonatal CoA, RAA and DAA. Visual inspection was undertaken to verify expected anatomy per subgroup. The results of the multi-label cardiac vessel UNETR segmentation showed 100% per-vessel detection rate for both normal and abnormal aortic arch anatomy.ConclusionsThis work introduces the first set of 3D black-blood T2-weighted CMR atlases of normal and abnormal fetal cardiovascular anatomy including detailed segmentation of the major cardiovascular structures. Additionally, we demonstrated the general feasibility of using deep learning for multi-label vessel segmentation of 3D fetal CMR images.

Abstract 11766: Late Gestation Fetal Oxygenation is Associated With Birthweight and Head Circumference in Patients With Cyanotic Congenital Heart Disease

Introduction: Abnormal fetal growth and development are evident in patients with cyanotic congenital heart disease (cCHD). However, the relationship between growth and fetal oxygenation is unknown. We sought to investigate the relationship between fetal hemodynamics and fetal growth in cCHD using fetal cardiovascular Magnetic Resonance Imaging (MRI). Hypothesis: The impaired fetal oxygenation would be associated with diminished fetal brain and body growth in cCHD. Methods: We performed a prospective observational study in fetuses diagnosed with cCHD at our institution from June 2010 to January 2020. Late-gestational fetal cardiovascular MRI was performed in 152 fetuses with cCHD to assess fetal blood flow (phase-contrast MRI) and oxygen saturation (T2 oximetry) in the major fetal vessels to calculate oxygen delivery to the brain and body according to our previously published techniques. Results are provided as medians with IQR and compared with 30 gestational age-matched normal controls using Mann-Whitney U test. A Pearson’s correlation was used to examine the relationships between variables. Results: Compared with normal controls, fetuses with cCHD had significantly reduced birth weight Z-scores [-0.41 (-0.29, 0.84) vs. -0.19 (-0.46, 0.37), p = 0.03], and neonatal head circumference Z-scores [0.1 (-1.75, 0.95) vs. 0.69 (0.1, 1.79), p = 0.003]. As a combined cohort, birthweight Z-score was correlated with fetal oxygen delivery (r = 0.33, p = 0.003), umbilical vein flow (r = 0.2, p = 0.006) and oxygen saturation (r = 0.25, p = 0.02). Birth head circumference Z-score was correlated with fetal cerebral oxygen delivery (r = 0.33, p = 0.01) and ascending aorta oxygen saturation (r = 0.33, p = 0.009). We also found an inverse relationship between ascending aorta oxygen saturation and superior vena cava flow (r = -0.24, p = 0.036). Conclusions: In conclusion, we observed associations between placental function in late gestation and birthweight, as well as cerebral oxygen delivery in utero and head circumference at birth. Our findings are in keeping with the concept that cCHD impacts fetal development through abnormal circulatory physiology and placental function.

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

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. To assess the clinical utility of fetal cardiovascular magnetic resonance imaging in cases in which fetal echocardiography could not visualize all relevant anatomy. 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. Fetal cardiovascular magnetic resonance examination requested by the patient's pediatric cardiologist. Any change in patient management because of diagnostic information gained from fetal cardiovascular magnetic resonance imaging. 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%). 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.

Feasibility of ventricular volumetry by cardiovascular MRI to assess cardiac function in the fetal sheep.

The application of fetal cardiovascular magnetic resonance imaging (CMR) to assess fetal cardiovascular physiology and cardiac function through the quantification of ventricular volumes has previously been investigated, but the approach has not yet been fully validated. Ventricular output measurements calculated from heart rate and stroke volumes (SV) of the right and left ventricles measured by ventricular volumetry (VV) exhibited a high level of agreement with phase-contrast (PC) blood flow measurements in the main pulmonary artery and ascending aorta, respectively. Ejection fraction of the right ventricle, which is lower than that of the left ventricle in postnatal subjects, was similar to the left ventricular ejection fraction in the fetus; probably due to the different loading conditions present in the fetal circulation. This study provides evidence to support the reliability of VV in the sheep fetus, providing evidence for its use in animal models of human diseases affecting the fetal circulation. The application of ventricular volumetry (VV) by cardiovascular magnetic resonance imaging (CMR) in the fetus remains challenging due to the small size of the fetal heart and high heart rate. The reliability of this technique in utero has not yet been established. The aim of this study was to assess the feasibility and reliability of VV in a fetal sheep model of human pregnancy. Right and left ventricular outputs by stroke volume (SV) measured using VV were compared with 2D phase-contrast (PC) CMR measurements of blood flow in the main pulmonary artery (MPA) and ascending aorta (AAo). At 124-140days (d) gestation, singleton bearing Merino ewes underwent CMR under general anaesthesia using fetal femoral artery catheters, implanted at 109-117d, to trigger cine steady state free precession acquisitions of ventricular short-axis stacks. The short-axis cine stacks were segmented at end-systole and end-diastole, yielding right and left ventricular SV, ejection fraction, and cardiac outputs (SV×heart rate). PC cine acquisitions of MPA and AAo were analysed to measure blood flow, which served as comparators for the right and left cardiac outputs by VV. There was good correlation and agreement between VV and PC measures of ventricular outputs with no significant bias (r2 =0.926; P<0.0001; Bias=-4.7±10.5mlmin-1 kg-1 ; 95% limits of agreement: -15.9 to 25.2mlmin-1 kg-1 ). This study validates fetal VV by CMR in a large animal model of human pregnancy and provides preliminary reference values of fetal sheep right and left ventricles 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.

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

BackgroundValidating 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.MethodsExisting 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.ResultsOverall, 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.ConclusionThe 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.

Dynamic fetal cardiovascular magnetic resonance imaging using Doppler ultrasound gating

BackgroundFetal cardiovascular magnetic resonance (CMR) imaging may provide a valuable adjunct to fetal echocardiography in the evaluation of congenital cardiovascular pathologies. However, dynamic fetal CMR is difficult due to the lack of direct in-utero cardiac gating. The aim of this study was to investigate the effectiveness of a newly developed Doppler ultrasound (DUS) device in humans for fetal CMR gating.MethodsFifteen fetuses (gestational age 30–39 weeks) were examined using 1.5 T CMR scanners at three different imaging sites. A newly developed CMR-compatible DUS device was used to generate gating signals from fetal cardiac motion. Gated dynamic balanced steady-state free precession images were acquired in 4-chamber and short-axis cardiac views. Gating signals during data acquisition were analyzed with respect to trigger variability and sensitivity. Image quality was assessed by measuring endocardial blurring (EB) and by image evaluation using a 4-point scale. Left ventricular (LV) volumetry was performed using the single-plane ellipsoid model.ResultsGating signals from the fetal heart were detected with a variability of 26 ± 22 ms and a sensitivity of trigger detection of 96 ± 4%. EB was 2.9 ± 0.6 pixels (4-chamber) and 2.5 ± 0.1 pixels (short axis). Image quality scores were 3.6 ± 0.6 (overall), 3.4 ± 0.7 (mitral valve), 3.4 ± 0.7 (foramen ovale), 3.6 ± 0.7 (atrial septum), 3.7 ± 0.5 (papillary muscles), 3.8 ± 0.4 (differentiation myocardium/lumen), 3.7 ± 0.5 (differentiation myocardium/lung), and 3.9 ± 0.4 (systolic myocardial thickening). Inter-observer agreement for the scores was moderate to very good (kappa 0.57–0.84) for all structures. LV volumetry revealed mean values of 2.8 ± 1.2 ml (end-diastolic volume), 0.9 ± 0.4 ml (end systolic volume), 1.9 ± 0.8 ml (stroke volume), and 69.1 ± 8.4% (ejection fraction).ConclusionHigh-quality dynamic fetal CMR was successfully performed using a newly developed DUS device for direct fetal cardiac gating. This technique has the potential to improve the utility of fetal CMR in the evaluation of congenital pathologies.

New advances in fetal cardiovascular magnetic resonance imaging for quantifying the distribution of blood flow and oxygen transport: Potential applications in fetal cardiovascular disease diagnosis and therapy.

Until recently, our modern understanding of fetal circulatory physiology has been largely based on invasive measurements made in fetal sheep. However, new MRI technology developed by our group has provided equivalent information about the distribution of blood flow and oxygen transport noninvasively. The initial findings largely confirm prior estimates about the human fetal circulation extrapolated from fetal sheep data and human ultrasound data. Here we describe the hemodynamics of the normal late gestation human fetal circulation by MRI and speculate about what the advent of this technology might mean in terms of the management of fetuses affected by placental insufficiency and congenital heart disease.

OP05.05: New advances in fetal cardiovascular magnetic resonance imaging

OP05.05: New advances in fetal cardiovascular magnetic resonance imaging

The value of cardiovascular magnetic resonance in the diagnosis of fetal aortic arch anomalies

Background: Here we report our preliminary experience of using fetal cardiovascular magnetic resonance (CMR) imaging, particularly with transverse views at the level of the aortic arch, in the diagnosis of aortic arch anomalies.Materials and methods: Between January 2013 and December 2015, routine prenatal obstetric ultrasound (US), echocardiography (Echo), and 1.5 T CMR were performed on approximately 600 pregnant women. CMR included balanced fast field echo and single-shot fast spin echo sequences. The images were analyzed using an anatomic segmental approach by two radiologists. The prenatal imaging findings were compared with postnatal diagnoses, from imaging or autopsy.Results: A total of 22 cases with suspected aortic arch anomalies were found by prenatal Echo. These included the following: right aortic arch, 18 cases; double aortic arch, 2 cases; atrial isomerism, 3 cases including 2 with right aortic arch; and pulmonary atresia, aortic overriding and ventricular septal defect, 1 case. Fetal CMR diagnoses were: right aortic arch with aberrant left subclavian artery, 9 cases; right aortic arch with mirror-image branching, 8 cases; double aortic arch, 4 cases; left aortic arch with right aberrant subclavian artery, 1 case. 16 cases were born alive and subsequently underwent evaluation by Echo or MRI and 6 cases had autopsies. There were 23 aortic arch anomalies. Prenatal Echo misdiagnosed 5 of these (5/23), and missed the diagnosis in 4 cases (4/23). Consequently, the accuracy of prenatal Echo was 60.8% (14/23). Both prenatal Echo and CMR misdiagnosed the same single case as a double aortic arch. The correct diagnosis was found to be right aortic arch with aberrant subclavian artery. Consequently, the accuracy of fetal CMR was 95.6% (22/23).Conclusion: Unlike prenatal Echo, fetal CMR is unaffected by fetal position. Fetal CMR with transverse views at the level of the aortic arch is a useful adjunct for the diagnosis of fetal aortic arch anomalies.

Dynamic imaging of the fetal heart using metric optimized gating

Advances in fetal cardiovascular magnetic resonance imaging have been limited by the absence of a reliable cardiac gating signal. The purpose of this work was to develop and validate metric-optimized gating (MOG) for cine imaging of the fetal heart. Cine MR and electrocardiogram data were acquired in healthy adult volunteers for validation of the MOG method. Comparison of MOG and electrocardiogram reconstructions was performed based on the image quality for each method, and the difference between MOG and electrocardiogram trigger times. Fetal images were also acquired, their quality evaluated by experienced radiologists, and the theoretical error in the MOG trigger times were calculated. Excellent agreement between electrocardiogram and MOG reconstructions was observed. The experimental errors in adult MOG trigger times for all five volunteers were ± (7, 25, 17, 8, and 13) ms. Fetal images captured normal and diseased cardiac dynamics. MOG for cine imaging of the fetal myocardium was developed and validated in adults. Using MOG, the first gated MR images of the human fetal myocardium were obtained. Small moving structures were visualized during radial contraction, thus capturing normal fetal cardiac wall motion and permitting assessment of cardiac function.

Preliminary experience with cardiovascular magnetic resonance in evaluation of fetal cardiovascular anomalies.

BackgroundThe cardiovascular system is the part of the fetal anatomy that most frequently suffers from congenital pathology. This study shows our preliminary experience with fetal cardiovascular magnetic resonance (CMR) to evaluate congenital cardiovascular abnormalities.MethodsBetween January 2006 and June 2011, Prenatal routine obstetric ultrasound (US), echocardiography and CMR data from 68 pregnant women carrying fetuses with congenital cardiovascular anomalies were compared with postnatal diagnoses (postnatal imagings, surgery and autopsy). All prenatal CMR was performed at 1.5 T. Imaging sequences included steady-state free-precession (SSFP) sequences, real-time SSFP and single-shot turbo spin echo (SSTSE) sequences. The images were analyzed with an anatomic segmental approach by two radiologists.ResultsFetal CMR yielded the same diagnosis as postnatal findings in 79% (54/68) of patients. The diagnostic sensitivity of routine obstetric US for cardiac anomalies was 46% (31/68). The diagnostic sensitivity of fetal echocardiographic examination by a fetal cardiac specialist was 82% (56/68). In 2 (3%) of 68 cases, diagnoses with both echocardiography and CMR were incorrect when compared with postnatal diagnosis. In ten (15%) cases, diagnosis at echocardiography was incorrect and that at CMR was correct. In twelve (18%) cases, diagnosis at echocardiography was correct and that at CMR was incorrect. Ten cases missed or misdiagnosed by echocardiography but correctly diagnosed by fetal CMR included asplenia syndrome (n = 2), interrupted inferior vena cava of polysplenia syndrome (n = 1), tricuspid incompetence (n = 1), double outlet right ventricle (n = 2), double aortic arch (n = 1), right pulmonary artery hypoplasia (n = 1), right-sided aortic arch of tetralogy of Fallot (n = 1) and hypoplastic left heart syndrome of a twin fetus (n = 1).ConclusionFetal CMR is a promising diagnostic tool for assessment of congenital cardiovascular abnormalities, especially in situations that limit echocardiography.