Magnetic resonance imaging of fetal persistent left superior vena cava

Prenatal MR Diagnosis of Total Anomalous Pulmonary Venous Connection and Related Brain Growth Changes

BACKGROUND

Prenatal diagnosis of total anomalous pulmonary venous connection (TAPVC) is challenging, and little is known about how it affects brain development.

PURPOSE

To evaluate the utility of fetal MRI to diagnose TAPVC and related brain growth changes.

STUDY TYPE

Retrospective case-control study.

POPULATION

Twenty-one fetuses (23.0 to 30.8 weeks, mean 26.4 weeks) with pre-natal MRI diagnosis of TAPVC. Post-natal images and surgery were available in 18 fetuses. Brain volumes in TAPVC fetuses were compared with age and sex matched 100 cases of normal controls and 38 fetuses with tetralogy of Fallot (TOF).

SEQUENCE

Single shot turbo spin echo sequence for evaluating fetal brain, and steady-state free precession (SSFP) sequence for evaluating fetal cardiovascular structures at 1.5 T.

ASSESSMENT

TAPVC type was determined by visualizing the drainage of the common pulmonary vein and dilated coronary sinus: supracardiac, intracardiac and infracardiac. The fetal pulmonary edema was evaluated, and fetal brain volumes were measured using automatic segmentation.

STATISTICAL TESTS

One-way analysis of variance and post hoc least square difference tests to evaluate differences in variables between TAPVC, TOF and control groups. A P value <0.05 was considered significant.

RESULTS

Of the 21 cases of TAPVC, 10 (47.6%) were identified as supracardiac, 8 (38.1%) as intracardiac, and 3 (14.3%) as infracardiac. Eighteen cases were confirmed by postnatal imaging and surgery; the remaining three cases had no confirmation. Six cases were associated with other cardiovascular abnormalities. Key MRI features of fetal TAPVC included a dilated coronary sinus and vertical vein. Fetal pulmonary edema was seen in six cases. Compared to controls, TAPVC fetuses had lower cerebellum and brainstem volumes and higher e-CSF, while had larger subcortical brain tissue, cerebellum, brainstem, e-CSF, and intracranial cavity volumes than those of TOF cases.

DATA CONCLUSION

Fetal MRI may be a useful modality for evaluating fetal TAPVC and altered brain development.

EVIDENCE LEVEL

3 TECHNICAL EFFICACY: Stage 3.

The Evolution and Developing Importance of Fetal Magnetic Resonance Imaging in the Diagnosis of Congenital Cardiac Anomalies: A Systematic Review

Magnetic Resonance Imaging (MRI) is a reliable method, with a complementary role to Ultrasound (US) Echocardiography, that can be used to fully comprehend and precisely diagnose congenital cardiac malformations. Besides the anatomical study of the fetal cardiovascular system, it allows us to study the function of the fetal heart, remaining, at the same time, a safe adjunct to the classic fetal echocardiography. MRI also allows for the investigation of cardiac and placental diseases by providing information about hematocrit, oxygen saturation, and blood flow in fetal vessels. It is crucial for fetal medicine specialists and pediatric cardiologists to closely follow the advances of fetal cardiac MRI in order to provide the best possible care. In this review, we summarize the advance in techniques and their practical utility to date.

Update on fetal cardiovascular magnetic resonance and utility in congenital heart disease

Background

Congenital heart disease (CHD) is the most common birth defect, affecting approximately eight per thousand newborns. Between one and two neonates per thousand have congenital cardiac lesions that require immediate post-natal treatment to stabilize the circulation, and the management of these patients in particular has been greatly enhanced by prenatal detection. The antenatal diagnosis of CHD has been made possible through the development of fetal echocardiography, which provides excellent visualization of cardiac anatomy and physiology and is widely available. However, late gestational fetal echocardiographic imaging can be hampered by suboptimal sonographic windows, particularly in the setting of oligohydramnios or adverse maternal body habitus.

Main body

Recent advances in fetal cardiovascular magnetic resonance (CMR) technology now provide a feasible alternative that could be helpful when echocardiography is inconclusive or limited. Fetal CMR has also been used to study fetal circulatory physiology in human fetuses with CHD, providing new insights into how these common anatomical abnormalities impact the distribution of blood flow and oxygen across the fetal circulation. In combination with conventional fetal and neonatal magnetic resonance imaging (MRI) techniques, fetal CMR can be used to explore the relationship between abnormal cardiovascular physiology and fetal development. Similarly, fetal CMR has been successfully applied in large animal models of the human fetal circulation, aiding in the evaluation of experimental interventions aimed at improving in utero development. With the advent of accelerated image acquisition techniques, post-processing approaches to correcting motion artifacts and commercial MRI compatible cardiotocography units for acquiring gated fetal cardiac imaging, an increasing number of CMR methods including angiography, ventricular volumetry, and the quantification of vessel blood flow and oxygen content are now possible.

Conclusion

Fetal CMR has reached an exciting stage whereby it may now be used to enhance the assessment of cardiac morphology and fetal hemodynamics in the setting of prenatal CHD.

Fetal Cardiac MRI: A Review of Technical Advancements

Magnetic resonance imaging (MRI) is an appealing technology for fetal cardiovascular assessment. It can be used to visualize fetal cardiac and vascular anatomy, to quantify fetal blood flow, and to quantify fetal blood oxygen saturation and hematocrit. However, there are practical limitations to the use of conventional MRI for fetal cardiovascular assessment, including the small size and high heart rate of the human fetus, the lack of conventional cardiac gating methods to synchronize data acquisition, and the potential corruption of MRI data due to maternal respiration and unpredictable fetal movements. In this review, we discuss recent technical advances in accelerated imaging, image reconstruction, cardiac gating, and motion compensation that have enabled dynamic MRI of the fetal heart.

Cardiac Findings in Fetal and Pediatric Autopsies: A 15-Year Retrospective Review

INTRODUCTION

Congenital heart defects (CHDs) carry significant morbidity and mortality in pediatric patients. This study determined the spectrum of CHDs based on fetal and pediatric autopsies.

METHODS

Autopsy reports over a 15-year period were reviewed. Postmortem findings were correlated with echocardiography records.

RESULTS

From 608 autopsies, 119 cases with CHDs were identified (11% of fetal, 53% of neonatal, 18% of infant, and 4.5% of childhood autopsies). Persistent left superior vena cava was the most common individual defect. 41% of cases had extracardiac malformations. 18.5% of cases had chromosomal abnormalities. Prenatal echocardiography was available in 52 cases, showing 85% correlation with autopsy findings. Defects missed by echocardiography were generally of mild severity.

CONCLUSION

Postmortem examination is important to delineate the anatomy of CHDs, and recognize extracardiac malformations for identification of possible genetic syndromes. This information can be used for parental counseling and for assessment of accuracy of pre-mortem imaging studies.

MR imaging of subaortic and retroesophageal anomalous courses of the left brachiocephalic vein in the fetus

The purpose of this study was to report fetal cases of subaortic and retroesophageal anomalous courses of the left brachiocephalic vein (LBCV) evaluated by fetal cardiac magnetic resonance imaging (MRI). A retrospective review of 7282 fetal cardiac MRI from June 2006 to March 2017, nine cases of anomalous courses of the LBCV were correctly diagnosed by fetal cardiac MRI, one case of abnormal subaortic left brachiocephalic vein (ASLBV) missed by fetal MRI was identified postnatally during further imaging of the TOF. The diagnosis was confirmed postnatally by cardiac CT/MRI. An ASLBV was found in 8 cases, a retroesophageal LBCV was found in 2 additional cases with right aortic arch and aberrant left subclavian artery. 3 of 8 ASLBV cases were with a right aortic arch, 4 ASLBV cases had additional cardiovascular anomalies with one case isolated. 7 of 8 ASLBV and 2 retroesophageal LBCV were correctly diagnosed by fetal cardiac MRI; however fetal cardiac MRI missed 2 cases of associated pulmonary atresia (PA). Prenatal echocardiography (echo) correctly diagnosed five ASLBV and one retroesophageal LBCV as well as associated intracardiac anomalies. Fetal cardiac MRI can be a useful adjunct in the identification of subaortic and retroesophageal anomalous courses of the LBCV prenatally.

Spatially Resolved MR-Compatible Doppler Ultrasound: Proof of Concept for Triggering of Diagnostic Quality Cardiovascular MRI for Function and Flow Quantification at 3T

OBJECTIVE

We demonstrate the use of a magnetic-resonance (MR)-compatible ultrasound (US) imaging probe using spatially resolved Doppler for diagnostic quality cardiovascular MR imaging (MRI) as an initial step toward hybrid US/MR fetal imaging.

METHODS

A newly developed technology for a dedicated MR-compatible phased array ultrasound-imaging probe acquired pulsed color Doppler carotid images, which were converted in near-real time to a trigger signal for cardiac cine and flow quantification MRI. Ultrasound and MR data acquired simultaneously were interference free. Conventional electrocardiogram (ECG) and the proposed spatially resolved Doppler triggering were compared in 10 healthy volunteers. A synthetic "false-triggered" image was retrospectively processed using metric optimized gating (MOG). Images were scored by expert readers, and sharpness, cardiac function and aortic flow were quantified. Four-dimensional (4-D) flow (two volunteers) showed feasibility of Doppler triggering over a long acquisition time.

RESULTS

Imaging modalities were compatible. US probe positioning was stable and comfortable. Image quality scores and quantified sharpness were statistically equal for Doppler- and ECG-triggering (p ). ECG-, Doppler-triggered, and MOG ejection fractions were equivalent (p ), with false-triggered values significantly lower (p < 0.0005). Aortic flow showed no difference between ECG- and Doppler-triggered and MOG (p > 0.05). 4-D flow quantification gave consistent results between ECG and Doppler triggering.

CONCLUSION

We report interference-free pulsed color Doppler ultrasound during MR data acquisition. Cardiovascular MRI of diagnostic quality was successfully obtained with pulsed color Doppler triggering.

SIGNIFICANCE

The hardware platform could further enable advanced free-breathing cardiac imaging. Doppler ultrasound triggering is applicable where ECG is compromised due to pathology or interference at higher magnetic fields, and where direct ECG is impossible, i.e., fetal imaging.