Fetal Magnetic Resonance Imaging as a Complement to Fetal Ultrasonography

Super-resolution Reconstruction MRI Application in Fetal Neck Masses and Congenital High Airway Obstruction Syndrome

Objective

Reliable airway patency diagnosis in fetal tracheolaryngeal obstruction is crucial to select and plan ex utero intrapartum treatment (EXIT) surgery. We compared the clinical utility of magnetic resonance imaging (MRI) super-resolution reconstruction (SRR) of the trachea, which can mitigate unpredictable fetal motion effects, with standard 2-dimensional (2D) MRI for airway patency diagnosis and assessment of fetal neck mass anatomy.

Study Design

A single-center case series of 7 consecutive singleton pregnancies with complex upper airway obstruction (2013-2019).

Setting

A tertiary fetal medicine unit performing EXIT surgery.

Methods

MRI SRR of the trachea was performed involving rigid motion correction of acquired 2D MRI slices combined with robust outlier detection to reconstruct an isotropic high-resolution volume. SRR, 2D MRI, and paired data were blindly assessed by 3 radiologists in 3 experimental rounds.

Results

Airway patency was correctly diagnosed in 4 of 7 cases (57%) with 2D MRI as compared with 2 of 7 cases (29%) with SRR alone or paired 2D MRI and SRR. Radiologists were more confident (P = .026) in airway patency diagnosis when using 2D MRI than SRR. Anatomic clarity was higher with SRR (P = .027) or paired data (P = .041) in comparison with 2D MRI alone. Radiologists detected further anatomic details by using paired images versus 2D MRI alone (P < .001). Cognitive load, as assessed by the NASA Task Load Index, was increased with paired or SRR data in comparison with 2D MRI.

Conclusion

The addition of SRR to 2D MRI does not increase fetal airway patency diagnostic accuracy but does provide improved anatomic information, which may benefit surgical planning of EXIT procedures.

Congenital central nervous system anomalies: Ten-year single center experience on a challenging issue in perinatal medicine

Objective

Our goal was to highlight the prenatal diagnosis and management of central nervous system (CNS) anomalies through sharing our clinic’s experience.

Material and Methods

We evaluated prenatal findings and postnatal outcomes of neonates who had a CNS anomaly diagnosis in our clinic over a ten-year period. A total of 183 cases with various CNS anomalies were included in the study. Birth or termination preferences of mothers were recorded in all cases, and postnatal diagnosis concordance and prognosis after surgical procedures were evaluated in mothers who chose to continue the pregnancy.

Results

The mean maternal age was 28.2±5.5 years, mean gravida was 2.2±1.3, and the mean gestational age at diagnosis was 30.5±5.5 weeks. Seventy-five out of 183 (41%) patients chose to terminate their pregnancy. Twenty babies (26.6%) in the termination of pregnancy group had additional anomalies. One hundred eight patients gave birth at our institution. The mean birth weight was 3060±647.5 g, the mean gestational week at delivery was 37.9±1.7 weeks, and mean APGAR score (5th minute) was 8.8±2.3. Four neonates died on the postpartum first day. The postnatal diagnosis of 60 of the 108 (55.5%) patients who gave birth was concordant with the prenatal diagnosis, and 32 of the 108 (29.6%) babies underwent surgical interventions.

Conclusion

CNS anomalies have a broad spectrum and variable prognoses. This study highlights the limitations of prenatal diagnoses, and the need for parents to have this information in order to determine the course of their pregnancy and prepare themselves for the postnatal challenging treatment/rehabilitation process.

A survey of pediatric diagnostic radiologists in North America: current practices in fetal magnetic resonance imaging

BACKGROUND

Fetal magnetic resonance imaging (MRI) is an imaging examination in evolution. Rapid developments over recent decades have led to better image quality, an increased number of examinations and greater impact on patient care.

OBJECTIVE

To gather data regarding current practices among established programs in North America and provide information to radiologists interested in implementing or growing a fetal MRI service.

MATERIALS AND METHODS

An electronic survey containing 15 questions relevant to the use of fetal MRI was submitted to pediatric radiologists and neuroradiologists. Items regarded scheduling and reporting logistics, magnet strength, patient positioning and patient preparation. Answers and comments were collected, and descriptive statistics were summarized.

RESULTS

One hundred and six survey responses were evaluated. Of the survey responses, 62/106 (58.5%) allow fetal MR scheduling any time during the day and 72/105 (68.6%) exclusively use 1.5-T strength platforms for fetal MRI, while only 7/105 (6.7%) use exclusively 3 T. Patient positioning is variable: supine, 40/106 (37.8%); left lateral decubitus, 22/106 (20.8%), and, patient's choice, 43/106 (40.6%). Of the centers responding, 51/104 (49.0%) require no particular fasting instructions, while 20/104 (19.2%) request the patient avoid caffeine before the scanning.

CONCLUSION

Logistical trends in performing fetal MRI may supplement the American College of Radiology's published technical standards and offer guidance to radiologists new to the field.

The role of intrauterine magnetic resonance in the management of myelomenigocele

OBJECTIVE

To assess the role of magnetic resonance imaging (MRI) in the management of myelomenigocele.

BACKGROUND

Spinal dysraphism or neural tube defects (NTD) encompass a heterogeneous group of congenital spinal anomalies that result from the defective closure of the neural tube early in gestation. Myelomeningocele is the most common type of NTD that is compatible with life, with high survival rates but lifelong physical impairments.

CONCLUSION

MRI is an important adjunct to ultrasound in assessing NTD, as it pertains to pre-surgical planning and perinatal management. However, it should not be considered a replacement for ultrasonography, which continues to be the gold standard for fetal anatomic evaluation.

Antenatal management of fetal neurosurgical diseases

The advance in the imaging tools during the pregnancy (ultrasound and magnetic resonance) allowed the early diagnose of many fetal diseases, including the neurological conditions. This progress brought the neurosurgeons the possibility to propose treatments even before birth. Myelomeningocele is the most recognized disease that can be treated during pregnancy with a high rate of success. Additionally, this field can be extended to other conditions such as hydrocephalus and encephaloceles. However, each one of these diseases has nuances in the diagnostic evaluation that should fit the requirements to perform the fetal procedure and overbalance the benefits to the patients. In this article, the authors aim to review the neurosurgical aspects of the antenatal management of neurosurgical conditions based on the experience of a pediatric neurosurgery center.

Magnetic resonance imaging of fetal persistent left superior vena cava

This study aimed to evaluate the diagnostic accuracy of fetal magnetic resonance imaging (MRI) for persistent left superior vena cava (LSVC). Prenatal echocardiography (echo) and/or ultrasound (US) and MRI data for 49 fetuses with persistent LSVC, confirmed via postnatal diagnoses between January 2010 and October 2015, were retrospectively reviewed. All prenatal MRI was performed at 1.5 T. Imaging sequences included steady-state free-precession (SSFP), single-shot turbo spin echo (SSTSE), and other sequences. All 49 cases of fetal persistent LSVC were correctly diagnosed via MRI, but only 34 cases (69.4%) were correctly diagnosed via an initial US and/or echo before MRI. Of the 15 cases that were not correctly diagnosed via US and/or echo, 8 had congenital heart diseases (CHDs) and 7 were without CHDs; however, they were associated with extracardiac abnormalities or maternal obesity. Thirty-five cases were associated with other cardiovascular abnormalities; 8, with extracardiac abnormalities; and 6, with no associated condition. In 44 (89.8%) cases, the innominate veins were absent; the remaining cases had innominate veins. In 14.3% of patients (7 cases), the persistent LSVC drained directly into the atrium. Fetal MRI can detect persistent LSVC and play an adjunctive role along with US in the evaluation of persistent LSVC.

Utility of fetal magnetic resonance imaging in assessing the fetus with cardiac malposition

OBJECTIVE

Abnormal cardiac axis and/or malposition prompts evaluation of congenital heart disease; however, etiology may be difficult to clarify using obstetrical ultrasound or fetal echocardiography (echo) alone. We aimed to use fetal magnetic resonance imaging (MRI) as a complementary tool to identify causes of cardiac malposition.

METHODS

Review of fetuses diagnosed with cardiac malposition by fetal ultrasound and echo was performed. Etiology was classified as either because of heterotaxy syndrome or extracardiac masses. Reclassification was then performed with fetal MRI findings. Results were compared with postnatal diagnoses.

RESULTS

Forty-two fetuses were identified as having abnormal cardiac axis and/or malposition. Twenty three of 42 cases (55%) had extracardiac anomalies, while 19 (45%) were because of heterotaxy. Twelve of 42 (29%) cases were reassigned by fetal MRI (five in heterotaxy group and seven in the lung anomaly group). Four cases (33%) had both cardiac disease and extracardiac masses, not previously recognized. Fetal MRI clarified heterotaxy subtype or removed heterotaxy diagnosis in five (26%) patients. Fetal MRI findings were confirmed in 8 of these 12 cases postnatally.

CONCLUSION

Fetal MRI is a useful complementary tool to define etiology of cardiac malposition in complex cases for informative prenatal counseling and planning. © 2016 John Wiley & Sons, Ltd.

Overcoming foetal motion using interactive real-time magnetic resonance imaging

OBJECTIVE

Foetal MRI has become an established image modality in the prenatal diagnosis of CNS anomalies, but image quality can be severely affected by foetal movements. The objective was to overcome these inherent motion problems by applying interactive real-time MRI and to evaluate the diagnostic usefulness of the applied real-time MRI sequence in relation to standard protocols.

METHODS

Ten healthy foetuses (gestation week 21·3 ± 0·5) were scanned using a system, which allowed visual feedback and interactive slice positioning in real time. The data were compared to a control group of 14 healthy foetuses (gestation week 21·0 ± 0·8) who had previously been scanned using standard MRI. Comparisons were carried out by two radiologists with regard to cerebral anthropometric sizes, presence of important brain structures, degree of movement, clinical image value, image quality and ability to obtain correct slice planes.

RESULTS

Two out of eight anthropometric sizes were statistically different between the two groups. Representation of cerebral structures was found in 70-100% in the real-time group. No statistically differences were found in clinical image value and image quality. The mean ability to obtain optimal slice planes was higher in the real-time group, but it was not significant.

CONCLUSION

Imaging of the foetal brain using the proposed interactive real-time MRI system is a promising alternative to traditional foetal MRI for anthropometrics or as a supplement for the representation of foetal brain structures in cases in which foetal motion causes challenges in relation to obtaining optimal slice planes using conventional MRI techniques.

Morphological features and length measurements of fetal lateral ventricles at 16-25 weeks of gestation by magnetic resonance imaging

Normal growth of the lateral ventricles (LVs) was characterized three-dimensionally using magnetic resonance imaging (MRI) data from 16 human fetuses at 16-25 weeks of gestation. The LV was differentiated into four primary regions, the anterior horn, central parts, posterior horn, and inferior horn, at 16 weeks of gestation. The LV changed shape mainly by elongation and narrowing, which corresponded to the external and internal growth of the surrounding cerebrum. Six length parameters measured in the LV correlated with biparietal diameter by simple regression analysis (R(2) range, 0.56-0.93), which may be valuable for establishing a standardized prenatal protocol to assess fetal well-being and development across intrauterine periods. No correlation was found between biparietal diameter and LV volume (R(2) = 0.13).

The clinical relevance of fetal MRI in the diagnosis of Type IV cystic sacrococcygeal teratoma--a review

The introduction of fetal magnetic resonance imaging (MRI) has improved the prenatal evaluation of uterine, placental and fetal anatomy. However, its utilization has mostly been restricted to fetal central nervous system anomalies. We review how adjunct fetal MRI was performed and diagnosis of cystic type IV sacrococcygeal teratoma was made. We also discuss the clinical relevance of fetal MRI in differentiating this lesion from other selected abdominal/pelvic cystic malformations and lesions.

The fundamentals of fetal MR imaging: Part 1

Congenital malformations detected in any fetal system using ultrasound may be further evaluated with magnetic resonance imaging (MRI) to improve counseling, to plan deliveries appropriately, and sometimes to enable fetal interventions. In this first half of a 2-part review, the history and safety factors regarding fetal MRI, as well as the practical aspects of image acquisition, are discussed. In addition, as central nervous system anomalies are most commonly and best evaluated using fetal MRI, challenging central nervous system anomalies, such as fetal ventriculomegaly, posterior anomalies, and neural tube defects, detected using prenatal ultrasound are also reviewed with a focus on the fundamental implications of these diagnoses.

Fetal magnetic resonance imaging at 3.0 T

Magnetic resonance imaging (MRI) has been used to image the in utero fetus for the past 3 decades. Although not as commonplace as other patient-oriented MRI, it is a growing field and demonstrating a role in the clinical care of the fetus. Indeed, the body of literature involving fetal MRI exceeds 3000 published articles. Indeed, there is interest in accessing even the healthy fetus with MRI to further understand the development of humans during the fetal stage. On the horizon is fetal imaging using 3.0-T clinical systems. Although a clear path is not necessarily determined, experiments, theoretical calculations, advances in pulse sequence design, new hardware, and experience from imaging at 1.5 T help define the path.

Serial fetal MRI for the diagnosis of Aicardi syndrome

Aicardi syndrome (AS) is defined by the triad of corpus callosum agenesis, chorioretinal "lacunae" and infantile spasms. Additional neuroimaging findings including migrational abnormalities are common. We report on serial neuroimaging findings of a female fetus with ventriculomegaly, corpus callosum agenesis and focal migrational abnormalities, suggestive of AS. Postnatal neuroimaging follow-up as well as ophthalmological evaluation and occurrence of infantile spasms confirmed the prenatally suspected diagnosis of AS. This case points out the key role of serial fetal magnetic resonance imaging (MRI) in detecting the full spectrum of pathologies associated with fetal ventriculomegaly. The associated neuroimaging findings may go undetected on prenatal ultrasound, but are important in terms of diagnosis and counseling of the parents. Additionally, this case emphasizes the importance of serial fetal MRI studies to more accurately delineate the progression of findings during brain development.

Morphology and morphometry of fetal liver at 16-26 weeks of gestation by magnetic resonance imaging: Comparison with embryonic liver at Carnegie stage 23

AIM

Normal liver growth was described morphologically and morphometrically using magnetic resonance imaging (MRI) data of human fetuses, and compared with embryonic liver to establish a normal reference chart for clinical use.

METHODS

MRI images from 21 fetuses at 16-26 weeks of gestation and eight embryos at Carnegie stage (CS)23 were investigated in the present study. Using the image data, the morphology of the liver as well as its adjacent organs was extracted and reconstructed three-dimensionally. Morphometry of fetal liver growth was performed using simple regression analysis.

RESULTS

The fundamental morphology was similar in all cases of the fetal livers examined. The liver tended to grow along the transversal axis. The four lobes were clearly recognizable in the fetal liver but not in the embryonic liver. The length of the liver along the three axes, liver volume and four lobes correlated with the bodyweight (BW). The morphogenesis of the fetal liver on the dorsal and caudal sides was affected by the growth of the abdominal organs, such as the stomach, duodenum and spleen, and retroperitoneal organs, such as the right adrenal gland and right kidney. The main blood vessels such as inferior vena cava, portal vein and umbilical vein made a groove on the surface of the liver. Morphology of the fetal liver was different from that of the embryonic liver at CS23.

CONCLUSION

The present data will be useful for evaluating the development of the fetal liver and the adjacent organs that affect its morphology.

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

BACKGROUND

The 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.

METHODS

Between 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.

RESULTS

Fetal 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).

CONCLUSION

Fetal CMR is a promising diagnostic tool for assessment of congenital cardiovascular abnormalities, especially in situations that limit echocardiography.

MRI: is there a role in obstetrics?

Magnetic resonance imaging has a complementary role in obstetrical imaging to ultrasound (US). Although US has advantages as an initial imaging technique, there are significant numbers of patients who cannot be adequately evaluated for a variety of reasons including calvarial calcification, oligoanhydramnios, or simply obesity. MR can provide additional information that cannot be obtained by US and is invaluable in central nervous system anomaly evaluation, airway management, and planning for postnatal intervention. Newer techniques established in the postnatal population such as spectroscopy, diffusion-weighted imaging, and functional imaging have future applications in the fetus.

Ultrafast MRI of the fetus: an increasingly important tool in prenatal diagnosis of congenital anomalies

OBJECTIVE

To demonstrate the additional utility of ultrafast magnetic resonance imaging (MRI) of the fetus in the evaluation of sonographically detected or equivocal fetal congenital anomalies.

MATERIAL AND METHODS

Twenty five pregnant women with ultrasound detected fetal congenital anomalies underwent ultrafast fetal MRI.

RESULTS

MRI findings altered the diagnosis of two cases of giant arachnoid cyst and sizable interhemispheric cyst associated with agenesis of the corpus callosum. MRI added additional findings of occult spinal diastematomyelia in two out of four cases of Chiari/meningocele malformation. MRI revealed impaired sulcation and unilateral cleft palate in suspected case of Walker-Warburg syndrome. In the remaining 18 cases MRI confirmed the diagnosis of Meckel-Gruber syndrome in three cases, hydronephrosis in six cases, cerebral ventriculomegaly in five cases, isolated omphalocele in three cases and findings suggestive of aneuploidy in the last case.

CONCLUSION

Ultrasound is the screening method of choice for evaluation of the fetus. Ultrafast MRI is a complementary adjunctive modality with excellent tissue contrast that can image the fetus in multiple planes and add information in sonographically detected or equivocal congenital anomalies that may be significant to establish definitive accurate diagnosis and hence adequate management and counseling.

Prenatal presentation and postnatal management of congenital thoracic malformations

The antenatal finding of a congenital thoracic malformation (CTM) leads to anxiety in the parents and uncertainty as to the optimal management. The antenatal spectrum of CTM includes congenital cystic adenomatoid malformation, sequestration, congenital lobar emphysema, enteric and bronchogenic cysts, and bronchial atresia. Most lesions require no antenatal intervention, and shrink substantially in the third trimester, but if fetal hydrops develops, then antenatal intervention is required, occasionally medical but more usually surgical, because mortality is high. If the baby is symptomatic in the newborn period, then some form of surgical intervention is clearly required. The asymptomatic baby presents a therapeutic dilemma. Advocates of early surgery point to the complications of CTM, which include infection, pneumothorax, bleeding and malignant transformation. Those who are proponents of conservative management retort that some CTM disappear postnatally, and that the complication rate is unknown; many children appear never to need surgery. Furthermore, there is clearcut evidence that excision of a CTM does not totally eliminate the risk of a subsequent malignancy. It is clear that, both antenatally and postnatally, counselling of the family on a case by case basis is needed. The limitations of present evidence should be stressed. Different families will make different decisions about postnatal surgery in an asymptomatic baby. If surgery is performed, morbidity is low, particularly with a video-assisted thoracoscopic (VATS) procedure.

Babies with myelomeningocele in Poland: parents' attitudes on fetal surgery versus termination of pregnancy

BACKGROUND

Recent surgical advances have resulted in fetal surgery becoming an option for children with myelomeningocele (MMC). However, there is little information about the parents' attitudes towards such therapy.

METHODS

Following a lecture on the current status and problems of fetal surgery for MMC, a 12-item questionnaire was administered to 58 parents of children with MMC. Questionnaire topics included knowledge of the disease and treatment options, as well as attitudes and concerns towards fetal surgery or termination of pregnancy.

RESULTS

Following the lecture, 14 (out of 58) parents felt that knowledge of the disease would allow for abortion to be an option, while 18 were uncertain. Once informed of potential risks and benefits of fetal surgery, 34 parents had a positive or rather positive attitude towards this procedure.

CONCLUSIONS

On the basis of these results, it was concluded that this population is potentially interested in the use of fetal surgery.