MRI of fetal GI tract abnormalities

Evaluating T1-weighted MRI techniques for fetal gastrointestinal diagnostics: A comparative study

PURPOSE

In clinical practice, fetal gastrointestinal magnetic resonance imaging (MRI) encounters significant challenges. T1-weighted images are particularly susceptible to the effects of fetal and maternal movements compared to other weighted images, complicating the acquisition of satisfactory results. This study aimed to compare three fast 3D-T1 weighted gradient echo (GRE) sequences-free-breathing stack-of-stars VIBE (STAR-VIBE), breath-hold VIBE (BH-VIBE), and free-breathing multi-average VIBE (MA-VIBE)-for fetal gastrointestinal MRI in fetuses with both normal and abnormal gastrointestinal tracts between 21 and 36 weeks of gestation.

METHODS

This study enrolled 67 pregnant women who underwent fetal abdominal MRI at our hospital between October 2022 and October 2023, during their gestational period of 21-36 weeks. Among these participants, 22 were suspected of having fetal gastrointestinal anomalies based on ultrasound findings, while the remaining 45 were considered to have normal fetal gastrointestinal development. All subjects underwent True fast imaging with steady-state precession sequence scanning along with three T1-weighted imaging techniques on a Siemens 1.5-T Aera scanner: STAR-VIBE, BH-VIBE, and MA-VIBE. Two radiologists evaluated image quality, intestinal clarity, and lesion conspicuity using a five-point scale where higher scores indicated superior performance for each technique; they were blinded to the acquisition schemes used. Interobserver variability assessments were also conducted.

RESULTS

The free-breathing MA-VIBE sequence demonstrated significantly better performance than both STAR-VIBE and BH-VIBE in terms of fetal gastrointestinal MRI quality (3.81 ± 0.40 vs. 3.35 ± 0.70 vs. 2.90 ± 0.64; p < .05). The STAR-VIBE and BH-VIBE sequences exhibited moderate consistency (kappa = 0.586 and kappa = 0.527 respectively; P < .05), whereas the MA-VIBE sequence showed higher consistency (kappa = 0.712; P < .05).

CONCLUSION

The free-breathing MA-VIBE sequence provided superior visualization for assessing fetal intestinal conditions compared to other methods employed in this study. On a 1.5 T MRI device, T1-weighted images based on the free-breathing MA-VIBE sequence can effectively overcome motion artifacts and compensate for the reduced signal-to-noise ratio caused by the application of acceleration techniques, thus significantly improving the quality of T1-weighted images.

MR Imaging of the Fetal Gastrointestinal Anomalies

Fetal MR imaging has been shown to be a useful tool for the diagnosis of fetal gastro-intestinal pathologies. To recognize the various pathologies, it is, however, essential to know the normal MR imaging appearance of the fetal bowel at various gestational ages. By providing additional information to ultrasound in case of a fetal gastrointestinal anomaly, MR imaging helps to improve planning for the delivery, postnatal management, and improves parental counseling.

Ultrasound and magnetic resonance imaging features of fetal urogenital anomalies: A pictorial essay

This pictorial essay focuses on ultrasound (US) and magnetic resonance imaging (MRI) features of fetal urogenital anomalies. Fetal urogenital malformations account for 30%-50% of all anomalies discovered during pregnancy or at birth. They are usually detected by fetal ultrasound exams. However, when ultrasound data on their characteristics is insufficient, MRI is the best option for detecting other associated anomalies. The prognosis highly depends on their type and whether they are associated with other fetal abnormalities.

Magnetic resonance imaging of fetal abdominal pathology: a complementary tool to prenatal ultrasound

Fetal magnetic resonance imaging (MRI) is increasingly being used worldwide as a complementary tool to prenatal ultrasound (US) for multiple fetal pathologies. The aim of this article is to describe and illustrate how MRI can help US to evaluate fetal abdominal anomalies, based on cases performed in a tertiary public university hospital. Prenatal US, fetal MRI and postnatal imaging of these cases will be shown side-by-side to describe and illustrate the added value of fetal MRI in the different organs/systems and its impact on clinical management.

A Spectrum of Ultrasound and MR Imaging of Fetal Gastrointestinal Abnormalities: Part 1 Esophagus to Colon

Ultrasound (US) and magnetic resonance imaging (MRI) are two modalities for diagnosing fetal gastrointestinal (GI) anomalies. Ultrasound (US) is the modality of choice. MRI can be used as a complementary method. Despite its expanding utilization in central nervous system (CNS) fetal malformation, MRI has not yet been established for evaluation of fetal GI abnormalities. Therefore, more attention should be paid to the clinical implications of MRI investigations following screening by US.

Ultrasound and Fetal MRI Complementary Contributions to Appropriate Counseling in Small Bowel Obstruction

OBJECTIVE

Bowel obstructions beyond the duodenum represent a heterogeneous group of congenital anomalies with a highly variable prognosis, the main issue being postnatal short bowel syndrome (SBS). The objective of our study was to evaluate the contributions of fetal MRI in cases of bowel obstruction.

MATERIALS AND METHODS

A retrospective analysis of all newborns, for whom both ante-natal ultrasound and fetal MRI were available, referred to our center for suspected bowel obstruction was performed. Examinations were reviewed blinded to the postnatal outcome. Key outcome measures included exact diagnosis and the existence of postoperative SBS. We evaluated the contribution of MRI in determining precise location and etiology of the bowel obstruction, dilatation of the proximal bowel loops, and assessment of the quality of the remaining distal bowel loops.

RESULTS

Twenty-five newborns were included. There were 19 single obstructions and 6 complex forms (4 apple peel syndromes and 2 multiple atresias). MRI correctly identified the affected segment of the small bowel in 59.1% of the cases. MRI identified the mechanism of obstruction in 72% of cases. MRI reliably predicted an abnormal appearance of the bowel distal to the obstruction in 100% of the severe cases (3/3) and in 66.7% of complex forms (4/6).

CONCLUSION

Our study suggests that fetal MRI, when done in addition to prenatal ultrasound, is contributory in the management of fetuses with suspected bowel obstruction. MRI may be particularly useful in determining the location and origin of the bowel obstruction and in assessing the quality of the bowel distal to the obstruction, which might assist in the prediction of SBS and more detailed prenatal counseling.

Prenatal diagnosis of intestinal nonrotation using magnetic resonance imaging: Is it possible?

BACKGROUND

Malrotation of the bowel refers to any variation in the rotation and fixation of the gastrointestinal tract during the first trimester and is most commonly detected postnatally. Nonrotation of the bowel and incomplete rotation of the bowel are subtypes of malrotation.

OBJECTIVE

To determine if the nonrotation subtype of malrotation of the bowel can be detected on prenatal magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Cases from 2012 to 2018 with nonrotation of the bowel without obstruction confirmed by imaging, surgery and/or autopsy were compared to prenatal imaging. Prenatal imaging was retrospectively reviewed to determine if prenatal diagnosis of malrotation could be made. Exclusion criteria included diaphragmatic hernia, omphalocele and gastroschisis.

RESULTS

Ten cases of nonrotation diagnosed postnatally by upper gastrointestinal series (upper GI)/small bowel follow-through (SBFT) or autopsy had prenatal MRI. Prenatal MR studies were performed for assessment of heterotaxy syndrome with congenital heart disease (6/10), congenital heart disease with additional anomalies (suspected VACTERL [vertebral, anorectal, cardiac, tracheoesophageal, renal, limb] and suspected lung agenesis, ventriculomegaly) (3/10) and skeletal dysplasia (1/10). Eight upper GI/SBFT cases demonstrated nonrotation of the bowel without obstruction with the small bowel completely on one side of the abdomen contralateral to the stomach and the colon ipsilateral to the stomach; four cases were confirmed by surgery. The small bowel in one upper GI/SBFT case was unilateral contralateral to the stomach with a meandering colon. One case had nonrotation diagnosed at autopsy. There were no cases of postnatal midgut volvulus. Retrospective review of the 10 cases had prenatal MRI performed between 23 and 37 weeks of gestation. The coronal plane was the most optimal plane to assess the position of the stomach, small bowel and colon in relationship to each other. The small bowel was best assessed on T2-weighted images while the colon was best assessed on T1-weighted images. A nonrotated position of the small bowel was present in all 10 fetal MRI cases mirroring postnatal findings, with the small bowel contralateral to the stomach in 9/10 cases and ipsilateral to the stomach (in the right abdomen) in 1/10 cases. The colon was visualized by prenatal MRI in 9/10 cases, with 1 case limited due to a lack of T1-weighted imaging. A nonrotated position of the colon contralateral to the small bowel was present in 7/9 cases. In 2/9 cases, the colon was wandering, positioned on both sides of the midline. Colonic position in all nine cases matched postnatal findings. No cases presented with prenatal bowel obstruction.

CONCLUSION

Detection of nonrotation of the bowel is possible on prenatal MRI.

[A case of neonatal gastrointestinal duplication]

Les duplications digestives sont définies comme des malformations tubulaires ou kystiques, siégeant sur un segment du tube digestif, de la cavité buccale à l´anus. Elles représentent une entité rare. Le diagnostic anténatal est possible quand il s´agit d´une forme kystique volumineuse. Nous rapportons le cas d´une patiente de 33 ans, primipare sans antécédents médicaux ou chirurgicaux dont la grossesse était mal suivie. Une seule échographie faite à 8 semaines d´aménorrhée (SA). Au cours du troisième trimestre l'examen échographique a montré une image kystique anéchogène de 3cm, à paroi propre, hautement situé dans le pelvis, non vascularisée. Cette image paraît de localisation antérieure, indépendante des reins et de la vessie. Afin de mieux explorer cette image et ses caractéristiques, une imagerie par résonance magnétique (IRM) fœtale a été réalisée montrant une image kystique à paroi propre, bien limitée, venant au contact des anses grêliques sur le versant mésentérique. Le diagnostic d´une duplication digestive a été fortement consolidé. L´accouchement s´est déroulé sans incidents par voie haute à 39 SA pour infertilité primaire de 7 ans. L´échographie post-natale a renforcé cette hypothèse, en montrant une formation kystique au niveau de l´hypochondre gauche, de 45 mm x 19 mm, multi cloisonnée, pouvant cadrer avec une duplication digestive. Le nouveau-né a été adressé à la consultation externe de chirurgie pédiatrique pour meilleure prise en charge et programmation d´un acte chirurgical dans les premiers 6 mois. La découverte d´une image fœtale kystique anéchogène pose le problème du diagnostic étiologique d´une part et du suivi et prise en charge post-natale d´autre part.

Comparison of the colon with T1 breath-hold vs T1 free-breathing-A retrospective fetal MRI study

OBJECTIVES

Fetal magnetic resonance imaging (MRI) plays an increasingly important role in the prenatal diagnosis of gastrointestinal abnormalities. During gestation, the bowel develops T1-weighted hyperintensity due to meconium formation. Currently used T1-weighted sequences are performed in maternal breath-hold (BH) technique, which may take up to 20 s. The free-breathing (FB) T1-weighted 3D radial VIBE (volumetric interpolated breath-hold examination) sequence requires no breath-hold, improving patient comfort. This study aimed to address how well the FB acquisition technique can visualize large bowel structures compared to the routinely performed breath-hold sequence.

METHODS

Forty-seven fetal MRI studies between 21 and 36 weeks of gestation without abdominal pathologies on prenatal MRI and ultrasound were included. All fetal scans were performed using a Philips Ingenia 1.5 T MRI. Coronal T1-weighted BH and FB sequences without fat suppression were compared. The following acquisition parameters were used (T1, FB): resolution 1.137 mm, 1.004 mm; matrix size 288 × 288, 448 × 448; FOV 328 mm, 450 mm; TR 81-132 ms, 3.47 ms; TE 4.6 ms, 1.47 ms. Due to the necessity of the breath-hold the duration of the sequence could not exceed 20 s (mean duration of the T1-weighted BH sequence 15.17 s, and mean duration of the FB sequence 26.42 s). In all examined fetuses the following structures were evaluated with respect to their visibility (0-not visible, 1-partially visible, 2-clearly visible): rectum, sigmoid, descending, transverse and ascending colon, cecum. Furthermore, motion artifacts were assessed (0-none, 1-intermediate, 2-severe motion artifacts), and the signal intensity (SI) ratio between maternal fat and fetal rectum SI was calculated.

RESULTS

No significant differences in the visibility of sigmoid and colon between BH and FB were detected, only the cecum could be seen slightly better (in 29.8 % of cases) using BH technique. Motion artifacts were similar between BH and FB. There was a non-significant SI difference (p = 0.68) in the rectum, with a higher SI in the BH sequence.

CONCLUSIONS

The FB acquisition technique compared to T1 using BH is equal regarding visibility of bowel structures and artifacts. Due to non-inferiority to the BH technique, the FB sequence is a good alternative in cases where BH cannot be performed. As the FB sequence further allows for thinner slices with a good signal, even small bowel loops may be visualized.

Magnetic resonance imaging of the fetal gastrointestinal system

In this paper the authors review the normal imaging appearance of the fetal gastrointestinal tract and patterns of fetal gastrointestinal tract obstruction. The authors include a detailed summary from esophagus to the rectum, including the expected pattern of meconium and small-bowel contents at different gestational ages. Common fetal gastrointestinal tract obstructions are reviewed with accompanying case examples, emphasizing the role of the meconium and bowel-caliber patterns in establishing differential diagnoses. This review also includes imaging pitfalls, complications of gastrointestinal tract obstruction, and implications for patient care.

How to read a fetal magnetic resonance image 101

Accurate antenatal diagnosis is essential for planning appropriate pregnancy management and improving perinatal outcomes. The provision of information vital for prognostication is a crucial component of prenatal imaging, and this can be enhanced by the use of fetal MRI. Image acquisition, interpretation and reporting of a fetal MR study can be daunting to the individual who has encountered few or none of these examinations. This article provides the radiology trainee with a general approach to interpreting a fetal MRI. The authors review the added value of prenatal MRI in the overall assessment of fetal wellbeing, discuss MRI protocols and techniques, and review the normal appearance of maternal and fetal anatomy. The paper concludes with a sample template for structured reporting, to serve as a checklist and guideline for reporting radiologists.

Imaging of open spinal dysraphisms in the era of prenatal surgery

Over the last decade fetal surgery to repair open spinal dysraphisms has become an acceptable and in some cases desirable alternative to the traditional method of postnatal closure. Fetal MRI is an essential part of the workup in these patients, not only to select the appropriate candidates for fetal surgery but also to guide prenatal counseling and perinatal management. In this article we review current surgical techniques for prenatal repair, relevant imaging findings in the era of fetal surgery, and expected imaging findings of the brain and spine in the fetal and postnatal periods.

Cloacal malformation: A rare case report and review of prenatal imagings

RATIONALE

Cloacal malformation (CM) is a serious type of anorectal and urogenital tract malformation. However, prenatal ultrasound (US) detection of CM is challenging. In this paper, we reported a rare case of CM prenatally diagnosed by US and magnetic resonance imaging (MRI), as well as reviewed the prenatal US and MRI characteristics of CM in the literature.

PATIENT CONCERNS

A 30-year-old pregnant woman complained of cystic mass in the fetal abdomen detected by prenatal US.

DIAGNOSIS

Fetus CM.

INTERVENTIONS

The fetus was diagnosed as fetal CM by US and MRI, then the pregnant woman received a drug-induced labor treatment. After the neonate was delivered, the measurement was performed on the weight, length, head circumference, abdomen circumference, and bilateral thigh circumference.

OUTCOMES

A female dead neonate was delivered from the vagina of the gravida, showing congenital anus absence. Prenatal ultrasound demonstrated right kidney duplication, hydronephrosis, and right ureteral dilatation. Meanwhile, prenatal MRI showed a cystic cavity, double collecting systems of right kidney, right ureteral dilatation, and right rectum dilatation. In addition, general parameters are as follows: weight: 2280 g; length: 39 cm; head circumference: 26.3 cm; abdomen circumference: 31 cm; right thigh circumference: 17 cm, and left thigh circumference: 18 cm.

LESSONS

US combined with MRI can not only provide reliable evidence for fetal CM in the third trimester but also offer crucial information to the pregnant women to establish clinic treatment programs as early as possible.

Appearance of fetal intestinal obstruction on fetal MRI

OBJECTIVE

To retrospectively analyze the imaging findings of fetal intestinal obstruction diagnosed by MRI and compare with postnatal surgery findings.

METHODS

MRI data of 3346 pregnant women were retrospectively analyzed; we found 47 cases of suspected fetal small intestinal obstruction. Twenty-nine underwent postnatal surgery.

RESULTS

We identified one case of jejunal obstruction secondary to perforation, five annular pancreas, 10 duodenal stenoses, four jejunal stenoses, five jejunal atresias, two ileal atresias, four intestinal volvulus, and four intestinal malrotations. We further found four cases of duodenal stenosis with intestinal malrotation (two cases also showed volvulus). On fetal MRI, annular pancreas and duodenal obstruction manifested as a "double bubble." Jejunal stenosis appeared as a "triple bubble." Jejunal and ileal atresia mainly manifested as proximal dilatation with high signal on T1WI. Intestinal volvulus showed a sausage-like intestinal distortion and mixed signals on T1WI and DWI sequences. Intestinal malrotations were characterized as abnormal duodenal morphology. We missed two malrotations; one jejunal obstruction was misdiagnosed.

CONCLUSION

Prenatal MRI can accurately determine the degree of intestinal obstruction and help qualitatively diagnose its possible etiology according to changes in MRI signals in multiple sequences, providing guidance for prenatal counseling.

Biometric analysis of the foetal meconium pattern using T1 weighted 2D gradient echo MRI

Objectives:

Foetal MRI is used to assess abnormalities after ultrasonography. Bowel anomalies are a significant cause of neonatal morbidity, however there are little data concerning its normal appearance on antenatal MRI. This study aims to investigate the pattern of meconium accumulation throughout gestation using its hyperintense appearance on T₁ weighted scans and add to the current published data.

Methods:

This was a retrospective cohort study in a tertiary referral clinical MRI centre. Foetal body MRI scans of varying gestational ages were obtained dating between October 2011 and March 2018. The bowel was visualised on T₁ weighted images. The length of the meconium and the width of the meconium at the rectum, sigmoid colon, splenic flexure and hepatic flexure was measured. Presence or absence of meconium in the small bowel was noted. Inter- and intrarater reliability was assessed.

Results:

181 foetal body scans were reviewed. 52 were excluded and 129 analysed. Visualisation of the meconium in the large bowel became increasingly proximal with later gestations, and small bowel visualisation was greater at earlier gestations. There was statistically significant strong (r = 0.6–0.8) or very strong (r = 0.8–1.0) positive correlation of length and width with increasing gestation. Interrater reliability was moderate to excellent (r = 0.4–1.0).

Conclusion:

This study provides new information regarding the pattern of meconium accumulation throughout gestation. With care, the results can be used in clinical practice to aid diagnosis of bowel pathology.

Advances in knowledge:

The findings of this study provide further information concerning the normal accumulation of foetal meconium on MR imaging, an area where current research is limited.

Antenatally detected liver and biliary pathology

Liver and biliary pathology in the neonate are rare and include a broad range of structural, neoplastic, infectious, genetic, and metabolic diseases. While most conditions present postnatally, antenatal detection is increasing given recent advances in antenatal imaging capabilities. In certain structural or obstructive liver diseases, antenatal detection now proves essential to help guide treatment and prevent morbidity. We review the epidemiology, pathophysiology, common antenatal diagnostic findings, and recommendations for surgical liver and biliary pathology in the neonate.

Imaging of anorectal malformations in utero

PURPOSE

To document the imaging findings suggestive of anorectal malformation (ARMs) on prenatal US and MRI.

METHODS

Retrospective evaluation of the screening US and prenatal MRI exams of the rectum and ano-perineal region in normal fetuses and in patients with ARMs.

RESULTS

Examples showing the normal rectal and anoperineal anatomy on prenatal US and MRI exams and the imaging findings observed in different types of confirmed ARMS.

CONCLUSIONS

Prenatal diagnosis of ARMs requires both a systematic evaluation of the fetal pelvis and perineum and an appropriate knowledge of its suggestive imaging findings.

Prenatal imaging of anorectal malformations - 10-year experience at a tertiary center in Switzerland

BACKGROUND

Anorectal malformation is a spectrum of congenital defects of the distal bowel, mostly diagnosed at birth.

OBJECTIVE

To describe the prenatal imaging findings of anorectal malformations, explore the causes of the low rates of prenatal diagnosis, compare the accuracy of prenatal ultrasound (US) and magnetic resonnance imaging [MRI] and evaluate the relevance of information obtained at MRI.

MATERIALS AND METHODS

Children treated for anorectal malformation at our hospital and with available prenatal studies were retrospectively identified and included in the study. We reviewed prenatal imaging exams, listed findings suggestive of the diagnosis, and compared results with the final classification.

RESULTS

Fourteen fetuses and neonates - eight with intermediate-high type anorectal malformation and six with cloacae - fulfilled the inclusion criteria. All had associated congenital anomalies. Prenatal exams included 13 US and 8 MRI exams, with 7 children having both exams. Suggestive findings for anorectal malformation were detected in 50% of the cases prenatally and in 85% upon review. They were prospectively detected in 31% and 50% of the cases at US and MRI and retrospectively in 62% and 100% at US and MRI, respectively. MRI was superior to US because it improved the diagnosis, especially in cloacae, and provided relevant additional information that changed management in two cases.

CONCLUSION

The most important signs suggesting anorectal malformation are an absent target sign and anomalous distal bowel wall and rectal fluid. Complementary prenatal MRI improves the diagnosis of anorectal malformation.

Enteric duplication cysts in children: varied presentations, varied imaging findings

Enteric duplication cysts (EDCs) are rare congenital malformations formed during the embryonic development of the digestive tract. They are usually detected prenatally or in the first years of life. The size, location, type, mucosal pattern and presence of complications produce a varied clinical presentation and different imaging findings. Ultrasonography (US) is the most used imaging method for diagnosis. Magnetic resonance (MR) and computed tomography (CT) are less frequently used, but can be helpful in cases of difficult surgical approach. Conservative surgery is the treatment of choice. Pathology confirms the intestinal origin of the cyst, showing a layer of smooth muscle in the wall and an epithelial lining inside, resembling some part of the gastrointestinal tract (GT). We review the different forms of presentation of the EDCs, showing both the typical and atypical imaging findings with the different imaging techniques. We correlate the imaging findings with the surgical results and the final pathological features. TEACHING POINTS: • EDCs are rare congenital anomalies from the digestive tract with uncertain pathogenesis. • More frequently, diagnosis is antenatal, with most EDCs occurring in the distal ileum. • Ultrasonography is the method of choice for diagnosis of EDCs. • Complicated EDCs can show atypical imaging findings. • Surgery is necessary to avoid complications.

Decreased rectal meconium signal on MRI in fetuses with open spinal dysraphism

OBJECTIVE

To evaluate rectal meconium signal in fetuses with open spinal dysraphism and correlate findings with postnatal exam.

METHODS

This is a single-institution Institutional Review Board-approved Health Insurance Portability and Accountability Act (HIPAA) compliant retrospective analysis of fetal MRIs of open spinal dysraphism from 2004 to 2016. Fetuses with diagnostic T1-weighted images and postnatal follow-up at our institution were included.

RESULTS

A total of 115 fetuses (average gestational age 23.9 ± 3.6 weeks) met inclusion criteria. Of these, 80% (92/115) had T1 hyperintense rectal meconium signal. Average height of the meconium column, measured from the base of the bladder to its most inferior extent, was 9.2 ± 4.3 mm in fetuses ≥20-week gestational age and 11.1 ± 4.4 mm in fetuses ≥23-week gestational age (n = 110) . None had bowel dilation. One of 115 fetuses had a simple form of anorectal malformation allowing complete repair in the neonatal period, but this fetus had a normal meconium column height on fetal MRI of 22 mm. The remaining 23/115 fetuses with lack of normal rectal meconium signal were born without evidence of anorectal malformation.

CONCLUSION

Decreased or absent T1-hyperintense rectal meconium signal in fetuses with open spinal dysraphism does not correlate with imperforate anus postnatal and may be a reflection of neurogenic bowel in this patient population.

Fetal MRI in management of complicated meconium ileus: Prenatal and surgical imaging

OBJECTIVE

To review fetal MRI cases surgically proven to have meconium ileus (MI) and obstruction, describe the common fetal MRI findings that distinguish cases of complicated MI, and to compare these findings with surgical images and perinatal outcomes.

METHOD

We performed a retrospective review of all fetal MRI examinations and the corresponding medical record from our tertiary care children's hospital over an 18-month period. Postnatal management and outcomes were reviewed for these patients, and those patients with surgical or postmortem diagnosis of complicated MI were included in the study.

RESULTS

Our analysis revealed 7 cases. In this cohort, 3 imaging features of the fetal bowel were repeatedly seen: gradient appearance of intraluminal bowel contents, abnormally localized meconium signal, and collapsed appearance of the colon on MRI. Surgical diagnoses confirmed MI. All live-born infants underwent surgical repair.

CONCLUSION

Fetal MRI should be included in the diagnostic algorithm of any pregnancy where fetal bowel obstruction is suspected to better risk stratify patients.

Growth of the colon and rectum throughout gestation: evaluation with fetal MRI

Background

Congenital abnormalities of the gastrointestinal tract are increasingly being evaluated by prenatal magnetic resonance imaging (MRI). However, there is a paucity of reports describing the normal quantitative development of the fetal colon and rectum on MRI.

Purpose

To provide growth curves of the MRI estimated diameter of the fetal colon and rectum as a function of gestational age.

Material and Methods

This is a retrospective review of 191 singleton fetal MRI studies at 25–39 weeks of gestation. Measurements included maximal diameter of the ascending, transverse, and descending colon on coronal and sagittal views, maximal diameter of the rectum on coronal and sagittal views, and maximal diameter of the rectum at the level of the bladder base on sagittal views. Median growth curves were built using a generalized additive model. Confidence regions were built for 10th, 25th, 75th, and 90th percentiles.

Results

Smoothed growth curves for the median, and one and three quartiles for each of the five sections as a function of gestational age were calculated. All graphs had a slightly exponential curve.

Conclusion

This study provides normal ranges of the prenatal colon and rectum as a function of gestational age. They may serve as reference values when interpreting fetal MRI.

Fetal Body Imaging: When is MRI Indicated?

Recent improvements in fetal therapies and perinatal care and the multidisciplinary involvement in fetal medicine have increased the demand for more accurate prenatal diagnosis. Fetal Magnetic Resonance Imaging (MRI) is a complementary imaging technique for the assessment of thoraco-abdominal anomalies for which Ultrasonography (US) is not conclusive. It is indicated in selected situations to precise the prognosis in diaphragmatic hernia, to characterise the nature and extension of a pulmonary malformation, to locate a bowel atresia or to better depict an abdominal cystic lesion or tumoural extension. It has become a mandatory complementary diagnostic tool and improves the management of the fetuses and newborns.

Prenatal diagnosis and outcome of fetal gastrointestinal obstruction

INTRODUCTION

The purpose of this study was to evaluate the accuracy of prenatal diagnosis for fetuses with gastrointestinal (GI) obstruction with correlation to postnatal outcomes.

METHODS

Fetuses diagnosed with GI obstruction (excluding esophageal and duodenal) were reviewed for those evaluated between 2006 and 2016. Prenatal diagnosis and imaging studies were compared to postnatal findings. Outcomes evaluated included diagnostic accuracy, rate of other anomalies, neonatal length of stay, incidence of short bowel syndrome, and discharge with TPN or gastrostomy.

RESULTS

Forty-eight patients were diagnosed prenatally with obstruction. Six patients were excluded owing to incomplete records and follow-up. Twelve fetuses were diagnosed with ultrasound alone, and thirty-four with ultrasound and MRI. A diagnosis of obstruction was accurate in 88.1% (n=37/42) with a positive predictive value of 91.3%, while US with MRI had an accuracy of 84.4%. Associated anomalies were highest among fetuses with anorectal obstruction (90.1%), compared to large (50%) or small bowel obstruction (28%). Survival rate was lowest for anorectal obstruction (54.5%), compared to large or small bowel obstruction (100% for both).

CONCLUSION

Fetal MRI is an accurate modality in the diagnosis of fetal GI obstruction and can complement findings characterized by ultrasound. Fetuses with anorectal obstruction have a higher rate of associated anomalies and the lowest survival.

LEVEL OF EVIDENCE

IIb.

Prenatal magnetic resonance and ultrasonographic findings in small-bowel obstruction: imaging clues and postnatal outcomes

BACKGROUND

Prenatal small-bowel obstruction can result from single or multiple atresias, and it can be an isolated abnormality or part of a syndrome. It is sometimes the first manifestation of cystic fibrosis. Accurate prediction of the level of obstruction and length of bowel affected can be difficult, presenting a challenge for counseling families and planning perinatal management.

OBJECTIVE

To review the prenatal US and MRI findings of small-bowel obstruction and to assess whether fetal MRI adds information that could improve prenatal counseling and perinatal management.

MATERIALS AND METHODS

We retrospectively reviewed 12 prenatally diagnosed cases of small-bowel obstruction evaluated by both US and MRI from 2005 to 2015. We analyzed gestational age at evaluation, US and MRI findings, gestational age at delivery and postnatal outcomes.

RESULTS

The final diagnoses were jejunal atresia (7), ileal atresia (1), cystic fibrosis (3) and combined jejunal and anal atresia (1). Four of the eight with jejunal atresia were found to have multiple small-bowel atresias. Prenatal perforation was noted in three. We identified a trend of increasing complexity of bowel contents corresponding to progressively distal level of obstruction, as indicated by increasing US echogenicity and high T1 signal on MRI. Seven cases of jejunal atresia and one case of ileal atresia demonstrated small ascending, transverse and descending colon (microcolon) with filling of a normal-diameter rectum. In contrast, all three fetuses with cystic fibrosis and the fetus with jejunal-anal atresia demonstrated microcolon as well as abnormal paucity or absence of rectal meconium. Polyhydramnios was present in nine. Eight were delivered prematurely, of whom seven had polyhydramnios. The fetus with jejunal and anal atresia died in utero. Postnatally, three had short gut syndrome, all resulting from multiple jejunal atresias; these three were among a subset of four fetuses whose bowel diameter measured more than 3 cm. Eight infants had no further gastrointestinal complications. The presence of multiple atresias was not predicted by prenatal US or MRI.

CONCLUSION

MR provides useful additional information regarding meconium distribution in the small bowel, which helps to clarify the level of obstruction. MR was additionally useful in the assessment of colon and rectal contents, serving as a fetal enema. Abnormally diminished meconium in the rectum suggests cystic fibrosis or combined small-bowel and colonic obstruction, information that is useful in counseling and preparing for postnatal care.

Fetal MR Imaging of Gastrointestinal Abnormalities

Fetal magnetic resonance (MR) imaging plays an increasing and valuable role in antenatal diagnosis and perinatal management of fetal gastrointestinal (GI) abnormalities. Advances in MR imaging data acquisition and use of motion-insensitive techniques have established MR imaging as an important adjunct to obstetric ultrasonography (US) for fetal diagnosis. In this regard, MR imaging provides high diagnostic accuracy for antenatal diagnosis of common and uncommon GI pathologic conditions. In the setting of fetal GI disease, T1-weighted images demonstrate the amount and distribution of meconium, which is crucial to the diagnostic capability of fetal MR imaging. Specifically, knowledge of the T1 signal intensity characteristics of fetal meconium, the normal pattern of meconium with advancing gestational age, and the expected caliber of small and large bowel in the fetus is key to diagnosis of abnormalities of the GI tract. Use of ultrafast T2-weighted sequences for evaluation of the expected location and morphology of fluid-containing structures, including the stomach and small bowel, in the fetal abdomen further aids in diagnostic confidence. Uncommonly encountered fetal GI pathologic conditions, especially cloacal dysmorphology, may demonstrate characteristic MR imaging patterns, which may add additional information to that from fetal US, allowing improved fetal and neonatal management. This article discusses common indications for fetal MR imaging of the GI tract, imaging protocols for fetal GI MR imaging, the normal appearance of the fetal GI tract with advancing gestational age, and the imaging appearances of common fetal GI abnormalities, as well as uncommon fetal GI conditions with characteristic appearances. (©)RSNA, 2016.

Megacystis microcolon intestinal hypoperistalsis syndrome: Case series and updated review of the literature with an emphasis on urologic management

INTRODUCTION

Megacystis microcolon intestinal hypoperistalsis (MMIHS) is a rare disorder characterized by distended nonobstructed bladder, microcolon, and decreased intestinal peristalsis. MMIHS has a particularly poor prognosis; however, when appropriately managed, survival can be prolonged.

STUDY DESIGN

A systematic review (1996-2016) was performed with the key words "megacystis microcolon intestinal hypoperistalsis syndrome." In addition, a case series of four patients is presented as well as algorithms for the diagnosis and treatment of MMIHS.

RESULTS

135 patients with MMIHS were identified in the literature. 73% (88/121) of the patients were female, 65% underwent diagnostic biopsy (64/99), and 63% (66/106) were identified with prenatal imaging. The majority of patients were treated with TPN as well as gastrostomy or ileostomy and CIC, however 15% (18/116) received multivisceral or intestinal transplant, and 30% (22/73) had a vesicostomy. The survival rate was 57% (68/121).

CONCLUSION

Appropriate management of MMIHS patients is crucial. An enlarged, acontractile bladder in a child with bowel motility problems should be considered diagnostic. Bladder distension can be managed with CIC or vesicostomy in addition to prophylactic antibiotics if frequent urinary tract infections are present. These patients often require gastrostomy or ileostomy as well as total parenteral nutrition. This management has led to significant improvement in survival rates.

Prenatal diagnosis of cloacal malformation

Persistent cloaca malformation is the most severe type of anorectal and urogenital malformation. Decisions concerning the surgical treatment for this condition are taken during the first hours of life and may determine the quality of life of these patients. Thus, prenatal diagnosis becomes important for a prompt and efficient management of the fetus and newborn, and accurate counseling of the parents regarding its consequences and the future of the baby. Careful evaluation by ultrasonography, and further in-depth analysis with MRI, allow prenatal detection of characteristic findings, which can lead to diagnose or at least suspect this condition. We reviewed our experience and the literature in order to highlight the most important clues that can guide the physician in the differential diagnosis.

Prenatal diagnosis of bowel malposition using T2-weighted fetal MRI sequences

OBJECTIVE

The goal of this study was to investigate the capability of T2-weighted magnetic resonance imaging (MRI) in revealing fetal bowel malposition.

MATERIALS AND METHODS

All fetal MRI examinations (excluding central nervous system MRI examinations) performed in our department from January 2005 to January 2014 were retrospectively studied by 2 independent observers for situs, stomach and jejunum location on T2-weighted images. Patients data were also reviewed for results of ultrasound examinations, MRI indication, and gestational age. Abnormally positioned jejunums were classified into 3 groups: intrathoracic (A), extra-fetal (B) and abnormal intra-fetal (C). Prenatal data were compared to postnatal imaging, surgery or autopsy findings that served as standard of reference.

RESULTS

A total of 709 fetal MRI examinations were analyzed. In 64 fetus (9%), the jejunum was not present in the left subgastric area on T2-weighted MR images. In these 64 fetuses, proximal jejunum was intrathoracic (41/64, 64%, group A), extra-fetal (11/64, 17%, group B), or intra-abdominal but abnormally positioned (12/64, 19%, group C). Interobserver agreement was 100%. All diagnoses for fetuses in groups A and B (52 cases) were confirmed postnatally (41 cases) or at autopsy (11 cases). In group C, bowel malposition was suspected after ultrasound in only 2/12 fetuses (16.6%); it was confirmed postnatally in 1 fetus but not confirmed in the remaining one. In the 10 remaining fetuses (83%), malposition was confirmed postnatally although not initially suspected.

CONCLUSION

T2-weighted fetal MR images are useful for the prenatal diagnosis of bowel malposition, even when they are unsuspected on ultrasound examination.

Prenatal Imaging of the Gastrointestinal Tract with Postnatal Imaging Correlation

Prenatal detection of a wide variety of anomalies and masses of the gastrointestinal tract is now possible. Prenatal imaging with ultrasonography and in selected cases magnetic resonance imaging provides invaluable information to the referring obstetrician, the maternal fetal medicine specialist, the neonatologist and pediatrician who will care for the child after birth, the surgeons and pediatric specialists who will repair or manage a prenatally detected anomaly, and of course to the parents, allowing them to prepare psychologically and financially for the specific interventions that may be needed for their child. Additional screening for associated anomalies can take place, route of delivery can be decided, and arrangements for delivery in an appropriate setting can be made. Prenatal detection also allows for consideration for pregnancy termination. This article will give a broad overview of anomalies of the gastrointestinal tract that can be detected prenatally and their imaging appearance postnatally.

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.

Laparoscopic versus open repair of recto-bladderneck and recto-prostatic anorectal malformations: a systematic review and meta-analysis

OBJECTIVE

The laparoscopically-assisted anorectal pull-through (LAARP) for recto-bladderneck and recto-prostatic anorectal malformations (RB/RP-ARMs) is believed to improve patient outcomes. We performed a systematic review of the effect of LAARP on postoperative mucosal prolapse and defecation dysfunction.

METHODS

A comprehensive search of MEDLINE, EMBASE, CENTRAL, and grey literature was performed (2000-2014). Full-text screening, data abstraction and quality appraisal were conducted in duplicate. Included studies reported a primary diagnosis of RB/RP-ARM and compared LAARP versus open repair (OPEN).

RESULTS

From 3681 retrieved articles, 7 studies enrolling 187 patients were analyzed. One was a randomized control trial, 6 were retrospective observational studies, and all were single-centre. The majority were of poor-moderate quality (MINORS scores: mean 16.42 (SD 2.225) out of 24). Mucosal prolapse was not significantly different after LAARP versus OPEN (p = 0.18). Defecation outcomes were inconsistently reported but were no different between LAARP and OPEN for either children >3 years old (p = 0.84), or all ages combined (p = 0.11).

CONCLUSION

We found no significant difference in rates of mucosal prolapse or defecation scores for LAARP compared to OPEN for children with RB/RP-ARMs. However, studies are small and of poor-moderate quality and results are heterogeneous. Comprehensive, standardized, reliable reporting is necessary to guide practice and inform postoperative guidelines.

LEVEL OF EVIDENCE

1c.

Role of magnetic resonance imaging in the prenatal diagnosis of gastrointestinal fetal anomalies

PURPOSE

This study was done to evaluate the role of fetal magnetic resonance imaging (MRI) in the study of gastrointestinal malformations in comparison to prenatal ultrasound (US).

MATERIALS AND METHODS

A prospective (2010-2012) study of 38 fetal MRI scans was performed on 38 fetuses between 24 and 38 weeks of gestation. All the fetuses had a US diagnosis of gastrointestinal anomalies. T2-weighted HASTE, T1-weighted fast gradient echo, TrueFISP and diffusion-weighted images of the fetal abdomen were obtained on a 1.5-Tesla magnet. All fetal MRI diagnoses were compared with postnatal US findings, autopsy or surgical reports.

RESULTS

Fetal MRI was able to confirm the sonographic findings in nine of 38 fetuses (23.7%), to provide additional information in 23 of 38 fetuses (60.6%), to exclude the US diagnosis in five cases (5.2%) and to change it in two cases (5.2%). It was not able to characterize a case of gastric duplication and a case of abdominal cystic lymphangioma (5.2%).

CONCLUSIONS

Fetal MRI can be used as a complementary imaging modality to US in prenatal evaluation of gastrointestinal anomalies and can be considered a valuable tool not only for confirming or excluding but also for providing additional information to fetal ultrasonographic findings.

Fetal MRI of hereditary multiple intestinal atresia with postnatal correlation

Hereditary multiple intestinal atresia (HMIA) is an extremely uncommon cause of congenital bowel obstruction. The morbidity and mortality of this disease differ significantly from those of isolated intestinal atresias and non-hereditary forms of multiple intestinal atresia. Most notably, despite successful operative repairs of the atresias found in this disease, HMIA maintains a 100% lethality rate from continued post-operative intestinal failure and an associated severe immunodeficiency. We present a case of HMIA evaluated with fetal MRI and subsequently diagnosed by a combination of corroborative postnatal imaging with surgical exploration and pathological examination.

[Fetal magnetic resonance imaging of thoracic and abdominal malformations]

CLINICAL/METHODICAL ISSUE

Diagnosis and differential diagnosis of fetal thoracic and abdominal malformations.

STANDARD RADIOLOGICAL METHODS

Ultrasound and magnetic resonance imaging (MRI).

METHODICAL INNOVATIONS

In cases of suspected pathologies based on fetal ultrasound MRI can be used for more detailed examinations and can be of assistance in the differential diagnostic process.

PERFORMANCE

Improved imaging of anatomical structures and of the composition of different tissues by the use of different MRI sequences.

ACHIEVEMENTS

Fetal MRI has become a part of clinical routine in thoracic and abdominal malformations and is the basis for scientific research in this field.

PRACTICAL RECOMMENDATIONS

In cases of thoracic or abdominal malformations fetal MRI provides important information additional to ultrasound to improve diagnostic accuracy, prognostic evaluation and surgical planning.

Imaging findings in megacystis-microcolon-intestinal hypoperistalsis syndrome

Megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS) is a rare and frequently lethal form of severe functional intestinal obstruction more commonly found in girls. Imaging features characteristic of this disease include a large dilated bladder, microcolon and intestinal dysmotility. Additional imaging findings may include intestinal malrotation, hydronephrosis and vesicoureteral reflux. It is usually fatal in the first year of life. Because presenting clinical and imaging features can mimic other causes of neonatal bowel obstruction, we compiled examples of this disorder to help the pediatric radiologist recognize imaging findings associated with MMIHS and aid in the development of a long-term management plan and in counseling the family regarding implications of this disorder. We reviewed recent and historical literature relevant to MMIHS and present the imaging and clinical features of four patients with MMIHS treated at our institution as examples of this uncommon disorder.

Fetal MR in the evaluation of pulmonary and digestive system pathology

BACKGROUND

Prenatal awareness of an anomaly ensures better management of the pregnant patient, enables medical teams and parents to prepare for the delivery, and is very useful for making decisions about postnatal treatment. Congenital malformations of the thorax, abdomen, and gastrointestinal tract are common. As various organs can be affected, accurate location and morphological characterization are important for accurate diagnosis.

METHODS

Magnetic resonance imaging (MRI) enables excellent discrimination among tissues, making it a useful adjunct to ultrasonography (US) in the study of fetal morphology and pathology.

RESULTS

MRI is most useful when US has detected or suspected anomalies, and more anomalies are detected when MRI and US findings are assessed together.

CONCLUSION

We describe the normal appearance of fetal thoracic, abdominal, and gastrointestinal structures on MRI, and we discuss the most common anomalies involving these structures and the role of MRI in their study.

TEACHING POINTS

• To learn about the normal anatomy of the fetal chest, abdomen, and GI tract on MRI. • To recognize the MR appearance of congenital anomalies of the lungs and the digestive system. • To understand the value of MRI when compared to US in assessing fetal anomalies.

Fetal bowel anomalies--US and MR assessment

The technical quality of prenatal US and fetal MRI has significantly improved during the last decade and allows an accurate diagnosis of bowel pathology prenatally. Accurate diagnosis of bowel pathology in utero is important for parental counseling and postnatal management. It is essential to recognize the US presentation of bowel pathology in the fetus in order to refer the patient for further evaluation or follow-up. Fetal MRI has been shown to offer some advantages over US for specific bowel abnormalities. In this paper, we review the normal appearance of the fetal bowel on US and MRI as well as the typical presentations of bowel pathologies. We discuss more specifically the importance of recognizing on fetal MRI the abnormalities of size and T1-weighted signal of the meconium-filled distal bowel.