Fetal MRI as complement to US in the diagnosis and characterization of anomalies of the genito-urinary tract

MR Imaging of the Fetal Genitourinary Tract

Fetal MR imaging overcomes many of the technical barriers of ultrasound and is an important diagnostic tool for fetal genitourinary (GU) anomalies. It is suited for evaluation of GU anomalies because of the fluid-sensitive sequences and superior soft tissue contrast. Often GU malformations are part of a multisystem genetic or congenital condition, and imaging the entire fetus with MR adds additional clarity about the extent of disease. It adds confidence to diagnoses of renal agenesis, urinary tract dilation, cystic disease, and tumors. It is particularly useful to delineate anatomy in complex GU malformations. This additional information guides counseling.

The value of fetal magnetic resonance imaging in diagnosis of congenital anomalies of the fetal body: a systematic review and meta-analysis

OBJECTIVES

To undertake a systematic review to assess the accuracy of fetal MRI in diagnosis of non-CNS congenital anomalies of the fetal body in comparison with antenatal ultrasound when correlated to postnatal diagnosis.

METHODS

Searches were conducted from electronic databases, key journals and reference lists for eligible papers. Inclusion criteria was original research studies comparing the diagnostic results of antenatal ultrasound, fetal MRI and final postnatal diagnosis via imaging, surgery or post-mortem testing. Studies of CNS anomalies were excluded. Studies were assessed for risk of bias by two reviewers working independently and data was then extracted by a single reviewer.

RESULTS

12 studies were included with a total of 361 eligible patients who underwent USS and MRI and had a postnatal diagnosis. USS alone had a diagnostic accuracy of 60.6% whereas MRI had an improved diagnostic accuracy of 86.4%. The overall odds ratio was 0.86 (CI 0.202-1.519 and p-value < 0.01).

CONCLUSION

Fetal MRI makes a significant contribution to accurate diagnosis of congenital abnormalities of the fetal body; especially in genito-urinary anomalies. More research is needed to improve the evidence base for the role of fetal MRI in diagnosis of congenital anomalies in other body systems.

[(Uro)genital developmental disorders]

CLINICAL ISSUE

Congenital anomalies of the urogenital tract are common, whereas isolated developmental disorders of the genital organs are rare and varied. The type and timing of imaging to characterize these developmental disorders and the planning of any treatment are the subject of discussion. The aim of this article is to provide a brief overview of embryology, diagnostic procedures, and examples of findings.

STANDARD RADIOLOGICAL METHODS

The primary procedure for imaging the genitals is sonography, which must be performed with appropriate empathy. In addition to the genitals, the general situation of the kidneys and urinary tract should be examined, as urogenital malformations are often combined. Dedicated magnetic resonance imaging (MRI) is indicated as advanced imaging in interdisciplinary consultations. Invasive procedures, such as genitography combined with micturition cystourethrography (MCU) using X‑rays or contrast-enhanced sonography, are rarely required. Computed tomography (CT) or excretory urography play no role.

CONCLUSION

Imaging plays an important role in the assessment of genital anomalies. Knowledge of embryology facilitates anatomical understanding and the assessment of pathologies.

[Congenital anomalies of the kidneys and urinary tract (CAKUT) : Embryology in radiology and fetal magnetic resonance imaging]

CLINICAL PROBLEM

Congenital anomalies of the kidney and urinary tract (CAKUT) are very common findings in fetal diagnostics. Their effects range from variants without pathological significance to pronounced functional impairment with the need for renal replacement therapy in childhood. Sometimes the genital organs are also affected. The aim of the article is to provide an overview of embryology and examples of key findings.

IMAGING PROCEDURES

In the fetal period, magnetic resonance imaging (MRI) is used, while postnatally, sonography with the option of contrast-enhanced micturition urosonography (MUS, ceVUS) dominates imaging in pediatric radiology, supplemented in individual cases by fluoroscopy (micturition cysturethrography) and MRI. Quantitative methods for assessing kidney function and excretion (MAG3 scintigraphy, functional MR urography) are essential when planning further therapeutic procedures, especially in obstructive uropathies.

CONCLUSION

Imaging plays an essential role in the assessment of abnormalities of the kidneys and urinary tract both pre- and postnatally. Knowledge of embryology facilitates anatomical understanding and assessment of pathologies.

Comparison of ultrasound and magnetic resonance imaging findings in evaluation of fetal congenital anomalies: A single-institution prospective observational study

Background

This study aimed to compare the ultrasound (USG) and fetal magnetic resonance imaging (MRI) findings in the evaluation of congenital fetal anomalies and to determine whether the management is changes significantly if MRI is combined with USG.

Methods

In this prospective observational cohort study, we performed fetal MRI in 90 consecutive cases of fetuses diagnosed or suspected as having congenital anomalies on a prior level II USG scan. We then compared the USG and MRI findings of each anomaly according to the diagnostic information yielded by each modality.

Results

Of 90 fetuses examined during 1 year study period, MRI and USG findings were equivalent in 13.3% of cases. MRI provided additional information in 68.8% cases, of which pregnancy management was changed in 5.6% cases. MRI provided additional information but did not change management in 63.3% of cases. USG provided additional information but did not change pregnancy management in 17.8% of cases. The difference was statistically significant with a p value of .000.

Conclusion

Fetal MRI is a significantly better modality than USG for detecting additional findings in anomalies of specific organ systems. Because of its high diagnostic yield for central nervous system (CNS) anomalies, it can be combined with USG for this subgroup. For non-CNS anomalies of genitourinary system, thorax, or in syndromic/complex malformations/conjoint twin pregnancy, it may be used as an adjunct to USG on a case to case basis. MRI has the potential to change the pregnancy management in few cases, but benefit is small to advocate a complete integration of MRI and USG for fetal anomaly scanning at present.

Fetal uropathies: pre- and postnatal imaging, management and follow-up

Congenital uropathies are the most common fetal anomalies. They include a wide spectrum of anomalies ranging from mild pelvis dilation to complex urinary tract malformations. Prenatal imaging not only allows for their diagnosis but, in experienced hands, it can differentiate obstructive from refluxing or malformative uropathies. Such precise prenatal information allows for intervention before birth in select cases or for adapting the postnatal workup to provide a better long-term outcome. For the different types of congenital uropathies, we describe their prenatal presentations on US and the complementary role of fetal MRI where indicated. We correlate these findings with postnatal workup and summarize the updated neonatal diagnostic and clinical/surgical management.

Added value of fetal MRI as a complementary method to antenatal ultrasound in the assessment of non-CNS fetal congenital anomalies

Background

Birth defects and congenital anomalies are different words used to describe developmental abnormalities that occur at birth. Congenital anomalies diagnosis during pregnancy is a difficult topic to which ultrasonography has made significant contributions. The availability of a generally safe, independent technique in the evaluation of prenatal anomalies would be a welcomed clinical and scientific alternative. Ultrasound (US) is the predominant modality for evaluating disorders related to fetus and pregnancy. In most situations, this examination by a professional operator offers sufficient information about fetal morphology, surroundings, and well-being. The abnormalities revealed by ultrasound can be subtle or inconclusive at times. MRI has been demonstrated to be useful in such circumstances in various studies. So the effective use of fetal MRI in the evaluation of non-CNS abnormalities of the body is a reason for adopting fetal MRI as an adjunct to US in obstetric imaging. This study aimed to examine the role of fetal MRI as a complementary method to the antenatal US in assessing non-CNS anomalies and how it changed or modified the diagnosis of anomalies.

Results

By analyzing the data of 30 pregnant females with fetal non-CNS congenital anomalies, the diagnostic accuracy of prenatal ultrasound alone in the detection of congenital anomalies was 76%, with a sensitivity of about 76%. And diagnostic accuracy of MRI alone was 96.6%, with a sensitivity of approximately 96.6%. Moreover, the diagnostic accuracy of combined prenatal US and prenatal MRI in the detection of congenital anomalies was 100%, with sensitivity about 100% and PPV about 100%.

Conclusion

Fetal MRI raises confidence in non-CNS malformation assessment. Compared to US, MRI overcomes many of the obstacles faced by the antenatal US. MRI is superior to the US in refining, changing, or adding more diagnostic information about the disease.

Fetal magnetic resonance imaging at 3 Tesla - the European experience

BACKGROUND

The Fetal Imaging Taskforce was established in 2018 by the European Society of Paediatric Radiology. The first survey on European practice of fetal imaging published in 2020 revealed that 30% of fetal magnetic resonance imaging (MRI) is performed at 3 tesla (T). The purpose of this second survey was to identify the impact of 3-T fetal MRI with an emphasis on image quality, diagnostic yield, and technical challenges and artifacts at higher field strengths.

OBJECTIVE

To describe the prenatal imaging practice at 3-T MRI units in various centres in Europe and to prepare recommendations on behalf of the Fetal Imaging Taskforce.

MATERIALS AND METHODS

A survey was sent to all members performing 3-T fetal MRI. Questions included practitioner experience, magnet brand, protocols, counselling, artifacts and benefits of imaging at higher field strengths.

RESULTS

Twenty-seven centres replied and reported improved spatial resolution and improved signal-to-noise ratio when performing fetal MRI at 3 T. Shading and banding artifacts and susceptibility to motion artifacts were common problems identified by practitioners at the higher field strength. For all neurological indications, practitioners reported a benefit of imaging at 3 T, most marked for posterior fossa evaluation and parenchymal lesions.

CONCLUSION

The use of 3-T magnets in fetal MRI has improved the availability and quality of advanced imaging sequences and allowed for better anatomical evaluation. There remain significant challenges to minimize the impact of artifacts on image quality. This paper includes guidelines for clinical practice and imaging at 3 T.

Case Report: A Case Series of Rare High-Type Anorectal Malformations With Perineal Fistula: Beware of Urethral Involvement

Anorectal malformations (ARMs) are one of the more common congenital anomalies encountered in pediatric surgery where the majority are diagnosed in the early neonatal period. The etiology of ARM remains uncertain and is likely to be multifactorial. A majority of ARMs result from abnormal development of the urorectal septum in early fetal life. There can be a broad range of presentation features varying from low anomalies with perineal fistula to high anomalies mandating intricate management. To develop a standardized system for comparison in follow-up studies, the Krickenbeck classification was introduced according to the type of fistula. According to the Krickenbeck classification of ARM, those with a rectoperineal fistula are classified as low-type ARM and are usually managed with a perineal anoplasty without colostomy. In this case series, we describe two rare cases of distinct high and intermediate ARM with rectoperineal fistulas, which were thought to be low-type ARM but were subsequently found to have urethral involvement. Our cases consisted of high and intermediate ARMs, which were successfully treated with posterior sagittal anorectoplasty as described. These cases exemplified rare variants of ARM where rectoperineal fistulas can be associated with high-type anomalies. Rare-variant ARM with rectopenile or rectoscrotal fistula can be associated with high-type anomalies in contrast to classical rectoperineal fistulas. A high index of suspicion should remain in cases with previous urinary tract infection despite normal imaging. Careful planning is also needed with consideration of possible need for urethral repair during anoplasty, which was needed in both our cases.

MRI evaluation of fetal tethered-cord syndrome: correlation with ultrasound findings and clinical follow-up after birth

AIM

The study aimed to describe the features of magnetic resonance imaging (MRI) in fetuses with tethered-cord syndrome (TCS) or lower spinal cord (LSC) and to analyse the clinical outcomes and complications during follow-up.

MATERIALS AND METHODS

This is a retrospective study of fetuses diagnosed with TCS or LSC using MRI from January 2015 to August 2019. The average gestational week (GW) at MRI examination was 25.46 ± 4.73 GW (range: 21-39 GW). MRI was used¹ to identify the anatomical landmarks of the spine²; to measure the width of the conus medullaris and record the ending position of the LSC³; and to analyse other neurological deformities. The diagnostic results between MRI and ultrasonography (US) were compared.

RESULTS

A total of 38 fetuses with suspected intracranial or spinal lesions on US or MRI were included. Among all fetuses, 17 fetuses were diagnosed with LSC or TCS without associated anomalies. Twenty-one fetuses had complications of central nervous system (CNS) anomalies, one fetus also had a diagram hernia, and one fetus had an inverse foot. MRI provided more diagnoses than US in nine fetuses. Two cases of diastematomyelia detected on MRI were missed on US. The capability of MRI was comparable with that of US in terms of displaying spina bifida.

CONCLUSION

In the present study, fetal MRI showed better performance than US for depicting TCS and related CNS abnormalities. MRI provided clinicians with additional information in terms of prenatal counselling and management.

Update on the Prenatal Diagnosis and Outcomes of Fetal Bilateral Renal Agenesis

Importance

Bilateral renal agenesis is a rare congenital anomaly associated with poor prognosis.

Objective

The aims of this article are to review and summarize evidence on prenatal diagnosis and outcomes of bilateral renal agenesis.

Evidence Acquisition

A search was undertaken using PubMed and ClinicalTrials.gov databases from January 1, 1998, to September 1, 2018. Search terms include "prenatal diagnosis" OR "outcomes" AND "bilateral renal agenesis." Search was limited to English language.

Results

Fetal ultrasonography is the primary imaging modality for prenatal diagnosis of fetal urogenital tract abnormalities. However, ultrasonography is limited by several factors; it is operator dependent and associated with small field of view, has limited soft-tissue acoustic contrast, and is also influenced by patient habitus and fetal position. Color Doppler ultrasonography can be used as an adjunct to exclude bilateral renal agenesis by visualizing renal arteries. In the literature, prenatal magnetic resonance imaging has been reported to be equal to or superior to prenatal ultrasonography. Bilateral renal agenesis with oligohydramnios/anhydramnios is associated with a poor prognosis; perinatal death occurs secondary to pulmonary hypoplasia in the majority of cases.

Conclusions

Ultrasonography in combination with color Doppler ultrasonography permits the fetal urinary tract to be assessed in the first and early second trimester of gestation. The magnetic resonance imaging can be used as a complementary adjunctive modality in equivocal or inconclusive ultrasonographic findings.

The use of fetal MRI for renal and urogenital tract anomalies

Fetal anomalies are detected in approximately 2% of all fetuses and, among these, genitourinary tract abnormalities account for 30% to 50% of all structural anomalies present at birth. Although ultrasound remains the first line diagnostic modality, fetal MRI provides important additional structural and functional information, especially with the development of faster sequences and the use of functional sequences. The added value of MRI-based imaging is three-fold: (a) improvement of diagnostic accuracy by adequate morphological examination, (b) detection of additional anomalies, and (c) in addition, MRI has the potential to provide information regarding renal function. In this review, we describe the role of fetal MRI in the anatomical evaluation of renal and urogenital tract anomalies, and we also touch upon the contribution of functional MRI to the diagnostic workup of these conditions.

Prenatal diagnosis of renal duplication by magnetic resonance imaging

Purpose: To determine the value of fetal magnetic resonance imaging (MRI) to detect renal duplication.Methods: In this retrospective study, prenatal MRI and ultrasound (US) diagnoses were compared with postnatal imaging and/or surgical data. Twenty-six pregnant women (average age, 32 years; range, 29-36 years) underwent MRI at a mean gestational age of 25 weeks (range, 21-33 weeks). MRI was performed with a 1.5-T unit within 1 week after prenatal ultrasound examination. The steady-state free-precession (SSFP), single-shot turbo spin echo (SSTSE), and T₁-weighted fast imaging sequences were used.Results: Twenty-four cases of fetal renal duplications diagnosed using prenatal MRI were judged to be correct when compared with postnatal imaging and surgical follow-up. In 18 of 26 cases, the diagnoses established using prenatal US were correct when compared with postnatal diagnosis. In 2 of 26 cases, the diagnosis with both prenatal US and MRI were not entirely correct when compared with postnatal diagnosis. In the two cases, magnetic resonance (MR) identified left two pelvicalyceal systems but could not found ipsilateral ectopic ureteral orifice, US only found left hydronephrosis but could not found duplex collection system. In other six cases, MR corrected the US diagnosis by providing a more accurate renal morphology or additional diagnostic information.Conclusions: MRI is an effective method for the diagnosis of fetal duplex kidney deformity and associated ureteral and other abnormalities.

Magnetic resonance imaging for evaluation of foetal multicystic dysplastic kidney

We sought to evaluate the diagnostic value of foetal magnetic resonance imaging (MRI) for multicystic dysplastic kidney (MCDK) disease. We retrospectively identified 55 foetuses with MCDK diagnosed (51 unilateral; 4 bilateral) by foetal MRI. We analysed the anatomical findings by prenatal MRI and compared them with the prenatal ultrasound (US) and postnatal findings. Additional diagnostic information added by MRI was recorded. The gestational age of the 55 foetuses ranged from 22 to 35 weeks (mean, 26.5 ± 3.6 weeks). The age of the pregnant women ranged from 23 to 40 years (mean, 31 ± 4.2 years). All 55 cases were performed at 1.5 T magnetic resonance unit. MRI sequences, including steady-state free precession (SSFP), single-shot fast spin echo (SSFSE), T₁-weighted imaging (T₁WI), and diffusion weighted imaging (DWI) sequences. Follow-up was obtained for 53 cases (2 cases of autopsy, 51 cases of postnatal imaging or surgery confirmed). Among the 51 unilateral cases, 16 cases were associated with other urinary tract anomalies, 3 cases with extra-renal anomalies, and the remaining 32 cases without associated anomalies. 2 of 16 cases with contralateral renal agenesis were with oligohydramnios and pulmonary hypoplasia. 2 of 4 bilateral MCDK presented with oligohydramnios and pulmonary hypoplasia. 52 of 53 cases were correctly diagnosed by MRI compared with the final diagnoses; 40 of 53 (75.5%) cases were correctly diagnosed by prenatal ultrasound. Both prenatal ultrasound and MRI failed to correctly diagnose one case bilateral MCDK, and MRI correctly changed the ultrasound diagnosis in 12 cases. Foetal MRI can add additional diagnostic information to prenatal US in the assessment of MCDK, even change the prenatal counselling and decisions.

Prenatal parental decision-making and postnatal outcome in renal oligohydramnios

BACKGROUND

Previous studies on renal oligohydramnios (ROH) report highly variable outcome and identify early onset of ROH and presence of extrarenal manifestations as predictors of adverse outcome in most cases. Data on termination of pregnancy (TOP) and associated parental decision-making processes are mostly missing, but context-sensitive for the interpretation of these findings. We provide here a comprehensive analysis on the diagnosis, prenatal decision-making and postnatal clinical course in all pregnancies with ROH at our medical centre over an 8-year period.

METHODS

We report retrospective chart review data on 103 consecutive pregnancies from 2008 to 2015 with a median follow-up of 554 days.

RESULTS

After ROH diagnosis, 38 families opted for TOP. This decision was associated with onset of ROH (p < 0.001), underlying renal disease (p = 0.001) and presence of extrarenal manifestations (p = 0.02). Eight infants died in utero and 8 cases were lost to follow-up. Of the 49 liveborn children, 11 received palliative and 38 underwent active care. Overall survival of the latter group was 84.2% (n = 32) corresponding to 31% of all pregnancies (32 out of 103) analysed. One third of the surviving infants needed renal replacement therapy during the first 6 weeks of life.

CONCLUSIONS

Over one third of pregnancies with ROH were terminated and the parental decision was based on risk factors associated with adverse outcome. Neonatal death was rare in the actively treated infants and the overall outcome promising. Our study illustrates that only careful analysis of the whole process, from prenatal diagnosis via parental decision-making to postnatal outcome, allows sensible interpretation of outcome data.

Current State of Fetal Intervention for Lower Urinary Tract Obstruction

PURPOSE OF THE REVIEW

In this article, we explore the origins of intervention of fetal lower urinary tract obstruction, and we specifically discuss the background and recent outcomes of vesicoamniotic shunt placement and fetal cystoscopy. The article seeks to provide a comprehensive overview of the field while bringing the reader quickly up to speed on the pertinent literature and the critical data that are available to guide decision-making regarding intervention.

RECENT FINDINGS

Appropriate patient selection for fetal intervention remains challenging despite advances in prenatal imaging. Both a randomized controlled trial and multiple systematic reviews show evidence of a perinatal survival benefit following fetal intervention but rates of renal morbidity remain very high. Despite 30 years of research, fetal lower urinary tract obstruction remains a difficulty entity to treat. Intervention may lead to survival, but physicians and caregivers must remain alert for the distinct possibility of long-term renal morbidity in survivors.

Fetal MRI compared with ultrasound for the diagnosis of obstructive genital malformations

OBJECTIVE

To compare the accuracy of magnetic resonance imaging (MRI) and ultrasound (US) to diagnose and characterize congenital obstructive genital abnormalities.

METHOD

Retrospective cohort of 20 fetuses who underwent a fetal MRI following a US diagnosis of obstructive urogenital malformation. We compared MRI and US findings and their correlation with the definitive diagnosis.

RESULT

The correct diagnosis was obtained in 6/20 (30%) cases and 19/20 cases (95%) with US and MRI, respectively. MRI revealed additional information to US in 15/20 cases (75%) and modified the prenatal management in 14 fetuses (70%). The identification rates of the most important anatomical landmarks for the diagnosis, using US and MRI, were compared. Bladder: US 17/20 (85%) vs MRI 20/20 (100%) P = 0.23; vagina: US 6/19 (31.5%) vs MRI 19/19 (100%) P < 10^-4 ; uterus: US 11/19 (57.8%) vs MRI 19/19 (100%) P = 0.003, kidneys: US: 40/40 (100%) MRI: 40/40 (100%) P = 1, ureters: US 14/40 (35%) vs MRI 30/40 (75%) P=0.001, rectum: US 6/20 (30%) MRI 20/20 (100%) P < 10^-4 , and sacrum: US 20/20 (100%) vs MRI 17/20 (85%) P = 0.23.

CONCLUSION

In fetuses with obstructive urogenital malformations, MRI facilitates assessment of major pelvic organs and provides significant information that may alter the prenatal management.

Lower urinary tract obstruction: fetal intervention based on prenatal staging

The authors present an overview of lower urinary tract obstruction (LUTO) in the fetus with a particular focus on the insult to the developing renal system. Diagnostic criteria along with the challenges in estimating long-term prognosis are reviewed. A proposed prenatal LUTO disease severity classification to guide management decisions with fetal intervention to maintain or salvage in utero and neonatal pulmonary and renal function is also discussed. Stage I LUTO (mild form) is characterized by normal amniotic fluid index after 18 weeks, normal kidney echogenicity, no renal cortical cysts, no evidence of renal dysplasia, and favorable urinary biochemistries when sampled between 18 and 30 weeks; prenatal surveillance is recommended. Stage II LUTO is characterized by oligohydramnios/anhydramnios, hyperechogenic kidneys but absent renal cortical cysts or apparent signs of renal dysplasia and favorable fetal urinary biochemistry; fetal vesicoamniotic shunting (VAS) or fetal cystoscopy is indicated to prevent pulmonary hypoplasia and renal failure. Stage III LUTO is oligohydramnios/anhydramnios, hyperechogenic kidneys with cortical cysts and renal dysplasia and unfavorable fetal urinary biochemistry after serial evaluation; fetal vesicoamniotic shunt may prevent severe pulmonary hypoplasia but not renal failure. Stage IV is characterized by intrauterine fetal renal failure, defined by anhydramnios and ultrasound (US) findings suggestive of severe renal dysplasia, and is associated with death in 24 h of life or end-stage renal disease (ESRD) within the first week of life; fetal vesicoamniotic shunt and fetal cystoscopy are not indicated.

Anterior Urethral Valve: Uncommon Association with Renal Duplicity

Anterior urethral valves (AUVs) is an unusual cause of congenital obstruction of the male urethra, being 15–30 times less common than posterior urethral valves. We present a case of AUV diagnosed at 24th gestational week. Ultrasonography and fetal MRI revealed hydronephrotic kidneys with ureteral duplicity, a distended bladder and perineal cystic mass which confirmed dilated anterior urethra in a male fetus. Diagnosis was confirmed postnatally by voiding cystourethrogram and surgery.

Inter-rater reliability of the APD, SFU and UTD grading systems in fetal sonography and MRI

INTRODUCTION

Antenatal hydronephrosis (ANH) is frequently detected on screening obstetric ultrasonography. Common ANH grading systems include the anterior-posterior diameter (APD) and the Society for Fetal Urology (SFU) grading system. Recent developments in the management of ANH include the use of fetal magnetic resonance imaging (MRI), and a new grading system - Urinary Tract Dilation (UTD). This study reviewed patients who underwent fetal MRI and ultrasound, and compared the grading systems across these imaging modalities.

MATERIALS AND METHODS

Patients who underwent paired fetal MRI and ultrasound studies between January 2012 and January 2014 were included. Two pediatric urologists and a pediatric radiologist reviewed the studies. Data collected included APD, SFU grade, and UTD grade. Fleiss' kappa statistic determined the inter-rater reliability (IRR) of the SFU and UTD grading within each imaging modality. Intra-class correlation assessed the consistency of the APD measurements.

RESULTS

Forty-seven patients and 88 renal units were evaluated. Median gestational age was 22 weeks. Kappa values of the SFU grading system indicated fair IRR for ultrasound imaging and moderate IRR for MRI imaging, while the UTD grading system reached moderate IRR for both. The IRR of the SFU grading system was improved with the use of MRI, while the UTD grading system was no different. The APD intraclass correlation coefficient improved significantly when measured by MRI. As the ultrasound SFU grade increased, the odds of the MRI SFU grade being scored higher increased by a factor of 3.7. There was no difference between ultrasound and MRI when using the UTD grading system.

DISCUSSION

This study was the first to assess the UTD system in a cohort of patients who underwent paired ultrasound and MRI studies. The results suggested that the UTD system might improve IRR, compared with the SFU system. The use of fetal MRI may improve the IRR of the SFU grading system. It also found that the proportion of SFU grades was affected by the imaging modality, raising the possibility that MRI 'overcalls' the SFU grade, compared with ultrasound. This difference was not observed using the UTD grading system. The most important limitation was the selection bias favoring complex pathology with severe ANH diagnosed at an early gestational age.

CONCLUSIONS

In this unique cohort, the UTD system improved IRR when compared to the SFU grading system. Fetal MRI improved the IRR of the SFU grading system, and improved the APD intraclass correlation. The SFU grading was likely to be higher when assessed by MRI vs ultrasound, but the UTD grade was not affected by the imaging modality.

Diagnostic accuracy of ultrasonography and magnetic resonance imaging for the detection of fetal anomalies: a blinded case-control study

OBJECTIVES

To compare the accuracy of two-dimensional ultrasound (2D-US), three-dimensional ultrasound (3D-US) and magnetic resonance imaging (MRI) for the diagnosis of congenital anomalies without prior knowledge of indications and previous imaging findings.

METHODS

This was a prospective, blinded case-control study comprising women with a singleton pregnancy with fetal congenital abnormalities identified on clinical ultrasound and those with an uncomplicated pregnancy. All women volunteered to undergo 2D-US, 3D-US and MRI, which were performed at one institution. Different examiners at a collaborating institution performed image interpretation. Sensitivity and specificity of the three imaging methods were calculated for individual anomalies, based on postnatal imaging and/or autopsy as the definitive diagnosis. Diagnostic confidence was graded on a four-point Likert scale.

RESULTS

A total of 157 singleton pregnancies were enrolled, however nine cases were excluded owing to incomplete outcome, resulting in 148 fetuses (58 cases and 90 controls) included in the final analysis. Among cases, 13 (22.4%) had central nervous system (CNS) anomalies, 40 (69.0%) had non-CNS anomalies and five (8.6%) had both CNS and non-CNS anomalies. The main findings were: (1) MRI was more sensitive than 3D-US for diagnosing CNS anomalies (MRI, 88.9% (16/18) vs 3D-US, 66.7% (12/18) vs 2D-US, 72.2% (13/18); McNemar's test for MRI vs 3D-US: P = 0.046); (2) MRI provided additional information affecting prognosis and/or counseling in 22.2% (4/18) of fetuses with CNS anomalies; (3) 2D-US, 3D-US and MRI had similar sensitivity for diagnosing non-CNS anomalies; (4) specificity for all anomalies was highest for 3D-US (MRI, 85.6% (77/90) vs 3D-US, 94.4% (85/90) vs 2D-US, 92.2% (83/90); McNemar's test for MRI vs 3D-US: P = 0.03); and (5) the confidence of MRI for ruling out certain CNS abnormalities (usually questionable for cortical dysplasias or hemorrhage) that were not confirmed after delivery was lower than it was for 2D-US and 3D-US.

CONCLUSIONS

MRI was more sensitive than ultrasonography and provided additional information that changed prognosis, counseling or management in 22.2% of fetuses with CNS anomalies. False-positive diagnoses for subtle CNS findings were higher with MRI than with ultrasonography. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

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.

Prenatal pelvic MRI: additional clues for assessment of urogenital obstructive anomalies

OBJECTIVE

Ultrasound prenatal evaluation of pelvic cystic mass can be challenging. After having ruled out a cloaca anterior to a large hydrocolpos, it is important to differentiate between combined urogenital anomalies such as urogenital sinus and isolated genital anomalies.

PATIENTS AND METHODS

We reviewed the charts of 13 women referred for a third trimester pelvic MRI for cystic pelvic mass discovered in second trimester ultrasound. We evaluated MRI compared with postnatal surgical findings in order to determine clues for improving prenatal diagnoses.

RESULTS

MRI excluded the diagnosis of cloacal malformation in nine cases with no false negative. Once a cloaca is ruled out, a different signal between the bladder and the hydrocolpos on T2 sequences is in favor of an isolated genital obstruction. In contrast, in case of urogenital sinus, the vagina is filled with a mixture of genital secretions and urine, which gives it an MRI signal similar to the bladder on T2 sequences.

CONCLUSION

Third trimester fetal MRI is an essential exam for characterization of pelvic cystic mass diagnosed by ultrasound. This exam appears valuable for invalidating the diagnosis of cloacal malformation and for differentiating between isolated genital obstruction and urogenital sinus.

Anorectal Malformations: Finding the Pathway out of the Labyrinth

Anorectal malformations (ARMs) are a complex group of congenital anomalies involving the distal anus and rectum, as well as the urinary and genital tracts in a significant number of cases. Most ARMs result from abnormal development of the urorectal septum in early fetal life. In most cases, the anus is not perforated and the distal enteric component ends blindly (atresia) or as a fistula into the urinary tract, genital tract, or perineum. ARMs are also present in a great number of syndromes and associations of congenital anomalies. The classification of ARMs is mainly based on the position of the rectal pouch relative to the puborectal sling, the presence or absence of fistulas, and the types and locations of the fistulas. All of this information is crucial in determining the most appropriate surgical approach for each case. Imaging studies play a key role in evaluation and classification of ARMs. In neonates, clinical and radiologic examinations in the first 3 days of life help determine the type of ARM and the need for early colostomy. In older children, preoperative pelvic magnetic resonance imaging is the most efficient diagnostic method for evaluating the size, morphology, and grade of development of the sphincteric musculature.

Fetal blood flow velocimetry by phase-contrast MRI using a new triggering method and comparison with Doppler ultrasound in a sheep model: a pilot study

OBJECT

We present the first study demonstrating the feasibility of antenatal blood flow velocimetry performing ECG triggered phase-contrast (PC)-MRI in the fetal aorta by using a newly developed Doppler ultrasound trigger.

MATERIALS AND METHODS

Five pregnant sheep carrying singleton fetuses (gestational age 121 days) were anesthetized to undergo fetal 2D PC-MRI in the fetal descending aorta (1.5 T) using a newly developed MR-compatible Doppler ultrasound trigger for fetal cardiac triggering. Inter-operator variability was assessed for PC-MR measurements and reproducibility was tested by repeated scans in one fetus. Inter-modality comparison was performed by Doppler ultrasound velocimetry.

RESULTS

Fetal cardiac triggering was possible in all examinations. PC-MR velocimetry revealed a mean inter-operator variability of 3 ± 5%. Average peak systolic flow velocities of 62.5 ± 4.4 cm/s were in good agreement with Doppler ultrasound measurements of 62.0 ± 9.2 cm/s (p (Lord's U test) ≫ 0.05).

CONCLUSION

Fetal PC-MR velocimetry was successfully performed using the newly developed MR-compatible Doppler ultrasound trigger for intrauterine fetal cardiac triggering, demonstrating high inter-operator and inter-modality agreement. This new method has the high potential for alternative assessment of hemodynamic decompensation of the fetal circulation.

The Frequencies of the Urinary Anomalies which were Detected in a Foetal Autopsy Study

AIM

The detection of foetal urinary abnormalities in the antenatal period will help in an adequate post natal management and it will also have a bearing on the decision of the termination of the pregnancy. The purpose of the present study was to detect urinary anomalies in the antenatal period by doing autopsies of the aborted foetuses.

SETTINGS AND DESIGN

A cross-sectional study.

METHODS AND MATERIAL

A total of 226 aborted foetuses were autopsied. The urinary anomalies which were related to the renal parenchyma, the pelvi-ureteral system and the urinary bladder were recorded. The associated anomalies of the other organ systems were also noted. The incidences of the different urinary anomalies among the aborted foetuses were calculated. The gestational ages at which the various anomalies were detected were also studied.

RESULTS

Twenty nine of the 226 fetuses were detected to have 34 urinary anomalies. Renal agenesis was the single most common anomaly. Overall, the anomalies which were related to the renal parenchyma accounted for 67.65 % of all the urinary anomalies, while the anomalies of the pelvi-ureteral system and the bladder constituted 20.59% of the detected urinary anomalies. The anomalies of the renal parenchyma (renal agenesis and horse-shoe and polycystic kidneys) were more frequently seen in the foetuses with a shorter gestational age as compared to the gestational ages of the foetuses which showed pelvi-ureteral anomalies. The cumulative incidence of the foetuses with urinary anomalies by 30 weeks of gestation was 12.83%.

CONCLUSIONS

A significant proportion of the aborted foetuses was detected to have urinary anomalies. An early antenatal detection of these and associated anomalies has significance, as this may help in an early postnatal diagnosis and management. The degree and the extent of the detected anomalies could also help in the decision making regarding the therapeutic abortions and the future pregnancies.

Penile biometry on prenatal magnetic resonance imaging

OBJECTIVE

In view of the implementation of magnetic resonance imaging (MRI) as an adjunct to ultrasonography in prenatal diagnosis, this study sought to demonstrate normal penile growth on prenatal MRI.

METHODS

This was a retrospective study of MRI of 194 male fetuses (18-34 weeks' gestation) with normal anatomy or minor abnormalities. On sagittal T2-weighted MRI sequences, we measured penile length from the glans tip to the scrotal edge (outer length) and from the glans tip to the symphyseal border (total length). Descriptive statistics, as well as correlation and regression analysis, were used to evaluate penile length in relation to gestation. T-tests were calculated to compare mean outer/total length on MRI with published ultrasound data.

RESULTS

Mean length values, including 95% CIs and percentiles, were defined. Penile length as a function of gestational age was expressed by the following regression equations: outer mean length = - 5.514 + 0.622 × gestational age in weeks; total mean length = - 8.865 + 1.312× gestational age in weeks. The correlation coefficients, r = 0.532 and r = 0.751, respectively, were statistically significant (P < 0.001). Comparison of outer penile length on MRI with published ultrasound penile length data showed no significant differences, while total penile length on MRI was significantly greater than ultrasound penile length (P < 0.001).

CONCLUSION

Our MRI results provide a reference range of fetal penile length, which, in addition to ultrasonography, may be helpful in the identification of genital anomalies. Outer penile length on MRI is equivalent to penile length measured on ultrasound, whereas total length is significantly greater.

Male sexual development in utero: testicular descent on prenatal magnetic resonance imaging

OBJECTIVE

To visualize in utero male fetal testicular descent on magnetic resonance imaging (MRI) and to correlate it with gestational age.

METHODS

This retrospective study included 202 MRI examination results of 199 male fetuses (17-39 gestational weeks) with normal anatomy or minor congenital abnormalities, following suspicion of anomalies on prenatal ultrasound examination. Using a 1.5-Tesla unit, multiplanar T2-weighted sequences were applied using a standard protocol to image and identify the scrotal content. The relative frequencies of unilateral and bilateral testicular descent were calculated and correlated with gestational age.

RESULTS

Between 17 and 25 gestational weeks, neither unilateral nor bilateral testicular descent was visualized on MRI. Testicular descent was first observed at 25 + 4 weeks, in 7.7% of cases. 12.5% of 27-week fetuses showed unilateral descent and 50% showed bilateral descent. Bilateral descent was observed in 95.7% of cases, on average, from 30 to 39 weeks.

CONCLUSIONS

Our results chart the time course of testicular descent on prenatal MRI, which may be helpful in the identification of normal male sexual development and in the diagnosis of congenital abnormalities, including the early detection of cryptorchidism.

Abnormalities of the penis in utero--hypospadias on fetal MRI

OBJECTIVE

To demonstrate the visualization of penile abnormalities on fetal magnetic resonance imaging (MRI).

METHODS

This retrospective study included five fetuses (25+0 to 31+6 gestational weeks) with penile abnormalities, positively depicted on fetal MRI, using prenatal ultrasonography (US) as a standard of reference. On MRI, the penis, as well as the scrotum and testicles, were evaluated. All fetal organs were reviewed to define penile abnormalities as isolated or in association with other anomalies. Furthermore, US and MRI findings were compared.

RESULTS

Posterior hypospadias were demonstrated in all five fetuses, and abnormal testicular descent in two. Associated anomalies were present in all five fetuses on MRI, including abdominal/urogenital pathologies in four; brain pathologies in three; and craniofacial, cardiac, musculoskeletal, pathologies each in one fetus, and intrauterine growth retardation in one fetus. Compared to US, additional MRI findings were shown in four of five fetuses.

CONCLUSIONS

Our MRI results demonstrate the visualization of fetal penile abnormalities and associated pathologies, which may provide information for perinatal management. MRI may show additional findings compared to prenatal US in certain cases.