Comparison of magnetic resonance urography with ultrasound studies in detection of fetal urogenital anomalies

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.

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.

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.

Imaging in fetal genital anomalies

Genital anomalies are a heterogeneous group of congenital pathologies that have become increasingly relevant since the Chicago Consensus of 2005. Their postnatal diagnosis has developed significantly in the last two decades, while prenatal diagnosis seems to be underdeveloped, with few protocols available, fragmented scientific literature, and low diagnostic rates. This review aims to examine the current status of this subspecialty from the perspective of prenatal imaging. Indications for the evaluation of fetal genitalia can be divided into medical and non-medical reasons. Medical reasons include sex-linked disorders, detection of other anomalies, relevant family history, or multiple pregnancy. Non-medical reasons include parental request for sex disclosure. Disclosure of fetal sex may be associated with ethical, legal, and medical issues. The main imaging technology used is 2D ultrasound, although there are other complementary techniques such as 3D, MRI, or Color Doppler. Regarding working methodology, several authors have drawn attention to the lack of standardized protocols and guidelines. Most guidelines tend to limit their recommendations to study indications and ethical issues. Technical proposals, measurements, or working methods have not yet been standardized. Fetal sex determination is usually divided into early and late gestation. Early gestation is based on the sagittal sign. Late gestation is based on direct visualization. There are several measurements to describe male and female genitalia, such as penile length, bilabial diameter, or scrotal diameter. Prenatal diagnosis of genital pathologies presents some particularities such as the wide spectrum of phenotypes, the high frequency of associated deformities, or the time of diagnosis. Some of the most frequent pathologies are ambiguous genitalia, fetal sex discordance, hypospadias, micropenis, clitoromegaly, ovarian cysts, hydro(metro)colpos, and cloacal anomalies. Higher-quality studies and direction from scientific societies through the implementation of clinical guidelines are needed.

A Case of Multicystic Dysplastic Kidney Presenting as a Single Midline Pelvic Cyst

We present an unusual case of a female neonate presenting with a single midline pelvic cyst. Prenatal imaging was suggestive of multicystic dysplastic kidney (MCDK), but postnatal imaging was atypical for this diagnosis given the location and singular cyst noted. The patient ultimately underwent surgical exploration and was diagnosed with an ectopic MCDK. Ectopic MCDK should be considered in the differential diagnosis of unilocular cystic pelvic lesions identified in the perinatal period.

Posterior urethral valves: Role of prenatal diagnosis and long-term management of bladder function; a single center point of view and review of literature

Posterior Urethral Valves (PUV) are the most common cause of lower urinary tract obstruction. More severe forms are detected early in pregnancy (mainly type I), while other forms are usually discovered later in childhood when investigating lower urinary tract symptoms. Bladder dysfunction is common and is associated with urinary incontinence in about 55% (0%-72%). Despite the removal of the obstruction by urethral valve ablation, pathological changes of the urinary tract can occur with progressive bladder dysfunction, which can cause deterioration of the upper urinary tract as well. For this reason, all children with PUV require long-term follow-up, always until puberty, and in many cases life-long. Therefore, management of PUV is not only limited to obstruction relief, but prevention and treatment of bladder dysfunction, based on urodynamic observations, is paramount. During time, urodynamic patterns may change from detrusor overactivity to decreased compliance/small capacity bladder, to myogenic failure (valve bladder). In the past, an aggressive surgical approach was performed in all patients, and valve resection was considered an emergency procedure. With the development of fetal surgery, vesico-amniotic shunting has been performed as well. Due to improvements of prenatal ultrasound, the presence of PUV is usually already suspected during pregnancy, and subsequent treatment should be performed in high-volume centers, with a multidisciplinary, more conservative approach. This is considered to be more effective and safer. Primary valve ablation is performed after clinical stability and is no longer considered an emergency procedure after birth. During childhood, a multidisciplinary approach (pediatric urologist, nephrologist, urotherapist) is recommended as well in all patients, to improve toilet training, using an advanced urotherapy program with medical treatments and urodynamic evaluations. The aim of this paper is to present our single center experience over 30 years.

Real-Life Diagnostic Accuracy of MRI in Prenatal Diagnosis

There is some controversy about the value of fetal MRI in prenatal diagnosis, and most of the studies examine its accuracy in central nervous system (CNS) pathology. The objective of this retrospective study was to assess the diagnostic accuracy and usefulness of fetal MRI in the prenatal diagnosis of central nervous system (CNS) pathology and non-CNS pathology. Patients referred to the Radiology Department between 2007 and 2018 for a fetal MRI after detection of an anomaly in the fetal ultrasound, a high-risk pregnancy, or an inconclusive fetal ultrasound (n = 623) were included in the study. Postnatal diagnosis was used to assess the diagnostic accuracy of MRI. Fetal MRI was considered to provide additional information over fetal ultrasound when findings of the fetal MRI were not detected in the fetal ultrasound or when established a pathological condition that was not detected in the fetal ultrasound. Fetal MRI provided useful information for the perinatal management and prognosis over fetal ultrasound when findings of the fetal MRI changed the postnatal prognosis, leaded to the decision to legally terminate the pregnancy, changed prenatal or postnatal follow-up, or helped in the planning of prenatal or postnatal treatment. Fetal MRI offered an accurate diagnosis in 97% of cases (compared to 90.4% of fetal ultrasound; p < 0.001). Concordance between fetal ultrasound and fetal MRI was 92.1%. Fetal MRI provided additional information over fetal ultrasound in 23.1% of cases. In 11.6% of cases, the information was useful for the perinatal management and prognosis. In 45 cases (7.2%), fetal MRI was the only accurate diagnosis. In conclusion, fetal MRI has a superior diagnostic accuracy, especially in CNS pathology, and provides additional useful information in CNS, thoracic, and abdominal pathology.

Prenatal Diagnosis and Findings in Ureteropelvic Junction Type Hydronephrosis

The widespread use of obstetric ultrasonography has increased the detection rate of antenatal hydronephrosis. Although most cases of antenatal hydronephrosis are transient, one third persists and becomes clinically important. Ultrasound has made differential diagnosis possible to some extent. Ureteropelvic junction type hydronephrosis (UPJHN) is one of the most common cause of persistent fetal hydronephrosis and occurs three times more in male fetuses. It is usually sporadic and unilateral. However, when bilateral kidneys are involved and presents with severe hydronephrosis, the prognosis may be poor. Typical ultrasound findings of UPJHN is hydronephrosis without hydroureter. The size and appearance of the fetal bladder is usually normal without thickening of the bladder wall. Several grading systems are developed and increasingly being used to define the severity of prenatal hydronephrosis and provides much more information about prediction of postnatal renal prognosis. If fetal urinary tract dilation is detected; laterality, severity of hydronephrosis, echogenicity of the kidneys, presence of ureter dilation should be assessed. Bladder volume and emptying, sex of the fetus, amniotic fluid volume, and presence of associated malformations should be evaluated. Particularly the ultrasonographic signs of renal dysplasia, such as increased renal parenchymal echogenicity, thinning of the renal cortex, the presence of cortical cysts, and co-existing oligohydramnios should be noticed. Unfortunately, there is no reliable predictor of renal function in UPJHN cases. Unilateral hydronephrosis cases suggesting UPJHN are mostly followed up conservatively. However, the cases with bilateral involvement are still difficult to manage. Timing of delivery is also controversial.

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.

Prenatal Urinary Tract Dilatation

Urinary tract dilatation (UTD) is the most common congenital anomaly detected on prenatal ultrasonography (US), affecting 1% to 3% of all pregnancies. This article focuses on the prenatal detection of UTD and the postnatal evaluation and management based on the UTD grading system risk assessment. Prophylactic antibiotics and postnatal imaging are discussed. The recent management trend is for a more conservative approach to minimize unnecessary testing and exposures to the fetus and neonate while detecting those who may have clinically significant disorder. The renal bladder US remains a critical part of the evaluation and helps guide further investigations.

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.

Agreement between static magnetic resonance urography and diuretic renal scintigraphy in patients with ureteropelvic junction obstruction after pyeloplasty

BACKGROUND

Ureteropelvic junction obstruction (UPJO) is the most common cause of hydronephrosis within childhood that usually treat by surgery. According to anatomical variations in different individuals, scheduling similar procedures for all patients is not suitable, and thus the best decision for an appropriate surgical technique should be considered separately for each patient. Regardless of the type of applied technique, creating a funnel-shape UPJ with a suitable size is a successful treatment. In this context, the assessment of a successful surgical treatment in a short-term follow-up means repairing revealed anatomical defects. The present study aimed to compare the diagnostic value of static magnetic resonance urography (MRU) and diuretic-based renalscintigraphy (DRS) in patients with UPJO after pyeloplasty.

MATERIALS AND METHODS

A total of 30 consecutive patients with UPJO, who underwent unilateral pyeloplasty between 2012 and 2013 were assessed. All subjects underwent DRS and also MRU about 1-month after the former procedure.

RESULTS

The Kendall's tau correlation showed a very strong correlation between results of MRU and diuretic renal scintigraphy (r = 0.932, P < 0.001). This strong correlation was also shown by Somers'd test (r = 0.932, P < 0.001) similarly.

CONCLUSIONS

Our study shows a strong agreement between DRS and MRU to assess UPJO. MRU static fluid has a high accuracy for assessment of renal system anatomy. Due to the lack of dangerous consequences of contrast materials, MRU can be the best option instead of DRS.

Renal dysplasia

Renal dysplasia is an aberrant developmental disease usually diagnosed during the perinatal and childhood years. Prevalence is estimated at 0.1% of infants (via ultrasound screening) and 4% of fetuses and infants (via autopsy study). Occurrences may be combined with abnormalities in the collecting system or associated with complex syndromes. Histopathology shows primitive tubules surrounded by a fibromuscular collar. The differential diagnosis includes renal dysplasia, hypoplasia, and renal atrophy. Immunohistochemical expression of the paired box genes 2 and 8 (PAX2/8) and Wilms tumor 1 (WT1) is increased in the primitive ducts and fibromuscular collar, respectively. Renal dysplasia pathogenesis is not well understood, but may be caused by a nephron-inductive deficit due to ampullary inactivity or abnormal budding of the ureteric bud from the mesonephric duct. Either the PAX2 mutation only or cross-talk with the p53 pathway is involved in this deficit. Nephrectomy is the treatment of choice for symptomatic renal dysplasia.

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.

Prenatal diagnosis of bladder exstrophy by fetal MRI

PURPOSE

To review our experience with prenatal diagnosis of bladder exstrophy by fetal magnetic resonance imaging (MRI). Bladder exstrophy can be diagnosed by ultrasonography (US) evaluation of the fetus based on absence of bladder filling, low-set umbilicus, small genitalia and lower abdominal mass, although in some instances more accurate anatomical information is desired.

MATERIAL AND METHODS

We studied three patients at mean gestational age of 27.3 weeks. The fetal MRI exam was performed on axial, sagittal, coronal planes and echo gradient in the best plan for acquisition of fetus. Images were analyzed by a group of three radiologists with experience in fetal MRI.

RESULTS

The MRI defined a lower abdominal mass prolapsing below the umbilical vessels, having the ureters ending on it in an anterior position. A cloacal malformation or a cloacal exstrophy could be excluded, as well as other accompanying spinal abnormalities. The renal system and oligohydramnios could be well documented.

CONCLUSIONS

The MRI showed a detailed scenario of the abnormality with advantages over the US evaluation in regard to excluding cloacal anomalies. MRI allowed accurate sexual differentiation and may be indicated after suspected bladder exstrophy on US evaluation.

Multicystic dysplastic kidney disease presenting with a single large cyst in a fetus-anatomical basis and radiological aspects

Multicystic dysplastic kidney (MCDK) is a congenital maldevelopment in which the renal cortex is characteristically replaced by numerous cysts of multiple sizes. MCDK presenting as a single predominant large cyst in morphology is less common. We report on the prenatal imaging findings and perinatal management of a fetus with MCDK unusually presenting as a single predominant large cyst, erroneously interpreted as a severe fetal hydronephrosis. Details of the perinatal history, radiological evaluation, morphological characteristic, and clinical aspect of this case are presented. We also discuss a few studies addressing the sensitivity of magnetic resonance urography for the prenatal diagnosis of MCDK.

Bladder agenesis and bilateral ectopic ureters draining into the vagina in a female infant: demonstrated by MR imaging

Complete agenesis of the bladder and urethra is an extremely rare congenital anomaly and most of these patients are stillborn or die during infancy. We report the case of a 1-month-old female infant with bladder and urethral agenesis who presented with bilateral dilated and tortuous ectopic ureters draining into the vagina diagnosed using MR imaging. Our patient was maintained on antibiotic prophylaxis and she remained well during the 3-year follow-up. MR imaging can be used as a valuable modality for genitourinary abnormalities, particularly in cases of inconclusive ultrasound or retrograde pyelography findings.

Precise delineation of ureterocele anatomy: virtual magnetic resonance cystoscopy

PURPOSE

To evaluate the application of virtual magnetic resonance cystoscopy (VMRC) in precise detection of ureterocele extension compared with conventional cystoscopy (as the gold standard) and other imaging modalities.

MATERIALS AND METHODS

Medical records of 55 patients, with confirmed diagnosis of ureterocele during endoscopic surgery, were reviewed retrospectively. Thirty-two of them (14 girls and 18 boys, age range: 4-22 months) whom underwent investigation with magnetic resonance urography, voiding cystourethrography, and ultrasonography were included. Images were obtained using T1-scanner with pulse sequences (TR = 30-50 ms, TE = 2-8 ms, echo train length = 8 moderate, filip angel = 40°). Using multiplanar reformation from source images, the bladder was evaluated to determine ureterocele anatomy. Virtual findings were compared with other imaging studies.

RESULTS

Cystoscopy confirmed 3(9%) bilateral and 9(28%) unilateral intravesical ureteroceles, and 20(63%) ectopic type. VMRC was the most sensitive method in detection of ureterocele anatomy and its extension (detection rate: 94%) It detected one case of bilateral intravesical and three ectopic types, which were not detected in other imaging modalities.

CONCLUSION

VMRC is a promising non-invasive technique in exact detection of ureterocele extension prior to endoscopic operation. It permits evaluation of concurrent genitourinary abnormalities and facilitates preoperative planning especially in complex ectopic ureteroceles. It may be indicated as a clinical routine, when conventional cystoscopy is contraindicated.