Fetal Anomalies: Comparison of MR Imaging and US for Diagnosis

How to Perform Fetal MR Imaging

This article provides the readers with practical guidance on how to perform fetal MR imaging, including technical considerations such as scanner field strength and use of appropriate radiofrequency receive coils, and summarizes the role, strengths, and limitations of the various MR imaging sequences. The authors review the various factors to consider in scan preparation, including study indication, timing, maternal preparation, and the creation of an institutional fetal imaging protocol. Additional factors that go into scan optimization during acquisition including prioritizing maternal comfort and ways to troubleshoot various artifacts that maybe encountered in fetal imaging are discussed.

Examining Craniofacial and Velopharyngeal Structures in Premature Infants: A Window Into the Womb

BACKGROUND

Very little is known about how the velopharynx and levator veli palatini muscle develop in utero. The purpose of this study was to describe craniofacial, velopharyngeal, and levator veli palatini dimensions in a group of infants born prematurely and imaged before 40 weeks gestation.

METHODS

A retrospective, descriptive study design was utilized to examine the MRI scans of 6 infants less than 40 weeks' gestation. Imaging was initially completed for medically necessity and pulled from patients' charts retrospectively for the purpose of this study. Craniofacial, velopharyngeal, and levator veli palatini dimensions were analyzed.

RESULTS

All linear measures were consistently shorter across all variable categories. While effective VP ratio was less favorable for speech in infants under 40 weeks' gestation, angle measures such as LVP angle of origin, NSB angle, SNA angle, and SNB angle were relatively unchanged.

CONCLUSIONS

Linear craniofacial, VP, and LVP variables tend to be smaller in infants under 40 weeks' gestation than those reported within the first 6 months of life while angulation is relatively similar. Future research in this area may be relevant to better diagnosis of craniofacial conditions in utero.

Fetal neurosurgery

Among fetal surgical procedures, neurosurgery stands out due to the number of cases and the possibility of developing new procedures that can be performed in the fetal period. To perform fetal neurosurgical procedures, there is a need for specialized centers that have experts in the diagnosis of fetal pathologies and a highly complex obstetrics service with specialized maternal-fetal teams associated with a pediatric neurosurgery center with expertise in the diverse pathologies of the fetus and the central nervous system that offers multidisciplinary follow-up during postnatal life. Services that do not have these characteristics should refer their patients to these centers to obtain better treatment results. It is essential that the fetal neurosurgical procedure be performed by a pediatric neurosurgeon with extensive experience, as he will be responsible for monitoring these patients in the postnatal period and for several years. The objective of this manuscript is to demonstrate the diagnostic and treatment possibilities, in the fetal period, of some neurosurgical diseases such as hydrocephalus, tumors, occipital encephalocele, and myelomeningocele.

Efficacy of Systematic Early-Second-Trimester Ultrasound Screening for Facial Anomalies: A Comparison between Prenatal Ultrasound and Postmortem Findings

Second-trimester 2D ultrasound (US) assessment of the fetal anatomy, as proposed by worldwide guidelines, allows detecting the majority of fetal malformation. However, the detection rates of fetal facial anomalies seem to still be low, mostly in cases of isolated facial malformation. The purpose of this research was to assess and analyze the concordance between the antenatal imaging findings from second-trimester US screening and the results of fetal postmortem autopsy. Between January 2010 and January 2020, there were 43 cases where fetuses with prenatal ultrasound diagnosis of a face abnormality, associated or not with a genetic syndrome or chromosomal disorder, following intrauterine death (IUD) or termination of pregnancy (TOP) after the 13 weeks of pregnancy, underwent autopsy in the Pathological Anatomy section of Bari Polyclinic specializing in feto-placental autopsies. The diagnosis of the fetal facial defects at ultrasound was compared with the findings at autopsy in all cases. A very high level of agreement between prenatal ultrasound and autopsy findings was found for facial abnormalities associated with genetic syndromes or numerical abnormality of chromosomes. A lower level of concordance was instead found in isolated facial defects or those associated with other organ anomalies, but not associated with genetic syndrome or numerical chromosome anomaly. A detailed examination of aborted fetuses led to successful quality control of early-second-trimester ultrasound detection of facial anomalies; however, it was less accurate for the isolated ones. It is, thus, reasonable to propose a systematic early-second-trimester prenatal ultrasound screening for facial anatomy by operators specialized in fetal medicine field, using 2D, 3D, and 4D techniques (two-, three-, and four-dimensional ultrasound).

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.

A Spectrum of Ultrasound and MR Imaging of Fetal Gastrointestinal Abnormalities: Part 2 Anorectal Malformation, Liver, and Abdominal Wall Anomalies

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.

Fetal MRI Neuroradiology: Indications

Fetal MRI is a safe, noninvasive examination of the fetus and placenta, a complement to ultrasonography. MRI provides detailed CNS evaluation, including depicting parenchymal architecture and posterior fossa morphology, and is key in prenatal assessment of spinal dysraphism, neck masses, and ventriculomegaly. Fetal MRI is typically performed after 22 weeks gestation, and ultrafast T1 and T2-weighted MRI sequences are the core of the exam, with advanced sequences such as diffusion weighted imaging used for specific questions. The fetal brain grows and develops rapidly, and familiarity with gestational age specific norms is essential to MRI interpretation.

A comparison of the accuracy of fetal magnetic resonance imaging and ultrasonography for the diagnosis of fetal congenital malformations of the spine and spinal cord

PURPOSE

To determine the diagnostic value of fetal magnetic resonance imaging (MRI) for congenital spine/spinal cord malformations.

METHODS

This single-center retrospective study included 120 cases of fetal spine/spinal cord abnormalities detected using fetal ultrasonography (US) and further examined by fetal MRI between 2016 and 2020. Cases were divided into three groups (congenital spine, spinal cord, and spine + spinal cord malformations) based on US assessment. We analyzed the accuracy of fetal US and MRI relative to postnatal imaging.

RESULTS

The diagnostic accuracy of fetal MRI for fetal spinal cord, spine, and spine + spinal cord malformations was 86.2% (25/29), 89.4% (42/47), and 86.3% (38/44), respectively, and the corresponding rates for fetal US were 51.7% (15/29), 87.2% (41/47), and 68.2% (30/44). The diagnostic accuracy did not differ between fetal MRI and US for congenital spine malformations (P > 0.05); for congenital spinal cord malformations and congenital spine+spinal cord malformations, the diagnostic accuracy was significantly higher for fetal MRI than for fetal US (P < 0.05).

CONCLUSIONS

Fetal MRI is effective in the assessment of congenital spine/spinal cord malformations. It can yield information that supplements US findings, especially for congenital spinal cord malformations, and can improve the accuracy of fetal diagnosis. This article is protected by copyright. All rights reserved.

Fetal brain MRI: how it added to ultrasound diagnosis of fetal CNS anomalies-1 year experience

Background

Central nervous system (CNS) anomalies are the most commonly diagnosed abnormalities of all fetal malformations and are usually primarily discovered on routine prenatal ultrasonography (US). Fetal magnetic resonance imaging (MRI) is a non-invasive technology with high soft tissue contrast that is documented to increase the diagnostic accuracy for detection of fetal brain anomalies.

The aim of our study is to analyze the value of adding magnetic resonance imaging (MRI) of the fetal brain to antenatal ultrasound in the diagnosis of fetal central nervous system (CNS) anomalies.

Results

We diagnosed various CNS anomalies including twelve cases with infra- and supra-tentorial arachnoid cysts, six cases had Dandy-Walker malformation (DWM) and its variants, 1 case with mega cisterna magna, 2 cases of holoprosencephaly, 1 case of hydranencephaly, 2 cases with supratentorial hydrocephalus, 1 case of craniopharyngioma, 6 cases with corpus callosum (CC) agenesis, 1 case of extradural hematoma, and 8 cases with Meckel-Gruber syndrome (MGS). MRI diagnosis confirmed the ultrasound finding, without additional information in 23 cases (57.5%%), added an extra finding in 11 cases (27.5%), differentiated between 2 pathologies in 3 cases (7.5%), and changed the diagnosis in 3 cases (7.5 %).

The 40 pregnancies resulted in 27 births (67.5%), 2 died directly after birth (5%), 7 terminations (17.5%), and 4 intrauterine fetal deaths (IUFD) (10 %).

Conclusion

Ultrasound is the gold standard imaging modality for anomaly scan in the second and third trimesters; however, MRI of the fetal brain might be a clinically valuable complement especially when ultrasound examination is inconclusive due to maternal obesity, severe oligohydramnios, or in complicated cases with unclear diagnosis.

ACR Appropriateness Criteria® Second and Third Trimester Screening for Fetal Anomaly

The Appropriateness Criteria for the imaging screening of second and third trimester fetuses for anomalies are presented for fetuses that are low risk, high risk, have had soft markers detected on ultrasound, and have had major anomalies detected on ultrasound. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

IntraVoxel Incoherent Motion (IVIM) MRI of fetal lung and kidney: Can the perfusion fraction be a marker of normal pulmonary and renal maturation?

PURPOSE

To investigate the use of IntraVoxel Incoherent Motion (IVIM) MRI in the study of microstructural tissue changes occurring in fetal lung and kidney during gestation.

METHODS

34 normal pregnancies were enrolled. Patients were divided into two groups based on gestational age (GA): group A (21-29 weeks) and group B (30-39 weeks). MR examinations were performed at 1.5T, with a standard fetal MR protocol including a Diffusion-Weighted Echo-Planar Imaging sequence with 10 different b-values (0, 10, 30, 50, 75, 100, 200, 400, 700, 1000s/mm²). For each fetus, two bilateral ROIs were manually placed in lung and renal parenchyma. Mean values of perfusion fraction f, pseudo-diffusion coefficient D* and diffusion coefficient D were obtained. The correlation between IVIM parameters and GA was investigated.

RESULTS

In renal ROIs a positive correlation between f_kidney and GA (p < 0.005) was found; similarly f_lung showed a statistically significant correlation with GA (p < 0.001). F mean values were significantly higher in group B compared to group A in both renal (p = 0.0002) and lung (p = 0.018) ROIs. No correlation was found in D and D* as a function of GA.

CONCLUSIONS

The IVIM perfusion fraction f may be considered as a potential marker of pulmonary and renal maturation in relation to hemodynamic changes described in intrauterine life. Our results highlight that IVIM model is useful as an additional prenatal diagnostic tool to study lung and renal development.

The importance of a thorough clinical examination in adolescent girls presenting with acute urinary retention

We present an adolescent girl with a 1-day history of acute urinary retention and lower abdominal pain. She was admitted to the paediatric ward for ongoing treatment and investigations. Due to a myriad of factors including pain and anxiety, challenges posed included an incomplete initial abdominal and external genital examination. This case report highlights the importance of a focused history and performing an appropriate sensitive examination at the time of presentation. Furthermore, we explore the common causes of new onset urinary retention and unravel the case as it unfolds. We also highlight differential diagnoses (however, uncommon), which must be considered and not overlooked to avoid unnecessary investigations and to ensure timely management.

The application of in utero magnetic resonance imaging in the study of the metabolic and cardiovascular consequences of the developmental origins of health and disease

Observing fetal development in utero is vital to further the understanding of later-life diseases. Magnetic resonance imaging (MRI) offers a tool for obtaining a wealth of information about fetal growth, development, and programming not previously available using other methods. This review provides an overview of MRI techniques used to investigate the metabolic and cardiovascular consequences of the developmental origins of health and disease (DOHaD) hypothesis. These methods add to the understanding of the developing fetus by examining fetal growth and organ development, adipose tissue and body composition, fetal oximetry, placental microstructure, diffusion, perfusion, flow, and metabolism. MRI assessment of fetal growth, organ development, metabolism, and the amount of fetal adipose tissue could give early indicators of abnormal fetal development. Noninvasive fetal oximetry can accurately measure placental and fetal oxygenation, which improves current knowledge on placental function. Additionally, measuring deficiencies in the placenta’s transport of nutrients and oxygen is critical for optimizing treatment. Overall, the detailed structural and functional information provided by MRI is valuable in guiding future investigations of DOHaD.

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.

Fetal magnetic resonance imaging contributes to the diagnosis and treatment of meconium peritonitis

BACKGROUND

Meconium peritonitis (MP) is a rare fetal disease that needs to be urgently identified for surgical intervention. We report a series of 35 patients diagnosed prenatally with MP by magnetic resonance imaging (MRI), illustrate the imaging findings and investigate the predictive value of these findings for postpartum management.

METHOD

A consecutive cohort of patients diagnosed with MP who were born at our institution from 2013 to 2018 was enrolled retrospectively. The prenatal ultrasound and MRI findings were analyzed. Fisher's exact probability test was used to evaluate the predictive value of MRI for surgical intervention between the operative group and the nonoperative group.

RESULTS

Ascites (30/35) and distended bowel loops (27/35) were two of the most common prenatal MP-related findings on fetal MRI. Of the 35 infants, 26 received surgical intervention. All fetuses with MRI scans showing bowel dilatation (14/26, p = 0.048) and micro-colorectum (13/26, p = 0.013) required surgery. There were no significant differences in the number of fetuses with meconium pseudocysts and peritoneal calcifications between the two groups.

CONCLUSION

Fetuses with bowel dilatation and micro-colorectum on MRI may need postpartum surgical intervention. Infants with only a small amount of ascites and slight bowel distention were likely to receive conservative treatment.

Prenatal diagnosis of congenital head, face, and neck malformations-Is complementary fetal MRI of value?

OBJECTIVES

The aim of this study was to evaluate the role of fetal magnetic resonance imaging (MRI) as a complement to ultrasound (US) in the prenatal diagnosis of craniofacial anomalies.

METHODS

A historical cohort study including all pregnant women who were referred for fetal MRI because of antenatal diagnosis of craniofacial anomalies on screening US. Prenatal diagnostic US, MRI, and postnatal diagnosis were compared for consistencies and discrepancies.

RESULTS

Forty-five pregnant women with 73 suspected fetal craniofacial anomalies diagnosed by US underwent MRI. In 40 out of 73 anomalies (54.8%), US and MRI findings were in complete agreement with postnatal diagnoses. MRI correctly ruled out the diagnosis of 24 anomalies suspected on US and diagnosed four additional pathologies that were not demonstrated by US. Out of the 85 anomalies (suspected by imaging or confirmed postnatally), confident diagnosis could be made by MRI in 68 anomalies (80%), not diagnosed in 10 (11.8%), and over-diagnosed in seven (8.2%). By US, confident diagnosis could be made in 44 anomalies (51.8%), not diagnosed in 11 (12.9%), and over-diagnosed in 30 (35.3%).

CONCLUSION

MRI is valuable in the antenatal evaluation of fetal craniofacial anomalies and may be useful as an adjunct to US in the prenatal work-up of craniofacial anomalies.

A simulation study on the effect of optimized high permittivity materials on fetal imaging at 3T

PURPOSE

One of the main concerns in fetal MRI is the radiofrequency power that is absorbed both by the mother and the fetus. Passive shimming using high permittivity materials in the form of "dielectric pads" has previously been shown to increase the B 1 + efficiency and homogeneity in different applications, while reducing the specific absorption rate (SAR). In this work, we study the effect of optimized dielectric pads for 3 pregnant models.

METHODS

Pregnant models in the 3rd, 7th, and 9th months of gestation were used for simulations in a birdcage coil at 3T. Dielectric pads were optimized regions of interest (ROI) using previously developed methods for B 1 + efficiency and homogeneity and were designed for 2 ROIs: the entire fetus and the brain of the fetus. The SAR was evaluated in terms of the whole-body SAR, average SAR in the fetus and amniotic fluid, and maximum 10 g-averaged SAR in the mother, fetus, and amniotic fluid.

RESULTS

The optimized dielectric pads increased the transmit efficiency up to 55% and increased the B 1 + homogeneity in almost every tested configuration. The B 1 + -normalized whole-body SAR was reduced by more than 31% for all body models. The B 1 + -normalized local SAR was reduced in most scenarios by up to 62%.

CONCLUSION

Simulations have shown that optimized high permittivity pads can reduce SAR in pregnant subjects at the 3rd, 7th, and 9th month of gestation, while improving the transmit field homogeneity in the fetus. However, significantly more work is required to demonstrate that fetal imaging is safe under standard operating conditions.

MR Imaging of Fetal Musculoskeletal Disorders

This article outlines the main findings in prenatal musculoskeletal disorders. Three main technologies are generally used to obtain images within the uterus during pregnancy: ultrasound (US), MR imaging, and computed tomography (CT). Currently, the primary imaging method used for fetal assessment during pregnancy is US because it is patient friendly, useful, cost-effective, and (considered) safe. MR imaging is generally performed when US yields equivocal results because it offers additional information about fetal abnormalities and conditions in situations in which US is unable to provide high-quality images.

The role of a novel magnetic resonance imaging sequence in the evaluation of the fetal skeleton: a pilot study

Objective

We aimed to study the role of magnetic resonance imaging (MRI), including a novel MRI sequence-the modified volumetric interpolated breath-hold examination (VIBE)-in the characterization of the fetal skeleton. This novel sequence was useful for reconstructing three-dimensional images of the skeleton.

Materials and Methods

We enrolled 22 pregnant women whose fetuses had shown congenital abnormalities on ultrasound examinations. The women underwent prenatal fetal MRI in a 1.5-T scanner with a T2-weighted modified VIBE sequence. Three-dimensional reconstructions of the fetal skeleton were performed manually on the instrument itself or via an interactive pen-tablet workstation.

Results

Three-dimensional reconstructions of the fetal skeleton were performed after the acquisition of modified VIBE MRI sequences, and it was possible to characterize the fetal skeleton in all MRI examinations.

Conclusion

A detailed evaluation of the three-dimensional reconstructions of fetal skeleton performed after acquisition of a modified VIBE MRI sequence allowed a full characterization of the skeleton. However, improvements to the proposed sequence should be addressed in future studies.

Fetal Lung Volumes by MRI: Normal Weekly Values From 18 Through 38 Weeks' Gestation

OBJECTIVE

The purpose of this study is to establish normal total fetal lung volume reference ranges from 18 to 38 weeks' gestation at 1-week intervals.

MATERIALS AND METHODS

A retrospective analysis of 665 patients who underwent fetal MRI at two tertiary fetal centers from 2001 to 2013 was performed. Total fetal lung volume was measured in at least two planes, either manually or using a 3D workstation. The mean, median, SD, minimum, maximum, and lower and upper quartiles for total fetal lung volume were determined per gestational week. A t test was used to compare our values to previously reported values. A new formula to calculate total fetal lung volume derived from our data was created using a regression model. Comparisons between total fetal lung volume obtained by different imaging planes and manual versus semiautomatic calculation were also performed.

RESULTS

The mean normal total fetal lung volume showed a weekly increase from 18 through 35 weeks' gestation. Means were compared with the expected total fetal lung volume generated by the Rypens formula, showing statistically significant lower mean total fetal lung volume from week 19 to week 22 (p < 0.05). Comparison between our data-derived total fetal lung volume formula and the Rypens formula showed very similar values at every gestational age. No difference in total fetal lung volume was seen when comparing imaging planes or manual versus semiautomatic methods.

CONCLUSION

Measured mean total fetal lung volume values at 19-22 weeks are significantly lower than those predicted by the Rypens formula. Therefore, we propose preferential use of our values for prenatal counseling and delivery planning.

Three-dimensional reconstruction of fetal abnormalities using ultrasonography and magnetic resonance imaging

Objective: We aimed to compare three-dimensional (3D) fetal malformation images obtained using ultrasonography (US) and magnetic resonance imaging (MRI) on the same day during the third trimester of pregnancy. Methods: Total 33 fetuses were selected from cases evaluated for malformations. Morphological abnormalities were first scanned using 3DUS. MRI was used to confirm the previous preliminary 3DUS findings, and diagnoses were confirmed postnatally. 3DUS scans were performed transabdominally using an Rab (4-8 L) probe, Voluson 730 Pro/Expert and E8 (General Electric, Healthcare, Zipf, Austria). MRI was performed using a 1.5-T scanner (Magneton Avanto, Siemens, Erlangen, Germany) with a body coil. The 3D reconstruction of the structure of interest was manually performed from a True FISP sequence using an interactive pen tablet (Syngo multimodality 2009B, Siemens, Erlangen, Germany). Results: Despite recent advancements in 3DUS, the quality of 3D images obtained from MRI was superior during the third trimester. 3DUS had certain limitations, such as being influenced by the fetal position, the volume of amniotic fluid, and maternal obesity. Fetal movements during image acquisition were one of the main challenges for MRI. Conclusion: The quality of the 3D images obtained using MRI was superior to that of images obtained using US during the third trimester of pregnancy.

Different information by MRI compare to ultrasound in fetal intracranial space occupying lesions

PURPOSE

The purpose of this study was to evaluate the value of prenatal magnetic resonance imaging (MRI) in characterizing fetal intracranial space occupying lesions in comparison to prenatal ultrasound.

METHODS

This retrospective study included 50 fetuses (mean age 26 years, mean gestational weeks 31 + 1 GW) with intracranial space occupying lesions, suspected by prenatal screening ultrasound. T2-weighted, T1-weighted, SSFP, and diffusion-weighted sequences of the fetal brain were obtained on a 1.5 T unit. Pathology (n = 5), postmortem MRI (n = 3), or postnatal US (n = 42) was available as standard of reference.

RESULTS

The fetal MRI provided correct diagnosis in 49 cases (98%), while 35 (70%) by ultrasound, and MRI failed in 1 case (2%), while ultrasound failed in 15 cases (30%). Fetal MR and ultrasound were concordant in 35 of 50 cases (70%), completely discordant in 4 (8%), and partially discordant in 11 (22%) cases.

CONCLUSIONS

MRI could provide detailed information about the minor lesions, such as focal hemorrhage and periventricular nodules. Meanwhile, it could provide whole view of the lesion in order to delineate the surrounding anatomical structure. But there are still some limitations of its soft-tissue resolution in a case with teratoma; more effort is needed to improve the sequences.

PVR: Patch-to-Volume Reconstruction for Large Area Motion Correction of Fetal MRI

In this paper, we present a novel method for the correction of motion artifacts that are present in fetal magnetic resonance imaging (MRI) scans of the whole uterus. Contrary to current slice-to-volume registration (SVR) methods, requiring an inflexible anatomical enclosure of a single investigated organ, the proposed patch-to-volume reconstruction (PVR) approach is able to reconstruct a large field of view of non-rigidly deforming structures. It relaxes rigid motion assumptions by introducing a specific amount of redundant information that is exploited with parallelized patchwise optimization, super-resolution, and automatic outlier rejection. We further describe and provide an efficient parallel implementation of PVR allowing its execution within reasonable time on commercially available graphics processing units, enabling its use in the clinical practice. We evaluate PVR's computational overhead compared with standard methods and observe improved reconstruction accuracy in the presence of affine motion artifacts compared with conventional SVR in synthetic experiments. Furthermore, we have evaluated our method qualitatively and quantitatively on real fetal MRI data subject to maternal breathing and sudden fetal movements. We evaluate peak-signal-to-noise ratio, structural similarity index, and cross correlation with respect to the originally acquired data and provide a method for visual inspection of reconstruction uncertainty. We further evaluate the distance error for selected anatomical landmarks in the fetal head, as well as calculating the mean and maximum displacements resulting from automatic non-rigid registration to a motion-free ground truth image. These experiments demonstrate a successful application of PVR motion compensation to the whole fetal body, uterus, and placenta.

Magnetic resonance imaging of fetal persistent left superior vena cava

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

Placenta Maps: In Utero Placental Health Assessment of the Human Fetus

The human placenta is essential for the supply of the fetus. To monitor the fetal development, imaging data is acquired using (US). Although it is currently the gold-standard in fetal imaging, it might not capture certain abnormalities of the placenta. (MRI) is a safe alternative for the in utero examination while acquiring the fetus data in higher detail. Nevertheless, there is currently no established procedure for assessing the condition of the placenta and consequently the fetal health. Due to maternal respiration and inherent movements of the fetus during examination, a quantitative assessment of the placenta requires fetal motion compensation, precise placenta segmentation and a standardized visualization, which are challenging tasks. Utilizing advanced motion compensation and automatic segmentation methods to extract the highly versatile shape of the placenta, we introduce a novel visualization technique that presents the fetal and maternal side of the placenta in a standardized way. Our approach enables physicians to explore the placenta even in utero. This establishes the basis for a comparative assessment of multiple placentas to analyze possible pathologic arrangements and to support the research and understanding of this vital organ. Additionally, we propose a three-dimensional structure-aware surface slicing technique in order to explore relevant regions inside the placenta. Finally, to survey the applicability of our approach, we consulted clinical experts in prenatal diagnostics and imaging. We received mainly positive feedback, especially the applicability of our technique for research purposes was appreciated.

A systematic review and meta-analysis to determine the contribution of mr imaging to the diagnosis of foetal brain abnormalities In Utero

Objectives

This systematic review was undertaken to define the diagnostic performance of in utero MR (iuMR) imaging when attempting to confirm, exclude or provide additional information compared with the information provided by prenatal ultrasound scans (USS) when there is a suspicion of foetal brain abnormality.

Methods

Electronic databases were searched as well as relevant journals and conference proceedings. Reference lists of applicable studies were also explored. Data extraction was conducted by two reviewers independently to identify relevant studies for inclusion in the review. Inclusion criteria were original research that reported the findings of prenatal USS and iuMR imaging and findings in terms of accuracy as judged by an outcome reference diagnosis for foetal brain abnormalities.

Results

34 studies met the inclusion criteria which allowed diagnostic accuracy to be calculated in 959 cases, all of which had an outcome reference diagnosis determined by postnatal imaging, surgery or autopsy. iuMR imaging gave the correct diagnosis in 91 % which was an increase of 16 % above that achieved by USS alone.

Conclusion

iuMR imaging makes a significant contribution to the diagnosis of foetal brain abnormalities, increasing the diagnostic accuracy achievable by USS alone.

Key points

• Ultrasound is the primary modality for monitoring foetal brain development during pregnancy

• iuMRI used together with ultrasound is more accurate for detecting foetal brain abnormalities

• iuMR imaging is most helpful for detecting midline brain abnormalities

• The moderate heterogeneity of reviewed studies may compromise findings

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.

Radiological Diagnosis of Neonatal Hydrometrocolpos- A Case Report

A three-day-old female child presented to us with abdominal distension and lower limb swelling. On ultrasound examination, there was a cystic mass contiguous with the uterus in the lower abdomen and pelvis which showed fluid- debris level. This mass was causing displacement of the urinary bladder anteriorly. MRI confirmed the findings of ultrasound. A diagnosis of hydrometrocolpos secondary to imperforate hymen was made following physical examination. Neonatal hydrometrocolpos is a rare condition which requires a high index of suspicion for diagnosis. Hydrometrocolpos refers to the accumulation of secretions within the endometrial and endovaginal canal. Diagnosis can be made prenatally or post natally using ultrasonography and magnetic resonance imaging. Early diagnosis reduces the incidence of complications.

The history of MR imaging as seen through the pages of radiology

The first reports in Radiology pertaining to magnetic resonance (MR) imaging were published in 1980, 7 years after Paul Lauterbur pioneered the first MR images and 9 years after the first human computed tomographic images were obtained. Historical advances in the research and clinical applications of MR imaging very much parallel the remarkable advances in MR imaging technology. These advances can be roughly classified into hardware (eg, magnets, gradients, radiofrequency [RF] coils, RF transmitter and receiver, MR imaging-compatible biopsy devices) and imaging techniques (eg, pulse sequences, parallel imaging, and so forth). Image quality has been dramatically improved with the introduction of high-field-strength superconducting magnets, digital RF systems, and phased-array coils. Hybrid systems, such as MR/positron emission tomography (PET), combine the superb anatomic and functional imaging capabilities of MR imaging with the unsurpassed capability of PET to demonstrate tissue metabolism. Supported by the improvements in hardware, advances in pulse sequence design and image reconstruction techniques have spurred dramatic improvements in imaging speed and the capability for studying tissue function. In this historical review, the history of MR imaging technology and developing research and clinical applications, as seen through the pages of Radiology, will be considered.

When Closure Fails: What the Radiologist Needs to Know About the Embryology, Anatomy, and Prenatal Imaging of Ventral Body Wall Defects

Ventral body wall defects (VBWDs) are one of the main categories of human congenital malformations, representing a wide and heterogeneous group of defects sharing a common feature, that is, herniation of one or more viscera through a defect in the anterior body wall. Gastroschisis and omphalocele are the 2 most common congenital VBWDs. Other uncommon anomalies include ectopia cordis and pentalogy of Cantrell, limb-body wall complex, and bladder and cloacal exstrophy. Although VBWDs are associated with multiple abnormalities with distinct embryological origins and that may affect virtually any system organs, at least in relation to anterior body wall defects, they are thought (except for omphalocele) to share a common embryologic mechanism, that is, a failure involving the lateral body wall folds responsible for closing the thoracic, abdominal, and pelvic portions of the ventral body wall during the fourth week of development. Additionally, many of the principles of diagnosis and management are similar for these conditions. Fetal ultrasound (US) in prenatal care allows the diagnosis of most of such defects with subsequent opportunities for parental counseling and optimal perinatal management. Fetal magnetic resonance imaging may be an adjunct to US, providing global and detailed anatomical information, assessing the extent of defects, and also helping to confirm the diagnosis in equivocal cases. Prenatal imaging features of VBWDs may be complex and challenging, often requiring from the radiologist a high level of suspicion and familiarity with the imaging patterns. Because an appropriate management is dependent on an accurate diagnosis and assessment of defects, radiologists should be able to recognize and distinguish between the different VBWDs and their associated anomalies. In this article, we review the relevant embryology of VBWDs to facilitate understanding of the pathologic anatomy and diagnostic imaging approach. Features will be illustrated with prenatal US and magnetic resonance imaging and correlated with postnatal and clinical imaging.

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.

Additional value of fetal magnetic resonance imaging in the prenatal diagnosis of central nervous system anomalies: a systematic review of the literature

OBJECTIVES

To analyze literature on the additional value of fetal magnetic resonance imaging (MRI) in assessing central nervous system (CNS) anomalies suspected by ultrasound.

METHODS

A search was performed of PubMed, EMBASE, Cochrane library and the reference lists of identified articles. Inclusion criteria were CNS anomalies suspected/diagnosed by ultrasound, MRI performed after ultrasound, and postmortem examination by autopsy or postnatal assessment. MOOSE guidelines were followed. Outcomes assessed were positive/negative agreement between ultrasound and MRI, additional information provided by MRI, and discordance between ultrasound and MRI. Pooled sensitivity and specificity of MRI were calculated using the DerSimonian-Laird method. Postnatal/postmortem examinations were used as the reference standard.

RESULTS

We identified thirteen articles which included 710 fetuses undergoing both ultrasound and MRI. MRI confirmed ultrasound-positive findings in 65.4% of fetuses and provided additional information in 22.1%. MRI disclosed CNS anomalies in 18.4% of fetuses. In 2.0% of cases, ultrasound was more accurate than MRI. In 30% of fetuses, MRI was so different from ultrasound that the clinical management changed. Agreement was observed mainly for ventriculomegaly (51.3%). Disagreement was noted mainly for midline anomalies (48.6%). Pooled sensitivity of MRI was 97% (95% CI, 95-98%) and pooled specificity was 70% (95% CI, 58-81%).

CONCLUSIONS

MRI supplements the information provided by ultrasound. It should be considered in selected fetuses with CNS anomalies suspected on ultrasound.

Standardized fetal anatomical examination using magnetic resonance imaging: a feasibility study

OBJECTIVE

To determine whether a standard complete fetal anatomical survey, as recommended for ultrasound examination guidelines, is feasible using a standardized magnetic resonance imaging (MRI) protocol.

METHODS

Based on guidelines for ultrasound examination, we created a specific MRI protocol for fetal anatomical survey. This protocol was then tested prospectively in 100 women undergoing fetal MRI examination for various specific indications at a median gestational age of 30 weeks. The feasibility of using MRI to perform the fetal anatomical survey was analyzed by two reviewers (A and B) based on 26 predefined anatomical criteria, yielding a score ranging from 0 to 26 (26 meaning successful complete anatomical study). Reproducibility was analyzed using percentage agreement and modified kappa statistics.

RESULTS

The mean score for the standardized MRI anatomical survey was 24.6 (SD, 1.4; range, 15-26) for Reviewer A and 24.2 (SD, 1.7; range, 15-26) for Reviewer B (P = 0.1). Twenty-two, two and two criteria could be assessed in > 95%, 80-95% and < 80% of cases by Reviewer A and 19, four and three criteria could be assessed in > 95%, 80-95% and < 80% of cases by Reviewer B. For both reviewers, the two most difficult criteria to evaluate were aorta and pulmonary artery. Inter-reviewer agreement was above 90% for 22 of the 26 anatomical criteria and adjusted kappa coefficients for each criterion demonstrated good, moderate and poor agreement for 22, two and two criteria, respectively.

CONCLUSION

Our data support the hypothesis that standardized fetal anatomical examination might be achieved and reproducible using MRI, although improvement is required for the cardiac part of the examination.

Potential of magnetic resonance for imaging the fetal heart

Significant congenital heart disease (sCHD) affects 3.6 per 1000 births, and is often associated with extracardiac and chromosomal anomalies. Although early mortality has been substantially reduced and the rate of long-term survival has improved, sCHD is, after preterm birth, the second most frequent cause of neonatal infant death. The prenatal detection of cardiac and vascular abnormalities enables optimal parental counselling and perinatal management. Echocardiography (ECG) is the first-line examination and gold standard by which cardiac malformations are defined. However, adequate examination by an experienced healthcare provider with modern technical imaging equipment is required. In addition, maternal factors and the gestational age may lower the image quality. Fetal magnetic resonance imaging (MRI) has been implemented over the last several years and is already used in the clinical routine as a second-line approach to assess fetal abnormalities. MRI of the fetal heart is still not routinely performed. Nevertheless, fetal cardiac MRI has the potential to complement ultrasound in detecting cardiovascular malformations and extracardiac lesions. The present work reviews the potential of MRI to delineate the anatomy and pathologies of the fetal heart. This work also deals with the limitations and continuing developments designed to overcome the current problems in cardiac imaging, including fast fetal heart rates, the lack of ECG-gating, and the presence of fetal movements.

Congenital lung lesions: prenatal MRI and postnatal findings

BACKGROUND

Congenital lung lesions refer to a spectrum of malformations and developmental abnormalities of the foregut, pulmonary airways and vasculature. These lesions range from small, asymptomatic to large space-occupying masses that can increase risk of fetal death and respiratory compromise after birth. Prenatal sonography has been used for routine screening in pregnancy. The advent of prenatal magnetic resonance imaging leads to complementary use in the diagnosis of fetal anomalies, including in fetuses with congenital lung lesions.

OBJECTIVE

To determine whether fetal MRI can differentiate congenital lung lesions by comparing prenatal diagnosis with postnatal imaging and pathology.

MATERIALS AND METHODS

In a 4-year period, 76 fetuses with suspected lung lesions were referred for fetal MRI. We retrospectively reviewed the MR exams and assigned a specific diagnosis based on predetermined criteria. We then compared the prenatal diagnosis to postnatal imaging and pathology.

RESULTS

Of 76 cases, 7 were excluded because of an alternative diagnosis. Of the 69 remaining patients, 3 died and 13 were lost to follow-up. Among the 53 patients, there were 56 lung lesions. Four of these lesions were difficult to diagnose because of size and location. Based on imaging records we gave the remaining 52 lesions a specific prenatal diagnosis: 28 congenital pulmonary airway malformations (CPAM), 4 bronchopulmonary sequestrations (BPS), 9 cases of overinflation, 9 hybrid lesions and 2 bronchogenic cysts. The prenatal diagnosis was concordant with postnatal evaluation in 51 of the 52 lung lesions. One fetus given the diagnosis of CPAM prenatally was diagnosed with a hybrid lesion postnatally.

CONCLUSION

Prenatal MRI is highly accurate in defining congenital lung anomalies. When fetal MRI findings suggest a specific diagnosis, postnatal findings confirmed the prenatal MRI diagnosis in 98% of cases.

Two neonates with congenital hydrocolpos

Introduction. Neonatal hydrocolpos is a rare condition. Hydrocolpos is cystic dilatation of the vagina with fluid accumulation due to a combination of stimulation of secretary glands of the reproductive tract and vaginal obstruction. The differential for a neonatal presentation of lower abdominal mass includes urogenital anomalies, Hirschsprung's, disease or sacrococcygeal teratoma. Prenatal diagnosis and early newborn imaging studies leads to early detection and treatment of these cases. Case. We report here two cases of neonatal hydrocolpos with prenatal diagnosis of lower abdominal mass. Postnatally, ultrasound, MRI imaging, and cystoscopy confirmed large cystic mass as hydrocolpos with distal vaginal obstruction. Both patients had enlarged renal system secondary to mass effect. Conclusion. High index of suspicion for hydrocolpos in a newborn presenting with fetal diagnosis of infraumbilical abdominal mass will facilitate timely intervention and prevention of complications.

MRI and ultrasound fusion imaging for prenatal diagnosis

OBJECTIVE

A combination of magnetic resonance imaging (MRI) images with real time high-resolution ultrasound known as fusion imaging may improve prenatal examination. This study was undertaken to evaluate the feasibility of using fusion of MRI and ultrasound (US) in prenatal imaging.

STUDY DESIGN

This study was conducted in a tertiary referral center. All patients referred for prenatal MRI were offered to undergo fusion of MRI and US examination. All cases underwent 1.5 Tesla MRI protocol including at least 3 T2-weighted planes. The Digital Imaging and Communications in Medicine volume dataset was then loaded into the US system for manual registration of the live US image and fusion imaging examination.

RESULTS

Over the study period, 24 patients underwent fusion imaging at a median gestational age of 31 (range, 24-35) weeks. Data registration, matching and then volume navigation was feasible in all cases. Fusion imaging allowed superimposing MRI and US images therefore providing with real time imaging capabilities and high tissue contrast. It also allowed adding a real time Doppler signal on MRI images. Significant fetal movement required repeat-registration in 15 (60%) cases. The average duration of the overall additional scan with fusion imaging was 10 ± 5 minutes.

CONCLUSION

The combination of fetal real time MRI and US image fusion and navigation is feasible. Multimodality fusion imaging may enable easier and more extensive prenatal diagnosis.

Fetal magnetic resonance imaging (MRI): a tool for a better understanding of normal and abnormal brain development

Knowledge of the anatomy of the developing fetal brain is essential to detect abnormalities and understand their pathogenesis. Capability of magnetic resonance imaging (MRI) to visualize the brain in utero and to differentiate between its various tissues makes fetal MRI a potential diagnostic and research tool for the developing brain. This article provides an approach to understand the normal and abnormal brain development through schematic interpretation of fetal brain MR images. MRI is a potential screening tool in the second trimester of pregnancies in fetuses at risk for brain anomalies and helps in describing new brain syndromes with in utero presentation. Accurate interpretation of fetal MRI can provide valuable information that helps genetic counseling, facilitates management decisions, and guides therapy. Fetal MRI can help in better understanding the pathogenesis of fetal brain malformations and can support research that could lead to disease-specific interventions.

Fetal MRI: An approach to practice: A review

MRI has been increasingly used for detailed visualization of the fetus in utero as well as pregnancy structures. Yet, the familiarity of radiologists and clinicians with fetal MRI is still limited. This article provides a practical approach to fetal MR imaging. Fetal MRI is an interactive scanning of the moving fetus owed to the use of fast sequences. Single-shot fast spin-echo (SSFSE) T2-weighted imaging is a standard sequence. T1-weighted sequences are primarily used to demonstrate fat, calcification and hemorrhage. Balanced steady-state free-precession (SSFP), are beneficial in demonstrating fetal structures as the heart and vessels. Diffusion weighted imaging (DWI), MR spectroscopy (MRS), and diffusion tensor imaging (DTI) have potential applications in fetal imaging. Knowing the developing fetal MR anatomy is essential to detect abnormalities. MR evaluation of the developing fetal brain should include recognition of the multilayered-appearance of the cerebral parenchyma, knowledge of the timing of sulci appearance, myelination and changes in ventricular size. With advanced gestation, fetal organs as lungs and kidneys show significant changes in volume and T2-signal. Through a systematic approach, the normal anatomy of the developing fetus is shown to contrast with a wide spectrum of fetal disorders. The abnormalities displayed are graded in severity from simple common lesions to more complex rare cases. Complete fetal MRI is fulfilled by careful evaluation of the placenta, umbilical cord and amniotic cavity. Accurate interpretation of fetal MRI can provide valuable information that helps prenatal counseling, facilitate management decisions, guide therapy, and support research studies.

Virtual bronchoscopy for evaluating cervical tumors of the fetus

We report on four cases of fetal cervical tumor, comprising three lymphangiomas and one teratoma, evaluated by ultrasound and magnetic resonance imaging (MRI) between 26 and 37 weeks' gestation. The aim was to investigate the use of virtual bronchoscopy to evaluate fetal airway patency in each case. A three-dimensional (3D) model of the airway was created from overlapping image layers generated by MRI. The files obtained were manipulated using 3D modeling software, allowing the virtual positioning of observation cameras, adjustment of lighting parameters and creation of simulated 3D movies for analysis of a virtual path through the model. In all fetuses, fetal airway patency was clearly demonstrated by virtual bronchoscopy and this was confirmed postnatally. MRI with virtual bronchoscopy could become a useful tool for studying fetal airway patency in cases of cervical tumor.