Normal anatomy of the fetus at MR imaging

Fetal teratogenicity in a rhesus macaque (Macaca mulatta): Association with the chronic maternal treatment of amitriptyline

Amitriptyline is a tricyclic antidepressant commonly prescribed in humans for pain and sleep disorders and in non-human primates for self-injurious behaviors. Here, we report a clinical case on the teratogenic effect of maternal-fetal amitriptyline exposure.

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.

Prenatal diagnosis of congenital anomalies of genito-urinary system on fetal magnetic resonance imaging

Background

The aim of this study is to elucidate the spectrum of commonly encountered anomalies affecting fetal genito-urinary system (GUS) on fetal MRI and examine its utility in providing better morphological information resulting in improved diagnostic accuracy and in detecting additional malformations. The study also aims to highlight the promising role of fetal MRI in the detection and characterization of renal fusion anomalies like the horseshoe kidney or developmental abnormalities such as renal agenesis/ectopia.

Results

The mean age of study participants was 29 years ± 3 years. The gestation age of pregnant mothers ranged from 18 weeks and 1 day to 39 weeks and 0 day. Amniotic fluid was reduced or absent in 41% (N = 13) and normal in 59% (N = 18) of participating mothers. Overall, urinary obstruction was the commonest anomaly encountered (29%) followed by the multicystic dysplastic kidney (MCDK) (22%). Bilateral renal disease was seen in all mothers having features of anhydramnios {B/L MCDK (N = 3), autosomal recessive polycystic kidney disease (ARPKD) (N = 2), posterior urethral valves (PUV) (N = 2), B/L renal agenesis (N = 3), and megacystis (N = 1)}. Fusion anomalies (horseshoe kidney) and rotation anomaly (malrotation) were detected in one case each. Additional extrarenal findings were seen on fetal MRI in 35% (N = 11) cases.

Conclusions

Fetal MRI improves diagnostic accuracy in anomalies affecting the fetal kidney and genito-urinary systems by better morphological delineation. It has the ability to detect additional extra-renal malformations and perform a more accurate assessment of associated pulmonary hypoplasia. The diffusion-weighted sequence is particularly useful in confirming the diagnosis of renal agenesis/ectopia.

Morphometric study of the primary ossification center of the frontal squama in the human fetus

PURPOSES

Detailed morphometric data on the development of ossification centers in human fetuses is useful in the early detection of skeletal dysplasias associated with a delayed development of ossification centers and their mineralization. Quantitative analysis of primary ossification centers of cranial bones is sporadic due to limited availability of fetal material.

MATERIAL AND METHODS

The size of the primary ossification center of the frontal squama in 37 human (16 males and 21 females) spontaneously aborted human fetuses aged 18-30 weeks was studied by means of CT, digital-image analysis and statistics.

RESULTS

With neither sex nor laterality differences, the best-fit growth dynamics for the primary ossification center of the frontal squama was modelled by the following functions: y = 13.756 + 0.021 × (age)² ± 0.024 for its vertical diameter, y = 0.956 + 0.956 × age ± 0.823 for its transverse diameter, y = 38.285 + 0.889 × (age)² ± 0.034 for its projection surface area, and y = 90.020 + 1.375 × (age)² ± 11.441 for its volume.

CONCLUSIONS

Our findings for the primary ossification center of the frontal squama may be conducive in monitoring normal fetal growth and screening for inherited faults and anomalies of the skull in human fetuses.

Quantitative anatomy of the ulna's shaft primary ossification center in the human fetus

PURPOSE

There has been little information in the medical literature regarding the growing ulna in the human fetus, though such knowledge appears to be potentially useful in diagnosing skeletal dysplasias, characterized by a disrupted or completely halted growth of the fetus. Therefore, longitudinal measurements of long bones are extremely conducive in assessing both pregnancy and fetal anatomy.

MATERIALS AND METHODS

Using methods of CT, digital-image analysis and statistics, the size of the ulna's shaft primary ossification center in 48 (26 males and 22 females) spontaneously aborted human fetuses aged 17-30 weeks was studied.

RESULTS

With no sex differences, the best fit growth dynamics for the ulna's shaft primary ossification center was modeled by the following functions: y = - 8.476 + 1.561 × age ± 0.019 for its length, y = - 2.961 + 0.278 × age ± 0.016 for its proximal transverse diameter, y = - 0.587 + 0.107 × age ± 0.027 for its middle transverse diameter, y = - 2.865 + 0.226 × age ± 0.295 for its distal transverse diameter, y = - 50.758 + 0.251 × (age)2 ± 0.016 for its projection surface area, and y = - 821.707 + 52.578 × age ± 0.018 ± 102.944 for its volume.

CONCLUSIONS

The morphometric characteristics of the ulna's shaft primary ossification center show neither sex nor bilateral differences. The ulna's shaft primary ossification center grows linearly with respect to its length, transverse dimensions and volume, and follows a quadratic function with respect to its projection surface area. The obtained morphometric data of the ulna's shaft primary ossification center is considered normative for respective prenatal weeks and may be of relevance in both the estimation of fetal ages and the diagnostic process of congenital defects.

Quantitative anatomy of the primary ossification center in the fetal pubis bone

Purposes

Skeletodysplasiae and hereditary dysostoses constitute a group of over 350 disorders of the skeletal system. Knowledge about development of the pubic primary ossification center may be useful in both determining the fetal stage and maturity, and for detecting congenital disorders. The present study was performed to quantitatively examine the pubic primary ossification center with respect to its linear, planar, and volumetric parameters.

Materials and methods

Using methods of computed tomography (CT), digital-image analysis and statistics, the size of the pubic primary ossification center in 33 spontaneously aborted human fetuses (18 males and 15 females) aged 22–30 weeks was studied.

Results

With no sex and laterality differences, the best-fit growth dynamics for the pubic primary ossification center was modeled by the following functions: y = − 13.694 + 0.728 × age ± 0.356 for its sagittal diameter, y = − 3.350 + 0.218 × age ± 0.159 for its vertical diameter, y = − 61.415 + 2.828 × age ± 1.519 for its projection surface area, and y = − 65.801 + 3.173 × age ± 2.149 for its volume.

Conclusions

The size of the pubic primary ossification center shows neither sex nor laterality differences. The growth dynamics of the vertical and sagittal diameters, projection surface area, and volume of the pubic ossification centers follow proportionately to fetal age. The obtained numerical findings of the pubic ossification center are considered age-specific reference data with clinical implications in the diagnostics of congenital defects.

Morphometric study of the primary ossification center of the fibular shaft in the human fetus

PURPOSES

Precise morphometric data on the development of ossification centers in human fetuses may be useful in the early detection of skeletal dysplasias associated with delayed ossification center development and mineralization. The present study was performed to quantitatively examine the primary ossification center of the fibular shaft with respect to its linear, planar and volumetric parameters.

MATERIALS AND METHODS

Using methods of CT, digital-image analysis (Osirix 3.9 MD) and statistics (Student's t-test, Shapiro-Wilk, Fisher's test, Tukey's test, Kruskal-Wallis test, regression analysis), the size of the primary ossification center of the fibular shaft in 47 spontaneously aborted human fetuses (25 ♂ and 22 ♀) aged 17-30 weeks was studied. In each fetus, the assessment of linear dimensions (length, transverse diameters for: proximal end, middle part and distal end), projection surface area and volume of the fibular shaft ossification center was carried out.

RESULTS

With no sex and laterality differences, the best fit growth dynamics for the primary ossification center of the fibular shaft was modelled by the following functions: y = - 13.241 + 1.567 × age ± 1.556 (R2 = 0.94) for its length, y = - 0.091 + 0.063 × age ± 0.073 (R2 = 0.92) for its proximal transverse diameter, y = - 1.201 + 0.717 × ln(age) ± 0.054 (R2 = 0.83) for its middle transverse diameter, y = - 2.956 + 1.532 × ln(age) ± 0.090 (R2 = 0.89) for its distal transverse diameter, y = - 69.038 + 4.699 × age ± 4.055 (R2 = 0.95) for its projection surface area, and y = - 126.374 + 9.462 × age ± 8.845 (R2 = 0.94) for its volume.

CONCLUSIONS

The ossification center in the fibular shaft follows linear functions with respect to its length, proximal transverse diameter, projection surface area and volume, and natural logarithmic functions with respect to its middle and distal transverse diameters. The obtained morphometric data of the fibular shaft ossification center is considered normative for their respective prenatal weeks and may be of relevance in both the estimation of fetal age and the ultrasound diagnostics of congenital defects.

The primary ossification of the human fetal ischium: CT, digital-image analysis, and statistics

Purposes

Details concerning the normal growth of the pelvic girdle in the fetus are of importance in the early detection of congenital defects. This study was executed to quantitatively evaluate the primary ossification center of the ischium with relation to its linear, planar and volumetric parameters.

Materials and methods

Using methods of CT, digital-image analysis, and statistics, geometrical dimensions of the ischium’s primary ossification center in 42 spontaneously aborted human fetuses (21 ♂ and 21 ♀) aged 18–30 weeks were calculated.

Results

With no sex and laterality differences, the best fit growth dynamics for the ischium’s primary ossification center were displayed by the following functions: y = − 10.045 + 0.742 × age ± 0.013 (R² = 0.97) for its vertical diameter, y = − 5.212 + 0.385 × age ± 0.008 (R² = 0.97) for its sagittal diameter, y = − 36.401 + 0.122 × (age)² ± 45.534 (R² = 0.96) for its projection surface area, and y = − 1052.840 + 368.470 × ln(age) ± 12.705 (R² = 0.91) for its volume.

Conclusions

Neither male–female nor right–left differences are found for any of the morphometric parameters of the ischium’s primary ossification center. With relation to fetal ages in weeks, the ischium’s primary ossification center grows proportionately in vertical and sagittal diameters, second-degree polynomially in projection surface area, and logarithmically in volume. The quantitative findings of the ischium’s primary ossification center are considered age-specific reference data of relevance in the diagnostics of innate defects.

Three-dimensional growth of tibial shaft ossification in the human fetus: a digital-image and statistical analysis

PURPOSES

Tibial shaft ossification in terms of its size and growth may be criticalin describing both the fetal stage and maturity, and in identifying innate disorders. The present study was executed to quantitatively assess ossification of the tibial shaft, taking its morphometric linear, planar and volumetric parameters into account.

MATERIALS AND METHODS

With the use of methods of CT, digital-image analysis and statistics, the evolutionof tibial shaft ossification in 47 spontaneously aborted human fetuses at the age of 17-30 weeks was studied.

RESULTS

Without any male-female and right-left morphometric differences, the best fit growth dynamics fortibial shaft ossification was modelled by the following functions: y = 5.312 + 0.034 × (age)² ± 0.001 (R² = 0.89) for its length, y = - 2.855 + 0.307 × age ± 0.009 (R² = 0.96) for its proximal transverse diameter, y = - 0.758 + 0.153 × age ± 0.005 (R² = 0.88) for its middle transverse diameter, y = - 1.844 + 0.272 × age ± 0.09 (R² = 0.90) for its distal transverse diameter, y = - 40.263 + 0.258 × (age)² ± 0.007 (R² = 0.94) for its projection surface area, and y = - 287.996 + 1.186 × (age)² ± 0.037 (R² = 0.92) for its volume. The femoral-to-tibial ossification length ratio was 1.15 ± 0.1.

CONCLUSIONS

The size of tibial shaft ossification displays neither sex nor laterality differences. Tibial shaft ossification follows quadratic functions with respect to its length, projection surface area and volume, and linear functions with respect to its proximal, middle and distal transverse diameters. The obtained morphometric data of tibial shaft ossification are considered normative age-specific references of relevance in both the estimation of fetal ages and the ultrasound diagnostics of congenital defects.

Quantitative anatomy of the ilium's primary ossification center in the human fetus

Purpose

An understanding of the development of the ilium’s primary ossification center may be useful in both determining the fetal stage and maturity, and for detecting congenital disorders. This study was performed to quantitatively examine the ilium’s primary ossification center with respect to its linear, planar and volumetric parameters.

Materials and methods

Using methods of CT, digital-image analysis and statistics, the size of the ilium’s primary ossification center in 42 spontaneously aborted human fetuses of crown–rump length (CRL) ranged from 130 to 265 mm (aged 18–30 weeks) was studied.

Results

With no sex and laterality differences, the best fit growth dynamics for the ilium’s primary ossification center was modelled by the following functions: y = − 63.138 + 33.413 × ln(CRL) ± 1.609 for its vertical diameter, y = − 59.220 + 31.353 × ln(CRL) ± 1.736 for its transverse diameter, y = − 105.681 + 1.137 × CRL ± 16.035 for its projection surface area, and y = 478.588 + 4.035 × CRL ± 14.332 for its volume. The shape of the ilium’s primary ossification center did not change over the study period, because its transverse -to- vertical diameter ratio was stable at the level of 0.94 ± 0.07.

Conclusions

The size of the ilium’s primary ossification center displays neither sex nor laterality differences. The ilium’s primary ossification center grows logarithmically with respect to its vertical and transverse diameters, and linearly with respect to its projection surface area and volume. The shape of the ilium’s primary ossification center does not change throughout the examined period. The obtained quantitative data of the ilium’s primary ossification center is considered normative for respective prenatal weeks and may contribute to the prenatal ultrasound diagnostics of congenital defects.

Magnetic Resonance Imaging Verification of a Case of Sacrococcygeal Teratoma

Although rare, sacrococcygeal teratoma is the most common congenital neoplasm, occurring in 1 in 40,000 infants. Approximately 75% of affected infants are female. The aim of the present study was to correlate ultrasonography and magnetic resonance imaging (MRI) findings in patients with fetal sacrococcygeal teratoma. Three pregnant women in 27th week of gestation underwent fetal MRI after ultrasonography examination, with findings suggestive for fetal sacrococcygeal teratoma. Tumor size, location, extent and content were evaluated both by MRI and ultrasonography. Findings regarding tumor location, size and content were similar for both methods. There was a large well-circumscribed mixed, cystic/solid oval mass, originating from right sacro-gluteal region and projecting into the amniotic cavity, 132 × 110 × 76 mm in size. The mass had a heterogeneous appearance. The T1 high signal suggested fat component of the tumor, while T1 and T2 hypointense components suggested calcified/bony components. There was also T1 hypointense component consistent with cystic and fluid component. The imaging findings were characteristic for sacrococcygeal teratoma. There was not obvious lumbar or thoracic spinal involvement. There was no gross intrapelvic or abdominal extension, and even sacrum and coccyx appeared deformed. The amount of amniotic fluid was increased. MRI was superior to ultrasonography in the evaluation of the exact tumor extent, accurately demonstrating pelvic involvement in all of the three cases. Fetal MRI has shown to be a valuable adjunct to obstetric sonography in the evaluation of fetal sacrococcygeal teratoma, because of its higher accuracy in the determination of tumors extent and content, playing a significant role in the therapeutic planning and increasing the chances of cure for these fetuses.

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

OBJECTIVE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Prenatal diagnosis of a vein of Galen aneurysmal malformation with MR imaging - report of two cases

BACKGROUND

Vein of Galen malformations (VGMs) are rare congenital defects of cerebral vessels. They are formed between the 6(th) and 11(th) week of gestation. The background of this defect involves presence of one or more arterovenous fistulas directing bloodflow toward a persistent, dilated, proximal part of median prosencephalic vein (MProsV). Ultrasound examination is a basic test for diagnosis of VGMs. It has now become possible to acquire images of diagnostic value using magnetic resonance (MR) techniques.

CASE REPORT

This work presents two cases of vein of Galen aneurysms diagnosed prenatally with magnetic resonance imaging. In both patients fetal CNS malformations were diagnosed in ultrasound examinations. MR imaging of the fetal head was performed for further diagnostics.

CONCLUSIONS

Because of the ability to precisely determine the size of the ventricular system, presence of raised intraventricular pressure and topographic relationships between pathologically changed vessels and particular cerebral structures as well as the presence of ischemic areas MR examination is currently not only complementary to ultrasonography, but is becoming an independent examination method in the diagnostics of vein of Galen malformations.

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.

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

OBJECTIVE

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

MATERIAL AND METHODS

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

RESULTS

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

CONCLUSION

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

Fetal gastrointestinal MRI: all that glitters in T1 is not necessarily colon

BACKGROUND

It has been described that both the colon and distal ileum present with a physiological hypersignal on T1-weighted sequences during the second and third trimesters of pregnancy because of their protein-rich meconium content, it was unclear whether the normal characteristics that have been described on fetal MRI can be applied to gastrointestinal (GI) obstructions.

OBJECTIVE

To analyse the localisation value of T1 hypersignal within dilated bowel loops in fetuses with gastrointestinal tract obstruction.

MATERIALS AND METHODS

A retrospective 4-year multicentre study analysing cases of fetal GI obstruction in which MRI demonstrated T1 hypersignal content in the dilated loops. Data collected included gestational age (GA) at diagnosis, bowel appearance on US, CFTR gene mutations and amniotic levels of gastrointestinal enzymes. The suggested prenatal diagnosis was eventually compared to postnatal imaging and surgery.

RESULTS

Eleven patients were included. The median GA at US diagnosis was 23 weeks (range 13-32). In eight cases there was a single dilated loop, while several segments were affected in three. The median GA at MRI was 29 weeks (range 23-35). One case presented with cystic fibrosis mutations. Final prenatally suspected diagnoses were distal ileal atresia or colon in nine cases and proximal atresia in two. Postnatal findings were proximal jejunal atresia in nine cases and meconium ileus in two. In five cases the surgical findings demonstrated short bowel syndrome.

CONCLUSION

In cases of fetal occlusion, T1 hypersignal should not be considered as a sign of distal ileal or colonic occlusion. The obstruction may be proximal, implying a risk of small bowel syndrome, which requires adequate parental counselling.

Fetal central nervous system malformations on MR images

Sonography is the method of choice for prenatal malformation screening but it does not always provide sufficient information for correct diagnosis or adequate abnormality evaluation. Fetal magnetic resonance imaging (MRI) is considered as a valuable second line imaging tool for confirmation, completion and correction of sonographic findings. Fetal MRI has proven its value in the evaluation of central nervous system pathologies, especially of midline and posterior fossa malformations. The role of MRI is not only to confirm or exclude possible lesions but also to define their full extent, aiding in their characterization, and to demonstrate associated abnormalities. The authors describe the most common anomalies of CNS revealed by fetal MRI in a chronological way related to the age of pregnancy, with a review of own MR images and with reference to the literature and own experience.

MR venography in the detection of pelvic venous congestion

PURPOSE

To investigate the feasibility of using magnetic resonance venography (MRV) to detect pelvic venous congestion (PVC).

METHODS

A prospective study of 23 female patients with signs and symptoms of PVC, who underwent duplex sonography, MRV and phlebography (P). Examinations were interpreted in a blinded fashion. Visualization of venous anatomy, presence of venous incompetence and congestion grade were evaluated. Sensitivity and specificity of MRV using P as reference were calculated.

RESULTS

MRV agreed with P in 96% (Cohen-K-value 0.646) and in 70% (K 0.555) of the cases respectively in the venous anatomy and congestion grade. Sensitivity and specificity of MRV were 88% and 67% for ovarian veins, 100% and 38% for hypogastric veins and 91% and 42% for the pelvic plexus.

CONCLUSIONS

In this prospective study MRV showed high sensitivity in the evaluation of patients with suspected PVC. Routine use of this diagnostic method requires further studies in larger patient cohorts.

Correlação entre os achados ultra-sonográficos e de ressonância magnética no teratoma sacrococcígeo fetal

OBJETIVO: Correlacionar os achados ultra-sonográficos e de ressonância magnética no teratoma sacrococcígeo fetal. MATERIAIS E MÉTODOS: Três pacientes com idade gestacional entre 30 e 35 semanas, com diagnóstico ultra-sonográfico suspeito de teratoma sacrococcígeo fetal, foram submetidas a ressonância magnética e, posteriormente, a ultra-sonografia para correlação dos achados. Tanto na ressonância magnética quanto na ultra-sonografia foram avaliadas as dimensões, a localização, a extensão e os conteúdos dos tumores. RESULTADOS: A ultra-sonografia e a ressonância magnética obtiveram resultados semelhantes em relação à localização, ao tamanho e ao conteúdo dos tumores. Todas as lesões localizavam-se na região sacrococcígea, com dimensões médias de 6,0 cm x 9,0 cm. Quanto ao conteúdo dos tumores, um dos casos era completamente cístico e dois eram sólidos e císticos. A extensão exata das lesões foi mais bem avaliada pela ressonância magnética do que pela ultra-sonografia, mostrando de forma adequada o acometimento pélvico nos três casos. CONCLUSÃO: A ressonância magnética fetal é capaz de complementar os achados ultra-sonográficos do teratoma sacrococcígeo fetal, uma vez que determina com melhor precisão o conteúdo e a extensão do tumor, auxiliando na conduta terapêutica e aumentando as chances de cura desses fetos.

MR imaging characteristics of the normal fetal gastrointestinal tract and abdomen

Fetal magnetic resonance imaging (MRI) is considered a valuable second line imaging tool for confirmation, completion and correction of complex fetal ultrasonography findings. Fetal MRI has proven its value in pathologies of the central nervous system. Few studies have focussed on the value of fetal MRI in abdominal pathologies. With the continuing advances in hardware and software, fetal MRI is progressively valuable in fetal abdominal pathologies. A proper knowledge of the normal fetal abdominal anatomy and signal intensities is essential. The current manuscript reviews normal fetal abdominal anatomy.

Fetal Magnetic Resonance Imaging as a Complement to Fetal Ultrasonography

Ultrasonography is the screening method of choice for the evaluation of the fetus. It is safe, inexpensive, and easily performed. However, it is operator dependent, and evaluation may be limited because of fetal position, maternal obesity, overlying bone, and/or oligohydramnios. Magnetic resonance imaging is an alternative modality that uses no ionizing radiation, has excellent tissue contrast and a large field of view, is not limited by obesity or overlying bone, and can image the fetus in multiple planes, no matter the fetal lie. Faster scanning techniques allow studies to be performed without sedation in the second and third trimester with minimal motion artifact.

Localized pigmented villonodular synovitis of the knee: acute onset in pregnancy

A pregnant patient in the first trimester presented with acute onset knee pain and effusion. As the clinical status was mimicking septic arthritis, surgery was performed. Arthroscopy demonstrated a local synovial tumor and excision was performed with arthrotomy. Microscopic evaluation revealed localized pigmented villonodular synovitis. Due to the presence of necrosis and hematoma in the tumor, we hypothesize that, that torsion or bleeding of the tumor in the presence of physiological pregnancy- related metabolic changes might have been the cause of acute presentation.

Magnetic resonance imaging and the detection of fetal brain anomalies, injury, and physiologic adaptations

PURPOSE OF REVIEW

Magnetic resonance imaging is playing an increasingly prominent role in depicting brain maturation, especially gyral formation that follows a temporospatial pattern, and in detecting developmental abnormalities of the cortex and other brain sectors. Knowledge of the technical advantages and limitations of in-utero magnetic resonance imaging techniques, relative to those of the postnatal period, is essential to optimize magnetic resonance sequences for early diagnosis. This includes an understanding of the changes in both brain anatomy and magnetic resonance signals that occur with an increase in gestational age.

RECENT FINDINGS

Magnetic resonance imaging has evolved has an important adjunct in the diagnosis of brain malformations, particularly in the late-second or third trimester. Noxious conditions elicit more of a chronic rather than acute response in the fetal brain, which differs from that observed postnatally. Clinical applications of proton magnetic resonance spectroscopy may help elucidate fetal brain maturation and its abnormalities from a metabolic point of view.

SUMMARY

Indications for fetal brain magnetic resonance imaging have increased because of improvements in magnetic resonance techniques and the ability to detect subtle changes within the cerebral parenchyma, especially in fetuses at increased risk of brain damage.

Methods of fetal MR: beyond T2-weighted imaging

The present work reviews the basic methods of performing fetal magnetic resonance imaging (MRI). Since fetal MRI differs in many respects from a postnatal study, several factors have to be taken into account to achieve satisfying image quality. Image quality depends on adequate positioning of the pregnant woman in the magnet, use of appropriate coils and the selection of sequences. Ultrafast T2-weighted sequences are regarded as the mainstay of fetal MR-imaging. However, additional sequences, such as T1-weighted images, diffusion-weighted images, echoplanar imaging may provide further information, especially in extra- central-nervous system regions of the fetal body.

Fetal abdominal magnetic resonance imaging

This review deals with the in vivo magnetic resonance imaging (MRI) appearance of the human fetal abdomen. Imaging findings are correlated with current knowledge of human fetal anatomy and physiology, which are crucial to understand and interpret fetal abdominal MRI scans. As fetal MRI covers a period of more than 20 weeks, which is characterized not only by organ growth, but also by changes and maturation of organ function, a different MR appearance of the fetal abdomen results. This not only applies to the fetal intestines, but also to the fetal liver, spleen, and adrenal glands. Choosing the appropriate sequences, various aspects of age-related and organ-specific function can be visualized with fetal MRI, as these are mirrored by changes in signal intensities. Knowledge of normal development is essential to delineate normal from pathological findings in the respective developmental stages.

A review of the current use of magnetic resonance imaging in pregnancy and safety implications for the fetus

This paper presents an overview of the application of and risks of exposure to Magnetic Resonance Imaging (MRI) in pregnancy. It reviews the risks to the fetus by considering the hazards in terms of the three main components of an MRI system. These are the static magnetic field, the time-varying magnetic gradient fields and the pulsed radio frequency fields. The hazards discussed are biological effects, miscarriage, heating effects and acoustic noise exposure. This paper also presents a survey of MRI sites within the United Kingdom to ascertain the extent of MRI usage in pregnancy. To validate the situation of MRI in pregnancy a survey was sent to 352 MR units throughout the United Kingdom. The questions were grouped to assess (a) maternal MRI diagnosis (b) fetal MRI and (c) work practices for pregnant MRI staff. The results showed that 91% of sites were imaging pregnant women in need of diagnosis in the second and third trimester. This paper highlights that MRI can add information for fetal central nervous system abnormalities identified by ultrasound screening, however within the UK direct fetal imaging was only performed in 8% of sites. This paper indicates the need for research to be undertaken for specific MRI clinical conditions. It also advises that risk assessment for pregnant staff working in MRI is performed, and that there is a clear need for further research into the effects of MRI in pregnancy as there is a need for clear authoritive advice.

IRM thoracique fœtale

Fetal thoracic MR includes the study of the lungs and the mediastinum. Fetal lungs are T2 hyperintense because of their high water contents and are clearly delineated. Their volume can be measured with MR and normal data have been published. The evaluation of the fetal lung volume is of paramount importance in the case of suspected pulmonary hypoplasia. MR is contributive in the analysis of diaphragmatic hernias to assess the diagnosis, to detail the herniated abdominal contents and in a less extent, to predict outcome. In most of the cases, MR does not provide additional information (compared to US) in the evaluation of bronchopulmonary sequestrations or congenital cystic adenomatoid malformations. Pulmonary arteries and veins are currently poorly visualized. MR seems to be an accurate modality to assess the diagnosis of esophageal atresia.

The fetus cannot exercise like an astronaut: gravity loading is necessary for the physiological development during second half of pregnancy

On the basis of published Magnetic Resonance Images and the values of the specific fetal and amniotic fluid weights, apparent weight of the fetus from the 18th week of gestation until term was determined. Up to the 21-22nd gestation week the fetus is in conditions similar to neutral floating, while after the 26th gestation week the apparent weight of the fetus is 60-80% of the actual weight. Decreased effect of the buoyant forces that affect the fetus in human species during the last trimester has a number of implications for the colonization of the solar system. During space flight it is impossible to apply the existing countermeasures against microgravity deconditioning of the muscular and cardiovascular systems to the fetus. Absence of gravitational loading during the last trimester of gestation would cause hypotrophy of the spinal extensors and lower extremities muscles, reduction in the amount of myosin heavy chain type I in the extensor muscles of the trunk and legs, hypoplasy and osteopeny of the vertebras and lower extremities long bones, and hypotrophy of the left ventricle of the heart muscle. Because of decreased capacity of postural and locomotor stability, acquisition of the gross developmental milestones such as sitting, standing and walking could be delayed. In the authors' opinion, only artificial gravity (rotating platform) during space flight will allow physiological development of the human fetus. Independency of offspring's of the guinea pig as regards locomotion and nursing increases probability of successful breeding in microgravity compared with rat offspring's, and make this species a candidate for future experiments under conditions of microgravity and hypergravity. Examining the gestation of this species in different gravities requires first the experimental determination of the amount of buoyant force to which the fetus is exposed in physiological conditions.

Fetal Anomalies: Comparison of MR Imaging and US for Diagnosis

PURPOSE

To compare prenatal ultrasonography (US) and magnetic resonance (MR) imaging for the diagnosis of fetal anomalies.

MATERIALS AND METHODS

Images of 27 fetuses (28 diagnostic cases) with anomalies diagnosed at US were evaluated; in these fetuses, prenatal MR imaging was performed within 15 days of US. Prenatal US and MR imaging findings were compared with postnatal diagnoses. Postnatal evaluation included US, MR imaging, autopsy, surgery, voiding cystourethrography, computed tomography, angiography, and physical examination.

RESULTS

In seven diagnostic cases, US and MR imaging findings were in complete agreement with postnatal diagnoses. MR imaging correctly provided additional information to the US-determined diagnosis in another seven and correctly changed the US diagnosis in three. The MR imaging-determined diagnosis was incorrect and the US diagnosis was correct in four cases. In seven cases, the diagnoses at both US and MR imaging were incorrect when correlated with the postnatal outcome. MR imaging was most valuable in the assessment of anomalies of the central nervous system.

CONCLUSION

MR imaging may have a place as an adjunct to US in evaluation of fetal anomalies, particularly those involving the central nervous system.

MR imaging of fetal abnormalities

Our purpose was to evaluate the capability of ultrafast single-shot fast spin-echo MR imaging to assess normal fetal anatomy and abnormalities of different fetal organ systems. Fetal MR imaging was performed prospectively in consecutive 40 pregnant women because of abnormal findings or suspected fetal abnormalities on prenatal US. No statistically significant difference between US and MR imaging was found for the detection of abnormality in any organ system. MR imaging was slightly superior to US with regard to cerebral abnormalities only. In four (10%) of 40 fetuses, additional information provided by MR imaging altered counseling. However, MR imaging of the extremities-face and soft tissues was limited because of the lack of real-time information.

Single uterine axial fast acquisition magnetic resonance fetal survey: is it feasible?

OBJECTIVES

To determine which non-biometric components of the ultrasound fetal survey can routinely be seen on a single fast acquisition magnetic resonance (MR) sequence aligned axial to the maternal uterus.

STUDY DESIGN

The non-biometric components of the routine fetal ultrasound examination were applied retrospectively to the initial MR single-shot fast spin-echo acquisition aligned axial to the maternal uterus in the normal fetus to determine whether these parameters could be routinely evaluated. Nineteen women with anatomically normal fetuses had a total of 31 MR studies performed for fetal or maternal indications, either as part of an indicated examination or as part of a study protocol approved by the institutional review board. The images in these 31 MR studies were reviewed by two independent examiners who were blinded to the other's assessment; concordance was necessary for a component to be adequately assessed. The Wilcoxon rank sum test was used to determine the effect of gestational age and fetal lie on the ability to assess non-biometric parameters.

RESULTS

Assessment was possible in 85% of the non-biometric parameters. Cord insertion, external genitalia and the four-chamber view of the heart were most problematic. In only two cases was the four-chamber view of the heart identified. Longitudinal lie allowed significantly more parameters (82%) to be evaluated than transverse lie (45%) (p < 0.003). No difference based on gestational age was found.

CONCLUSION

A single fast acquisition axial MR sequence can evaluate 85% of the non-biometric components of the fetal ultrasound survey. Fetal lie is an important confounder in the ability to resolve fetal anatomy with a single MR axial uterine acquisition.

Fetal liver magnetic resonance imaging in anterior body wall defects: a study of specimens from the museum of pathology

PURPOSE

The purpose of the study was to evaluate the appearance of liver anatomy in fetuses with complex anterior body wall defects (ABWD) using magnetic resonance imaging (MRI).

METHODS

Nineteen specimens from the National Museum of Pathological Anatomy (Vienna) with a wide range of ABWD were studied on a 1.5-T MR scanner (T1- and T2-weighted sequences) with special focus on the liver and the relationship between the large lesion and the adjacent structures.

RESULTS

The contrast of T2-weighted sequences was superior to that of the T1-weighted images. The liver was found in an intraabdominal location in 3 cases and in a completely extraabdominal location in 11 fetuses. Five fetuses had a very special configuration or position of the liver. Furthermore, the images showed an anteriorly located confluence of hepatic veins into the inferior vena cava in 5 specimens. Associated malformations of the complexly structured malformations involved the urogenital tract, the central nervous system (CNS), the cardiac system and the musculoskeletal system. Prenatal fast magnetic resonance imaging (MRI) in one fetus confirmed the liver in a both inside/outside position, whereas the diagnosis at fetal ultrasound scan (US) in this case had been uncertain.

CONCLUSIONS

These results show that MRI may play an important part in antenatal diagnosis of ABWD, complementary to prenatal US. Prenatal fast MRI should be considered if fetal US yields ambiguous findings.

The value of fast MR imaging as an adjunct to ultrasound in prenatal diagnosis

The aim of this study was to evaluate the role of MR imaging of the fetus to improve sonographic prenatal diagnosis of congenital anomalies. In 40 fetuses (not consecutive cases) with an abnormality diagnosed with ultrasound, additional MR imaging was performed. The basic sequence was a T2-weighted single-shot half Fourier (HASTE) technique. Head, neck, spinal, thoracic, urogenital, and abdominal fetal pathologies were found. This retrospective, observational study compared MR imaging findings with ultrasonographic findings regarding detection, topography, and etiology of the pathology. The MR findings were evaluated as superior, equal to, or inferior compared with US, in consent with the referring gynecologists. The role of these findings in relation to pregnancy management was studied and compared with postnatal follow-up in 30 of 40 babies. Fetal MRI technique was successful in 36 of 39 examinations and provided additional information in 21 of 40 fetuses (one twin pregnancy with two members to evaluate). More precise anatomy and location of fetal pathology (20 of 40 cases) and additional etiologic information (8 of 40 cases) were substantial advantages in cerebrospinal abnormalities [ventriculomegaly, encephalocele, vein of Galen malformation, callosal malformations, meningo(myelo)cele], in retroperitoneal abnormalities (lymphangioma, renal agenesis, multicystic renal dysplasia), and in neck/thoracic pathology [cervical cystic teratoma, congenital hernia diaphragmatica, congenital cystic adenomatoid lung malformation (CCAM)]. This improved parental counseling and pregnancy management in 15 pregnancies. In 3 cases, prenatal MRI findings did not correlate with prenatal ultrasonographic findings or neonatal diagnosis. The MRI provided a more detailed description and insight into fetal anatomy, pathology, and etiology in the vast majority of these selected cases. This improved prenatal parental counseling and postnatal therapeutic planning.

[Fetal thoracic MR imaging]

Ultrasonography is the method of choice for prenatal malformation screening, but it does not always provide sufficient informations to allow a correct diagnosis or an adequate abnormality evaluation. Fetal MRImaging (MRI) indications are increasing in order to complete sonographic findings. It has been initially used for evaluation of cerebral abnormalities, but it is more and more applied to other fetal areas. An adequate analysis of fetal chest and abdomen can be obtained with fast T2 and T1 weighted sequences. This allows an easy diagnosis of congenital diaphragmatic hernia and an evaluation of the consequences on pulmonary growth. Other pulmonary malformations can be also easily identified (cystic adenoid malformation, sequestration, bronchogenic cyst, tracheal or bronchial atresia). Therefore, fetal thoracic MRI contributes to a better understanding and evaluation of fetal thoracic malformations, which is particularly useful for their postnatal management.

Fast MR imaging in obstetrics

Ultrasonography (US) is the initial imaging modality of choice for evaluation of patients in obstetrics. However, the results of US are not always sufficient. Magnetic resonance (MR) imaging, which uses no ionizing radiation, may be an ideal method for further evaluation. Although MR imaging is not recommended during the first trimester and use of contrast material is not recommended in pregnant patients, fast MR imaging is useful in various obstetric settings and can provide more specific information with excellent tissue contrast and multiplanar views. In pregnant patients with acute conditions, various diseases (eg, red degeneration of a uterine leiomyoma) may be diagnosed. MR imaging allows characterization of pelvic masses discovered during pregnancy and diagnosis of postpartum complications (eg, abscess, hematoma, ovarian vein thrombosis). In pregnant patients with hydronephrosis, MR urography can demonstrate the site of obstruction and the cause (eg, a ureteral stone). MR pelvimetry may be beneficial in cases of breech presentation. Contrast material-enhanced dynamic MR imaging allows one to evaluate the vascularity of a placental polyp, detect the viable component of a gestational trophoblastic tumor, and diagnose a uterine arteriovenous malformation. MR imaging enables diagnosis of rare forms of ectopic pregnancy and early diagnosis of ectopic pregnancy.

MR imaging of fetal sacrococcygeal teratoma: diagnosis and assessment

OBJECTIVE

The purpose of this study was to evaluate the usefulness of MR imaging in the diagnosis and assessment of fetal sacrococcygeal teratoma and to determine if MR imaging provides information not seen on obstetric sonography.

SUBJECTS AND METHODS

Twelve pregnant women were referred for fetal MR imaging of sacrococcygeal teratoma seen at obstetric sonography. The presence, size, content extension, and compressive effects of each mass were determined and correlated with the sonographic findings and with postnatal studies, including surgery and pathology. The extent of each sacrococcygeal teratoma was classified according to the American Association of the Pediatrics Surgery Section (types I-IV).

RESULTS

There is a complete agreement of sonographic and MR imaging measurements. The sacrococcygeal teratomas appeared cystic with few septa in three fetuses, markedly septated or even microcystic in eight, and completely solid in one. The sonographic description of the content corresponded well to MR imaging findings in 10 of 12 fetuses. An agreement on the extent of each mass was observed in nine patients, whereas there is a disagreement in three, including in one fetus with an extension of the tumor within the spinal canal recognized only at MR imaging. The MR imaging findings were confirmed by postnatal studies in 10 patients.

CONCLUSION

Sacrococcygeal teratomas had characteristic MR imaging appearances that allowed a complete assessment in most fetuses. Because of MR imaging, the prenatal evaluation was changed in some patients and affected counseling of the parents and treatment. MR imaging is a valuable adjunct to obstetric sonography for the prenatal evaluation of sacrococcygeal teratoma.

Periventricular cystic lesions in a preterm infant after a car accident during pregnancy

We report on a preterm infant born at 30+5/7 gestational weeks who developed severe cystic cerebral lesions after exposure to a car accident one day before delivery. The literature on car accidents during pregnancy is reviewed with specific focus on neonatal neurological outcome.

Prenatal diagnosis of an ectopic intrathoracic kidney in right-sided congenital diaphragmatic hernia using color Doppler ultrasonography

The prenatal sonographic features of a fetus with right-sided congenital diaphragmatic hernia diagnosed at 33 weeks are presented. Color Doppler demonstrated an abnormal course of the right renal artery, arising from the aorta and feeding the intrathoracic right kidney. This case report stresses the role of color Doppler in defining which organs have herniated in fetuses with diaphragmatic hernia.

The role of magnetic resonance imaging in prenatal diagnosis of fetal anomalies

Magnetic resonance imaging (MR) has become a useful adjuvant in evaluating fetal structural anomalies when ultrasound (US) is equivocal. It has a significant promise in confirming a US suspected abnormality and providing new information that was previously not available. The first studies on prenatal MR were hindered by fetal motion and long acquisition times. This degraded imaging and, therefore, maternal or fetal sedation was needed. Since fast and ultrafast MR with scan times of <1 s have become available, the amount of motion artifacts is decreased and sedation is no longer needed.MR has proved to be especially beneficial in detecting CNS anomalies. Agenesis of the corpus callosum, migration abnormalities and abnormalities of the posterior fossa are better seen on MR. Masses in the fetal neck and thorax can be identified on MR, as some abdominal anomalies. However, the fetal skeletal is difficult to visualize with MR. In the future, it is most likely that real time MR will become clinically available which would improve MR imaging even more.

Management of choledocholithiasis during pregnancy by magnetic resonance cholangiography and laparoscopic common bile duct stone extraction. Surg Laparosc Endosc Percutan Tech. 2000;10:323-325. [PMID: 11083218 DOI: 10.1097/00129689-200010000-00013]

Management of common bile duct (CBD) stones during pregnancy is a difficult problem. The authors reported the case of a patient who was 22 weeks' pregnant who had a symptomatic CBD stone successfully treated by the association of magnetic resonance cholangiography and laparoscopic CBD stone removal. The patient delivered a healthy baby boy at 39 weeks. Magnetic resonance cholangiography and laparoscopic CBD exploration is a viable option in the management of CBD stones in pregnant patients that carries a low risk for the fetus while preserving the advantages of minimally invasive surgery for the mother.

Chorioangioma: antenatal diagnosis with fast MR imaging

We report a case of chorioangioma of the placenta, in which fast magnetic resonance imaging (MRI) was useful adjunct to ultrasonography for the antenatal diagnosis. MRI allowed clear demonstration of 6.8 x 6.0 cm solid placental mass along with hydramnios and anatomically normal fetus. On T(1)-weighted breath-hold spoiled gradient-echo (fast low-angle shot [FLASH]) images, chorioangioma was mostly isointense to the placenta, but had an area of high signal intensity near the base and at the periphery, suggestive of hemorrhage. On T(2)-weighted half-Fourier single-shot fast spin echo (HASTE) images, the mass showed heterogeneous high signal intensity, but had an area of low signal intensity near the surface.

MR imaging of non-CNS fetal abnormalities: a pictorial essay

The recent popularity of prenatal magnetic resonance (MR) imaging has been associated with the development of ultrafast MR imaging techniques such as the single-shot fast spin-echo sequence. However, the majority of previous reports have concerned the fetal central nervous system (CNS) and chest disorders. MR imaging can demonstrate non-CNS fetal anatomy and pathologic conditions clearly. With its excellent tissue contrast, MR imaging provides information that supplements that provided by ultrasonography (US), especially in cases of neck, chest, and gastrointestinal lesions. Because of its large field of view, MR imaging allows evaluation of the relationship between a large lesion and adjacent structures. MR imaging should be considered if the diagnosis of a suspected non-CNS lesion is unclear at fetal US. MR imaging plays an important complementary role to US in cases of non-CNS fetal lesions and will be further accepted for fetal imaging in the future.