Fetal MRI: head and neck

Fetal Head and Neck Imaging

Prenatal MRI plays an essential role in the evaluation of the head and neck. This article overviews technical considerations and both isolated and syndromic anomalies of the fetal calvarium, globes and orbits, ears, maxilla, mandible, and neck.

Ultrasound and fetal magnetic resonance imaging: Clinical performance in the prenatal diagnosis of orofacial clefts and mandibular abnormalities

Cleft lip, with or without cleft palate, is the most common congenital craniofacial anomaly and the second most common birth defect worldwide. Micrognathia is a rare facial malformation characterized by small, underdeveloped mandible and frequently associated with retrognathia. Second- and third-trimester prenatal ultrasound is the standard modality for screening and identification of fetal orofacial abnormalities, with a detection rate in the low-risk population ranging from 0% to 73% for all types of cleft. The prenatal ultrasonography detection can also be performed during the first trimester of pregnancy. Given the potential limitations of obstetric ultrasound for examining the fetal face, such as suboptimal fetal position, shadowing from the surrounding bones, reduce amniotic fluid around the face, interposition of fetal limbs, umbilical cord and placenta, and maternal habitus/abdominal scars, the use of adjunct imaging modalities can enhance prenatal diagnosis of craniofacial anomalies in at-risk pregnancies. Fetal magnetic resonance imaging (MRI) is a potentially useful second-line investigation for the prenatal diagnosis of orofacial malformations with a pooled sensitivity of 97%. In this review, we discuss the role of ultrasound and fetal MRI in the prenatal assessment of abnormalities of the upper lip, palate, and mandible.

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.

Fetal Brain Anatomy

"Fetal brain development has been well studied, allowing for an ample knowledge of the normal changes that occur during gestation. Imaging modalities used to evaluate the fetal central nervous system (CNS) include ultrasound and MRI. MRI is the most accurate imaging modality for parenchymal evaluation and depiction of developmental CNS anomalies. The depiction of CNS abnormalities in a fetus can only be accurately made when there is an understanding of its normal development. This article reviews the expected normal fetal brain anatomy and development during gestation. Additional anatomic structures seen on brain imaging sequences are also reviewed."

Fetal Neuroimaging Updates

MR imaging is used in conjunction with ultrasound screening for fetal brain abnormalities because it offers better contrast, higher resolution, and has multiplanar capabilities that increase the accuracy and confidence of diagnosis. Fetal motion still severely limits the MR imaging sequences that can be acquired. We outline the current acquisition strategies for fetal brain MR imaging and discuss the near term advances that will improve its reliability. Prospective and retrospective motion correction aim to make the complement of MR neuroimaging modalities available for fetal diagnosis, improve the performance of existing modalities, and open new horizons to understanding in utero brain development.

Brain fetal neuroradiology: a beginner's guide

The importance of fetal magnetic resonance imaging (MRI) in the prenatal diagnosis of central nervous system (CNS) anomalies is rapidly increasing. Fetal MRI represents a third level examination usually performed, as early as 18-20 weeks of gestational age, when a second level (expert) neuro-ultrasonography (US) evaluation raises the suspicion of a CNS anomaly or when a genetic disorder is known. Compared to the US, MRI has the advantage to allow a better visualization and characterization of brain structures so to detect anomalies not visible in the US, thus resulting in relevant implications for parent counselling and pregnancy management. Moreover, the improvement of MRI technologies permits to obtain ultrafast sequences, which minimize the drawback of movement artifacts, and to perform advanced studies. This review aims at providing a practical guide for trainees and fellows who are approaching fetal MRI. In the first part, we provide information about indications, safety and protocols based on the state-of-the-art sequences, with a mention on the innovations related to the use of a 3T scanner. The second part is focused on the normal development of the human fetal brain related to its MR appearance, whose knowledge is essential to detect possible abnormalities. The last section briefly describes the most frequent abnormalities in the fetal brain and spine as depicted by MRI.

Role of prenatal imaging in the diagnosis and management of fetal facio-cervical masses

Congenital facio-cervical masses can be a developmental anomaly of cystic, solid, or vascular origin, and have an inseparable relationship with adverse prognosis. This retrospective cross-sectional study aimed at determining on the prenatal diagnosis of congenital facio-cervical masses, its management and outcome in a large tertiary referral center. We collected information on prenatal clinical data, pregnancy outcomes, survival information, and final diagnosis. Out of 130 cases of facio-cervical masses, a total of 119 cases of lymphatic malformations (LMs), 2 cases of teratoma, 2 cases of thyroglossal duct cyst, 4 cases of hemangioma, 1 case of congenital epulis, and 2 cases of dermoid cyst were reviewed. The accuracy of prenatal ultrasound was 93.85% (122/130). Observations of diameters using prenatal ultrasound revealed that the bigger the initial diameter is, the bigger the relative change during pregnancy. Magnetic resonance imaging (MRI) revealed that 2 cases of masses were associated with airway compression. In conclusion, ultrasound has a high overall diagnostic accuracy of fetal face and neck deformities. Prenatal US can enhance the management of ambulatory monitoring and classification. Furthermore, MRI provided a detailed assessment of fetal congenital malformations, as well as visualization of the trachea, presenting a multi-dimensional anatomical relationship.

Pyriform Sinus Fistula in the Fetus and Neonate: A Systematic Review of Published Cases

Purpose: To provide recommendations for the diagnosis and treatment of pyriform sinus fistula (PSF) in the fetus and neonate through a systematic review of the published literature. Methods: PubMed and Embase (1968-2019) were searched, and additional publications were obtained by searching the references by hand. The two reviewers assessed all papers and extracted the following variables: demographics, clinical features, diagnostic tests, interventions, and prognoses. Results: Forty-two papers were included, comprising a total of 158 cases. PSF presented almost exclusively on the left side (95.56%). Patients usually presented with a neck mass (100%) and respiratory distress (43.18%). The false-negative rate (FNR) of prenatal ultrasonography (US) was significantly higher than that of prenatal magnetic resonance imaging (MRI) (P < 0.01). For the diagnosis of PSF in neonates, computerized tomography (CT) and MRI were the most accurate diagnostic modalities. Ex utero intrapartum treatment (EXIT) was performed during delivery in 6 patients (26.09%). Among 135 patients with a reported date of definitive surgery, 117 (86.67%) underwent surgery during the neonatal period. Complications after definitive surgery appeared in 5 patients (3.16%), and all of them recovered spontaneously within 3 months. Furthermore, recurrence occurred in 4 patients (2.53%). Conclusion: In fetal cases with PSF suspected by US, MRI is necessary to confirm the diagnosis. During the neonatal period, patients with PSF typically present with a neck mass and respiratory distress, and CT/MRI appears to be the preferred diagnostic method. Definitive surgery is effective for treating neonatal PSF, with a low complication rate and low recurrence rate.

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.

Multidisciplinary management of congenital giant head and neck masses: Our experience and review of the literature

BACKGROUND

Large fetal head and neck (HN) masses can be life-threatening at birth and postnatally owing to airway obstruction. The two most frequent congenital masses that may obstruct the airway are lymphatic malformation (LM) and teratoma. The aim of this paper was to evaluate the results of our experience in the management of giant congenital HN masses and to conduct a literature review.

METHODS

The study involved a consecutive series of 13 newborns (7 females) affected by giant HN masses. Prenatal diagnosis was achieved by means of ultrasound (US) and fetal magnetic resonance imaging (MRI). Delivery was performed by means of EXIT procedure in case of radiological evidence of airway obstruction. In the postnatal period all feasible therapeutic options (surgery, sclerotherapy, medical therapy) were discussed and adopted by a multidisciplinary team. Twelve patients underwent surgery and one received Rapamycin for one month, with consequent surgical resection owing to increasing size of the mass.

RESULTS

The histopathological diagnosis was LM in 11 cases and teratoma in 2 cases. Airway obstruction was solved in 11 cases; 2 LM patients required a tracheotomy because of persistent airway obstruction. Major complications were flap necrosis (one patient) and facial nerve palsy (2 cases). Recurrence occurred in 5 patients.

CONCLUSIONS

The management of congenital HN masses is always challenging and necessarily requires an interdisciplinary approach. Current therapeutic options include surgery, sclerotherapy, medical therapy or a combination of them. When they are large enough to obstruct the airway, a patient-centered approach should guide timing and modality of treatment.

LEVEL OF EVIDENCE

IV.

Fetal Evaluation and Airway Management

Congenital causes of airway obstruction once noted at birth are now diagnosed prenatally. The adoption of ex utero intrapartum treatment has allowed for planned airway stabilization on placental support, dramatically decreasing the incidence of hypoxic injury or peripartum demise related to neonatal airway obstruction. Airway access is gained either through laryngoscopy, bronchoscopy, or a surgical airway. In complete airway obstruction, primary resection of the obstructing lesion may be performed before completion of delivery. This article reviews the current and emerging methods of fetal evaluation, indications for ex utero intrapartum treatment, and provides a detailed description of the procedure and necessary personnel.

Fetal Head and Neck Masses: MRI Prediction of Significant Morbidity

OBJECTIVE

The purpose of this study is to determine which MRI parameters of fetal head and neck masses predict high-morbidity neonatal outcomes, including ex utero intrapartum treatment (EXIT) procedure.

MATERIALS AND METHODS

This retrospective study (2004-2016) included parameters of polyhydramnios (based on largest vertical pocket), mass effect on the trachea, mass midline extension, and morphologic grade and size of masses. The morbid cohort included those requiring an EXIT procedure, difficult intubation at delivery, or lethal outcome. Predictive modeling with a multivariable logistic regression and ROC analysis was then performed.

RESULTS

Of 36 fetuses, five were delivered by EXIT procedures, there was one neonatal death within 12 hours after delivery, and another neonate required multiple intubation attempts. The remaining 29 fetuses were delivered at outside institutions with no interventions or neonatal morbidity. The largest vertical pocket and mass effect on the trachea were selected as independent predictors by the logistic regression. The cross-validated ROC AUC was 0.951 (95% CI, 0.8795-1).

CONCLUSION

The largest vertical pocket measurement and mass effect on the trachea were the most contributory MRI parameters that predicted significant morbidity in fetuses with masses of the face and neck, along with other significant parameters. These parameters predict significant morbid neonatal outcomes, including the need for EXIT procedures.

How to make an accurate diagnosis of fetal pyriform sinus fistula in utero: experience at a single medical center in mainland China

OBJECTIVE

The aim of this study was to make an accurate diagnosis of pyriform sinus fistula (PSF) for prenatal diagnosis.

STUDY DESIGN

Medical records were reviewed for all 35 pyriform sinus fistula patients presenting between 2011 and 2017. Ultrasonography (US), fetal magnetic resonance imaging (MRI) and karyotyping were offered during gestation, while computer tomography (CT) and barium esophagography were performed after birth.

RESULTS

Patients included 21 males (60%) and 14 females (40%) with a sex ratio of 1.5:1. The lesion was located on the left side in 32 (91.4%) cases, the right side in 2 (5.7%), and was bilateral (2.8%) in only one case. The sensitivity of CT, MRI, ultrasonography and barium esophagography were 100% (35/35), 69.2% (9/13), 22.9% (8/35), and 80% (20/25), respectively. If the diagnosis was correct, there was almost no recurrence after treatment. Karyotype analysis of all fetuses was normal.

CONCLUSIONS

Pyriform sinus fistula is more commonly seen in the left side. Compared with ultrasonography, MRI has more advantages in prenatal diagnosis, and it is more accurate in postpartum CT examination. The outcome of children with pyriform sinus fistula may be guarded when it correct diagnosis.

MR Imaging of the Fetal Face: Comprehensive Review

The human face is a complex anatomic structure with an equally complex embryologic development. Derangement of the developmental process can result in various structural anomalies, which range from a mainly cosmetic deformity, such as cleft lip, to potentially life-threatening conditions such as arhinia. These anomalies (a) can occur as isolated anomalies; (b) can be associated with intracranial, spinal, or dental anomalies; or (c) can be a part of various syndromes, thus serving as diagnostic clues in such cases. Proper evaluation of fetal facial deformities can help in prognostication, family counseling, and prenatal or early postnatal intervention. Ultrasonography (US) is the first line of investigation in these cases. However, when US does not allow complete evaluation of these anomalies owing to its inherent limitations, magnetic resonance (MR) imaging allows comprehensive evaluation of the anomaly itself and also evaluation of various associations and the treatment approach. The embryology of the fetal facial structures is considered with regard to the MR imaging technique and the MR imaging anatomy. The MR imaging features of various structural anomalies are described and classified into six groups, namely, orofacial clefts, orbital anomalies, nasal anomalies, facial masses, external ear anomalies, and abnormal face shape or profile. Also, the key associations and relevant treatment implications are reviewed. The article provides a "one-stop shop" review of these unique disorders-from basic understanding of the embryology to applying the knowledge in clinical practice, helping the interprofessional team and the patients alike. ^©RSNA, 2018.

Highlights on MRI of the fetal body

Fetal MRI is a level III diagnostic tool performed subsequently a level II prenatal ultrasound (US), in cases of inconclusive ultrasonographic diagnosis or when a further investigation is required to confirm or improve the diagnosis, to plan an appropriate pregnancy management. Fetal MRI plays an increasingly important role in the prenatal diagnosis of fetal neck, chest and abdominal malformations, even if its role has been amply demonstrated, especially, in the field of fetal CNS anomalies. Due to its multiparametricity and multiplanarity, MRI provides a detailed evaluation of the whole fetal respiratory, gastrointestinal and genitourinary systems, especially on T2-weighted (W) images, with a good tissue contrast resolution. In the evaluation of the digestive tract, T1-W sequences are very important in relation to the typical hyperintensity of the large intestine, due to the presence of meconium. The objective of this review is to focus on the application of fetal MRI in neck, chest and abdominal diseases.

Can we make an accurate diagnosis of pyriform sinus fistula by fetal MRI?

AIM

To review the fetal magnetic resonance imaging (MRI) features of pyriform sinus fistula (PSF) and to compare them with the postnatal clinical and surgical findings. The relevant medical literature is also discussed.

MATERIALS AND METHODS

The location, shape, signal, effects of adjacent structures and in utero changes detected on fetal MRI were reviewed in three cases of PSF. The patient's respiratory status at birth, the application of ex utero intrapartum therapy (EXIT), infectious complications in the neonatal period, and the surgical and pathological findings were also reviewed and discussed. The study consisted of three pregnant women between 18 and 38 years of age, each with a single fetus. Fetal MRI was performed at 26 and 38 weeks of gestation in case 1, at 34 weeks of gestation in case 2, and at 34 and 38 weeks of gestation in case 3. Postnatal clinical follow-up extended from 9 months to 3 years.

RESULTS

All lesions were well-circumscribed unilobular cysts with slightly thickened walls at the neck area. Case 1 was irregular in shape, and the other two cases were oval and extended longitudinally along the neck. The fluid contents showed signals consistent with amniotic fluid. Close contact with the thyroid gland was demonstrated to be a fairly characteristic feature that could be recognised on fetal MRI. The in utero follow-up detected slight changes in the signal, wall characteristics, contour, and airway deviation. Case 1 was bilaterally affected, causing it to be initially mistaken as macro-cystic lymphangioma. The diagnosis was corrected with the aid of postnatal imaging; however, a prenatal diagnosis was correctly made in cases 2 and 3. Airway obstruction was not observed in any of the three cases, and thus, EXIT was not applied. The fetal MRI findings were in good agreement with the postnatal clinical and surgical findings. In addition to the higher spatial delineation provided by fetal MRI, as described in the literature, the observation of close contact with the thyroid gland and a flattened deformity of the thyroid gland are other characteristic features.

CONCLUSION

Fetal MRI is useful for displaying characteristics of PSF that can enable an accurate prenatal diagnosis.

Fetal goiter conservatively monitored during the prenatal period associated with maternal and neonatal euthyroid status

Congenital goiter is considered a rare occurrence, and may be related to hypothyroidism, hyperthyroidism, or euthyroidism. In this report, we describe a case of fetal goiter identified in the 34th gestational week in a 41-year-old secundigravida with normal thyroid functions. A conservative approach was followed; the fetal goiter was monitored via ultrasound, which suggested this was a case of hyperthyroidism. After the birth, tests indicated that the newborn was euthyroidic. Consequently, a more detailed study using non-invasive procedures was deemed necessary to discover the precise cause of the fetal goiter during the gestational period.

Congenital Brain Tumor within the First 2 Months of Life

Congenital brain tumors (CBTs), defined as tumors presenting within 60 days after birth, are extremely rare and account for only 0.5-1.9% of all pediatric brain tumors. Teratoma is the most common type of CBT, although there are many other poorly described forms. Prenatal diagnosis of CBT is often difficult and usually based on clinical characteristics and radiological findings with magnetic resonance imaging and ultrasonography. The prognosis of patients with CBT depends on the histopathological features of the tumor and its location. Even after several investigations have been performed, a clear direction for diagnosis and treatment of fetal intracranial tumors is still lacking. Further studies are thus needed to clarify its clinical characteristics and establish recommendations for management.

Perinatal Thoracic Mass Lesions: Pre- and Postnatal Imaging

Chest masses present a common problem in the perinatal period. Advances in prenatal ultrasound, supplemented by fetal magnetic resonance imaging, now allow early detection and detailed characterization of many thoracic lesions in utero. As such, in asymptomatic infants, assessment with postnatal computed tomography or magnetic resonance imaging can often be delayed for several months until the time at which surgery is being contemplated. Bronchopulmonary malformations comprise most of the thoracic masses encountered in clinical practice. However, a variety of other pathologies can mimic their appearances or produce similar effects such as hypoplasia of a lung or both lungs. Understanding of the key differentiating clinical and imaging features can assist in optimizing prognostication and timely management.

Normal mandibular growth and diagnosis of micrognathia at prenatal MRI

OBJECTIVE

The aim of this article is to present reference data for fetal mandibular growth on magnetic resonance imaging, enabling the diagnosis of micrognathia.

METHODS

Retrospectively, on 355 magnetic resonance scans of apparently facially normal fetuses [gestational age (GA), 20-36 weeks], mandibular anterior-posterior diameter (APD = mandibular size), inferior facial angle (IFA = mandibular position), and jaw index (APD normalized to biparietal diameter) were correlated with GA by Pearson correlation. APD-age relationship was modeled. A receding chin was subjectively determined. Ten fetuses with mandibular anomalies were compared with normal fetuses.

RESULTS

For GA, APD showed high correlation (r = 0.850; P < 0.001), IFA (r = 0.086; P = 0.119) no correlation, and jaw index (r = -0.139; P = 0.018) weak correlation. APD-age relationship was expressed by the following: APD = 0.281 + 0.989 * GA (r(2)  = 0.723). A receding chin was identified in 7/10 abnormal fetuses. APD, IFA, and jaw index of abnormal and normal fetuses were significantly different (P < 0.001). In 10/10 abnormal fetuses, IFA was <50.0°; in 7/10, jaw index was less than the fifth percentile (micrognathia); in 3/10, jaw index was at low normal range (retrognathia).

CONCLUSIONS

Subjective identification of micrognathia may be limited. Reference data provide quantitative evaluation of mandibular size and position. An IFA <50° reflects micrognathia or retrognathia; a jaw index less than the fifth percentile suggests micrognathia.