From the Guidelines
When a fetal encephalocele is diagnosed on ultrasound, the next best step is a fetal MRI rather than 3D imaging. This recommendation is based on the most recent and highest quality study, which suggests that fetal MRI is generally indicated following an ultrasound examination in which the information about the abnormality is incomplete 1. Fetal MRI provides superior soft tissue contrast and detailed anatomical information about the brain tissue involved in the encephalocele, which is crucial for accurate assessment and prognosis.
The benefits of fetal MRI in this context include better characterization of the neural tissue content, evaluation of associated brain malformations, and distinction between various types of encephaloceles (such as meningocele versus encephalomeningocele) 1. This information is essential for counseling parents about the prognosis, planning for delivery, and determining potential postnatal interventions. Additionally, MRI can detect additional abnormalities that might be missed on ultrasound, including cortical dysplasia, corpus callosum abnormalities, and other brain malformations that frequently accompany encephaloceles.
Key considerations for fetal MRI include:
- It is especially helpful for central nervous system anomalies, planning for prenatal and postnatal intervention, and for airway management in fetuses with neck masses 1.
- The ideal timing for fetal MRI is at or after 22 weeks gestation, although an MRI performed between 18 to 22 weeks may be of value in certain clinical indications and settings 1.
- Fetal MRI can provide important information that may confirm or complement the ultrasound findings and alter or modify patient management 1.
Overall, the use of fetal MRI following the diagnosis of a fetal encephalocele on ultrasound is supported by recent guidelines and studies, emphasizing its role in improving diagnostic accuracy and guiding clinical management 1.
From the Research
Next Steps After Diagnosing Fetal Encephalocele on Ultrasound
If a fetal encephalocele is diagnosed on ultrasound, the next best step is to use a more detailed imaging technique to confirm the diagnosis and assess the extent of the anomaly. The options for the next step are:
- 3D imaging
- Fetal MRI
Comparison of 3D Imaging and Fetal MRI
Both 3D imaging and fetal MRI can provide more detailed information about the fetal anatomy than ultrasound. However, fetal MRI is considered a more accurate and reliable method for diagnosing and evaluating fetal encephalocele 2, 3, 4. Fetal MRI can provide detailed images of the fetal brain and spine, which can help identify associated anomalies and guide prenatal management.
Advantages of Fetal MRI
The advantages of fetal MRI over 3D imaging include:
- Higher resolution and more detailed images of the fetal anatomy
- Ability to identify associated anomalies and guide prenatal management
- Confirmation of the diagnosis and assessment of the extent of the anomaly
- Providing accurate information for parental counseling and treatment planning 2, 3, 4
Studies Supporting Fetal MRI
Several studies have demonstrated the utility of fetal MRI in the diagnosis and evaluation of fetal encephalocele. For example, a study published in 2007 reported a case of Chiari III malformation diagnosed by fetal MRI, which confirmed the presence of an occipital encephalocele and identified additional bony defects in the upper cervical spine 2. Another study published in 2013 highlighted the importance of fetal MRI as a complementary method to ultrasound in the diagnosis of cortical malformations and other congenital CNS anomalies 3.
Decision Making
Based on the available evidence, fetal MRI is the recommended next step after diagnosing fetal encephalocele on ultrasound, due to its higher accuracy and ability to provide detailed images of the fetal anatomy 2, 3, 4.