Fetal MRI In Pregnancy: Indications, Safety And Access In Australia

Fetal magnetic resonance imaging can add valuable detail when an ultrasound finding is difficult to interpret or when a baby may have a complex condition. It produces detailed images of the fetal brain, chest, abdomen, spine, placenta and surrounding structures without using ionising radiation. The examination is usually arranged by a maternal-fetal medicine specialist, radiologist or paediatric team after a targeted ultrasound.

For families in Australia, the decision often involves more than choosing a scan. Timing, referral pathways, travel from regional areas, private fees and the availability of specialist imaging can all affect care. Understanding why MRI is proposed and how safety is managed can make the referral process less stressful.

Why Fetal MRI Is Requested

Ultrasound remains the primary imaging test during pregnancy. It is widely available, allows real-time assessment and can evaluate growth, anatomy, blood flow and the placenta. Fetal MRI is generally a problem-solving examination rather than a routine screening test. It is considered when MRI may answer a specific clinical question that ultrasound cannot answer reliably.

The extra information can help clinicians clarify anatomy, estimate the extent of a condition and plan care before and after birth. MRI may also be useful when the mother’s body size, reduced amniotic fluid, fetal position, multiple pregnancy or late gestation makes ultrasound images less clear.

A referral does not automatically mean that a serious abnormality is present. Sometimes the scan confirms that a suspected finding is normal or less extensive than first thought. In other cases, the images support a conversation about delivery location, neonatal surgery, paediatric treatment or postnatal testing.

Common Clinical Indications

The fetal brain is one of the most frequent reasons for MRI. Indications can include enlarged ventricles, suspected abnormalities of brain development, a posterior fossa concern, agenesis of the corpus callosum or an uncertain ultrasound finding. MRI can show cortical development and other brain structures with greater contrast, particularly later in pregnancy when ultrasound views become limited.

Chest and abdominal indications include suspected congenital diaphragmatic hernia, lung masses, airway obstruction, cystic lesions, bowel abnormalities and selected urinary tract conditions. MRI can help estimate lung volume and assess whether organs have moved into the chest, information that may influence neonatal stabilisation and specialist referral.

MRI may also be considered for spinal abnormalities, complex skeletal conditions, placental invasion, an unusual mass or selected complications in twins. The usefulness depends on gestational age, fetal movement, image quality and the precise question being asked. A specialist should explain what the scan can realistically add before it is booked.

Timing During Pregnancy

There is no single week that suits every examination. Many fetal MRI studies are performed from around 20 to 22 weeks onwards because fetal anatomy is more developed and the images may be easier to interpret. Brain imaging is often particularly informative in the second half of pregnancy, although the timing should be based on the suspected condition and the consequences of waiting.

MRI can be performed in the first trimester when there is a strong clinical reason, but clinicians generally avoid non-essential imaging at that stage. The decision weighs the urgency of the information against the limited evidence available for very early fetal exposure and the practical difficulty of obtaining useful images from a small, moving fetus.

Later scans may be affected by increasing fetal movement and reduced space, yet they can still provide important information. An urgent examination is not necessarily postponed simply because pregnancy is advanced. The referring team should explain whether the result could change monitoring, delivery planning or newborn treatment.

Safety And Contrast Considerations

MRI does not use X-rays or other ionising radiation. Current clinical practice considers non-contrast MRI an acceptable option in pregnancy when there is a clear medical indication. The scanner uses a strong magnetic field and radiofrequency energy, so the imaging team follows protocols designed to limit heating and exposure time.

A 1.5-tesla scanner is commonly used for fetal imaging, while 3-tesla systems may be suitable in experienced centres for selected cases. The team will ask about metal fragments, implants, pacemakers, medication pumps, previous surgery and other safety issues. Some devices are MRI-conditional rather than automatically unsafe, so accurate device information is important.

Gadolinium contrast is generally avoided during pregnancy unless the expected diagnostic benefit is compelling and alternatives are inadequate. It crosses the placenta and is cleared through the fetal kidneys into the amniotic fluid. For most fetal examinations, contrast is unnecessary because the purpose is to assess anatomy using specialised non-contrast sequences.

The scanner can be noisy, but the examination is designed with maternal and fetal safety in mind. Sedation is not routinely needed. If a mother feels anxious or claustrophobic, this should be mentioned when booking so the service can discuss preparation, positioning and whether an open or short-bore scanner is available.

What The Appointment Involves

Before the appointment, the radiology service checks the referral, gestational age and relevant ultrasound findings. Patients usually complete an MRI safety questionnaire and change out of clothing containing metal. Food and drink instructions vary, although many examinations do not require fasting. Bringing referral letters and previous imaging can help the radiologist compare findings.

During the scan, the mother lies on her back or, more commonly later in pregnancy, in a position tilted slightly to one side for comfort and circulation. Cushions can support the abdomen and knees. The patient needs to remain as still as possible, but normal breathing is allowed. Sequences are repeated when fetal movement makes an image unclear.

A typical examination may take 30 to 60 minutes, depending on the clinical question and the baby’s movement. Staff can communicate through an intercom, and the patient can usually signal if she needs assistance. The radiologist interprets the images alongside ultrasound and clinical information, then sends a report to the referring specialist.

MRI does not replace routine antenatal care. Results may be discussed by a multidisciplinary team that includes maternal-fetal medicine, radiology, neonatology, paediatric surgery, genetics or genetic counselling. If the findings affect possible steroid timing before preterm birth, clinicians may also review current antenatal steroid guidance alongside the wider care plan.

Access And Costs In Australia

Australia has fetal MRI services in major centres including Sydney, Melbourne, Brisbane, Perth and Adelaide, although availability differs between public hospitals, private radiology providers and tertiary women’s hospitals. A patient from regional New South Wales, Queensland or Western Australia may need to travel for the scan, sometimes with help from a state or territory patient transport scheme.

Referral arrangements vary. A public hospital may organise imaging through its maternal-fetal medicine service, while a private patient may be referred to a radiology practice with specialist fetal imaging expertise. Medicare and private health insurance coverage depend on the item, clinical indication, provider and billing arrangement, so families should ask about out-of-pocket costs before attending.

Local care often involves a GP, obstetrician or ultrasound specialist coordinating the referral. In smaller communities, telehealth can allow the metropolitan team to discuss the images and plan the appointment before a family travels. It is useful to confirm whether the service performs fetal MRI regularly rather than general MRI alone.

Families should also allow time for practical arrangements. Public transport and parking can be difficult around large Sydney or Melbourne hospitals, while rural families may need accommodation near a tertiary centre. A support person can be helpful, especially when the referral follows an unexpected ultrasound result.

Discussing Benefits And Limits

A fetal MRI report can improve diagnostic confidence, but it cannot answer every question. Image quality may be limited by movement, maternal discomfort, fetal position or the timing of the scan. Some findings still require postnatal examination, genetic testing, echocardiography or follow-up ultrasound.

Useful points to raise with the clinical team include:

• What specific question is the MRI intended to answer?
• Could the result change pregnancy monitoring or place of birth?
• What gestational age is best for this examination?
• Is contrast being considered, and why would it be necessary?

Before booking, families may also want to clarify:

• Which radiology service will interpret the images?
• What preparation, travel and appointment length should be expected?
• Are there public, private or concession-based billing options?
• When and how will the results be explained?

The archived FAOPS 2020 website reflects the specialist environment in which perinatal and neonatal teams share research, clinical experience and approaches to complex care. Although the Tokyo congress was cancelled in 2020 because of the pandemic, the broader principle remains relevant: fetal imaging decisions work best when obstetric, radiology and neonatal expertise are connected.

A referral for MRI should lead to a clear clinical conversation, not unnecessary alarm. Ask the referring team what they are investigating, how the result may affect care and which service will provide follow-up. With appropriate screening and specialist oversight, non-contrast fetal MRI can be a valuable part of pregnancy care when ultrasound leaves an important question unresolved.