Magnetic Resonance Imaging (MRI) is a non-invasive medical imaging technique that generates detailed images of organs and internal body structures. It uses strong magnetic fields and radio waves. This technology allows visualization of different tissue types, aiding in disease detection, diagnosis, and treatment monitoring. Unlike imaging methods that use ionizing radiation, MRI does not expose patients to X-rays.
Safety of MRI During Pregnancy
MRI is considered safe for use during pregnancy because it does not involve ionizing radiation, meaning no exposure risk for the developing fetus. Studies have shown no known harmful effects to the baby from MRI scans performed during pregnancy.
While MRI is considered safe, some considerations apply to different stages of pregnancy. MRI poses no known risk to the fetus in the second and third trimesters. In the first trimester, when organs are forming, MRI is performed only after consultation with a radiologist and when medically necessary. Some theoretical concerns exist regarding potential tissue heating or acoustic damage in the first trimester, but studies have not shown significant harm.
Gadolinium-based contrast agents (GBCAs) are avoided during pregnancy unless absolutely necessary, as they can cross the placenta and enter fetal circulation. While some older studies suggested potential risks like rheumatological conditions or stillbirth, newer research indicates most studies have not found definitive evidence of harm. If gadolinium is deemed essential, such as in cases of cancer, benefits are weighed against potential risks, and the lowest possible dose of certain types of agents may be considered.
Reasons for MRI During Pregnancy
MRI is considered when other imaging methods, such as ultrasound, do not provide enough information for a clear diagnosis. Ultrasound is often the first imaging choice during pregnancy, but MRI offers more detailed images, especially of soft tissues. This allows for a more precise evaluation of both maternal and fetal conditions.
For maternal conditions, MRI may investigate issues like neurological problems, unexplained abdominal pain, suspected appendicitis, or placental abnormalities. It provides clearer images of organs in the chest and abdomen, including the liver, kidneys, and pelvic structures. This is particularly helpful if other methods are inconclusive or if there are concerns about conditions such as inflammatory bowel disease or certain tumors.
In fetal evaluations, MRI is valuable for assessing complex anomalies identified by ultrasound. It often provides a more detailed look at the fetal brain for conditions like ventriculomegaly or spinal cord issues. MRI also helps clarify other structural problems, such as congenital diaphragmatic hernia or abnormalities in the chest, abdomen, or head and neck.
Important Considerations and Alternatives
When an MRI is considered during pregnancy, discussion with healthcare providers, including the obstetrician and radiologist, is essential. This ensures the scan’s necessity is clear and potential benefits outweigh any theoretical risks. Patients should be fully informed about the procedure and any alternatives.
Patient comfort during an MRI scan is also a consideration. The patient lies on a table that slides into a large, tube-shaped machine, and it is important to remain very still for the duration of the scan. MRI machines can be noisy, so ear protection is provided. Some facilities offer “open” MRI machines, which may provide more comfort than traditional closed-bore systems.
Ultrasound remains the primary imaging modality during pregnancy due to its safety and widespread availability. If ultrasound provides sufficient diagnostic information, it is generally preferred over MRI. However, if ultrasound images are unclear due to factors like fetal position, maternal body habitus, or limited fluid, MRI can provide additional details.