Does MRI scan harm the fetus?

Fetal MRI technique has been used in the world for more than 30 years, providing highly accurate diagnosis of fetal abnormalities. In Vietnam, in the past 10 years, MRI has been applied in some hospitals to help check for fetal abnormalities. This technique is non-invasive, safe for the fetus, providing information and clear images of the anatomical structure of the fetus. MRI is usually performed in the second and third trimesters of pregnancy, after abnormal fetal test or ultrasound results.

MRI uses a large magnet, radiofrequency pulses, and a computer to create images of the fetus in the womb. MRI uses magnetic fields instead of radiation (X-rays) to comprehensively detect abnormalities in the brain, spine, face, neck, chest, lungs, abdomen, pelvis (including intestines, kidneys, and bladder), placental structures, etc.

Fetal MRI is proven by the world not to be harmful to the fetus or the mother. In the case of your child having brain abnormalities on ultrasound, the doctor ordered an additional MRI examination, which is necessary. The reason is that nervous system abnormalities are difficult to accurately detect through ultrasound. At this time, the doctor will perform an additional MRI to help diagnose the most accurate central nervous system abnormalities such as cerebral cortex abnormalities, ventricular dilatation, corpus callosum agenesis, microcephaly, etc.

Ventricular dilatation is a manifestation of many different clinical conditions including brain structural abnormalities, cortical developmental abnormalities, intraventricular hemorrhage… The cause of this condition is often related to genetic abnormalities, intrauterine infections. To evaluate this abnormality, pregnant women often undergo specialized neurosonography and MRI. According to the American Association of Colleges of Radiology (ACR), MRI is indicated when ventricular dilatation is detected on ultrasound over 12 mm.

Cerebral cortical abnormalities are rare brain disorders caused by abnormal development of the outer layer of the fetal brain. Fetal MRI has a higher resolution than ultrasound, so it helps to better assess abnormalities in the morphology and structure of the Sylvian fissure (the lateral fissure located in the cerebral hemisphere, dividing the cerebral hemisphere into many lobes and cerebral lobes). This method is also effective in cases of other cortical fissure abnormalities such as microcephaly, cortical thickening, and smooth brain. At the same time, it also shows other accompanying abnormalities such as ganglion protrusion, posterior fossa abnormalities, and structural abnormalities of the skull base…

Agenesis of the corpus callosum is a severe malformation of the central nervous system due to failure of the corpus callosum to form during the embryonic period. The sensitivity of MRI in detecting corpus callosum abnormalities and associated neurological abnormalities is 100% compared to ultrasound which is 66-75%.

This method also overcomes the limitations of ultrasound including ossification of the skull vault, unfavorable fetal position, and low amniotic fluid. MRI also allows examining structures in areas that are difficult to access with ultrasound, such as the back of the eyeball, the skull base including the petrous bones, the semicircular canals, the cochlea, and the optic chiasm area.

MRI results provide additional diagnostic information for complex malformations, helping doctors assess whether to keep the pregnancy or terminate it, and recommend postnatal intervention methods.