MR Imaging in Pregnancy

Advantages of MR imaging are lack of ionizing radiation, multiplanar capability, and excellent soft-tissue contrast . The risks of MR imaging in pregnant patients have been investigated with computer simulations and animal models. Although we are unaware of any controlled studies, the risk to the fetus at 1.5-T magnet strength appears negligible and is outweighed by the potential benefit of making a necessary diagnosis . Safety at higher field strengths has not yet been adequately assessed.

--> In 2007, the ACR guidelines for MR imaging practices recommended that MR imaging be used when the risk-benefit ratio warrants the study. The risk to the fetus may be associated with potential heat effects of the magnetic field, specifically in the first trimester; however, the benefit to the pregnant patient may outweigh this risk as well. Another risk of MR imaging to be considered is the potential for acoustic injury. However, further investigative studies make this risk seem less likely, as noise is attenuated through amniotic fluid and is usually delivered to the fetus at less than 30 dB .

In 1991, the Safety Committee of the Society of Magnetic Resonance Imaging stated that “MR imaging may be used in pregnant women if other non-ionizing forms of diagnostic imaging are inadequate or if diagnosis would otherwise require exposure to ionizing radiation. Pregnant patients should be informed that, to date, there has been no indication that the use of clinical MR imaging during pregnancy has produced deleterious effects” .
The utility of MR imaging in pregnancy has been enabled with the development of single-shot fast spin-echo sequences