MRI effects on craniofacial size and crown-rump length in C57BL/6J mice in 1.5T fields.

Previous studies have shown magnetic resonance imaging to be potentially teratogenic for eye development. An investigation was undertaken to ascertain the effects of 1.5 Tesla magnetic resonance imaging fields on crown-rump length and craniofacial perimeter, two less sensitive teratologic end points of the C57BL/6J mouse. A sham control and two experimental groups of dams (N = 12, 11, 12) placed in different magnet locations were exposed to magnetic resonance imaging fields under clinically realistic conditions. A T-2 weighted spin-echo technique of 36-minutes duration was used on each dam. Crown-rump length was chosen because it is a standard measure of embryotoxicity. Craniofacial perimeter was evaluated because of its relationship to the anterior neural plate, the same region in the developing embryo that gives rise to the eyes. Magnetic resonance imaging fields were found to produce crown-rump and craniofacial perimeter measures smaller than control animals (p < 0.05) when exposed at the isocenter (p = 0.038 and 0.008 respectively). Groups exposed to magnetic resonance imaging fields at the magnet entrance showed p values of 0.004 and 0.053 respectively. The results confirmed magnetic resonance imaging teratogenicity in the C57BL/6J mouse and demonstrates the need for further experimental investigation to ascertain the clinical safety of magnetic resonance imaging for humans.