Heavily tattooed patients face a theoretical risk of burns and other adverse events when undergoing  MRI, researchers warn.

There are several case reports of MRI-related burns in the literature, they say. 

Colour pigments in tattoos are conductive, and if the tattoo absorbs a lot of energy from high-frequency magnetic fields, the skin can burn, they warn.

However, in a seven-year study of 350 people with between one and seven small tattoos — none of them larger than 20cm across — there was only one adverse reaction.