MRI machines do explode and send shrapnel everywhere. Emergency stopping them causes the helium that’s trapped in the part that rotates the magnets to become a gas, then expand as the magnets superheat. In some cases, this causes an understandable explosion.
Seriously happened once already this year https://healthimaging.com/topics/medical-imaging/magnetic-resonance-imaging-mri/mri-explosion-leaves-3-injured-including-2-hospital-staffers , the cop is lucky.
Unfortunately not how nicotine works