As someone who worked in medical imaging many years ago, I need to be the pedant who says, “Well, actually, a CAT scan (or CT scan) fires x-rays through the body and measures what gets through, while an MRI uses a strong magnetic field to align the spins of all hydrogen atoms in the body, then sends a radio wave to disrupt those spins and measures the energy emitted as the atoms realign. They’re completely different technologies.”

That’s why we also use positrons. So that all PET-scan.

But certain breeds of dogs can give lab results.