Star Trek: Medical Tricorder vs. Today: MRI Scanner
When Dr. Leonard “Bones” McCoy needed to examine an injured crewmember on some godforsaken alien planet, he used his trusty medical tricorder, a portable device with a detachable handheld scanner that Bones would wave over the patient for a quick diagnosis. (Alas, viewers at home couldn't see whether the tricorder's mini-CRT display actually spelled out "He's dead, Jim" for the good doctor's convenience.) Today’s equivalent is considerably larger than a standard-issue tricorder and not at all portable. The Magnetic Resonance Imagining (MRI) scanner visualizes the internal workings of the body and is very useful in diagnosing brain, cardiovascular, oncological, and musculoskeletal ailments. It won’t fit on a shoulder strap, though, nor will it diagnose alien life forms, as far as we know.