Visualisations-in-Medicine-MRI Hi-Res

This infographic is about MRI scans work.  It also contains some information about the history of MRIs.  Usually, we try to break our reviews into subheadings, but this is a sort of free-flowing piece, so I’m just going to to with it.

MRI – Magnetic Resonance Imaging – used to take high quality pictures of the insides of humans.  It was invented in 1977 by a guy named Raymond Damadian.  A photograph of an MRI shows a technician, a patient, the machine itself, and the motorized table that slides the patient into the MRI Scanning tube.  Ooh.  We can do headings after all.  Here we go:

The Inner Workings of an MRI

The MRI Scanning Tube consists of a radio frequency transmitter and receiver that sends and receives radio signals, a main magnetic coil that creates a uniform magnetic field, and x, y, and z magnetic coils that create varying magnetic fields.  These are pointed out on a diagram of the MRI.

A Step by Step Guide

Since the human body is 60-70% water, and water is made up of hydrogen and oxygen, and hydrogen atoms have protons that spin naturally, the MRI works by creating a uniform magnetic field around the patient, causing his or her hydrogen protons to spin and align with the magnetic field.  The radio signal transmitter then sends out radio wave pulses of varying frequencies, and when the frequency matches the frequency of the spinning proton, the energy wave is absorbed by the proton, causing the proton to tilt out of alignment with the magnetic field.  The pulse ends, and the proton returns to the alignment of the magnetic field, and the leftover signal is picked up by the receiver.

The hydrogen protons in the human body emit different types of waves, depending on what and where they are.  The computer in the MRI can tell the difference between bone and blood, for example, and cancerous tissue emits a longer signal than non-cancerous tissue.  The computer matches up all the signals to the different parts of the body, and is able to detect when a signal is abnormal.  In a scan output, different colors mean there are differences in tissue type, and the MRI creates an image of the body using the location data and tissue type data.


MRIs are used to detect tumors, cysts, hemorrhages, torn ligaments, brain infections, and more.  Radio waves have less energy than X-rays, making them less harmful than X-rays or CT scans.


So far, nobody has proved that there can be any lasting health damage from an MRI.  In the past, before certain protocols were implemented, patients experienced  wounds related to unsecured metal objects in the room, or metal objects inside the patient, getting drawn into the magnetic field and causing injury.

Design:  C-

Not attractive, and somewhat hard to read at the top.

Information:  B+

Explains the MRI very well.

Source: Chronic Sinusitus Treatment by Acclarent UK