Mri of knee

Fig-1: Typical MRI of knee demonstrating excellent view of both soft tissue and bone.

Patient having an mri scan full size landscape

X-ray technologist placing patient into the machine just before the test

Magnetic Resonance Imaging or MRI uses magnetic fields and radiowaves to obtain images. This relatively new technology (developed in the late 70's) is used to provide detailed images of the body in any plane. The biggest difference between MRI and CT is the use of ionizing radiation (MRI does not use any). MRI is becoming more and more common in diagnostic imaging, but is commonly used for soft tissue imaging more so then bone. MRI provides excellent images of the body's tendon and ligaments. For example MRI can provide images to diagnose a tear in an patient's medial cruciate ligament (MCL) of the knee. These tears are often heard about with sports injuries and many reports describe that an athlete must have an MRI of their knee to determine the damage.

X-ray technologists require one extra year of courses to become specialized in MRI. These courses can be taken by correspondance or in classroom. There is a clinical component required of this specialization, in which the students are required to spend several hours working regular shifts in an MRI unit to develop experience and apply knowledge.

The X-ray technologists are required to question each patient prior to performing the procedure. Questions are designed to determine if patients have any metallic items that can be removed or those that cannot. Also questions are designed to determine if any metal may exist in the eyes from previous jobs or hobbies

Because MRI uses an extremely strong magnet, it is important that anyone entering the room remove all metal. Deaths have been recorded around the world from carelessness in MRI suites. Common hospital items such as IV poles that usually accompany patients are not permitted near the magnet. Specialized equipment is required and the patients IV bags must be transferred.


Bontrager, K.L. & Lampignano, J.P. (2005). Radiographic Positioning and Related Anatomy. Elsevier Mosby, 6th Ed.