How Do You Read A Knee MRI?

How to Read an MRI of a Healthy Knee

MRIs are hard. All of our MRIs are read by Radiologists that know exactly how to read a knee MRI. Specifically: they specialize in reading only orthopaedic MRIs of the extremities. Why? Because There are so many subtleties in how to read an knee MRI.

First and foremost, you have to know your anatomy pretty well to know what you are looking at in all of these shadows and shades of grey. It's just not easy to pick things out visually. However, it can be done with the right amount of training and know-how. So, without getting into too much of an anatomy lesson, I’ll try to just teach some of the very basics of what we are looking at when we talk about how to read a knee MRI.

The View

Classically there are 3 different angles that the MRI is showing us. Each view is either looking at you from the front (Coronal View), the side (sagittal view), or from the top looking down (axial view).

The picture being shown by the MRI is actually a very thin “slice” of the body part in whatever angle you are viewing. Each new picture is a “slice” 1-2 mm further over or less than 1/12th of an inch. We can scroll all the way across in the same orientation.

The Image

Now, the computer can “spin” the image into one of two classically different ways. T1 images show normal anatomy better, but don’t show abnormalities and tears as well.

• In these, bone is typically very light colored.

• In the other way of looking at this, T2 images show bone to be very very black.

Water and blood look very white.

Because blood and fluid follow injury and inflammation, these T2 images are better at looking for injuries, inflammation, and tears. Something that is torn, but without a lot of extra fluid on T2, for example, may be indicative of an old or more chronic tear. T2 images come in lots of forms; Fat suppressed, proton density and others are all subsets of T2 imagery.

Reading A Knee MRI - Not That Easy!

If you want to know how to read a knee MRI, You really need to know these changes and subtleties. Otherwise, you won't know what you are looking at with MRI images. Taking a step back, if you don’t have a good handle on your normal anatomy, you’re kinda sunk.

There's an old saying, “knowledge is power” and for surgeons “anatomy knowledge is the ultimate power”.

Hope that helps! Good luck and stay active.