November 17, 2018

How to Read a CT Sinus Scan for the Layperson

It is actually not that difficult for non-medical individuals to learn how to accurately look at a CT Sinus scan and determine whether there is a sinus infection, nasal polyps, or is actually normal. Watch the video above to learn how to read a CT Sinus scan like a pro (well, almost like a pro).

But if you prefer to read, here's a brief explanation.

First, know your colors.

Air is BLACK
Bone is WHITE
Everything else like soft tissues and fluid is GREY

CT sinus scans are obtained in basically two different orientations: axial and coronal. Axial is if you slice the head in the horizontal plane whereas the coronal plane is in the vertical direction.

The coronal plane is most easily understood by non-medical individuals. Scroll around the CT Sinus scan until you find the CT images oriented in the coronal plane. You got the right one when you see both eyeballs positioned below the brain as shown in the picture below. This particular image slice probably contains the most information with respect to the sinus cavities. (Don't worry about the frontal and sphenoid sinuses because this is a basic tutorial.)

Next, a little anatomy lesson... take a look at where the sinuses are located and what they are called. The maxillary sinus cavities are located below the eyeballs (aka the "cheek" sinuses) while the ethmoid sinus cavities are located between the eyes.

When it comes to sinus cavities, you want to see BLACK, because black is air and air is normal. If you see anything other than BLACK in the sinus cavities, this would suggest some type of sinus abnormality. Let's take a look at a few examples of ABNORMAL images.

Grey discoloration within the right maxillary sinus cavity. Just
like water layering in a cup, you can see the same thing here.
Known as an air fluid level, it suggests an acute sinusitis
of the right maxillary sinus cavity.

Grey discoloration with "bubbles" suggesting an acute sinusitis
of the right maxillary sinus.

Severe nasal polyps involving all sinus cavities.
Note that there is no BLACK (or air) in the sinus cavities.

Not uncommonly, a small inclusion cyst denoted by a small
circular grey discoloration in the sinus cavity may be seen.
This is considered a benign condition and typically no
intervention is required.

With this background information, one should be able to at least intelligently be able to look at a CT Sinus scan and at least say whether there is any significant abnormality present in the sinus cavities (at least the maxillary and ethmoids).

Fauquier blog
Fauquier ENT

Dr. Christopher Chang is a private practice otolaryngology, head & neck surgeon specializing in the treatment of problems related to the ear, nose, and throat. Located in Warrenton, VA about 45 minutes west of Washington DC, he also provides inhalant allergy testing/treatment, hearing tests, and dispenses hearing aids.

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