Friday, August 1, 2008

Bits & Pieces on Radiology Procedures

It has been a little while since I posted. Not much interesting stuff going on around here. I'm busy working hard on my medical transcription course as I want to finish quite a few of the modules/units this month while I'm off from teaching. I just finished Medical Word Building and now I'm going through grammar. I never liked grammar and now I'm trying to remember everything I learned about nouns, pronouns, verbs, adverbs, etc. when I was in school - not to mention periods, commas, colons, semicolons, dashes and hyphens, etc. I must admit it is a good review.

As some of you know, this past Tuesday I had a bone scan to make sure my hip/leg bone are healing correctly as I had been experiencing increased pain over the past couple months. I'm happy to inform you that the scan showed nothing. So I guess the pain is coming from having done too much too soon such as playing tennis and walking a mile every day. Sigh....there went my summer of swimming, hiking, biking, and playing tennis. Actually, the pain is sort of a blessing in disguise. You see because I'm in a lot of pain if I'm on my feet too long I have been spending a lot more time sitting down working on my medical transcription, which is great.

Now for a little bit about orthopaedic radiology procedures. Several people have asked me about the difference between a bone scan, MRI, CT scan, etc. (by the way, I've experienced each of the following first hand and if you ever end up having to have one of those tests done and have any questions feel free to ask me!)so I decided to post a little about each one here - I know some of you consider medical stuff like this to be boring.....sorry. To help show the difference between the machines I found some images online and added them below.

CT Scans - Cat scans are a specialized type of x-ray. CT is very good for imaging bone structures. The CT scanner is a large, square machine with a hole in the center, something like a donut. The patient lies still on a table that can move up or down, and slide into and out from the center of the hole. Within the machine, a X-ray tube on a rotating gantry moves around the patient's body to produce the images, making clicking and whirling noises as the arm moves. It is pretty neat to lay there and watch the circle go around and around.

MRI - I remember my very first MRI and I was so scared (although there was honestly nothing to be scared about!). I didn't know what to expect and I hated the loud noise the MRI scanner makes even while having ear plugs and I disliked having to lie still for what seemed to me as a very long time. If I made any move whatsoever the nurse/tech would come in and tell me they had to retake the picture and to not move. The second time I had an MRI done I thought that I could make good use of my time while having to lie there and be still so I took along a book only to be informed that I wasn't allowed to read a book during the scan - oh well. I have had both a closed MRI (that is the scanner similar to a tunnel and it can make people feel claustrophobic because of the feeling of being surrounded in a small tube) and a open MRI. An open MRI is really nice because you can see all that is going on around you. The sides of the scanner are open so it doesn't make you feel as cramped as you would in a closed MRI. Out of all the radiological procedures the MRI is the loudest.

Generally speaking, MRI provides a more detailed soft tissue image than other scans, such as a CT scan. Unlike CT it uses magnets and radio waves to create the images. No x-rays are used in an MRI scanner. The patient lies on a couch that looks very similar the ones used for CT. They are then placed in a very long cylinder and asked to remain perfectly still. The machine will produce a lot of noise and examinations typically run about 30 minutes.

The cylinder that you are lying in is actually a very large magnet. The computer will send radio waves through your body and collect the signal that is emitted from the hydrogen atoms in your cells. This information is collected by an antenna and fed into a sophisticated computer that produces the images. These images look similar to a CAT scan but they have much higher detail in the soft tissues. Unfortunately, MRI does not do a very good job with bones.

One of the great advantages of MRI is the ability to change the contrast of the images. Small changes in the radio waves and the magnetic fields can completely change the contrast of the image. Different contrast settings will highlight different types of tissue. CT can not do this.

Pictured above is a closed MRI scanner and beside it is a photo of an open MRI scanner.

Bone Scan
A bone scan is performed by having a radiotracer (bone-seeking radionuclide) injected into the bloodstream through a peripheral vein. As it decays, the radiotracer emits gamma radiation, which is detected by a camera that slowly scans your body. The camera is used to capture images to be used to determine how much of the radiotracer collects in the bones.

There is a small amount of pain when the needle is inserted. During the scan there is no pain. You must remain still during the examination, and you will be instructed when to change positions by the technologist. You may experience some discomfort due to lying still for a prolonged period of time.

If a bone scan is performed to evaluate possible fracture or infection, images will be performed shortly after the radiotracer injection, as well as after a 3-hour delay, when the tracer has collected in the bones. This is called a 3-phase bone scan.

To evaluate bone disease, images are obtained only after the 3-hour delay. Information from the camera is recorded in a computer, which then processes the data and creates an image.

Normal result scans show areas which appear uniform and gray throughout all the bones in your body. Abnormal results are shown as "Hot spots" which are areas where there is increased bone uptake (accumulation) of the radiotracer; these appear black. And "Cold spots" which are areas where there is less uptake of the radiotracer. These appear light or white.