# Diagnosing knee problem - CT vs. MRI? **URL:** \ **Category:** Factual Questions\ **Created:** [November 14, 2006, 3:36am UTC](https://boards.straightdope.com/t/diagnosing-knee-problem-ct-vs-mri/380349 "2006-11-14T03:36:58Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![beckwall](https://avatars.discourse-cdn.com/v4/letter/b/b487fb/32.png) [@beckwall](https://boards.straightdope.com/u/beckwall)\ **Post date:** [November 14, 2006, 3:36am UTC](https://boards.straightdope.com/t/diagnosing-knee-problem-ct-vs-mri/380349/1 "2006-11-14T03:36:58Z")
OK, so I’m seeing the PA on Wed. to discuss on-going symptoms in my left leg. I really don’t think it’s a blown knee, cuz there are other nerve-y type things going on, including weird sensations in my foot. I hate MRIs. But if it will give me a better idea, including perhaps vascular involvement, I’ll do it. But if I can get by with a CT to see if my knee is wonky, then I’d like to do it that way. I actually chose to see my doc’s PA because he is amazingly thorough and caring. My ortho surgeon just wants to know when I’ll be ready for another hip replacement. :mad: No offense to doctors on board here. Anyone have pros and cons to offer on subject of diagnostic powers of CT vs MRI? ---
**Author:** ![Askance](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/askance/32/8281_2.png) [@Askance](https://boards.straightdope.com/u/Askance)\ **Post date:** [November 14, 2006, 3:54am UTC](https://boards.straightdope.com/t/diagnosing-knee-problem-ct-vs-mri/380349/2 "2006-11-14T03:54:11Z")
Why on earth are you asking us? Go with whichever technique your doctor says has the best “diagnostic power” in this case. If you don’t trust his/her advice, change doctors. ---
**Author:** ![beckwall](https://avatars.discourse-cdn.com/v4/letter/b/b487fb/32.png) [@beckwall](https://boards.straightdope.com/u/beckwall)\ **Post date:** [November 14, 2006, 6:08am UTC](https://boards.straightdope.com/t/diagnosing-knee-problem-ct-vs-mri/380349/3 "2006-11-14T06:08:39Z")
I was asking because it’s called “general questions” and I thought I might get an educated reply vs. a snarky opinion. So far, no luck. ---
**Author:** ![Nava](https://avatars.discourse-cdn.com/v4/letter/n/da6949/32.png) [@Nava](https://boards.straightdope.com/u/Nava)\ **Post date:** [November 14, 2006, 8:39am UTC](https://boards.straightdope.com/t/diagnosing-knee-problem-ct-vs-mri/380349/4 "2006-11-14T08:39:35Z")
They sort of show opposite things. Cat-scans (CT) use Xrays to create 3d images of the solid parts of the body; MRI uses magnetism to create 3D images of the water in the body, that is, of the soft tissues. (This is a simplification etc etc) So which one to use depends on what your doctor is looking for. An MRI wouldn’t be as useful to find broken bones as a regular Xray or a CT; OTOH if you’re looking for something “broken” in soft tissue, the Xray based techniques wouldn’t be any good. ---
**Author:** ![Neur0mancer\_1](https://avatars.discourse-cdn.com/v4/letter/n/46a35a/32.png) [@Neur0mancer\_1](https://boards.straightdope.com/u/Neur0mancer_1)\ **Post date:** [November 14, 2006, 8:04pm UTC](https://boards.straightdope.com/t/diagnosing-knee-problem-ct-vs-mri/380349/5 "2006-11-14T20:04:28Z")
[QUOTE=beckwall] OK, so I’m seeing the PA on Wed. to discuss on-going symptoms in my left leg. I really don’t think it’s a blown knee, cuz there are other nerve-y type things going on, including weird sensations in my foot. I hate MRIs. But if it will give me a better idea, including perhaps vascular involvement, I’ll do it. But if I can get by with a CT to see if my knee is wonky, then I’d like to do it that way. Anyone have pros and cons to offer on subject of diagnostic powers of CT vs MRI? [/QUOTE] CT of the knee has very limited uses, and is used primarily for evaluation of complicated fractures. MRI allows you to evaluate the soft tissues - vessels, nerves, tendons, ligaments, menisci, etc. I am sorry that you hate MRIs, but that is without a doubt the way to go. P.S. I am a radiologist