Whats the right length of time for a single MRI exam?
I've been working in MRI for a while now. I've seen routine lumbar spines that take 30 minutes and routine lumbars that take 5. Which one is right? On the patient side there is comfort and tolerance. After 15 minutes or so patients start to take a dive in the ability to remain still. This comes from a myriad of sources including pain, irritability, physical condition, and lack of explanation regarding the exam. Obviously they want to be in the scanner the least amount of time necessary.
The main things we can do to combat he aforementioned are to explain what to expect before the exam and make them as comfortable as possible during the exam. Some folks have real physical issues and you can only get them so far as comfort goes. Speed is this patients best friend.
On the technical side radiologists like high resolution, high signal images. A 10 NEX image is going to look prettier than a 2 NEX image.... but how much? A wise radiologist once told me to answer the question. Although this is a novel concept it is frequently ignored. Do you need a 512x512 matrix with 4 NEX to see the patients problem? Probably not. Can you see a disc protrusion or a broken ankle with 1 NEX? Usually yes.
Taking all this into consideration the answer to the original question is somewhere in between. What the radiologist would like and what the patient can tolerate rarely coexist. I'll put it this way- I'm claustrophobic and I can't hold still for more than 15 minutes. When I need an MRI I make sure the site has protocols that answer the question and get me out before I loose my mind.
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