Follow-up: MRI Question — What Can an MRI Without Contrast Show That an MRI With Contrast Cannot?

[Lisa88]

Dr. Ancill,
This is just a clarification. I was not asking for a diagnosis. And I will try to consult yet another neurologist/radiologist on all of this.
I would like to know what in general the difference is between non contrast and contrast MRI? If contrast is the more detailed and intense of the two, what can a non contrast MRI/IAC show that an MRI/IAC with contrast cannot? For example, is it vascular detail, or what?
I have been trying to find the answer to this simple question for a very long time.
Thanks.
Lisa

 

[Dr. Ancill]

The commonest contrast agent is gadolinium. This is used to literally enhance the contrast between normal tissue and inflamed or diseased tissue. It can be useful in trying to look for secondary cancer deposits - which can be quite small. In some circumstances, a contrast agent is used to see blood flow. There are risks with a contrast agent, although these are small - but these risks increase with kidney or liver disease. If a non-enhanced MRI is normal then a contrast one may be done to improve the resolution.