Hello, I need some help understanding the contrast need for a MRI. Now, I had a MRI four days ago to rule out MS/brain tumors becasue i've been having some headaches/diziness/mild confusion. The radiologist asked me before the test itself if i accept contrast to be injected in me if there is need for it. However, once they got me out of the MRI after 25 min or so they told me contrast wasn't needed and everything is clear. Now I need to ask, can they miss tumors on a non contrast MRI? My understanding is that the contrast just provides detail about the tumor, it doesn't show it, right? All tumors should still be detected by a non contrast MRI?