I have a small "hypodensity" on one kidney that was identified on a CT scan I had a few months ago for inguinal lymphadenopathy. Radiology report said it was too small to be clinically significant, whatever that means. The mass size was not quantified in the report. My Primary Care Physician (PCP) said these are fairly common and wasn't concerned enough to recommend any followup. But, I suppose that if your radiologist recommends an MRI, that's a good plan to follow. A caveat - my experience with MRI: I had one and found out I was claustrophobic when I freaked out after I got shoved into the tube. Had to abort and get a repeat w/ a lorazepam to keep me calm, which went much more smoothly. Also, they typically take a lot longer than a CT scan and you have to remain very still. So, again, may want to take a happy pill.

Good luck!