What does an MRI show?

Hi, TJP.  As I understand it, mammograms and MRIs see cancer and indications of cancer differently.  So, a mammogram might pick up the calcifications leading to a DCIS diagnosis (like mine did).  The MRI might not be able to see the calcifications, but it could see other areas of cancer.  (For example, when I had an MRI before surgery, it turned out my area of DCIS was a little bit bigger than they had thought from the mammogram.)  The surgeon is probably trying to get as complete information as possible before you have surgery so she knows how much to remove if you are having a lumpectomy or to help you make the best-informed decisions about treatment that you can.

Since the stereotactic biopsy is done with the needle, I think by definition there are no margins (because there is probably still some DCIS left and because the purpose of the biopsy is to see if there is cancer there, not to remove all of it -- the idea being that if there isn't cancer there you wouldn't have to go through a lumpectomy biopsy for no reason).  So, there will be margins when you have a lumpectomy (or mastectomy), but not now.

After surgery, you will know your margins and also will have more information about the DCIS.  Sometimes, women who have DCIS on biopsy turn out to have some invasive cancer (usually a small amount) after surgery that was not seen in the biopsy.

I hope this helps.  It sounds to me like your surgeon is being thorough and careful and I'm sure you'll feel like you have a lot better sense of what is going on after you meet with her on Wednesday.  In the meantime, hang in there!  

brace yourself for that MRI. Make sure you face and arms are comfortable....when I was put in, I thought I was comfortable but after a few minutes I wanted to adjust myself and you cant move at all the time you are in it.

The MRI is the perfect machine to see through the dense breast tissue, it was used in my case because my breasts were so dense...

After my stereotactic biopsy my surgeon sent me for a MRI. It showed a larger area of DCIS than the mammogram showed and also showed another suspiscious area which they removed when they did my lumpectomy. I've heard that some MRI's can show areas that aren't actually problems so can cause more worry, and for that reason some doctors don't do them. Dr. Susan Love says that she doesn't like to have them done because of that.

I debated about responding here, as I had a very different experience with MRI than most. While I don't want to alarm anybody, because MRI *is* the current 'gold standard', it can miss things. My invasive was picked up by u/s but not mammo...dense breasts. However, 4 u/s, 1 mammo and a breast MRI all missed a 6 cm DCIS lesion. It was a surprise on my initial pathology report after lumpectomy. Because of so many dirty margins for DCIS and MRI couldn't 'see' it, I opted for BMX. We didn't know if a second lumpectomy would get it all but more frightening to me was we didn't know if it was anywhere else in my breast...or the other one. This was not an easy decision but for me, the correct one. Having said that, I think MRI catches more than it misses but no test is 100%. Good luck in your decision.

Thanks for the update!  I find MRIs rather stressful for some reason (maybe a little bit of claustrophobia) so it is always a relief to have them over.  Good luck with the results on Monday!

Weighing in late here with my experience...

As others have said, an MRI can be helpful but is certainly not a perfect screening tool.  A mammogram picked up my very small area of calcifications, which a later biopsy confirmed was DCIS.  The follow-up MRI saw nothing more in that area but showed a new area of concern, which a biopsy revealed was benign.  However, my eventual lumpectomy showed over 2 cm more DCIS than what showed on the MRI.  So, the MRI couldn't see my DCIS but yet highlighted another area that turned out to be a false positive.  I know an MRI works great for some, but it was not a reliable screening for me (and I don't have dense breasts).

Good luck with your appointments!  

TJP, the BRCA results in and of themselves don't change what surgery is needed, but some women who test BRCA+ decide to have prophylactic mastectomies. Is this something you've thought about? If so, you should tell your doctor. If you think you'll want a PMX if you're BRCA+, there's no reason to rush ahead with the lumpectomy now. At least IMO.

I had genetic testing done too, and the surgeon recommended waiting until after the results came back before deciding on lumpectomy vs. mastectomy.  My results were negative and I had a lumpectomy but ended up with a mastectomy anyway due to narrow margins.  At that point, I chose to have a bmx because of my family history (even without the BRCA), and because I felt more comfortable knowing my chances for recurrence would be so low.

Good luck!