Breast MRI is playing an increasing role in imaging breast cancer see  more pics  

Early stage: pic, pic, pic

Advanced stage: pic, pic, pic, pic, pic, pic,  pic, pic, pic, pic, pic

PET versus MRI here, here, here

Woman with benign lesion in right breast cancer in left (go here)
Woman with lung cancer and obstructed venous drainage with large swollen breasts due to fluid backing up in the breasts (go here)

MRI may be useful in male breast cancer: see mammogram and MRI

An MRI will show normal anatomy well (here) and is helpful in following women who have had surgery (here) and radiation (here).

MRI of woman with previous cancer developed cancer in opposite breast (here) and woman with previous mastectomy with reconstruction developed recurrence in reconstructed breast (here)

MRI is good for women have had previous breast implants (augmentation) go here