An MRI-guided breast biopsy is rarely used, however, occasionally an MRI exam will demonstrate a suspicious breast abnormality which is not visible on mammography or ultrasound. In this case an MRI-guided biopsy is performed to make a diagnosis.
For this procedure the patient lies face-down on the MR (magnetic resonance) exam table with her breasts suspended below the table in a “breast coil,” which helps to hold the breast still. Preliminary MR imaging is performed after the patient receives an IV injection of a contrast agent and the radiologist reviews the images to locate and target the area of concern.
A computer system calculates the exact location of the abnormality in three-dimensional space. The skin is cleansed with an antiseptic solution and local anesthetic is injected into the skin and breast tissue. A biopsy probe introducer is placed by the radiologist into the breast and directed toward the abnormality. MR images are obtained to document that the probe is in good position.
A Mammotome biopsy device is then inserted through the introducer and multiple tissue samples are obtained with a single pass of the Mammotome. Once the tissue is removed, the radiologist then places a tiny metallic sterile biopsy clip marker through the introducer into the breast. This is required to document the area where samples were taken and may be used to guide a surgeon to this region if the pathology results are abnormal and surgical removal of the area is required.
MR images are then repeated to assess that the clip is in good position at the biopsy site. The biopsy introducer probe is then removed and pressure is held for several minutes to avoid bleeding. No stitches are required - typically a steri-strip is placed on the skin. A post-procedure mammogram is also performed to document the position of the biopsy clip marker and to assess for any post-biopsy complications. This mammogram is performed with only mild breast compression.
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