Lauren C. Friedlander MD, Presenter: Nothing to Disclose

Carol H. Lee MD, Abstract Co-Author: Nothing to Disclose

Christopher E. Comstock MD, Abstract Co-Author: Nothing to Disclose

Elizabeth A. Morris MD, Abstract Co-Author: Nothing to Disclose

D. David Dershaw MD, Abstract Co-Author: Nothing to Disclose

To determine how often lesions with benign concordant results on MRI guided core biopsy are actually missed and to determine the false negative rate of these procedures as detected by follow-up MRI.

This HIPPA compliant study was done with IRB approval. All breast MRI-guided core biopsies performed from January 2006 through June 2009 were retrospectively reviewed to identify those with benign concordant results and follow-up MR imaging. Cases in which immediate excision was recommended were excluded. Results of all subsequent MRI follow-up examinations and pathology for any subsequently recommended biopsy or excision of the same area were reviewed. Lesion appearance, size, and number of cores were compared between lesions that appeared to be adequately sampled and those that were missed. The false negative rate was calculated.

823 lesions underwent MRI-guided core biopsy. Initial pathology was malignant in 130, high risk or discordant in 249, and benign and concordant in 444. Of these, follow-up MRI was performed for 339 (76%). On follow-up, the targeted lesion appeared to have been missed in 28/339 (8.2%). Recommendations for these 28 cases were repeat biopsy or excision in 11 (39%), continued follow-up in 15 (53%), and no specific recommendation in 2 (7%). A total of 4 malignancies were identified on follow-up. These occurred in 1 of 11 cases for which repeat sampling was recommended, in 1 case for which continued follow-up MR was recommended but which then developed suspicious mammographic findings at the same site prompting biopsy, and in 2 cases where the initial follow-up MRI was thought to show adequate sampling but increase in the lesion on subsequent follow-up led to a diagnosis of invasive ductal carcinoma. Lesion appearance, size, and number of cores were not significantly different for missed lesions compared to all lesions. Total number of cancers ultimately diagnosed was 157/823 (18.5%), and the false negative rate for MRI biopsy was 2.5% (4/157).

Follow up MR imaging is important after benign MRI core biopsy results to identify unsuspected missed lesions. When the targeted lesion appears to have been sampled but is still partially present, continued MR follow-up may be of value to ensure lesion stability.

Follow-up breast MR imaging after MRI-guided core is prudent even for those cases with benign concordant results.

Friedlander, L, Lee, C, Comstock, C, Morris, E, Dershaw, D, Frequency of Unsuspected Missed Lesions and False-Negative Rate at MRI-guided Core Biopsy.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11034343.html