Gil Abramovici BA, Presenter: Nothing to Disclose

Martha Beretta Mainiero MD, Abstract Co-Author: Nothing to Disclose

To determine if baseline screening breast MRI has a higher rate of follow-up or biopsy recommendation than annual follow-up breast MRI in high risk women.

Following IRB approval, reports from 653 consecutive screening breast MRI exams done between September 2007 and December 2008 were reviewed retrospectively. All MRIs were performed on a 1.5T scanner with a 7 channel coil. Reports were reviewed to determine whether the study was a baseline or subsequent annual exam and were reviewed for BI-RADS assessment category. Pathology results from biopsies generated by BI-RADS 4 or 5 exams were recorded. Data were analyzed for statistical significance using a fisher’s exact test.

Of the 653 MRIs, 309/653 (47%) were baseline and 344/653 (54%) were annual screening studies with a prior MRI available for comparison at the time of interpretation. Of the baseline studies, 32/309 (10.4%) were interpreted as BI-RADS 3 and 18/309 (6%) were interpreted as BI-RADS 4. Of the BIRADS 4 exams in the baseline group, 2/18 (11.1%) were positive for malignancy on biopsy. Of the annual follow-up exams, 9/344 (2.6%) were interpreted as BI-RADS 3 and 16/344 (4.7%) were interpreted as BI-RADS 4. Of the BI-RADS 4 studies in the follow-up group, 3/16 (18.8%) were positive for malignancy on biopsy. The difference in BI-RADS 3 interpretation between the two groups was significant (p<0.001), but there was no significant difference in the rate of BI-RADS 4 interpretation or positive predictive value of the BI-RADS 4 interpretation between the two groups.

Baseline screening MRI was associated with a higher likelihood of a recommendation for short interval follow-up than annual follow-up MRI. There was no significant difference in likelihood in recommendation for biopsy or PPV of biopsy recommendation.

False positive examinations increase patient anxiety and cost of breast MRI, but limited data exist about the differences in false positive rate between baseline and subsequent follow-up studies.

Abramovici, G, Mainiero, M, Screening Breast MRI: Comparison of Interpretation of Baseline and Annual Follow-up Studies.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8012364.html