Extramammary Findings on Breast MR Examinations: Frequency, Clinical Relevance, and Patient Outcomes

To evaluate the frequency of extramammary findings on breast magnetic resonance (MR) images, recommendations for further imaging evaluation of each finding, and the subsequent effect on patient outcomes and health care expenditures.

Institutional review board approval was acquired for this HIPAA-compliant study. Informed consent was waived. Review of the institutional database identified 2324 breast MR examinations performed in women from January 1, 2010, to December 31, 2010. Breast MR imaging reports were reviewed for extramammary findings. Extramammary findings were categorized by using the computed tomography (CT) colonography reporting and data system (C-RADS). The electronic medical record was reviewed for each patient with a C-RADS category E3 and E4 finding to assess clinical relevance and pathologic outcome. If an E3 or E4 finding was previously described and evaluated, the finding was downgraded and assigned a final C-RADS E2 category. The cost of additional imaging was estimated by using the Medicare physician fee schedule. Statistical significance was assessed by using χ(2) statistics. A P value less than .05 indicated statistical significance, and 95% exact confidence intervals (CIs) were constructed.

Extramammary findings were identified in 391 of 2324 breast MR examinations (16.8%), which included 105 patients (4.5%) with E3 or E4 findings. Of the 2324 patients, 86 patients (3.7% [95% CI: 3.0%, 4.5%]) were recommended to undergo further imaging. After undergoing evaluation for additional imaging, a clinically important finding was found in nine patients (0.4% [95% CI: 0.2%, 0.7%]). Most frequently, hepatic lesions were the indication for additional imaging. Abdominal MR examinations accounted for 55% of costs related to additional imaging. Averaged across the entire cohort, further imaging evaluation and follow-up of incidental findings contributed an additional $16 to each breast MR imaging performed.

Additional imaging evaluation for E3 and E4 extramammary findings at breast MR imaging can identify clinically important disease without substantially increasing cost. .