Characteristics of probably benign breast MRI lesions.
OBJECTIVE
The purpose of our study was to describe the characteristics of probably benign breast MRI lesions and determine how these characteristics could be used to define the MRI BI-RADS 3 category.


METHODS
We prospectively collected morphology and kinetic data on lesions assessed as BI-RADS 3 in 2,569 consecutive breast MRI examinations from January 2003 through November 2006. The clinical indications for MRI, follow-up assessments, and pathology findings through May 2008 were collected from clinical records. Data were linked to the regional tumor registry to identify cases of malignancy in patients who did not follow-up at our institution. Frequency of BI-RADS 3 and cancer yield were calculated. Characteristics of probably benign lesions were analyzed for predictors of malignancy.


RESULTS
Three hundred sixty-two lesions were assessed as BI-RADS 3 in 260 (10.1%) of 2,569 examinations in 236 patients. The 362 lesions included 168 (46%) foci, 132 (36%) nonmasslike enhancements, and 62 (17%) masses. Delayed kinetic information was available in 275 lesions. The most suspicious delayed kinetic enhancement was persistent in 164 (60%) of 275, plateau in 47 (17%) of 275, and washout in 64 (23%) of 275. The cancer yield in patients with a BI-RADS 3 assessment was two (0.85%) of 236; both were ductal carcinoma in situ lesions. There were no malignancies in the 69 foci with 100% persistent enhancement.


CONCLUSIONS
The characteristics of BI-RADS 3 lesions were highly variable in our population, and the risk of malignancy was low (0.85%). Assigning foci with 100% persistent enhancement to the BI-RADS 2 category can decrease the frequency of BI-RADS 3 assessment and maintain a likelihood of malignancy in less than 2% of cases.
Eby
Peter R
PR
Department of Radiology, University of Washington Medical Center, Seattle, WA, USA. preby@u.washington.edu
DeMartini
Wendy B
WB
Gutierrez
Robert L
RL
Saini
Monica H
MH
Peacock
Sue
S
Lehman
Constance D
CD
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001941:Breast Diseases / Q000175:diagnosis*; D001943:Breast Neoplasms / Q000175:diagnosis; D003287:Contrast Media / Q000493:pharmacokinetics; D003937:Diagnosis, Differential; D005260:Female; D019786:Gadolinium DTPA / Q000493:pharmacokinetics; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008875:Middle Aged; D011446:Prospective Studies; D012042:Registries; D012189:Retrospective Studies
D003287:Contrast Media; C064925:gadodiamide; D019786:Gadolinium DTPA