MRI-detected suspicious breast lesions: predictive values of kinetic features measured by computer-aided evaluation.

OBJECTIVE: Computer-aided evaluation (CAE) programs for breast MRI provide automated lesion kinetic information. The CAE kinetic parameters that best predict malignancy have not been established. We compared three CAE kinetic features of suspicious breast MRI lesions to determine associations with benign or malignant outcomes.
MATERIALS AND METHODS: From 1,532 MRI examinations, all suspicious breast lesions initially detected with MRI and having CAE kinetics and subsequent biopsy were identified. Three CAE variables were compared for benign and malignant lesions: initial phase peak enhancement (greatest percentage signal intensity increase on first contrast-enhanced sequence), delayed phase enhancement categorized by a single type of kinetics comprising the largest percentage of enhancement (washout, plateau, or persistent), and delayed phase enhancement categorized by single most suspicious type of kinetics (any washout > any plateau > any persistent).
RESULTS: One hundred twenty-five lesions (42 malignant, 83 benign) comprised the analysis set. There were no significant differences in initial peak enhancement (p = 0.28) or delayed kinetics categorized by largest percentage enhancement types (p = 0.39) between benign and malignant lesions. There was a significant difference in delayed kinetics categorized by the most suspicious enhancement types (p = 0.005). Of lesions with washout as most suspicious (any washout), 45.7% were malignant compared with 20.0% with plateau and 13.3% with entirely persistent enhancement.
CONCLUSION: Of CAE kinetics analyzed, only delayed enhancement categorized by most suspicious type was significantly different between benign and malignant lesions. This supports the American College of Radiology BI-RADS Breast MRI Lexicon recommendation to report the "worst looking" kinetic curve.