METHODS: Spiculated breast masses, depicted by 3.0/1.5-T contrast-enhanced MRI between June 2008 and March 2014, were retrospectively analyzed. Patient\'s age, lesion size, minimum/average apparent diffusion coefficient values (ADCmin/ADCave), and BI-RADS descriptors were compared between malignant and benign lesions. Based on these results, we assessed criteria to define category 5 spiculated masses with a ≥95 % probability of malignancy and evaluated their diagnostic performance.
RESULTS: A total of 140 lesions (Malignant group, n = 131; Benign group, n = 9) were analyzed. Patient\'s age, lesion size, ADCmin and ADCave showed significant differences between the two groups, while none of the BI-RADS descriptors, including kinetic curve assessment, showed any significant difference in frequency. Multivariate logistic regression analysis demonstrated that patient\'s age and lesion size were the significant predictive factors of malignancy. Of all the assessed criteria for category 5 spiculated masses, \"age >50 years or size >9 mm, or both\" were selected as the best criteria to minimize the possibility of unnecessary re-biopsies and inappropriate follow-up for malignancies.
CONCLUSIONS: Patient\'s age and lesion size are useful to differentiate malignant from benign spiculated breast masses. In cases with non-malignant biopsy results, spiculated masses with \"age >50 years or size >9 mm, or both\" are more likely malignant.