Role of targeted-ultrasonography in further assessing incidentally detected breast lesions at dynamic magnetic resonance imaging

identification and characterisation of incidental enhancing lesions on breast dynamic-Magnetic Resonance Imaging (dynamic-MRI). Methods and Materials: We retrospectively reviewed 2500 consecutive breast dynamic-MRI during a 2-year period, identifying 142 incidental enhancing lesions categorised as 3, 4, 5 on BI-RADS MRI lexicon. Correlations between MRI lesion characteristics, histopathologic findings and US detection rate were analysed. The reference standard was histopathologic examiantion after needle biopsy or surgical excision in 102 of 142 (72%) lesions and follow-up (24 months) in 40/142 (28%). Statistical analysis used Chi-square test. Results: US correlation was made in 104/142 (73%) lesions. Higher US detection rate was observed for masses (84/104 [81%]) rather than nonmasses (12/21 [57%]) (p=0.04), for MRI BI-RADS category 4-5 (51/62 [82%])malignant and benign lesions [46/63 (73%) and 58/79 (73%)]. 8 of the malignancies were assessed as MRI BI-RADS 3 and 38 as MRI BI-RADS 4-5, in concordance to the presumed US suspect pattern. Sonographic correlation was also higher in invasive (39/50 [78%]) compared to non-invasive (7/13 [54%]) malignancies (p=0.15) although any statistically significant difference. Sensitivity, specificity, positive and negative predictive values regarding the US second-look, were respectively, 82%, 69%, 68% and 83%. Conclusion: Targeted-US identifies most of the incidental enhancing breast MRI lesions, especially those assessed as masses with a high grade of suspicion that necessitate further characterisation with US-guided needle biopsy. The lack of an US correlate does not obviate the need for biopsy