Introduction: Suspicious lesions on breast MRI are often initially evaluated using targeted ultrasound. However, workup varies. Data on the rate of correlate detection by morphology [mass, non-mass enhancement (NME), or focus] would be useful for developing practice guidelines.
Materials and methods: Breast MRI examinations from 1 January 2008 to 31 December 2010 were reviewed. BI-RADS 4 or 5 lesions on MRI evaluated with targeted ultrasound where definitive diagnosis was obtained were included. Statistical analysis was performed on aggregate data and at the lesion level.
Results: A total of 204 lesions were included in the study. A statistically significant difference in ultrasound correlate identification by morphology was found; a correlate was found in 49.3 % of masses, 15 % of NME, and 42.3 % of foci (p = 0.0006). Additional analysis within each morphology demonstrated significantly greater rate of malignancy in masses with an ultrasound correlate than masses without a correlate (p = 0.0062), while the rate of malignancy in NME and foci did not differ with ultrasound correlation.
Conclusions: Morphology of a suspicious lesion on breast MRI affects the probability of identifying an ultrasound correlate. As sonographic correlates are found in nearly half of masses and foci, targeted ultrasound should be the initial step in their workup.
Key points: • Lesion morphology on breast MRI affects the probability of ultrasound correlate identification. • An ultrasound correlate is significantly more likely for masses and foci. • Mass or focus should undergo targeted ultrasound before MRI-guided biopsy.