The value of breast MRI for BI-RADS category 4B mammographic microcalcification: based on the 5th edition of BI-RADS.

AIM: To investigate whether magnetic resonance imaging (MRI) can improve the positive predictive value (PPV) for Breast Imaging-Reporting and Data System (BI-RADS) category 4B mammographic microcalcification. MATERIALS AND METHODS: One hundred and eight consecutive patients with BI-RADS category 4B microcalcification without mass on mammography underwent breast MRI and subsequent histopathological confirmation between January 2009 and December 2015. Mammography and MRI findings were reviewed retrospectively, and imaging features were analysed according to the 5th edition of BI-RADS. The PPV of each descriptor was analysed to identify subgroups in which PPV could be improved by the addition of MRI. RESULTS: When the criteria of presence of enhancement on MRI was applied to category 4B microcalcification, PPV increased from 0.38 (41 of 108) to 0.82 (37 of 45) and reduced benign biopsy results by 88% (59 of 67). Four ductal carcinoma in situ lesions were missed. For amorphous microcalcification with regional or grouped distribution, MRI images increased PPV without missing malignancy. CONCLUSION: Breast MRI has the potential to improve PPV for category 4B mammographic microcalcification by reducing false-positive findings. If amorphous microcalcification with regional or grouped distribution on mammography shows no enhancement on MRI, follow-up could be considered rather than immediate biopsy. In addition, breast MRI might have the potential to guide the best site to biopsy in category 4B microcalcification.

Pretreatment MRI features associated with diagnostic accuracy of post-treatment MRI after neoadjuvant chemotherapy.

AIM: To investigate whether pretreatment magnetic resonance imaging (MRI) features are associated with diagnostic accuracy of post-treatment MRI for predicting pathologic complete response (pCR) after neoadjuvant chemotherapy (NAC) in patients with breast cancer. MATERIALS AND METHODS: From January 2005 and December 2016, 221 consecutive patients (mean age, 50 years; range, 20-81 years) who had undergone NAC, breast MRI before and after NAC, and surgery for invasive breast cancer were enrolled. Pretreatment and post-treatment MRI images were reviewed. Radiological complete response (rCR) was defined as the absence of both early and late enhancement on MRI after NAC. The association of pretreatment MRI features and post-treatment MRI diagnostic accuracy was assessed by using logistic regression analysis. RESULTS: Among 221 patients, 60 (27.1%) underwent pCR after NAC. The diagnostic accuracy of post-treatment MRI was 84.2% (186/221). False-positive diagnosis occurred in 21 cases and false-negative diagnosis occurred in 14 cases. Of pretreatment features, the presence of peritumoural oedema (odds ratio, 3; 95% confidence interval [CI]: 1.1, 8.0; p=0.03) and HER2 (human epidermal growth factor receptor 2)-positive status (odds ratio, 3.4; 95% CI: 1.2, 9.9; p=0.02) were significantly associated with false-positive MRI results. Dense fibroglandular tissue (odds ratio, 10.8; 95% CI: 1.1, 105.2; p=0.04), presence of rim enhancement (odds ratio, 7.5; 95% CI: 1.2, 38.3; p=0.02) and oestrogen receptor (ER)-positive status (odds ratio, 6.3; 95% CI: 1.2, 32.5; p=0.03) were significantly associated with false-negative MRI results. CONCLUSION: Pretreatment MRI features and cancer subtypes may be associated with diagnostic accuracy of post-treatment MRI after NAC in patients with breast cancer.