Apparent diffusion coefficient value in breast papillary lesions without atypia at core needle biopsy

The main aim of the study was to assess if the mean apparent diffusion coefficient (ADC) value was significantly different between papillary lesions (PL) without atypia and PLs with atypical or malignant foci. A secondary objective was to evaluate if patients mean age, MRI BI-RADS® descriptors and assessment category were significantly different between these two PL groups.

In this eight year retrospective study were included 122 patients (mean age, 51 years; range, 24-78) with 122 PLs without atypia at micro-histological examination after core needle biopsy (CNB) performed under sonographic guidance. All patients underwent surgical excision biopsy within 3 months after CNB. All patients underwent MRI examination before surgical excision, including STIR, DWI and Dynamic Contrast-Enhanced sequences.

Mean ADC value difference between PLs without and with atypia or malignant foci was statistically significant (p < 0.0001). Mean ADC value optimal threshold in order to distinguish the two groups was 1.418 × 10^-3 mm²/s. A mean ADC value ≤ 1.418 × 10^-3 mm²/s could predict atypical or malignant foci within a PL with 83.9% sensitivity and 75.8% specificity. No statistically significant difference was found with regard to patients mean age, MRI BI-RADS® descriptors and assessment category between these two PL groups.

Mean ADC value of PLs without atypia at CNB is an efficient tool in order to help distinguish between PLs without and with atypical or malignant foci at final pathology on surgical excision, and it could be used to help decide how to manage these lesions.