Rubina Noemi Cavallin, Abstract Co-Author: Nothing to Disclose

Marta Maria Panzeri, Abstract Co-Author: Nothing to Disclose

Giulia Cristel MD, Presenter: Nothing to Disclose

Claudio Losio MD, Abstract Co-Author: Nothing to Disclose

Mariagrazia Rodighiero MD, Abstract Co-Author: Nothing to Disclose

Alessandro Del Maschio MD, Abstract Co-Author: Nothing to Disclose

Percutaneous biopsy is mandatory for all suspicious BMRI-detected lesions (BI-RADS 4 of the Breast Imaging Reporting and Data System), but the malignancy rate is variable (from 2 to 95%) and BMRI-guided biopsy is an expensive procedure, frequently resulting in benign histopathology. Our purpose was to investigate whether DWI and tUS could help in this setting by reducing the number of cases assigned as BI-RADS 4.

From January 2008 to December 2012, 1757 patients underwent BMRI (1.5T) including T2-weighted sequences, DWI (b-values: 0-900s/mm2) and dynamic study. A BI-RADS score was assigned according to conventional morpho-dynamic criteria. For each suspicious enhancement (BI-RADS 4), the Apparent Diffusion Coefficient (ADC) value was quantified and an ultrasonographic correlate was searched. When both DWI and tUS downgraded the suspicious enhancement to BI-RADS 3 (probably benign), a short term follow-up was recommended. If at least one of the two methods (DWI and/or tUS) confirmed the suspicion, the lesion remained BI-RADS 4 and a biopsy was done using MRI or US-guidance. Histopathological results and radiological follow up data (minimum 6 months) were recorded and considered the gold standard. Diagnostic performance indicators of MRI+DWI and tUS were compared using Chi-square test.  

BMRI detected 152 BI-RADS 4 lesions in 120 patients: 52% (90/152) of them were proven to be breast cancers. Eighty percent (121/152) of the lesions were also DWI visible. The sensitivity, specificity, positive and negative predictive value of DWI in the characterization of these lesions were 98%, 87%, 93 and 96%, respectively. An ultrasonographic correlate was found in 66% of MRI lesions: the sensitivity, specificity, positive and negative predictive value of tUS were inferior to those of DWI (p<0,05) (77%, 82%, 86% and 74%, respectively). Twenty-eight percent (43/152) of the suspicious lesions were downstaged to BI-RADS 3 by means of both DWI and tUS: 7% of these revealed to be malignant during subsequent follow-up (2 DCIS and 1 tubular breast cancer).

The combination of Quantitative DWI and tUS showed a high accuracy in the characterization of BMRI-detected suspicious lesions, resulting in a reduction of false positives.

The use of DWI and tUS could theoretically reduce the need of unnecessary preoperative breast biopsies in case of BI-RADS 4 enhancing lesions.

Cavallin, R, Panzeri, M, Cristel, G, Losio, C, Rodighiero, M, Del Maschio, A, Diagnostic Performance of Diffusion-Weighted Imaging (DWI) versus Targeted Ultrasound (tUS) in the Characterization of Suspicious Enhancing Lesions at Breast Magnetic Resonance Imaging (BMRI).  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14017387.html