Pedro Slon MD, Abstract Co-Author: Nothing to Disclose

Jon Etxano MD, Presenter: Nothing to Disclose

Maria Paramo Alfaro MD, Abstract Co-Author: Nothing to Disclose

Romina Zalazar MD, Abstract Co-Author: Nothing to Disclose

Arlette Elizalde, Abstract Co-Author: Nothing to Disclose

Luis Pina MD, PhD, Abstract Co-Author: Nothing to Disclose

Fernando Martinez Regueira, Abstract Co-Author: Nothing to Disclose

Natalia Rodriguez-Spiteri, Abstract Co-Author: Nothing to Disclose

To assess the features of the tissue surrounding the additional detected cancers by US and DBT after  normal Mammography.

We retrospectively analyzed 75 histologically confirmed tumors in 55 patients (13 ductal carcinomas in situ and 62 invasive carcinomas). All the patients underwent Digital Mammography, US and Tomosynthesis. The tumors were classified in four categories according to the amount of peritumoral fat (I = >75%, II = 50-75%, III =25-75% and IV = <25%) evaluated by the diagnostic technique that best characterized the lesion. Gold Standard was established with histologycal study obtained after surgery. The detection rate of additional tumors by US and DBT was compared regarding to the percentage of peritumoral fat using the McNemar test (SPSS, 15.0)

Out of the 75 tumors, DM detected 42 (56%) and 33 (44%) were detected by additional techniques. The number of additional tumors detected by US was 14 (+18.6%) and by DBT was 17 (+22.6%). Out of these additional tumors, 7 (9.3%) were only detected by US,  4 (5.3%) only detected by DBT and 10 ( 13.3 %) were detected by both. The remaining 9 tumors were diagnosed with second look US after presurgical MRI. All of the additional tumors were invasive carcinomas. We did not find statistical differences between both techniques in Group I (US= 2 , DBT=2; p=1.00), Group II (US= 5 , DBT= 8; p=0.375) and Group III (US= 3, DBT= 2; p= 1.000). In Group IV (US=7, DBT=2; p=0,06) we found a trend to statistical significance, with 5 tumors detected on US and missed on DBT and no additional tumors diagnosed by DBT not detected by US.

Both US and DBT present similar results in the detection of additional breast cancers when they are predominantly surrounded by fat (more than 25%). However, we found that in tumors with less than 25% of peritumoral fat, US seems to be more sensitive than DBT.

This study supports that US seems to be better than DBT in the detection of tumors with a low quantity of surrounding fat, i.e, in dense breast (ACR density pattern IV).

Slon, P, Etxano, J, Paramo Alfaro, M, Zalazar, R, Elizalde, A, Pina, L, Martinez Regueira, F, Rodriguez-Spiteri, N, Analysis of the Influence of Surrounding Fat Tissue in the Detection Rate of Ultrasound and Digital Breast Tomosynthesis after Normal Mammography.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13023341.html