Breast Ultrasound Elastography is a complementary technique permitting a better characterization of breast lesions. 3D breast ultrasound elastography is a novel technique permitting a volumetric calculation of lesion stiffness. This could be particularly useful in patients with large breast tumors under pre-operative chemotherapy

3D breast ultrasound elastography provides volumetric lesion stiffness details in real time. 3D acquisition is compared to breast MRI in order to evaluate volume measurements calculated in ultrasound. Lesion elasticity is calculated in 3 planes with immediate reconstruction. The purpose of this prospective study is to evaluate the feasibility of this technique and compare the results to those of Breast MRI. For women receiving preoperative chemotherapy, this technique will be evaluated with regard to tumour shrinkage and lesion elasticity modifications under treatment.

Inclusion Criteria:

• Patients having already undergone a breast MRI
• Patients presenting with breast lesions measuring between20-50mm in ultrasound

Exclusion Criteria:

• Multifocal lesions
• History of breast cancer
• Breast implants
• Inflammatory breast disease
• Pregnancy