The aim of this study is to evaluate the ability of MRI to select patients for conservative treatment of breast cancer. Participants: female, over 18 years with breast cancer, stages I, II and III candidates for conservative surgery will be randomly randomized to do MRI or not according mammary density.

The aim of this study is to evaluate the ability of MRI to select patients for conservative treatment of breast cancer.An accurate assessment of the tumor is essential to select the best therapeutic strategy in the treatment of breast cancer.Currently, mammography, ultrasound and clinical examination are the standard techniques to assess the extent and location of the tumor.However, these imaging methods fail to assess the real size in approximately one third of patients eligible to conservative treatment.MRI has high sensitivity (95-100%) in the detection of invasive cancers as well as being able to detect hidden tumors, multifocality, multicentricity and cancer in the contralateral breast more often and greater accuracy than mammography or ultrasound.

Inclusion Criteria:

• Female,
• Over 18 years with breast cancer
• Clinical stages I, II and III candidates for conservative surgery

Exclusion Criteria:

• Contra-indication for breast MRI (ex. Metal implant)
• Claustrophobia
• Impossibility to stay in the prone position for more than an hour
• History of allergic reaction to the paramagnetic contrast
• History of chronic kidney disease on dialysis
• Personal history of breast cancer treated surgically in the last 12 months.
• Pregnancy or breastfeeding past 6 months