This clinical trial studies technetium Tc-99m sestamibi molecular breast imaging in predicting tumor response in patients with locoregional breast cancer that has spread from where it began in the breast to surrounding normal tissue who are receiving neoadjuvant chemotherapy. Comparing results of diagnostic procedures, such as technetium Tc-99m sestamibi molecular breast imaging, done before, during, and after chemotherapy may help doctors predict a patient's response to treatment and help plan the best treatment.

PRIMARY OBJECTIVE:

I. To evaluate the ability of technetium Tc-99m sestamibi (Tc 99m sestamibi) molecular breast imaging (MBI) to predict early response to neoadjuvant chemotherapy (NAC) and to assess residual disease at the completion of NAC in patients with locoregional invasive breast cancer.

SECONDARY OBJECTIVES:

I. To evaluate and qualitatively characterize Tc 99m sestamibi uptake by tumor on MBI at the baseline, after 2 cycles of NAC and at the completion of NAC.

II. To compare assessment of tumor response to NAC by MBI with digital mammography (DM), and breast ultrasound (US) exams.

III. To compare tumor size and distribution observed from MBI at the completion of NAC with extent of residual disease at surgery by pathological evaluation.

IV. To develop image acquisition and processing algorithm that quantifies the Tc 99m tumor uptake.

EXPLORATORY OBJECTIVE:

I. To determine effect of molecular subtype of cancer (Her2+, ER/PR/Her2- and ER+/Her2-) on diagnostic performance of MBI in predicting treatment response.

OUTLINE:

Patients undergo technetium Tc-99m sestamibi molecular breast imaging over 45 minutes at baseline (before start of NAC), after 2 courses of NAC (6-12 weeks, depending on the regimen), and the completion of NAC but before surgery. Patients also undergo breast ultrasound and mammographic imaging as standard of care at the same time points.

Inclusion Criteria:

1. Female of 18 years and older of any race
2. Has biopsy-proven invasive breast cancer (BI-RADS 6) and scheduled for neoadjuvant chemotherapy (NAC).
3. Newly diagnosed biopsy proven locoregional invasive breast cancer at MD Anderson Cancer Center, or referred to MD Anderson for treatment after initial radiologic (mammographic, sonographic, etc.) exams at an outside institution in whom NAC is planned.
4. Patients with stage T1 or greater (T1-T4), nodal involvement (N0 - N3), without metastasis (M0) invasive breast cancer, including patients with inflammatory breast cancer.
5. Patients who agree to sign an informed consent to undergo MBI

Exclusion Criteria:

1. Is under 18 years of age
2. Is pregnant (confirmed by the patient as Imaging Clinic standard of care) or nursing mother
3. Has lesions involving chest wall
4. Has known allergy to Tc99m sestamibi