Evaluation of Half-Dose Molecular Breast Imaging With Wide Beam Reconstruction Processing

Recent implementation of dose reduction strategies for Molecular Breast Imaging now allow
performance of MBI at an administered dose of 8 mCi Tc-99m sestamibi, which is reduced from
the previously used doses of 20-30 mCi. In order to safely introduce MBI as a screening
modality, we aim to perform MBI using 4 mCi Tc-99m sestamibi. An image processing algorithm
called Wide Beam Reconstruction (WBR) has been tailored for MBI technology with the goal of
allowing either the current administered dose or current acquisition time to be reduced by
half.

Inclusion Criteria:

Subgroup 1, Patients with breast lesions:

-At least one breast lesion detected by mammogram, ultrasound or breast MRI that measures
< 20 mm in greatest dimension, presents as a mass, is considered suspicious or highly
suggestive of malignancy according to the Breast Imaging Reporting and Data System Atlas
criteria (BIRADS 4 or 5), and is scheduled for core-needle biopsy or surgical biopsy.

OR

-At least one breast lesion that measures between > 10 mm but < 20 mm in greatest
dimension, presents as a mass, is biopsy-proven as malignant, and is scheduled for
surgical resection.

AND

- Age > 40 years

- Negative pregnancy test, postmenopausal, or surgically sterilized

Subgroup 2, Patients without known breast lesions:

- Negative screening mammogram performed at Mayo Clinic Rochester within 15 months
prior to performance of study MBI

- No signs or symptoms of breast disease

- Age > 40 years

- Negative pregnancy test, postmenopausal, or surgically sterilized

Exclusion Criteria:

- Vacuum-assisted or excisional biopsy has been performed prior to the study MBI.
Reason: these types of biopsies are more likely to remove all of the tumor

- MBI is performed after biopsy and neo-adjuvant chemotherapy is planned prior to
surgery. Reason: true tumor size will not be able to be ascertained from the final
pathology findings

- Breast implants. Reason: cases with breast implants will be easily identifiable on
blinded interpretation to take place at the study end

- Suspected that breasts will not fit in the MBI field of view. Reason: cases that
require tiled views or additional views will be easily identifiable on blinded
interpretation to take place at the study end

- Only one breast remaining. Reason: unilateral cases will be easily identifiable on
blinded interpretation to take place at the study end; injection timing is designed
for bilateral views

- Pregnancy test (if necessary) is not negative, or the patient is unable to complete
the pregnancy test

- Physically unable to sit upright and still remain still during two consecutive MBI
studies over the course of a 2-hour period.