Use of Low-dose Molecular Breast Imaging for the Detection of Small Breast Lesions

A total of 150 patients will be studied. Each patient will have a suspicious lesion on
mammogram, ultrasound or breast magnetic resonance imaging (MRI) for which biopsy is
scheduled. The lesion size on mammogram, ultrasound or breast MRI must be less than 2 cm in
diameter and must be considered "suspicious" or "highly suspicious" for malignancy. Following
injection of 8 mCi Tc-99m sestamibi, all patients will undergo craniocaudal (CC) and
mediolateral oblique (MLO) views of each breast using a molecular breast imaging (MBI) system
incorporating the latest hardware and software algorithms. Each image will be acquired for 10
minutes in dynamic mode as 4 x 2.5 minute images. Summation of a given number of frames from
each acquisition will yield images of an increasing mCi dose. Hence with an 8 mCi injection
and a dynamic acquisition mode, we can evaluate the sensitivity of MBI as a function of
administered doses of Tc-99m sestamibi ranging from 2 to 8 mCi. The thickness of the breast
will be recorded to determine its relevance to lesion detectability.

Patient Selection

The goal of this study is to enroll 150 female patients in this study. The rationale for a
study number of 150 patients is given in Appendix D. Patients referred for a mammogram,
ultrasound or breast MRI study at Mayo Clinic Rochester will be considered for the study if
they meet the following criteria:

- Have a lesion on mammogram, ultrasound or breast MRI that measured < 2 cm and is
considered suspicious or highly suggestive of malignancy according to the Breast Imaging
Reporting and Data System Atlas criteria (BI-RADS 4 or 5). (Note: while 2 cm is larger
than the desired lesion size that we wish to study, this limit was recommended by our
radiology colleagues as estimates of lesion size from mammography, ultrasound and MRI
are not exact)

- Are scheduled for biopsy (needle and/or surgical biopsy) of the suspicious lesion

- Are > 18 years of age

- Had a negative pregnancy test or must be postmenopausal or surgically sterilized

Eligible patients will be offered enrollment if the time interval between mammogram,
ultrasound or MRI and scheduled biopsy allows for performance of MBI. Patients with prior
needle biopsy of the lesion will be excluded from this study, as such biopsies may
effectively remove all or part of the lesion. Prospective patients will be identified by the
radiologist based on findings in their mammographic, ultrasound or MRI studies.

Inclusion Criteria:

Patients referred for a mammogram, ultrasound or breast MRI study at Mayo Clinic Rochester
will be considered for the study if they meet the following criteria:

- Have a lesion on mammogram, ultrasound or breast MRI that measured < 2 cm and is
considered suspicious or highly suggestive of malignancy according to the Breast
Imaging Reporting and Data System Atlas criteria (BI-RADS 4 or 5). (Note: while 2 cm
is larger than the desired lesion size that we wish to study, this limit was
recommended by our radiology colleagues as estimates of lesion size from mammography,
ultrasound and MRI are not exact)

- Are scheduled for biopsy (needle and/or surgical biopsy) of the suspicious lesion

- Are > 18 years of age

- Had a negative pregnancy test or must be postmenopausal or surgically sterilized

Exclusion Criteria: