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Objective:
Molecular breast imaging (MBI) can detect breast cancers occult on mammography and ultrasound. The goal of this study was development of an MBI-guided biopsy system that allows biopsy of lesions without the need to find a correlate through another modality such as mammography, ultrasound, or MRI.

Materials and Methods:
This was a prospective, IRB-approved, HIPPA-compliant study from July 2022–June 2023. Women 25 years or older with at least one BI-RADS category 2, 3, 4, or 5 finding on any breast imaging modality were eligible. MBI biopsy system: the system comprised a lower detector, upper fenestrated compression paddle, and upper detector. The MBI gantry can be rotated and upper detector retracted to allow biopsy access from a superior-inferior, oblique, or medial/lateral approach. The compression paddle allows for insertion of a needle guide and needle using commercially available biopsy kits. Lesion depth is calculated by triangulation, comparing relative lesion location on the upper detector at 0° and 15° positions. Lesion depth can also be calculated by analysis of relative activity in the lesion seen on upper and lower detectors. Biopsy Procedure: Patients were injected with 20 mCi 99mTc-sestamibi, which allows rapid (2 min/view) imaging. CC and MLO views of both breasts were obtained and reviewed by the radiologist to determine approach for biopsy. Once positioned, an ROI was placed over the lesion of interest. Lesion center of mass (X and Y-location) and lesion depth (Z-location) were calculated by methods described above. Upper detector was retracted to allow placement of a needle guide and needle for biopsy. Specimen images were obtained on the retracted upper detector procedure to confirm that the target was in the sample.

Results:
Twenty-one patients have been enrolled to date. In four patients, no lesion was seen and biopsy was not performed. Seventeen patients have been successfully biopsied with concordant pathology. Average lesion size was 17 mm (range 6–38 mm). Biopsy approach was lateral in 13 patients, craniocaudal in four. Lesion depth was 22 + 8 mm. Pathology results for patients who underwent biopsy were as follows: invasive ductal carcinoma (n = 1); fibroadenoma (n = 4); pseudo angiomatous stromal hyperplasia, and fibrocystic changes (n = 6). The total procedure time for all patients including bilateral prebiopsy imaging was 55 ? 13 minutes. If prebiopsy imaging is excluded, the total procedure time was 36 ? 7 minutes. One patient had a vasovagal reaction and one patient required > 10 min of manual compression postbiopsy for a hematoma. There were no other complications.

Conclusion:
The availability of MBI biopsy would streamline the patient experience for workup and diagnosis of MBI-detected findings and improve health equity by reducing barriers to optimal care for patients with a suspicious finding on MBI. This study presents early patient results of an efficient and effective MBI-guided biopsy system.