Evaluation of a Small Field of View Gamma Camera for Scintimammography in Patients With Atypical Ductal Hyperplasia, Atypical Lobular Hyperplasia, and Lobular Carcinoma In Situ

Management of atypical ductal hyperplasia (ADH), atypical lobular hyperplasia (ALH), and lobular carcinoma in situ (LCIS) diagnosed by breast needle core needle biopsy is controversial. Current practice is to recommend excisional biopsy to rule out malignant lesions, which have been reported in more than half of cases in some series. No consistent clinical, pathologic, or radiologic factors have been identified to select patients who do not require surgical excision. This is due, in part, to overlap in the mammographic features of benign and malignant lesions. Furthermore, reliance on mammography for surveillance of these high-risk patients is problematic. This highlights the need for a complementary imaging modality to improve the radiologic distinction between benign and malignant tumors and improve post-biopsy surveillance.

We are evaluating a new semiconductor-based gamma camera which we call Molecular Breast Imaging (MBI) which improves resolution by a factor of 2-3 compared to conventional gamma cameras, and, unlike mammography, is not affected by breast density. Preliminary clinical studies (IRB 0-1761-01)) have shown that scintimammography (SM) using Tc-99m sestamibi and the CZT camera (CZT-SM) has a high sensitivity and specificity for the evaluation of small (5-10 mm) lesions seen on mammography. We hypothesize that the MBI will reliably distinguish lesions that require excisional biopsy from lesions that do not. A secondary aim is to compare the role of MBI with mammography in post-biopsy surveillance.

We aim to enroll 50 Mayo patients who have received a diagnosis of ADH, ALH, or LCIS on core biopsy, who have not yet undergone excisional biopsy, and who consent to undergo MBI of both breasts. For images in which there is discordance with mammographic findings, ultrasound will be used to determine if additional abnormalities warrant excision. Using pathologic correlation, we will determine: 1) If residual foci of ADH, ALH, and LCIS are visible on MBI images; and 2) If MBI images can reliably predict contiguous or separate foci of malignant lesions in either breast.