Deborah J. Rhodes MD, Presenter: Nothing to Disclose

Carrie B. Hruska PhD, Abstract Co-Author: Institutional license agreement, Gamma Medica Ideas, Inc

Amy Lynn Conners MD, Abstract Co-Author: Nothing to Disclose

Robert Watson Maxwell MD, Abstract Co-Author: Member, Maxwell Publishing Company LLC Stockholder, Maxwell Publishing Company LLC

Cindy L. Tortorelli MD, Abstract Co-Author: Nothing to Disclose

Michael K. O'Connor PhD, Abstract Co-Author: Research Grant, General Electric Company Royalties, Gamma Medica Ideas, Inc

We previously demonstrated that addition of Molecular Breast Imaging (MBI) using 20 mCi Tc-99m sestamibi to screening mammography (SM) increased diagnostic yield for breast cancer (3.2 /1000 SM alone vs. 10.7/1000 for the combination; P = .016). After implementing radiation dose reduction techniques, we are comparing performance of incident SM and prevalent screen MBI in women with dense breasts.

Women presenting for SM with heterogeneously or extremely dense breasts on past prior SM were enrolled and underwent digital SM and MBI. MBI was performed with 8 mCi Tc-99m sestamibi and dual-head cadmium zinc telluride detectors. SMs were read independently; MBIs were initially blinded, then read in comparison with existing imaging. MBIs were assigned a final assessment score of 1-5 which parallels BI-RADS; scores of 3-5 on MBI were considered positive and led to diagnostic workup.

In 1640 women, 27 cancers were diagnosed in 21 patients. MBI detected cancer in 17/21 patients; SM in 5/21; and the combination in 19/21 (diagnostic yield 3.0/1000 for SM alone vs. 11.6/1000 for the combination). Diagnostic evaluation was recommended based on SM in 179 (10.9%) patients and blinded MBI in 174 (10.6%) patients. Following combined MBI-SM read, 290 (17.7%) patients underwent diagnostic evaluation. Biopsy was prompted by SM in 19 (1.2%) patients and by MBI in 49 (3.0%) patients. The number of breast cancers diagnosed per number of biopsies (PPV) was 26% for SM and 35% for MBI. Fourteen patients had cancer detected only on MBI: 4 ductal carcinoma in situ (DCIS); 2 tubular carcinoma; 6 invasive ductal carcinoma (IDC); and 2 invasive lobular carcinoma (ILC); median pathologic tumor size 12 mm; range 4-62 mm. Three of 14 were node positive. The 4 MBI occult cancers were node negative and included 1 DCIS, 1 IDC, and 2 ILC; median pathologic tumor size 6 mm, range 3-7 mm. Two patients had cancers detected on neither modality, including a 6 mm ILC detected on MRI and a 7 mm ILC detected on prophylactic mastectomy.  

This interim analysis supports low-dose MBI as an adjunct to SM in women with dense breasts. Recall rates for both modalities were similar. Follow-up at one-year will be necessary to establish sensitivity and specificity.

The supplemental diagnostic yield of adding screening low-dose MBI to SM in women with dense breasts is preserved at a lower administered radiation dose.

Rhodes, D, Hruska, C, Conners, A, Maxwell, R, Tortorelli, C, O'Connor, M, Low-Dose Molecular Breast Imaging with Tc-99m Sestamibi for Screening in Women with Mammographically Dense Breasts: Interim Analysis.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12024798.html