Cindy L. Tortorelli

JOURNAL CLUB: Molecular Breast Imaging at Reduced Radiation Dose for Supplemental Screening in Mammographically Dense Breasts

OBJECTIVE. The purpose of this study was to assess the diagnostic performance of supplemental screening molecular breast imaging (MBI) in women with mammographically dense breasts after system modifications to permit radiation dose reduction. SUBJECTS AND METHODS. A total of 1651 asymptomatic women with mammographically dense breasts on prior mammography underwent screening mammography and adjunct MBI performed with 300-MBq (99m)Tc-sestamibi and a direct-conversion (cadmium zinc telluride) gamma camera, both interpreted independently. The cancer detection rate, sensitivity, specificity, and positive predictive value of biopsies performed (PPV3) were determined. RESULTS. In 1585 participants with a complete reference standard, 21 were diagnosed with cancer: two detected by mammography only, 14 by MBI only, three by both modalities, and two by neither. Of 14 participants with cancers detected only by MBI, 11 had invasive disease (median size, 0.9 cm; range, 0.5-4.1 cm). Nine of 11 (82%) were node negative, and two had bilateral cancers. With the addition of MBI to mammography, the overall cancer detection rate (per 1000 screened) increased from 3.2 to 12.0 (p < 0.001) (supplemental yield 8.8). The invasive cancer detection rate increased from 1.9 to 8.8 (p < 0.001) (supplemental yield 6.9), a relative increase of 363%, while the change in DCIS detection was not statistically significant (from 1.3 to 3.2, p =0.250). For mammography alone, sensitivity was 24%; specificity, 89%; and PPV3, 25%. For the combination, sensitivity was 91% (p < 0.001); specificity, 83% (p < 0.001); and PPV3, 28% (p = 0.70). The recall rate increased from 11.0% with mammography alone to 17.6% (p < 0.001) for the combination; the biopsy rate increased from 1.3% for mammography alone to 4.2% (p < 0.001). CONCLUSION. When added to screening mammography, MBI performed using a radiopharmaceutical activity acceptable for screening (effective dose 2.4 mSv) yielded a supplemental cancer detection rate of 8.8 per 1000 women with mammographically dense breasts.

Gamma camera breast imaging lexicon

OBJECTIVE The standardized terminology and reporting structure of the BI-RADS for mammography, ultrasound, and MRI findings facilitates patient management. To date, no such terminology has been available for gamma camera breast imaging. We present an illustrated lexicon including description of background uptake, mass and nonmass uptake, lesion intensity, associated findings, and review of common artifacts. CONCLUSION This proposed lexicon should facilitate standardized interpretation, communication of results, and outcomes monitoring of examinations using dedicated devices for gamma camera breast imaging.

99mTc-sestamibi using a direct conversion molecular breast imaging system to assess tumor response to neoadjuvant chemotherapy in women with locally advanced breast cancer.

Purpose The objective of this study was to determine the ability of breast imaging with 99mTc-sestamibi and a direct conversion–molecular breast imaging (MBI) system to predict early response to neoadjuvant chemotherapy (NAC). Methods Patients undergoing NAC for breast cancer were imaged with a direct conversion–MBI system before (baseline), at 3 to 5 weeks after onset, and after completion of NAC. Tumor size and tumor-to-background (T/B) uptake ratio measured from MBI images were compared with extent of residual disease at surgery using the residual cancer burden. Results Nineteen patients completed imaging and proceeded to surgical resection after NAC. Mean reduction in T/B ratio from baseline to 3 to 5 weeks for patients classified as RCB-0 (no residual disease), RCB-1 and RCB-2 combined, and RCB-3 (extensive residual disease) was 56% (SD, 0.20), 28% (SD, 0.20), and 4% (SD, 0.15), respectively. The reduction in the RCB-0 group was significantly greater than in RCB-1/2 (P = 0.036) and RCB-3 (P = 0.001) groups. The area under the receiver operator characteristic curve for determining the presence or absence of residual disease was 0.88. Using a threshold of 50% reduction in T/B ratio at 3 to 5 weeks, MBI predicted presence of residual disease at surgery with a diagnostic accuracy of 89.5% (95% confidence interval [CI], 0.64%–0.99%), sensitivity of 92.3% (95% CI, 0.74%–0.99%), and specificity of 83.3% (95% CI, 0.44%–0.99%). The reduction in tumor size at 3 to 5 weeks was not statistically different between RCB groups. Conclusions Changes in T/B ratio on MBI images performed at 3 to 5 weeks following initiation of NAC were accurate at predicting the presence or absence of residual disease at NAC completion.

The Use of Molecular Breast Imaging to Assess Response in Women Undergoing Neoadjuvant Therapy for Breast Cancer: A Pilot Study

Purpose of the Report: To report our findings from a prospective pilot study evaluating the accuracy of molecular breast imaging (MBI) in assessing tumor response to neoadjuvant therapy (NT) for breast cancer. Materials and Methods: Twenty patients with newly diagnosed invasive breast cancer who were scheduled to receive NT underwent MBI before beginning and after completing NT before surgery. MBI was performed using a dual-detector cadmium-zinc-telluride gamma camera system mounted on a modified mammography gantry after patients had received an intravenous injection of 20 mCi of 99mTc sestamibi. Tumor extent was measured on MBI, and tumor-to-background (T/B) ratios of radiotracer uptake were determined through region-of-interest analysis. Pathologic measurement of tumor size was used as a standard and compared with post-NT tumor size derived from MBI. Results: Three patients in whom post-NT MBI could not be performed because of scheduling problems were excluded from analysis. Eighteen cancers were diagnosed in 17 patients. A correlation coefficient of r = 0.681 (P = 0.002) was found between MBI and residual tumor size. The average T/B ratio on MBI decreased from a pretreatment value of 3.0 to a posttreatment value of 1.4. The relative decrease in T/B ratio did not appear to be predictive of response. Conclusions: Measurements of tumor size by MBI and T/B ratios are limited in their predictive value regarding the pathologic extent of residual disease in women treated with NT for breast cancer. Alternate tumor-specific radiopharmaceuticals should be evaluated to provide information to improve planning and monitoring of breast cancer treatment.

Clinician's Guide to Imaging and Pathologic Findings in Benign Breast Disease

The discussion of abnormal results of breast imaging and abnormal pathologic findings can be challenging for health care professionals and often is stressful for patients. Although most imaging findings and biopsy results are negative and do not infer a substantial increase in breast cancer risk, the subsequent conversation between the patient and her practitioner is more effective and informative with a thorough review of the pathologic results and an appreciation of the importance of radiologic-histologic concordance. This article provides insight into and understanding of breast imaging and biopsy techniques and of histologic findings as a means to timely and appropriate decision making and action by the patient and her health care professional.

Evaluation of Molecular Breast Imaging in Women Undergoing Myocardial Perfusion Imaging with Tc-99m Sestamibi

BACKGROUND Our objective was to explore the potential benefits of molecular breast imaging (MBI) as a screening technique in women undergoing stress myocardial perfusion studies. METHODS MBI was offered to women receiving Tc-99m sestamibi injection for myocardial perfusion stress testing. During the required waiting period after stress isotope injection, MBI was performed using a dedicated breast imaging gamma camera system. MBI examinations were interpreted by breast radiologists, with review of a recent mammogram in cases with positive MBI. RESULTS Of 322 women enrolled, 313 completed MBI, comprising 5 with known breast cancer, 2 with known high-risk benign breast lesions, and 306 who were asymptomatic for breast disease with a recent negative mammogram. Analysis was limited to the 306 patients with no known breast disease. MBI was positive in 22 of 306, giving a recall rate of 7.2% (95% confidence interval [CI] 4.8-10.6]. MBI detected 4 new cancers, resulting in a supplemental diagnostic yield of 13.1/1000 women screened (95% CI 5.1-33.2). The number of cancers diagnosed per abnormal MBI examinations (PPV(1)) was 18% (4 of 22) (95% CI 7.3-38.5), and the number diagnosed per MBI-prompted biopsies (PPV(3)) was 44% (4 of 9) (95% CI 18.9-73.3). CONCLUSIONS The addition of MBI to clinically indicated stress myocardial perfusion imaging studies in women results in a high diagnostic yield of newly detected breast cancers while generating a low rate of additional unnecessary workup.

Diabetic Mastopathy as a Radiographically Occult Palpable Breast Mass

Diabetic mastopathy is an uncommon, benign disease of the breast that can occur in women with diabetes and clinically mimic breast cancer. We describe a patient with long-standing type 1 diabetes who presented with a palpable breast mass with negative imaging findings on mammography, ultrasonography, and breast MRI. Surgical biopsy and histopathology confirmed diabetic mastopathy. We use this case to highlight the recognition, radiographic features, pathology, and management of this benign breast condition and emphasize that, in diabetic patients, the differential diagnosis of a new breast mass should include diabetic mastopathy.