Evaluation of Molecular Breast Imaging in Women Undergoing Myocardial Perfusion Imaging with Tc-99m Sestamibi
Department of Radiology, Mayo Clinic, Rochester, MN 55905, USA. Journal of Women's Health
(Impact Factor: 2.05).
03/2012; 21(7):730-8. DOI: 10.1089/jwh.2011.3267
Our objective was to explore the potential benefits of molecular breast imaging (MBI) as a screening technique in women undergoing stress myocardial perfusion studies.
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.
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).
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.
Available from: Filipe Ramos Barra
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ABSTRACT: O câncer de mama é um dos mais prevalentes nas mulheres. A mamografia é um excelente método com impacto comprovado na redução da mortalidade pelo câncer de mama. Porém, não é um método perfeito, apresentando alguns pontos fracos, principalmente no rastreamento de mulheres com mamas densas, estadiamento e avaliação de tratamento. A ressonância magnética mamária mostrou a necessidade e importância da avaliação funcional mamária. Descrevemos dois métodos de avaliação funcional mamária e demonstramos nossa experiência com a mamografia digital com contraste e com a imagem molecular mamária realizada em gama-câmara específica. Estes dois métodos já estão disponíveis em nosso meio e apresentam resultados promissores na detecção de lesões mamográficas ocultas, confirmação de lesões suspeitas e redução de biópsias desnecessárias, podendo assim melhorar o estudo mamário, principalmente nos pontos falhos da mamografia.
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Molecular breast imaging (MBI) is a dedicated nuclear medicine breast imaging modality that employs dual-head cadmium zinc telluride (CZT) gamma cameras to functionally detect breast cancer. MBI has been shown to detect breast cancers otherwise occult on mammography and ultrasound. Currently, a MBI-guided biopsy system does not exist to biopsy such lesions. Our objective was to consider the utility of a novel conical slant-hole (CSH) collimator for rapid (<1 min) and accurate monitoring of lesion position to serve as part of a MBI-guided biopsy system.
An initial CSH collimator design was derived from the dimensions of a parallel-hole collimator optimized for MBI performed with dual-head CZT gamma cameras. The parameters of the CSH collimator included the collimator height, cone slant angle, thickness of septa and cones of the collimator, and the annular areas exposed at the base of the cones. These parameters were varied within the geometric constraints of the MBI system to create several potential CSH collimator designs. The CSH collimator designs were evaluated using Monte Carlo simulations. The model included a breast compressed to a thickness of 6 cm with a 1-cm diameter lesion located 3 cm from the collimator face. The number of particles simulated was chosen to represent the count density of a low-dose, screening MBI study acquired with the parallel-hole collimator for 10 min after a ∼150 MBq (4 mCi) injection of Tc-99m sestamibi. The same number of particles was used for the CSH collimator simulations. In the resulting simulated images, the count sensitivity, spatial resolution, and accuracy of the lesion depth determined from the lesion profile width were evaluated.
The CSH collimator design with default parameters derived from the optimal parallel-hole collimator provided 1-min images with error in the lesion depth estimation of 1.1 ± 0.7 mm and over 21 times the lesion count sensitivity relative to 1-min images acquired with the current parallel-hole collimator. Sensitivity was increased via more vertical cone slant angles, larger annular areas, thinner cone walls, shorter cone heights, and thinner radiating septa. Full width at half maximum trended in the opposite direction as sensitivity for all parameters. There was less error in the depth estimates for less vertical slant angles, smaller annular areas, thinner cone walls, cone heights near 1 cm, and generally thinner radiating septa.
A Monte Carlo model was used to demonstrate the feasibility of a CSH collimator design for rapid biopsy application in molecular breast imaging. Specifically, lesion depth of a 1-cm diameter lesion positioned in the center of a typical breast can be estimated with error of less than 2 mm using circumferential count profiles of images acquired in 1 min.
Available from: Michael K O'Connor
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ABSTRACT: Approaches to imaging the breast with nuclear medicine and∕or molecular imaging methods have been under investigation since the late 1980s when a technique called scintimammography was first introduced. This review charts the progress of nuclear imaging of the breast over the last 20 years, covering the development of newer techniques such as breast specific gamma imaging, molecular breast imaging, and positron emission mammography. Key issues critical to the adoption of these technologies in the clinical environment are discussed, including the current status of clinical studies, the efforts at reducing the radiation dose from procedures associated with these technologies, and the relevant radiopharmaceuticals that are available or under development. The necessary steps required to move these technologies from bench to bedside are also discussed.
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