Molecular Breast Imaging: Advantages and Limitations of a Scintimammographic Technique in Patients with Small Breast Tumors

Abstract

Preliminary studies from our laboratory showed that molecular breast imaging (MBI) can reliably detect tumors <2 cm in diameter. This study extends our work to a larger patient population and examines the technical factors that influence the ability of MBI to detect small breast tumors. Following injection of 740 MBq Tc-99m sestamibi, MBI was performed on 100 patients scheduled for biopsy of a lesion suspicious for malignancy that measured <2 cm on mammography or sonography. Using a small field of view gamma camera, patients were imaged in the standard mammographic views using light pain-free compression. Subjective discomfort, breast thickness, the amount of breast tissue in the detector field of view, and breast counts per unit area were measured and recorded. Follow-up was obtained in 99 patients; 53 patients had 67 malignant tumors confirmed at surgery. Of these, 57 of 67 were detected by MBI (sensitivity 85%). Sensitivity was 29%, 86%, and 97% for tumors <5, 6-10, and > or =11 mm in diameter, respectively. In seven patients, MBI identified eight additional mammographically occult tumors. Of 47 patients with no evidence of cancer at biopsy or surgery, there were 36 true negative and 11 false positive scans on MBI. MBI has potential for the regular detection of malignant breast tumors less than 2 cm in diameter. Work in progress to optimize the imaging parameters and technique may further improve sensitivity and specificity.

Collimator design for a dedicated molecular breast imaging‐guided biopsy system: Proof‐of‐concept

“…Figure 6 shows a simulated image of a MBI study performed with 150 MBq Tc-99m sestamibi. A 1-cm diameter lesion was modeled in the center (depth = 3 cm) of a 6-cm thick compressed breast of density 1.0 g/cm 3 . Comparison of the 10-min image with the 1-min image shows the impact of noise on image quality and the problem faced when using conventional parallel-hole collimation at low doses and short imaging times.…”

“…This detector was the LumaGEM (Gamma Medica-Ideas, Northridge, CA) consisting of a 96 × 128 array of 1.6 × 1.6 × 5.0 mm 3 CZT elements, yielding a total field-of-view of ∼15 × 20 cm 2 . A 6 cm thick breast (approximating the average thickness of the lightly compressed breast observed in MBI imaging 3,21 ) was simulated with a uniform density of 1.0 g/cm 3 . A tumor was simulated with a diameter of 1 cm, which is representative of the mammographically occult invasive cancers that have been observed in a screening population with MBI (median diameter 1.1 cm).…”

“…These technologies include those that detect 18 F-fluorodeoxyglucose (FDG) positron emissions such as positron emission mammography (PEM) and others that utilize single-photon emitting radiotracers (typically Tc-99m sestamibi) such as breast-specific gamma imaging (BSGI) and molecular breast imaging (MBI). [1][2][3] All of these dedicated technologies use small detectors with minimal dead space at the detector edge, permitting the breast to be placed in direct contact with the detector head, thereby allowing high spatial resolution imaging of small breast tumors.…”

Design of optimal collimation for dedicated molecular breast imaging systems

“…12,13 More recently, we have reported a significant increase in sensitivity with the use of a dual-head MBI system comprising two opposing dedicated gamma cameras, 14 and have shown this technique to be superior to screening mammography for the detection of breast cancer in women who have a mammographically dense breast pattern and are at increased risk of developing breast cancer. Interim results from a 1000-patient study have shown MBI to detect approximately three times as many cancers as screening mammography, while maintaining an equivalent specificity.…”

Use of99mTc-doxorubicin scintigraphy in females with breast cancer: a pilot study

“…Another promising tool is the use of dedicated apparatus for conventional nuclear medicine of the breast, called molecular breast imaging (MBI), which can detect malignant breast lesions ,1 cm. 11,12 Doxorubicin (Eurofarma, São Paulo, Brazil) is a potent antitumour agent that is widely used in chemotherapy for several types of cancer. 13 It acts by intercalating nucleotide bases, binding to the lipid membrane, and also inhibits the biosynthesis of macromolecules.…”