Positron emission mammography: high-resolution biochemical breast imaging.
ABSTRACT Positron emission mammography (PEM) provides images of biochemical activity in the breast with spatial resolution matching individual ducts (1.5 mm full-width at half-maximum). This spatial resolution, supported by count efficiency that results in high signal-to-noise ratio, allows confident visualization of intraductal as well as invasive breast cancers. Clinical trials with a full-breast PEM device have shown high clinical accuracy in characterizing lesions identified as suspicious on the basis of conventional imaging or physical examination (sensitivity 93%, specificity 83%, area under the ROC curve of 0.93), with high sensitivity preserved (91%) for intraductal cancers. Increased sensitivity did not come at a cost of reduced specificity. Considering that intraductal cancer represents more than 30% of reported cancers, and is the form of cancer with the highest probability of achieving surgical cure, it is likely that the use of PEM will complement anatomic imaging modalities in the areas of surgical planning, high-risk monitoring, and minimally invasive therapy. The quantitative nature of PET promises to assist researchers interested studying the response of putative cancer precursors (e.g., atypical ductal hyperplasia) to candidate prevention agents.
Conference Proceeding: Monte Carlo simulation study of a dual-plate PET camera dedicated to breast cancer imaging[show abstract] [hide abstract]
ABSTRACT: We studied the performance of a dual-plate positron emission tomography (PET) camera dedicated to breast cancer imaging using Monte Carlo simulation based on GATE open code software. The PET camera under development has two 10times15 cm<sup>2</sup> plates that are constructed from arrays of 1times1times3 mm<sup>3</sup> LSO crystals coupled to novel silicon-based ultra-thin (<300 mum) position-sensitive avalanche photodiodes (PSAPD). With the photodetector configured "edge-on", incoming photons see effectively 2-cm-thick of LSO with directly measured 3-mm photon depth-of-interaction. Simulations predict that this camera will have >10% sensitivity, and detector measurements show ~1 mm<sup>3</sup> intrinsic spatial resolution, <12% energy resolution, and ~2 ns coincidence time resolution. With a breast phantom including breast, heart and torso activity (concentration ratio of 1:10:1, respectively), count performance was studied under varying time and energy windows. We also studied visualization of hot spheres within the breast for 1times1times3 mm<sup>3</sup>, 2times2times10 mm<sup>3</sup>, 3times3times30 mm<sup>3</sup> and 4times4times20 mm<sup>3</sup> crystal resolutions at different plate separations. Images were reconstructed by focal plane tomography and 3D OS-EM with attenuation and solid angle corrections applied. With an activity concentration ratio of tumor:breast:heart:torso of 10:1:10:1, only the dual-plate PET camera comprising 1times1times3 mm<sup>3 </sup> crystals can resolve 2.5-mm tumor spheres with an average peak-to-valley ratio of 1.3 in only 30 seconds of acquisition timeNuclear Science Symposium Conference Record, 2005 IEEE; 11/2005
Article: Imaging in breast cancer: Single-photon computed tomography and positron-emission tomography.[show abstract] [hide abstract]
ABSTRACT: Although mammography remains a key imaging method for the early detection and screening of breast cancer, the overall accuracy of this test remains low. Several radiopharmaceuticals have been proposed as adjunct imaging methods to characterize breast masses by single-photon-emission computed tomography (SPECT) and positron-emission tomography (PET). Useful in characterizing indeterminate palpable masses and in the detection of axillary metastases, these techniques are insufficiently sensitive to detect subcentimetric tumor deposits. Their role in staging nodal involvement of the axillary areas therefore currently remains limited. Several enzymes and receptors have been targeted for imaging breast cancers with PET. [18F]fluorodeoxyglucose is particularly useful in the detection and staging of recurrent breast cancer and in assessing the response to chemotherapy. Several other ligands targeting proliferative activity, protein synthesis, and hormone and cell-membrane receptors may complement this approach by providing unique information about biological characteristics of breast cancer across primary and metastatic tumor sites.Breast cancer research: BCR 02/2005; 7(4):153-62. · 5.24 Impact Factor