Integrated PET+DBT for optimization of breast cancer therapy - Building on our previous work, we are proposing an innovative dual-mode breast cancer scanner combining positron emission tomography (PET) and x-ray tomosynthesis (XT). Patient-specific evaluation of breast cancer therapy has become a compelling application of quantitative positron emission tomography (PET) imaging. With the advent of neoadjuvant therapies, it has been shown repeatedly over the last decade by at least 11 studies that molecular imaging with clinical PET scanners can be used to gauge response of breast tumors to therapies within days. In this approach, a window of opportunity between diagnosis and surgery allows early evaluation of the effectiveness of the planned adjuvant therapy before breast cancer resection. After a baseline PET image followed by a subclinical dose of the planned therapy, a second PET scan can be used to evaluate treatment response. If there is no response then there is time to test second-line and other alternative therapies and to guide the selection of an effective post-surgical adjuvant therapy. Dedicated breast-imaging PET scanners have been proposed and evaluated since the late 1980s. Despite the sustained level of interest, clinical breast PET imaging with whole-body (WB) PET scanners has had little adoption, a reflection of the challenges of using breast PET imaging in the diagnostic setting. Our approach instead is to focus on the quantitative assessment of response to breast cancer therapy, a unique advantage of PET imaging. However, this advantage is lost when imaging small objects (< 2 cm) in whole-body (WB) PET scanners due to limited resolution. This has created a mismatch between current technological capability and clinical need: WB-PET is accurate down to roughly 2 cm, but lesions <2 cm in size are the most prevalent at breast cancer diagnosis. Thus a quantitative breast imaging high-resolution PET/XT scanner will enable patient-specific optimization of therapy in early-stage breast cancer. Our three aims are: (1) Development and construction of the PET/XT scanner. (2) Develop and implement the necessary quantitative data correction algorithms for the PET/XT rectangular geometry, and integrate them with accelerated image reconstruction. (3) Perform initial imaging studies with 10 breast cancer patients immediately after their scheduled clinical WB PET/CT imaging. Comparisons of the PET/XT and PET/CT images will be used to design a follow-up clinical trial. The PET/XT system will be useable immediately in local clinical trials evaluating new breast cancer therapies. Initial patient studies will also provide essential data for designing follow-up clinical trials evaluating translation to clinical practice.
