Optimization of nuclear medicine techniques to improve clinical management in solid cancers

The focus of this thesis is mainly on the use or optimization of nuclear medicine techniques for nodal staging and characterization in breast cancer. The first part focusses on sentinel lymph node (SLN) nonvisualization on preoperative imaging in breast cancer patients. Preoperative risk factors are identified for SLN nonvisualization on planar lymphoscintigraphy after an intratumoral injection. Subsequently, the added value of single photon emission computed tomography and radiotracer reinjection is described in patients with nonvisualization on lymphoscintigraphy. The nodal metastasis rate, surgical outcomes, and long-term outcomes are compared between patients with and without preoperative SLN visualization.
Part 2 describes the role of the portable gamma camera for intraoperative SLN identification, and the added value of integrating optical imaging into this system. In SLN procedures, SLNs may be missed due to the “shine-through” effect of the highly radioactive injection site. A phantom setup and a case series are used to study the detectability of SLNs near the injection site with the help of a portable gamma camera in comparison to conventional techniques.
For investigating the clinical relevance of intratumoral heterogeneity on ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT), it is required to 1) obtain biopsies from different tumor regions and correlate ¹⁸F-FDG uptake with immunohistochemistry results, and 2) correlate intratumoral heterogeneity with treatment outcome. Part 3 reports on in vitro accuracy tests of a prototype PET-guided system for breast cancer biopsy, and the association between intratumoral heterogeneity on ¹⁸F-FDG PET/CT and pathological complete response after neoadjuvant systemic treatment.