Imaging of Interventional Therapies in Oncology: Positron Emission Tomography/Computed Tomography

This chapter is intended to illustrate the utility of positron emission tomography (PET) in image-guided therapies. PET imaging provides functional images of the body allowing us to identify alterations in metabolism which better characterizes the presence of cancer, its prognosis, and early response to multimodality therapy. PET imaging is the most widely used clinical technique for molecular imaging and, in conjunction with traditional anatomic modalities such as computed tomography (CT), provides a better assessment of the status of oncology patients. PET/CT imaging has become widely available, particularly with the use of fluorodeoxyglucose (FDG) as an analogue to glucose metabolism, which in turn allows us to identify the presence of cancer and measure response to therapy. This chapter provides an overview of the biologic mechanisms which occur in cancer, and by using PET imaging, we take advantage of this altered biochemistry to improve our ability to stage the extent of cancer and direct appropriate biopsies of the primary tumor. PET/CT imaging can also provide a road map to allow nodal sampling which can be useful to stage and determine type of therapy. PET/CT has also been used to direct biopsy or verify suspected distant metastases which can allow earlier management decisions between potentially curative and palliative therapies. Finally, the minimally invasive therapies using image guidance can benefit by PET/CT to determine target delineation and any residual or recurrent disease. The future direction, particularly with the clinical use of novel radiotracers, is discussed as it pertains to imaging hypoxia to identify radiation resistant parts of tumor, DNA or proliferation imaging to assess early response, and angiogenesis PET imaging for targeted therapies.