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In this chapter, tumor imaging using conventional gamma camera techniques including single-photon emission computed tomography (SPECT) and SPECT/computed tomography (SPECT/CT) as well as less frequently employed or emerging radionuclide tumor therapies are addressed. The more commonly encountered entities of thyroid cancer and bone tumors and metastases are discussed in detail in Chapter 4 and Chapter 8 , respectively. Positron emission tomography (PET) imaging of neoplasms is discussed in Chapter 11 . The affinity of various tumors for specific radiopharmaceuticals is shown in Box 10.1 , and the relative value of various imaging procedures for different tumors is shown in Chapter 11 , Table 11.1 . Although some of these techniques have been largely supplanted by fluorine-18 fluorodeoxyglucose ( 18 F-FDG) PET/CT imaging, some are still useful in special settings.
Hodgkin disease
Non-Hodgkin lymphoma (especially high-grade)
Hepatoma
Bronchogenic carcinoma
Melanoma
Seminoma
Rhabdomyosarcoma
Gliomas (high-grade)
Thyroid carcinoma
Benign tumors (usually fade over 2 hours)
Osteosarcoma
Lymphoma (especially low-grade)
Kaposi sarcoma (gallium-negative)
Cancer metastases
Breast cancer
Parathyroid adenoma
Gliomas
Lymphoma
Thyroid
Amine precursor uptake and decarboxylation (APUD) cell tumors
Pancreatic islet cell
Pituitary adenoma
Pheochromocytoma
Neuroblastoma
Paraganglioma
Carcinoid
Gastrinoma
Vasoactive intestinal peptide-related tumors (VIPomas)
Medullary carcinoma of thyroid
Small cell lung cancer
Meningioma
Most tumors (see Chapter 11 )
Head and neck cancer
Esophageal cancer
Non–small cell lung cancer
Melanoma
Lymphoma
Colorectal cancer
Breast cancer
Poorly differentiated neuroendocrine and thyroid tumors
Thyroid cancer
Pheochromocytoma
Neuroblastoma
Paraganglioma
Lymphoma
During the past decade, new biotechnologic advances have spurred the development of increasingly sensitive and specific tumor imaging agents for use in both single-photon and positron imaging. As these agents have become available, they have spurred the concept of developing a drug or closely related group of drugs with high affinity to a particular tumor that can be labeled with a diagnostic imaging radionuclide to assess the location and extent of disease as well as separately labeled with a therapeutic radionuclide (such as a beta-emitter) to treat the neoplasm in a dosage commensurate with the tumor burden revealed by imaging. The success of treatment can be subsequently assessed using the diagnostic imaging version. This has been called “theranostics” (therapy + diagnosis). The simplest example is sodium iodide. Labeled with iodine-123, it is used diagnostically in differentiated thyroid cancer and its metastases. However, labeled with iodine-131, it becomes a therapeutic drug. More sophisticated compounds and their analogs are emerging for use with other tumors, such as somatostatin receptor radiopharmaceuticals for neuroendocrine malignancies. Tumor-imaging radiopharmaceuticals may be divided into two broad groups:
Those designed to target specific tumor antigens, receptors, or metabolic processes, including monoclonal antibodies, peptides such as somatostatin (octreotide), and metaiodobenzylguanidine (MIBG).
Those with nonspecific affinity for neoplastic tissue, including gallium-67 citrate ( 67 Ga), thallium-201 chloride ( 201 Tl), technetium-99m ( 99m Tc) sestamibi, and 18 F-FDG. These may be used to image a range of tumors in various organs.
Both categories of radiopharmaceuticals are used in clinical nuclear medicine practice. Typical administered activities and radiation doses for tumor-seeking radiopharmaceuticals in current use are given as sample techniques in Appendix E .
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