Approach to Oncologic Imaging



Approach to Oncologic Imaging



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Oncologic Imaging in Nuclear Medicine


In oncology, nuclear medicine provides whole-body analysis using various radiotracers that are utilized by tumors in such molecular pathways as glucose utilization, neurotransmitter function, and receptor uptake. The most commonly used oncology studies are F-18 FDG PET/CT and Tc-99m MDP bone scan.


F-18 FDG: A glucose analog, F-18-labeled fluorodeoxyglucose is taken up by many types of tumor cells in the glycolysis pathway and is trapped after phosphorylation by hexokinase. Three-dimensional images are obtained with a circular array of detectors and a CT scanner in the PET/CT bore.


Tc-99m MDP and F-18 NaF: Both Tc-99m MDP and F-18 NaF localize to regions of increased bone perfusion and osteoblastic response. Both types of bone scans can be used in oncologic imaging, although Tc-99m MDP bone scans are performed more commonly.


I-123 and I-131: Radioactive iodine is incorporated into normal and cancerous thyroid tissue through the sodium-iodide symporter. Dedifferentiated tumors may lose this symporter and thus their radioactive iodine avidity. F-18 FDG PET/CT is useful for dedifferentiated and anaplastic tumors.


Ga-68 dotatate and In-111 octreotide: Somatostatin receptors take up these tracers and allow for neuroendocrine tumor imaging. As F-18 FDG has low or variable avidity for these types of tumors, these are the tests of choice for pulmonary carcinoid and well-differentiated neuroendocrine tumors.


Ga-67: Rapidly dividing tumor cells utilize Ga-67 similarly to ferric ion and thus show higher uptake compared to surrounding tissue. Historically used to stage and follow therapy in lymphoma patients, it has been largely replaced by F-18 FDG PET/CT.


MIBG: An analog of norepinephrine, metaiodobenzylguanidine, localizes in benign and malignant neural crest tissue, where it is stored in neurosecretory granules. Imaging with I-123 MIBG is most common; therapy with I-131 MIBG is also available at some centers. Ga-68 dotatate PET/CT can also be used for diagnosis.


F-18 fluciclovine and Ga-68 PSMA: Both are used for prostate cancer imaging, as fluciclovine is an amino acid analog that is used by prostate cancer cells and PSMA interacts with the prostate-specific membrane antigen.



May 7, 2023 | Posted by in CARDIOVASCULAR IMAGING | Comments Off on Approach to Oncologic Imaging
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