A Guided Tour to PET in Oncology

Wichana Chamroonrat, MD

Division of Nuclear Medicine, Department of Diagnostic and Therapeutic Radiology, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand


SYNOPSIS

Positron Emission Tomography (PET) without suitable positron emitting radiotracers (PET tracers) is considered as camera without light. Currently, most clinically used PET tracers in oncology could be described into 3 groups according to their behaviors as parts of glucose metabolism (FluoroDeoxyGlucose: FDG), folate metabolism (Prostate-Specific Membrane Antigen: PSMA/folate hydrolase/glutamate carboxypeptidase) and somatostatin receptor.  The exact PET tracers in each group may vary upon availability. In Thailand, they are F-18 FDG, Ga-68/F-18 PSMA and Ga-68 DOTATATE (Figure). 

F-18 FDG, glucose analog, is a longstanding, most used PET tracer in most cancer types for more than 2 decades. At the beginning, it adds view of functioning cancer to its volume. It helps evaluate malignant mass not only size assessment but also malignant viability. It would continue to solely occupy oncologist’s heart as a single broad-spectrum oncologic PET tracer if other tracers could not prove themselves in the past recent years.   

PSMA PET tracers are recently popular and fast-growing used, particularly for prostate cancer as emphasized on its name (Prostate-Specific Membrane Antigen). Oncologist’s interest does not end at the diagnosis yield because it could give additional radio-therapeutic option once found positive PSMA PET or PSMA-avid lesion(s). This method is known as theranostic approach (diagnosis plus therapy) or PSMA RadioLigand Therapy (PRLT) for prostate cancer, using, for example, Lu-177 PSMA etc.

Ga-68 DOTA-TATE is one of several PET tracers which target somatostatin (SST) receptors. Neuroendrocrine neoplasm (NEN) is a rare disease which majorly expresses these SST receptors. Radiolabeled SST analogs have been used prior PSMA radiopharmaceuticals; however, they seem to be less utilized, likely due to lower disease-specific incidence. The theranostic agent for SST receptors is called Peptide Receptor Radionuclide Therapy (PRRT), using, for example, Lu-177 DOTA-TATE etc.

Figure1

Event Hours(1)

  • Lotus 1-2

    10:50 am – 11:10 am

    Assoc. Prof. Wichana Chamroonrat (Rama)