Applications of Positron Emission Tomography (PET) in Tumor Management

Positron emission tomography (PET), also referred to as positron computed tomography (PCT) provides cross sectional images of the body as do other axial tomographic techniques including x-ray computed tomography (x-ray CT) and nuclear magnetic resonance imaging (NMR) (also referred to as MRI, magnetic resonance imaging). Unlike x-ray CT images, which are anatomic representations of the attenuation characteristics of tissue, PET images reflect physiologic processes such as metabolism and blood flow (Phelps et al. 1982 and Phelps and Mazziotta 1985). While most of the initial clinical experience with MRI has also resulted in primarily anatomic representations of pathology, the full potential of this technique, like PET, remains to be explored. Nevertheless, studies to date have already demonstrated the potential of PET to provide quantitative and pictorial physiologic descriptions of neoplasms that complement anatomic images obtained with other modalities. This information is particularly relevant to radiation therapy where varying levels of tissue oxygenation and blood flow can have significant therapeutic implications and to oncology in general where metabolic parameters generated by PET studies can be significant both diagnostically and therapeutically.