Advances in positron emission tomographic imaging of lung cancer

Abstract

Positron emission tomography (PET) with [18F]fluorodeoxyglucose (FDG) has been established as a useful tool in the management of patients with non-small cell lung cancer and promises to be as valuable in the clinical management of other cancers. PET imaging with FDG allows the assessment of tumor glucose metabolism in vivo; however, a number of other PET tracers are being used in oncologic research to assess changes in other cellular processes associated with malignant transformation of the cell. [11C]-Labeled methionine and choline are being used to assess changes in cell membrane synthesis; however, small studies have not shown the added information from these tracers to be clinically useful. DNA synthesis can be assessed by measuring the uptake of the thymidine analog 3'-deoxy-3'-[18F]fluorothymidine, which may be more specific for evaluating malignancy without the problem of false-positive results from inflammatory lesions, as seen with FDG. Tumor hypoxia imaging with copper-labeled diacetyl-bis(N(4)-methylthiosemicarbazone) or [18F]fluoromisonidazole may provide a better method of predicting which tumors will respond best to conventional therapy. The role of PET will continue to evolve with further clinical studies using these and other new tracers.

Figure 2.

Pretherapy transaxial FDG-PET (left), [⁶⁰Cu]ATSM-PET (middle), and CT (right) images of the chest at the level of the patient's known NSCLC. The CT image shows increased soft tissue density in the left paratracheal space (arrow). There is markedly increased FDG uptake in this patient's known left paratracheal lung cancer (arrow) with mildly increased [⁶⁰Cu]ATSM uptake in the tumor (arrow). The [⁶⁰Cu]ATSM uptake is greater in the periphery of the lesion, whereas FDG uptake is uniform within the lung cancer.