Findings: A 2 cm round mass is seen superior to the right hilum on this patient's chest radiograph. Corresponding CT images demonstrate a noncalcified right upper lobe mass. Images obtained with F-18-FDG demonstrate intense uptake in the patient's right upper lobe mass, which makes it highly suspicious for malignancy. No mediastinal lymphadenopathy is seen.

Diagnosis: Lesion highly suspicious for primary lung cancer given the smoking history. Metastatic disease cannot be entirely excluded, however, no additional abnormal uptake of F-18-FDG was seen elsewhere.

Discussion: Oncologic imaging with F-18-FDG is being performed in several centers currently. Particularly, in patients where other modalities suggest presence of neoplasm and the lesions cannot be biopsied for one reason or another, use of PET scanning with F-18-FDG facilitates treatment planning. Malignant cells have an enhanced rate of glycolysis, an effect first noted by Warburg in 1930. FDG-PET reflects the physiologic distribution of glucose within the body. FDG, an analog of glucose, is metabolically trapped in the tissues after phosphorylation by hexokinase. FDG uptake varies in proportion to the activity of the hexokinase enzyme, which is upregulated in neoplastic tissues and also as a response to inflammation or infection. A whole body scan can be used as a screen for metastatic disease in patients with high suspicion for such. In conjunction with the history, new findings on chest radiograph, and confirmation by CT, diagnosis of neoplasm could easily be made in this patient, although biopsy could not be obtained.

References:
Strauss L, Conte P. The Applications of PET in clinical oncology.
J Nucl Med, 1991;32:623-648.

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