Early experience with PET scanning in thoracic tumours

Background. Positron emission tomography (PET) scan is an imaging technique which relies on metabolic properties of the lesions. In this study, we eva luated the potential contribution of PET for thoracic malignancy in a conse cutive series of patients presenting with multiple lesions or equivocal dia gnosis. Methods. PET with 2-18 F fluorodeoxyglucose (FDG) was carried out in 41 pat ients. The diagnosis was primary intrathoracic malignancy in 22 (Group 1). On routine staging using CT scan we found 29 additional lesions and assesse d these using PET scan. PET was performed to evaluate the number of metasta tic lesions in the lung in 11 (Group 2), to characterise undiagnosed pathol ogy in the chest in 4 (Group 3), to search clinically suspicious extrathora cic spread in 4 patients with known intrathoracic malignancy. Results. In Group 1, the sensitivity and specificity of PET was 81.2% and 9 2.3%. The accuracy of PET in the confirmation of metastatic disease to the chest was 73%. PET was falsely positive in a patient with chronic inflammat ory disease in Group 3 and highly accurate to characterise unknown patholog y in Group 4. Conclusions. Even though infection may cause false positive results, PET is a useful imaging technique for the evaluation of patients with thoracic tu mours.