Is a selective brain (18)F-FDG PET/CT study profitable in patients with small cell lung cancer?

To evaluate the diagnostic yield of a selective brain (18)F-FDG PET/CT in neurologically asymptomatic patients with small cell lung cancer.

Twenty-one neurologically asymptomatic patients referred to our service between July 2008 and December 2009 for staging of small cell lung cancer were included in the study. All underwent a standard (18)F-FDG PET/CT study followed by a selective brain PET/CT. The neurological findings were confirmed by CT scan with intravenous contrast, MRI or minimum clinical follow-up of 6 months. The brain PET/CT was considered positive if any alteration was observed in the FDG distribution that was not related with previously known benign lesion in the CT image.

Brain metastases were detected in 5 of the 21 patients (23.8%), these being correctly classified in 3 of them by the selective brain PET/CT. The stage was upgraded in one of them with the selective brain study. Only one patient showed a hypermetabolic lesion in the PET images in relationship to the lesions observed in the CT images. Sensibility, specificity, positive predictive value and negative predictive value were 60, 100, 100 and 88.89%, respectively.

Hypometabolic areas in the cerebral parenchyma are frequently associated to metastatic lesions in patients with small cell lung cancer. The selective brain PET/CT in these patients allows correct staging and early treatment of unsuspected metastasis.