Incidence of Brain Metastases on Follow-up 18F-FDG PET/CT Scans of Non-Small Cell Lung Cancer Patients: Should We Include the Brain?

J Nucl Med Technol. 2017 Sep;45(3):193-197. doi: 10.2967/jnmt.117.194571. Epub 2017 Jul 13.


The brain is the most common site of distant metastasis from lung cancer. Thus, MRI of the brain at initial staging is routinely performed, but if this examination is negative a follow-up examination is often not performed. This study evaluates the incidence of asymptomatic brain metastases in non-small cell lung cancer patients detected on follow-up 18F-FDG PET/CT scans. Methods: In this Institutional Review Board-approved retrospective review, all vertex to thigh 18F-FDG PET/CT scans in patients with all subtypes of lung cancer from August 2014 to August 2016 were reviewed. A total of 1,175 18F-FDG PET/CT examinations in 363 patients were reviewed. Exclusion criteria included brain metastases on initial staging, histologic subtype of small-cell lung cancer, and no follow-up 18F-FDG PET/CT examinations. After our exclusion criteria were applied, a total of 809 follow-up 18F-FDG PET/CT scans in 227 patients were included in the final analysis. The original report of each 18F-FDG PET/CT study was reviewed for the finding of brain metastasis. The finding of a new brain metastasis prompted a brain MRI, which was reviewed to determine the accuracy of the 18F-FDG PET/CT. Results: Five of 227 patients with 809 follow-up 18F-FDG PET/CT scans reviewed were found to have incidental brain metastases. The mean age of the patients with incidental brain metastasis was 68 y (range, 60-77 y). The mean time from initial diagnosis to time of detection of incidental brain metastasis was 36 mo (range, 15-66 mo). When MRI was used as the gold standard, our false-positive rate was zero. Conclusion: By including the entire head during follow-up 18F-FDG PET/CT scans of patients with non-small cell lung cancer, brain metastases can be detected earlier while still asymptomatic. But, given the additional scan time, radiation, and low incidence of new brain metastases in asymptomatic patients, the cost-to-benefit ratio should be weighed by each institution.

Keywords: 18F-FDG PET/CT; brain MRI; brain metastasis; incidental; non-small cell lung cancer.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Arizona / epidemiology
  • Brain Neoplasms / diagnostic imaging
  • Brain Neoplasms / epidemiology*
  • Brain Neoplasms / secondary*
  • Carcinoma, Non-Small-Cell Lung / diagnostic imaging*
  • Carcinoma, Non-Small-Cell Lung / epidemiology*
  • Comorbidity
  • Female
  • Fluorodeoxyglucose F18
  • Humans
  • Incidence
  • Lung Neoplasms / diagnostic imaging*
  • Lung Neoplasms / epidemiology*
  • Male
  • Middle Aged
  • Positron Emission Tomography Computed Tomography / methods
  • Positron Emission Tomography Computed Tomography / statistics & numerical data*
  • Radiopharmaceuticals
  • Reproducibility of Results
  • Risk Factors
  • Sensitivity and Specificity


  • Radiopharmaceuticals
  • Fluorodeoxyglucose F18