Background: Whole-body (WB) positron emission tomography (PET) with 2-[18F]-fluoro-2-deoxy-D-glucose (FDG) is more accurate than other imaging studies for detecting lung cancer and extrathoracic metastatic disease. Thoracic PET (from the skull base through the kidneys) may be equally as useful as WB PET (skull base to mid-thigh). With the recent introduction of hybrid CT-PET systems, use of thoracic PET would minimize radiation dose.
Methods: A retrospective review of a series of WB PET scans performed in our department was performed to identify patients evaluated for a solitary pulmonary nodule or newly diagnosed lung cancer who had distant extracranial and extrathoracic metastases detected by PET. All patients with true extrathoracic metastases were documented by ancillary radiologic and clinical data. Patients were staged according to the American Joint Committee on Cancer TNM system based on findings within the confines of a thoracic PET and WB PET. Comparison was made between staging based on thoracic and WB PET to determine if there was a significant difference.
Results: Of 1,026 studies, distant extracranial metastases were described in 35 patients with lung cancer. Findings were determined to be false-positive in nine patients. Of the 26 patients with true metastases on WB PET, 25 patients had metastatic lesions within the confines of thoracic PET. Relative to WB PET, the sensitivity of thoracic PET is 96.2% (95% confidence interval, 1 to 99.3%) for detection of distant metastases. Only one patient had an isolated metastasis that was detected only by WB PET. This patient would have been staged IIIB by thoracic PET as opposed to stage IV by WB PET.
Conclusions: Thoracic PET, when compared to WB PET, is 96.2% sensitive for detecting extrathoracic metastases in patients with newly diagnosed non-small cell lung cancer.