Combined 18F NaF and 18F FDG PET/CT: Initial results of a multi-center trial

Objectives 18F FDG PET/CT is a powerful imaging tool for cancer staging, but not all cancer lesions are identified due to variable rates of glucose metabolism. 18F can be used as a skeletal tracer in current PET/CT scanners. The combined administration of 18F and 18F FDG in a single PET/CT scan may improve patient convenience and cancer detection.

Methods This is a prospective study of 78 patients (pts) with proven cancers, who had separate 18F PET/CT, 18F FDG PET/CT and combined 18F/18F FDG PET/CT scans for evaluation of malignancy. There were 38 men and 40 women, 19-84 year-old. The 3 PET/CT scans were performed within a 2-4 weeks interval at 4 imaging centers. A direct comparison for each detected lesion was performed among the 3 scans by one central read site.

Results The 18F/18F FDG PET/CT compared favorably with the 18F PET/CT: only 2 skull lesions seen on 18F PET were missed on the corresponding combined PET. 18F/18F FDG images allowed for accurate interpretation of the uptake in the soft tissues, with similar findings as the 18F FDG PET/CT (subcentimeter lung nodules missed on PET in 2 patients). Skeletal disease was more extensive on 18F PET/CT PET than on the 18F FDG PET in 16 pts, while 18F PET showed osseous metastases and the 18F FDG PET was negative in 12 pts. The extent of skeletal lesions was similar in 12 pts on the 18F PET and 18F FDG PET. The remaining 38 pts had no osseous metastases identified on the 18F, the 18F FDG or the combined PET scans.

Conclusions This prospective trial shows that the combined 18F/18F FDG administration followed by single PET/CT scan is feasible for cancer detection. This opens the possibility for improved patient care and reduction in healthcare costs. Further evaluation of this proposed imaging modality is warranted to identify the most suitable clinical scenarios