Purpose: To compare combined whole-body PET and CT images of different canc
ers with PET images alone.
Materials and Methods: Thirty-two patients with known or possible cancers w
ere examined using a combined positron emission tomographic (PET) and compu
ted tomographic (CT) scanner. All data were acquired using this same combin
ed scanner. After an injection of F-18 fluorodeoxyglucose (FDG), noncontras
t helical CT imaging of the neck, chest, abdomen, or pelvis was performed.
The spiral CT was followed by a PET scan covering the same axial extent as
the CT.
Results: Coregistered PET-CT images identified and localized 55 lesions. In
10 patients (31%), areas with variable amounts of normal physiologic FDG u
ptake were distinguished from potential uptake of FDG in a nearby neoplasti
c lesion. Improved localization was achieved in 9 patients (for a total of
13 lesions, or 24%).
Conclusion: Combined PET-CT images appear more effective than PET images al
one to localize precisely neoplastic lesions and to distinguish normal vari
ants from juxtaposed neoplastic lesions.