The PET/CT scanning is very useful in equivocal clinical situations. A very small tumor is well detected by PET but can be missed by CT.On the other hand, a large tumor with minimal functional deviations may be seen on a CT image, but may not be detected by PET. In both situations, PET/CT would localize the tumor accurately. Overall, accuracy of diagnosis is increased by 20% to 25% when PET/CT is used instead of either alone. It should be noted that at present, while PET/CT whole-body scanning has been highly successful in detecting various oncologic conditions, the application of PET/CT in cardiac imaging has faced difficulty because of the motion of the heart. Ongoing research, however, is attempting to overcome this difficulty.
The spatial resolution of a PET scanner is a measure of the ability of the device to faithfully reproduce the image of an object, thus clearly depicting the variations in the distribution of radioactivity in the object.
Because of the increased sensitivity, specificity, and accuracy in detecting various tumors, fusion imaging using the PET/CT modality has become the state-of-the-art technique in the imaging field. PET/CT imaging eliminates the lengthy standard PET transmission scan, thus reducing the total scan time considerably. Because of the fact that the patient remains in the same position on the bed, the accurate alignment and fusion of the CT (anatomical) and PET (functional) images greatly improve the detection of lesions. For these reasons, PET/CT scanning is widely used in diagnostic oncologic applications