Background and Objective: Breathing movement can introduce heavy bias in both image
quality and quantitation in PET/CT. The aim of this paper is a review of the literature to
evaluate the benefit of respiratory gating in terms of image quality, quantification and lesion detectability.
Methods: A review of the literature published in the last 10 years and dealing with gated PET/CT
technique has been performed, focusing on improvement in quantification, lesion detectability and
diagnostic accuracy in neoplastic lesion. In addition, the improvement in the definition of radiotherapy
planning has been evaluated.
Results: There is a consistent increase of the Standardized Uptake Value (SUV) in gated PET images
when compared to ungated ones, particularly for lesions located in liver and in lung. Respiratory
gating can also increase sensitivity, specificity and accuracy of PET/CT. Gated PET/CT can
be used for radiation therapy planning, reducing the uncertainty in target definition, optimizing the
volume to be treated and reducing the possibility of “missing” during the dose delivery. Moreover,
new technologies, able to define the movement of lesions and organs directly from the PET sinogram,
can solve some problems that currently are limiting the clinical use of gated PET/CT (i.e.:
extended acquisition time, radiation exposure).
Conclusion: The published literature demonstrated that respiratory gating PET/CT is a valid technique
to improve quantification, lesion detectability of lung and liver tumors and can better define
the radiotherapy planning of moving lesions and organs. If new technical improvements for motion
compensation will be clinically validated, gated technique could be applied routinely in any