Background: Motion artifacts related to the patient’s breathing can be the cause of underestimation
of the lesion uptake and can lead to missing of small lung lesions. The respiratory gating (RG)
technology has demonstrated a significant increase in image quality.
Objective: The aim of this paper was to evaluate the advantages of RG technique on PET/CT performance
in lung lesions. The impact of 4D-PET/CT on diagnosis (metabolic characterization), staging and
re-staging lung cancer was also assessed, including its application for radiotherapy planning. Finally,
new technologies for respiratory motion management were also discussed.
Methods: A comprehensive electronic search of the literature was performed by using Medline database
(PubMed) searching “PET/CT”, “gated” and “lung”. Original articles, review articles, and editorials
published in the last 10 years were selected, included and critically reviewed in order to select relevant
Results: Many papers compared Standardized Uptake Value (SUV) in gated and ungated PET studies
showing an increase in SUV of gated images, particularly for the small lesions located in medium and
lower lung. In addition, other features as Metabolic Tumor Volume (MTV), Total Lesion Glycolysis
(TLG) and textural-features presented differences when obtained from gated and ungated PET acquisitions.
Besides the increase in quantification, gating techniques can determine an increase in the diagnostic
accuracy of PET/CT. Gated PET/CT was evaluated for lung cancer staging, therapy response
assessment and for radiation therapy planning.
Conclusion: New technologies able to track the motion of organs lesion directly from raw PET data,
can reduce or definitively solve problems (i.e.: extended acquisition time, radiation exposure) currently
limiting the use of gated PET/CT in clinical routine.