Amplitude-based optimal respiratory gating in positron emission tomography in patients with primary lung cancer

Respiratory motion during PET imaging introduces quantitative and diagnostic inaccuracies, which may result in non-optimal patient management. This study investigated the effects of respiratory gating on image quantification using an amplitude-based optimal respiratory gating (ORG) algorithm.

Whole body FDG-PET/CT was performed in 66 lung cancer patients. The respiratory signal was obtained using a pressure sensor integrated in an elastic belt placed around the patient's thorax. ORG images were reconstructed with 50%, 35%, and 20% of acquired PET data (duty cycle). Lesions were grouped into anatomical locations. Differences in lesion volume between ORG and non-gated images, and mean FDG-uptake (SUVmean) were calculated.

Lesions in the middle and lower lobes demonstrated a significant SUVmean increase for all duty cycles and volume decrease for duty cycles of 35% and 20%. Significant increase in SUVmean and decrease in volume for lesions in the upper lobes were observed for a 20% duty cycle. The SUVmean increase for central lesions was significant for all duty cycles, whereas a significant volume decrease was observed for a duty cycle of 20%.

This study implies that ORG could influence clinical PET imaging with respect to response monitoring and radiotherapy planning.

Quantifying lesion volume and uptake in PET is important for patient management. Respiratory motion artefacts introduce inaccuracies in quantification of PET images. Amplitude-based optimal respiratory gating maintains image quality through selection of duty cycle. The effect of respiratory gating on lesion quantification depends on anatomical location.