The clinical utility of phase-based respiratory gated PET imaging based on visual feedback with a head-mounted display system

OBJECTIVE

We developed a new respiratory-gated positron emission tomography (PET) imaging method (RGV-PET) that phase-based respiratory gated PET imaging (RG-PET) combine with head-mounted display (HMD)-guided "visual feedback." The purpose of this study was to investigate whether RGV-PET is effective at improving the quantitative measurement of tracer uptake in tumors using the phase-based respiratory gating method.

METHODS

Of the 41 enrolled patients with hepatobiliary or pancreatic cancer, 20 patients underwent RGV-PET and the remaining 21 patients underwent RG-PET. We measured the peak standardized uptake value (SUVpeak) of the primary lesion in each five bins obtained from both RG-PET and RGV-PET. The SUVpeak change rate calculated based on the ungated PET imaging. To evaluate the quantitative variation, the coefficient of variation of the SUVpeak change rate was compared between RG-PET and RGV-PET. In addition, we performed qualitative evaluation using visual score for the incidence of artifacts on four-dimensional-CT.

RESULTS

The coefficient of variation of the average SUVpeak change rate in RGV-PET was 7.01 ± 4.43, which was significantly lower than the values in RG-PET (10.72 ± 5.74, p < 0.05). A significant improvement in the SUVpeak change rate of RGV-PET was obtained in bins 1 and 2 compared to RG-PET ( p < 0.05). The visual score of RGV-PET was significantly lower than RG-PET ( p < 0.05).

CONCLUSION

RGV-PET was effective for respiratory stabilization and improved respiratory gating imaging quality.

ADVANCES IN KNOWLEDGE

The RGV-PET is applicable to various PET/CT respiratory gating imaging and may improve the quantitativeness of PET images.

Evaluation of a new motion correction algorithm in PET/CT: combining the entire acquired PET data to create a single three-dimensional motion-corrected PET/CT image

PURPOSE

This study evaluated the potential of Q.Freeze algorithm for reducing motion artifacts, in comparison with ungated imaging (UG) and respiratory-gated imaging (RG).

PATIENTS AND METHODS

Twenty-nine patients with 53 lesions who had undergone RG F-FDG PET/CT were included in this study. Using PET list mode data, five series of PET images [UG, RG, and QF images with an acquisition duration of 3 min (QF3), 5 min (QF5), and 10 min (QF10)] were reconstructed retrospectively. The image quality was evaluated first. Next, quantitative metrics [maximum standardized uptake value (SUVmax), mean standardized uptake value (SUVmean), SD, metabolic tumor volume, signal to noise ratio, or lesion to background ratio] were calculated for the liver, background, and each lesion, and the results were compared across the series.

RESULTS

QF10 and QF5 showed better image quality compared with all other images. SUVmax in the liver, background, and lesions was lower with QF10 and QF5 than with the others, but there were no statistically significant differences in SUVmean and the lesion to background ratios. The SD with UG and RG was significantly higher than that with QF5 and QF10. The metabolic tumor volume in QF3 and QF5 was significantly lower than that in UG.

CONCLUSION

The Q.Freeze algorithm can improve the quality of PET imaging compared with RG and UG.