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The aim of this study was to evaluate prospectively the effects of respiratory gating during FDG PET/CT on the determination of lesion size and the measurement of tracer uptake in patients with pulmonary nodules in a clinical setting.Eighteen patients with known pulmonary nodules (nine women, nine men; mean age, 61.4 years) underwent conventional FDG PET/CT and respiratory-gated PET acquisitions during their scheduled staging examinations. Maximum, minimum, and average standardized uptake values (SUVs) and lesion size and volume were determined with and without respiratory gating. The results were then compared using the two-tailed Student's t test and the nonparametric Wilcoxon's test to assess the effects of respiratory gating on PET acquisitions.Respiratory gating reduced the measured area of lung lesions by 15.5%, the axial dimension by 10.3%, and the volume by 44.5% (p = 0.014, p = 0.007, and p = 0.025, respectively). The lesion volumes in gated studies were closer to those assessed by standard CT (difference decreased by 126.6%, p = 0.025). Respiratory gating increased the measured maximum SUV by 22.4% and average SUV by 13.3% (p0.001 and p = 0.002).Our findings suggest that the use of PET respiratory gating in PET/CT results in lesion volumes closer to those assessed by CT and improved measurements of tracer uptake for lesions in the lungs.

OBJECTIVE. Many of the functions necessary for imaging and analyzing nuclear medicine studies are not available on radiology PACS. Over the past 20 years, we have developed a user-friendly, easily installed software package for nuclear medicine study analysis, display, Web access, and database storage and an integrated display for fused PET/CT. We are making this software available as free shareware that can be used without a license on any PC. The software package was developed as a cooperative effort between house and attending staff and our nuclear medicine programmer. Particular emphasis was put on making functions intuitive and user friendly.CONCLUSION. A shareware nuclear medicine PACS software package including a display for fused PET/CT studies has been developed, extensively clinically tested, and is freely available on the Internet.