Abstract
1369
Objectives Respiratory motion during PET/CT scan causes inaccuracies in characterization and measurement of FDG uptake of lung lesions. This study was designed to compare CT attenuation value and FDG uptake (SUV) of lung adenocarcinoma with or without ground glass appearance (GGA) between 20-s breath-hold (BH) PET/CT and free-breathing (FB) PET/CT.
Methods We studied 30 patients with lung adenocarcinoma who underwent clinical FB PET/CT, followed by deep-inspiration BH PET/CT of the thorax. In BH PET/CT, the patients were asked to hold their breath in deep inspiration for 10 s of CT scan and for 20 s of PET scan. Mean CT attenuation value in the ROI of each lesion (CT value) was measured in FB CT and BH CT. We also measured maximum tumor SUV in FB PET and BH PET.
Results In BH CT, part-GGA was seen in 16 patients but no GGA in the other 14 patients. For the 16 nodules with GGA, BH CT showed significantly lower CT values than FB CT (-137.0 HU ± 133.4 vs. -112.1 HU ± 124.4, p < 0.005), whereas no significant difference of CT values was observed between the two methods for the 14 nodules without GGA (29.7 HU ± 11.3 vs. 30.8 HU ± 12.2). In FB PET, SUVs of the 16 nodules with GGA were significantly lower than those of the 14 nodules without GGA (2.5 ± 1.4 vs. 9.5 ± 3.7, p < 0.0001). As compared with FB PET, BH PET showed a significant increase in SUV by 49.8% for the 16 nodules with GGA (p < 0.01) as well as by 27.2% for the 14 nodules without GGA (p < 0.005).
Conclusions BH PET/CT more precisely characterized lung adenocarcinoma with GGA by using CT attenuation values, as compared with FB PET/CT. In addition, 20-s BH PET significantly increased FDG uptake of lung nodules with GGA, which were poorly visualized in FB PET images. This technique is feasible in the clinical setting and requires only a minor increase in the examination time