Fig. 4

Delayed images on LFOV PET/CT showed the additional LNM in a 62-year-old primary PCa patient. Left supraclavicular LNM, para-aortic LNM and pelvic LNM could be detected on MIP of delayed LFOV images (tiles C–D), whereas MIP of early images could not make the clinically sufficient diagnoses (tiles A–B). Left supraclavicular small LNM (tiles C–D, G) was more distinguishable in the delayed image due to the increased SUV_max value (3.3 at 1 h p.i. vs. 5.3 at 3 h p.i.), which was confirmed as metastasis by LN biopsy. The para-aortic small LNM was faintly visible in the early image (tiles B, I), while it showed the increased SUV_max value (3.3 at 1 h p.i. vs. 11.1 at 3 h p.i.) in the delayed image (tiles D, J). Multiple foci with avid [⁶⁸ Ga]Ga-PSMA activity were demonstrated along the bilateral urinary tracts in early images (tiles A, B, L), whereas only one intense [⁶⁸ Ga]Ga-PSMA activity was observed in the left pelvic region in delayed images, with a SUVmax value of 15.2 (tiles C, D, M), the CT image showed a small nodular lesion with a size of 7.5*5.5 mm, which was verified as LNM. Without the urinary urine activity interference, the pelvic LNM was more visible on delayed image