FIGURE 4.

Images of 60-y-old man undergoing ¹⁸F-DCFPyL PET/CT for primary diagnostic assessment (prostate-specific antigen level on date of scan, 13.5; no previous therapies). (A) Whole-body maximum-intensity projection demonstrates multiple sites of suggestive radiotracer uptake (e.g., third right rib [arrowhead] and sixth right rib [arrow]). (B–D) Axial CT (B), axial ¹⁸F-DCFPyL PET (C), and axial ¹⁸F-DCFPyL PET/CT (D) show mild radiotracer uptake in right iliac LN (arrow). Although ER trained on ¹⁸F-DCFPyL PET called this lesion PSMA-RADS-4, the 2 remaining readers trained on ⁶⁸Ga-PSMA PET called it PSMA-RADS-3A (i.e., suggestive but indeterminate LN) (12). One might speculate that ¹⁸F-trained reader had higher confidence in lesion interpretation on ¹⁸F-DCFPyL PET scans because of higher sensitivity in detection rate of small lesions using ¹⁸F-labeled radiotracers than using ⁶⁸Ga-PSMA (27). (E–G) All 4 readers classified overall scan impression as PSMA-RADS-5, because CT (E) revealed findings corresponding to sixth right rib metastasis, with discernible radiotracer uptake on axial ¹⁸F-DCFPyL PET (F) and axial ¹⁸F-DCFPyL PET/CT (G) (doubled arrows). (H–J) Magnification of this sixth-rib suggestive site of uptake provided in axial CT (H), axial ¹⁸F-DCFPyL PET (I), and axial ¹⁸F-DCFPyL PET/CT (J) further suggested this to be malignant lesion at this uptake site (arrowhead).