Fig. 4.

Emblematic example of inconsistent PSMA-RADS and unstructured confidence reporting. The figure displays the case of a 72-year-old patient with a 95% pre-test probability for positive [⁶⁸Ga]Ga-PSMA-11 PET/CT according to [12, 13], showing two equivocal tracer uptakes in soft tissues. (A–C) Axial low-dose CT, fused PET/CT, and whole-body maximum intensity projection images at the standard acquisition. Two areas of equivocal tracer uptake in soft tissues close to the left ureter were present, with upstream dilatated ureter and hydronephrosis in the CT images, consistent with the suspicion of ureteral obstruction. These tracer uptakes were considered equivocal with an unstructured confidence score = 3 and PSMA-RADS 3 by 4/6 PET readers. The same sections represented in panels D–F show that the two areas slightly increased in uptake intensity at the forced diuresis late-phase abdominopelvic scan. After reviewing late-phase images, most PET readers (4/6) judged these two areas suspicious for PCa recurrence, increasing the unstructured confidence score from 3 to 4. By contrast, according to the PSMA-RADS 5-point scale [14], these lesions remained classified as PSMA-RADS 3 in all cases. Given the proximity to the left ureter and the consequent risk of compression, the patient underwent salvage surgery. Post-surgical histopathology confirmed the presence of nodal PCa recurrence