A 70-year-old man with rising PSA after radical prostatectomy undergoes PSMA PET/CT. What does PSMA PET/CT detect compared to conventional CT and bone scan in this clinical scenario?

• A PSMA PET/CT is equivalent to bone scan for bone metastases only
• B PSMA PET/CT cannot differentiate local recurrence from nodal disease
• C PSMA PET/CT is only useful for PSA > 10 ng/mL
• D PSMA PET/CT detects recurrence at significantly lower PSA levels and with higher accuracy ✓

Explanation

PSMA (prostate-specific membrane antigen) PET/CT, typically using Ga-68 or F-18 labelled PSMA ligands, detects biochemical recurrence at PSA levels as low as 0.2–0.5 ng/mL with sensitivity and specificity superior to conventional CT (which requires lesions >1 cm) and bone scan. It accurately localises local recurrence, pelvic nodal disease, and distant metastases, enabling targeted salvage radiotherapy. Studies like PROPSMA trial confirmed superiority of Ga-68 PSMA PET/CT over conventional staging. PSA thresholds of 10 ng/mL are outdated for PSMA PET.

Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.

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