Reading PSMA PET-CT in prostate cancer

PET-CT

First and second year — the floor first, then every step

PSMA PET finds nodal and bone disease earlier than CT and bone scan, at staging of high-risk disease and at biochemical recurrence; report with PROMISE / E-PSMA (miTNM) and know the physiological uptake and the non-prostate PSMA-avid lesions that mimic metastases.

Orient first

  • Physiological uptake: salivary and lacrimal glands, liver, spleen, kidneys, bowel, bladder (ureters mimic nodes).
  • Pitfalls: coeliac and stellate ganglia, rib fractures, Paget disease, fibrous dysplasia, haemangiomas, other tumours (renal, HCC, glioma) express PSMA.
  • PROMISE / E-PSMA reporting (miTNM, expression score) standardises the report (verify version).

Acquire the study

  • 68Ga-PSMA-11 or 18F-PSMA PET-CT from vertex to mid-thigh ~60 min after injection; diuretic and a late pelvic acquisition help separate bladder and nodes.

The manoeuvre

  • Prostate bed or gland: focal uptake; SUVmax.
  • Pelvic nodes (internal/external iliac, obturator, presacral) on the fused axial series — PSMA expression vs liver/spleen/parotid.
  • Extrapelvic nodes (retroperitoneal, supradiaphragmatic).
  • Bone: focal uptake with or without CT correlate; distinguish rib fracture (linear, healing).
  • Visceral: lung, liver.
  • miTNM stage and PSMA expression score per lesion.

What confirms it

  • PSMA-avid lesions with typical distribution and CT correlate, reported with miTNM.

What licenses you to exclude it

  • A negative PSMA PET at very low PSA does not exclude recurrence (detection depends on PSA — verify).

The classic misread

  • Calling ganglia or a ureter a nodal metastasis.

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