PSMA-PET Reporting: PROMISE & PSMA-RADS

Quick Answer

PROMISE and PSMA-RADS standardize how PSMA-PET is interpreted and reported so that reads are reproducible across readers, scanners, and time. PROMISE assigns a molecular-imaging TNM (miTNM) and a PSMA expression score referenced to normal organs (blood pool, liver, parotid). PSMA-RADS grades each lesion by the certainty that it represents prostate cancer (1 = benign → 5 = definite), each tied to a management implication. Using a framework — with recorded agent, uptake time, and reference-organ uptake — is what turns a PSMA-PET into an actionable, comparable report.

Why Standardize

PSMA-PET drives high-stakes decisions — extending radiotherapy fields, denying/allowing surgery, selecting radioligand therapy — yet uptake is not cancer-specific and varies with agent, uptake time, and reconstruction. Structured frameworks reduce inter-reader variability, make serial comparison valid, and communicate certainty (not just "positive/negative") to referrers.

PROMISE (miTNM + Expression)

PROMISE (Prostate Cancer Molecular Imaging Standardized Evaluation) provides:

• A molecular-imaging TNM (miTNM): local tumor (T), regional pelvic nodes (N), and distant disease (M) with anatomic sub-regions (e.g. M1a extrapelvic nodes, M1b bone, M1c viscera).
• A PSMA expression score for lesions, referenced to normal-organ uptake:

Recording the reference organs (blood pool, liver, parotid), agent, and uptake time makes the expression score reproducible. A later version (PROMISE V2) and the EANM E-PSMA standard refine these definitions.

PSMA-RADS (Lesion-Level Certainty)

PSMA-RADS assigns each lesion a level of certainty for prostate cancer, each with a management implication:

Category 3 is the "needs-resolution" tier — the sub-classes (3A–3D) name why the lesion is equivocal and point to the resolving step.

Reference Organs & the Expression Ladder

The blood pool → liver → parotid ladder anchors both the PROMISE expression score and lesion judgments. High physiologic parotid and renal uptake, and the celiac ganglion, are the recurring benign backgrounds. Reporting a lesion's uptake relative to these organs (rather than absolute SUV alone) improves cross-study comparability, though SUVmax of index lesions is still recorded for therapy selection and response.

How It Connects to Therapy

For ¹⁷⁷Lu-PSMA-617 selection, structured reads document that disease is PSMA-positive at the level required (VISION-type criteria), flag PSMA-low/discordant sites (paired FDG), and establish baseline lesion SUV/volume for response (RECIP 1.0, built on PROMISE). A standardized baseline is what makes a standardized response assessment possible.

Common Pitfalls

• Reporting "positive" without a certainty category — equivocal (RADS-3) and definite (RADS-5) disease carry very different implications.
• Omitting agent, uptake time, and reference-organ uptake, breaking serial comparability.
• Over-calling benign PSMA-avid structures (celiac ganglion, healing ribs, Paget/fibrous dysplasia) as disease — the frameworks exist partly to force this discipline.
• Mixing frameworks/versions across serial reports (PROMISE vs PROMISE V2 vs E-PSMA) without stating which was used.

Board Pearls

Report PSMA-PET with a framework, not just "positive/negative": PROMISE gives miTNM + a PSMA expression score referenced to blood pool → liver → parotid, and PSMA-RADS grades each lesion's certainty (1 benign → 5 definite), with category 3 the equivocal, needs-resolution tier.

Always record agent, uptake time, and reference-organ uptake so serial studies are comparable, and capture index-lesion SUVmax for therapy selection/response (RECIP).

The frameworks encode the recurring benign mimics (celiac ganglion, ribs/fractures, Paget/fibrous dysplasia) so they are not over-called; PSMA-RADS 3A–3D name the reason a lesion is equivocal (soft-tissue, bone, non-prostatic uptake, or anatomic-lesion-without-uptake) and point to the resolving step.

Related Pages

• Tracer: PSMA PET agents (biodistribution, detection-by-PSA).
• Disease: Prostate cancer and PSMA & biochemical recurrence.
• Therapy/response: ¹⁷⁷Lu-PSMA-617 and theranostics response criteria (RECIP).

Figure / Diagram Suggestions

• The blood pool → liver → parotid expression ladder as a visual scale (scores 0–3).
• A PSMA-RADS 1–5 decision plate with representative benign vs malignant patterns.
• A miTNM anatomic map (T / N / M1a–c sub-regions).

Self-Check (Board-Style)