PSMA PET/CT

What it does

PSMA PET/CT is a standard exam for primary staging of high-risk prostate cancer, for localising biochemical recurrence and for selecting patients for [177Lu]Lu-PSMA radioligand therapy. Upload the whole-body PSMA PET with its CT, acquired with a Ga-68 or F-18 ligand; the tracer is read from the DICOM radiopharmaceutical codes.

The run segments PSMA-avid lesions, suppresses physiological uptake, assigns each lesion to an organ and builds the molecular-imaging TNM (miTNM) codeline of PROMISE V2 with a miPSMA expression score. It also returns whole-body PSMA tumour volume (PSMA-TV) and total lesion PSMA (TL-PSMA), a PSMA-RADS category per lesion and, before therapy, the expression and discordance findings that bear on [177Lu]Lu-PSMA eligibility.

Intended use

Decision support for the reader who has to turn a PSMA study into a standard staging line: the miTNM codeline for the tumour board, a reproducible tumour-volume baseline, and a structured view of PSMA expression before radioligand therapy. Ganglia, rib fractures and the more frequent benign bone uptake of F-18 PSMA-1007 can mimic metastases; the PSMA-RADS category of each lesion expresses how likely it is to be prostate cancer. The Lu-PSMA eligibility section returns the expression and discordance signals the theranostics team works from.

Who it is for

Nuclear-medicine physicians and radiologists reporting PSMA PET, urologists and radiation and medical oncologists who act on the staging, and theranostics teams selecting patients for [177Lu]Lu-PSMA.

Accepted input

• PSMA PET: DICOM PET Image or Enhanced PET Image, whole-body, with the paired CT series.
• FDG PET/CT (optional): a same-period FDG study, used to look for FDG-positive, PSMA-negative disease.
• Prior PSMA PET/CT (optional, in prior_files): enables the response section.

Requirements

Requirement	Why
Radiopharmaceutical code, injected dose, injection time and half-life in the Radiopharmaceutical Information Sequence	Tracer identification and SUV
Patient's Weight (0010,1030)	SUV normalisation
Attenuation-corrected, decay-corrected PET	Quantitative SUV and the miPSMA comparison with reference organs
CT of the same session	Organ assignment of lesions and the blood-pool, liver and parotid references

Ligand-specific excretion matters: F-18 PSMA-1007 shows hepatobiliary excretion, while urinary activity in the ureters and bladder dominates with other ligands. Salivary and lacrimal glands, kidneys and bowel are suppressed as physiological uptake before lesions are counted.

Optional context

The clinical setting (primary staging, biochemical recurrence or therapy planning) and any prior treatment can be passed in clinical_context; they frame the guidance.

The result

Section	Content
Lesions	PSMA-avid lesion masks with SUVmax and organ assignment
PROMISE miTNM staging	miT, miN and miM codeline with the miPSMA expression score against blood pool, liver and parotid
PSMA tumour volume	Whole-body PSMA-TV and TL-PSMA
PSMA-RADS categories	Likelihood category per lesion (PSMA-RADS v2.0)
Lu-PSMA eligibility signals	PSMA expression relative to liver and FDG-positive, PSMA-negative discordant disease when an FDG study is given
Response (RECIP 1.0)	Matched lesions versus the prior PSMA PET with a RECIP 1.0 category and PPP assessment
Draft report	Opt-in (options.report): an English narrative that interprets the result for the reader (findings, impression, limitations); every number is checked against the findings

Standards

• DICOM: Segmentation for lesion masks; SR TID 1500 Measurement Report with per-lesion SUV and volumes in CID 85 SUV units; Key Object Selection; Encapsulated PDF.
• Staging and reporting: PROMISE V2 (2023) miTNM and miPSMA; E-PSMA reporting guideline; PSMA-RADS v2.0.
• Therapy and response: EANM/SNMMI 177Lu-PSMA guideline (2023) for eligibility; RECIP 1.0 and the PSMA PET progression (PPP) criteria for follow-up.

miPSMA expression score

The score grades lesion uptake against three references: below blood pool (0), equal to or above blood pool and below liver (1), equal to or above liver and below parotid gland (2), and equal to or above parotid gland (3). Each reference value is reported, so the grade can be checked against the numbers.

Related models

• nm/theranostics: after each [177Lu]Lu-PSMA cycle, post-therapy SPECT/CT dosimetry for kidneys, salivary glands and tumours.