Molecular imaging roadmap: FDG → PSMA → FAP → antigen and immune PET
From a sugar tracer that lights up most cancers to tracers that show a single protein, a stromal cell type, or the immune cells inside a tumour.
Overview
The molecular imaging roadmap moves from PET scanners and FDG, made routine by PET/CT, to receptor tracers such as 68Ga-DOTATATE and PSMA PET that outperform anatomic imaging and enable theranostics. The current step adds stromal FAPI PET and total-body scanners, and the emerging step brings drug-target and immune PET: TROP2, HER2, B7-H3 and Nectin-4 tracers to select and sequence ADCs, CD8 and granzyme PET to monitor immunotherapy, and PARP PET. The speculative end is multi-tracer same-day imaging, PET-guided adaptive radiotherapy and imaging-derived digital twins. Each new tracer converts a biopsy biomarker into a whole-body map; the route sits in the Imaging section and links PET, PET/CT, FDG PET, PSMA PET, FAPI PET, TROP2 PET, HER2 PET, immuno-PET, PARP PET and PET/MRI.
- 1975-2001historic
PET and FDG
PET scanners (1975) and FDG (1976) developed; FDG PET adopted for lymphoma, lung, melanoma staging in the 1990s; PET/CT (2001) makes it routine.
- 2008-2020historic
Receptor PET: SSTR and PSMA
68Ga-DOTATATE (Netspot 2016) and 68Ga/18F-PSMA (2020-21) show receptor tracers outperform anatomic imaging and enable theranostics.
- 2018-2026current
Stromal PET and total-body scanners
FAPI tracers image >90% of epithelial cancers with high contrast; registrational trials underway. Total-body PET (uEXPLORER, Quadra) enables 40x sensitivity, low-dose paediatric and dynamic imaging. 18F-FES (ER) approved 2020; 89Zr-girentuximab (CAIX) filed. Pylarify TruVu approved 2026.
- 2024-2028emerging
Drug-target and immune PET
TROP2, HER2, B7-H3, Nectin-4 antibody and nanobody tracers to select and sequence ADCs; CD8 and granzyme PET to predict and monitor immunotherapy response; PARP PET for PARP-inhibitor selection; AI quantification and radiomics on standard scans.
- 2028+speculative30% to 55%likely
Speculative
Multi-tracer same-day imaging on total-body PET; PET-guided adaptive radiotherapy (biology-guided RT); routine antigen PET before every ADC; imaging-derived digital twins of tumour heterogeneity feeding treatment algorithms.
Probability ranges are named estimates that the claim is borne out on roughly a five-year horizon. They are meant to be argued with: propose a revision with your name and reasoning via a pull request to src/data/confidence.ts.
Story
topPET and FDG
PET scanners (1975) and FDG (1976) developed; FDG PET adopted for lymphoma, lung, melanoma staging in the 1990s; PET/CT (2001) makes it routine.
Receptor PET: SSTR and PSMA
68Ga-DOTATATE (Netspot 2016) and 68Ga/18F-PSMA (2020-21) show receptor tracers outperform anatomic imaging and enable theranostics.
A prostate-cancer-specific PET scan that finds spread far earlier than CT or bone scan, and tells you whether a matched radioactive drug will work.
Somatostatin receptor 2 is a hormone receptor densely present on neuroendocrine tumours, and was the first theranostic target to reach routine care.
Stromal PET and total-body scanners
FAPI tracers image >90% of epithelial cancers with high contrast; registrational trials underway. Total-body PET (uEXPLORER, Quadra) enables 40x sensitivity, low-dose paediatric and dynamic imaging. 18F-FES (ER) approved 2020; 89Zr-girentuximab (CAIX) filed. Pylarify TruVu approved 2026.
FAPI PET is a PET scan that lights up the scaffolding around almost any solid tumour, including cancers the standard sugar scan misses.
PET and CT in one machine, so hot spots on the PET are pinned to exact locations on the CT.
Chinese imaging company that built uEXPLORER, the first total-body PET scanner.
Piflufolastat F-18 (Pylarify) is the leading PSMA PET tracer for prostate cancer, with a new formulation approved in March 2026.
Drug-target and immune PET
TROP2, HER2, B7-H3, Nectin-4 antibody and nanobody tracers to select and sequence ADCs; CD8 and granzyme PET to predict and monitor immunotherapy response; PARP PET for PARP-inhibitor selection; AI quantification and radiomics on standard scans.
An experimental PET scan that shows whether a tumour carries the TROP2 protein, so doctors could pick the right ADC before giving it.
HER2 PET is a PET scan using radiolabelled trastuzumab or smaller HER2 binders to map HER2 across all metastases at once.
PET scans built from radiolabelled antibodies or their fragments, to see any protein an antibody can reach, including immune cells inside tumours.
A PET tracer that measures how much of the DNA repair enzyme PARP a tumour has, to predict response to PARP inhibitors.
Speculative
Multi-tracer same-day imaging on total-body PET; PET-guided adaptive radiotherapy (biology-guided RT); routine antigen PET before every ADC; imaging-derived digital twins of tumour heterogeneity feeding treatment algorithms.
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