{"entity":{"id":"neuro-imaging-roadmap","kind":"roadmap","name":"Neuro-oncology imaging roadmap: FDG PET → amino acid PET → SSTR2 theranostics in meningioma","aka":[],"tldr":"Ordinary sugar-based PET scans do not work well in the brain because healthy brain tissue itself uses a lot of sugar. Nuclear medicine had to develop tracers that light up brain tumours specifically, first amino acid tracers for gliomas and then a receptor tracer that also opens the door to a matched radioactive treatment for meningioma.","summary":"FDG PET has a structural limitation in the brain: normal grey matter has high baseline glucose uptake, so FDG contrast between tumour and healthy brain tissue is poor, unlike its performance in most body cancers. This drove development from the 1980s onward of radiolabelled amino acid tracers, principally 11C-methionine and later 18F-FET, which exploit the increased amino acid transport of tumour cells against a low physiological background in normal brain.\n\nThese tracers were gradually adopted into formal guidance: the PET-RANO working group and EANO published evidence-based recommendations for PET imaging in gliomas in 2016, followed by the joint EANM/EANO/RANO/SNMMI practice guideline (version 1.0) for glioma PET imaging with radiolabelled amino acids and FDG, published in 2019, standardising acquisition and interpretation (for example, a tumour-to-brain ratio threshold of 1.6-1.8 for 18F-FET). An updated RANO/EANO policy review in 2025 strengthened several of these recommendations, including for delineating tumour extent and distinguishing recurrence from treatment-related change.\n\nA parallel and largely separate strand targets meningioma, a tumour that (unlike most gliomas) reliably overexpresses somatostatin receptor 2 (SSTR2). Rachinger et al. (2015) showed that 68Ga-DOTATATE PET uptake correlates with SSTR2 expression and outperforms MRI sensitivity (90% vs 79%) for discriminating meningioma from tumour-free tissue, and it is now used for surgical and radiotherapy planning, particularly at the skull base. Because meningioma expresses the same target as neuroendocrine tumours, it has become a candidate for the same theranostic pairing: a phase 1/2 trial of the alpha emitter 225Ac-DOTATATE (RYZ101) in progressive or recurrent intracranial meningioma opened at Ohio State, testing whether the SSTR theranostic model developed for neuroendocrine tumours extends into neuro-oncology.","asOf":"2026-09-22","links":[{"label":"Rachinger et al., increased 68Ga-DOTATATE uptake discriminates meningioma and tumour-free tissue (J Nucl Med 2015)","url":"https://pubmed.ncbi.nlm.nih.gov/25635133/"},{"label":"Joint EANM/EANO/RANO practice guidelines/SNMMI procedure standards for glioma PET, version 1.0 (2019)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC6351513/"},{"label":"Update to the RANO working group and EANO recommendations for PET imaging in gliomas (Lancet Oncology 2025)","url":"https://www.thelancet.com/journals/lanonc/article/PIIS1470-2045(25)00193-7/fulltext"},{"label":"ClinicalTrials.gov: RYZ101 for progressive/recurrent intracranial meningioma (NCT07150806)","url":"https://clinicaltrials.gov/study/NCT07150806"}],"tags":[],"related":["f-18","ga-68","c-11","ac-225"],"indications":["glioblastoma","meningioma"],"sections":[],"technologies":["pet","pet-ct","fdg-pet","sstr-pet","astatine-211-alpha-therapy"],"targets":["sstr2"],"drugs":["fludeoxyglucose-f18","ga68-dotatate","ryz101"],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"steps":[{"era":"1980s-1990s","title":"FDG's limits in the brain drive amino acid PET","description":"FDG PET is limited in neuro-oncology by high physiological glucose uptake in normal grey matter, which reduces tumour-to-background contrast. This drives clinical development of radiolabelled amino acid tracers, principally 11C-methionine, which show much better contrast against normal brain from the 1980s onward.","refs":["fdg-pet","glioblastoma"],"status":"historic"},{"era":"2000s-2016","title":"18F-FET and the first evidence-based PET guidance for glioma","description":"O-(2-[18F]fluoroethyl)-L-tyrosine (18F-FET), an 18F-labelled amino acid tracer with a longer half-life than 11C-methionine, is adopted widely in Europe through the 2000s and 2010s. The PET-RANO working group and EANO publish the first evidence-based recommendations for the clinical use of PET imaging in gliomas in Neuro-Oncology in 2016.","refs":["glioblastoma"],"status":"historic"},{"era":"2015","title":"68Ga-DOTATATE PET for meningioma","description":"Rachinger et al. show, using spatially precise neuronavigated tissue sampling during surgery, that 68Ga-DOTATATE PET uptake correlates with SSTR2 expression and detects meningioma tissue with higher sensitivity than MRI (90% vs 79%), establishing SSTR2 PET as a tool for meningioma delineation, particularly in the skull base and after treatment.","refs":["meningioma","sstr2","ga68-dotatate"],"status":"historic"},{"era":"2019-2025","title":"Joint practice guidelines standardise glioma PET","description":"The joint EANM/EANO/RANO/SNMMI practice guideline (version 1.0) for imaging gliomas with PET using radiolabelled amino acids and FDG is published in 2019, standardising acquisition protocols and uptake thresholds (for example, an 18F-FET tumour-to-brain ratio of 1.6-1.8). An updated RANO/EANO policy review in 2025 strengthens the recommendation level for several uses, including delineating glioma extent and distinguishing recurrence from treatment-related change.","refs":["glioblastoma"],"status":"current"},{"era":"2020-2026","title":"68Ga-DOTATATE PET in routine meningioma management","description":"SSTR2 PET with 68Ga-DOTATATE or DOTATOC becomes an established adjunct to MRI for meningioma treatment planning, particularly for delineating disease extent at the skull base, detecting bony invasion, and distinguishing residual tumour from post-surgical or post-radiation change.","refs":["meningioma","sstr2"],"status":"current"},{"era":"2025-2028","title":"Emerging: SSTR2 theranostics extends into meningioma therapy","description":"A phase 1/2 trial of the alpha emitter 225Ac-DOTATATE (RYZ101) for progressive or recurrent intracranial meningioma (WHO grades 1-3) opens at Ohio State, using 68Ga-DOTATATE PET to select and follow patients, testing whether the diagnostic-therapeutic SSTR2 pairing developed for neuroendocrine tumours can extend into a tumour type managed mainly by surgery and radiotherapy.","refs":["meningioma"],"status":"emerging"},{"era":"2028+","title":"Speculative: broader receptor and alpha-emitter use in brain tumours","description":"If SSTR2 theranostics in meningioma shows benefit, other brain and skull-base tumours with a defined receptor target could follow the same diagnostic-therapeutic pairing, and locoregional alpha-emitter delivery (for example convection-enhanced delivery of astatine-211 conjugates, under early investigation for glioma) could extend targeted radiotherapy to tumours where systemic dosing is limited by the blood-brain barrier.","refs":["astatine-211-alpha-therapy"],"status":"speculative"}],"watch":[{"item":"RYZ101 for progressive/recurrent intracranial meningioma, Ohio State trial","source":"https://clinicaltrials.gov/study/NCT07150806","refs":["meningioma"]}]},"route":"/roadmaps/neuro-imaging-roadmap/","neighbours":{"isotope":[{"id":"ac-225","kind":"isotope","name":"Actinium-225","route":"/isotopes/ac-225/"},{"id":"c-11","kind":"isotope","name":"Carbon-11","route":"/isotopes/c-11/"},{"id":"f-18","kind":"isotope","name":"Fluorine-18","route":"/isotopes/f-18/"},{"id":"ga-68","kind":"isotope","name":"Gallium-68","route":"/isotopes/ga-68/"}],"indication":[{"id":"glioblastoma","kind":"indication","name":"Glioma & glioblastoma","route":"/indications/glioblastoma/"},{"id":"meningioma","kind":"indication","name":"Meningioma","route":"/indications/meningioma/"}],"technology":[{"id":"astatine-211-alpha-therapy","kind":"technology","name":"Astatine-211 alpha therapy","route":"/technologies/astatine-211-alpha-therapy/"},{"id":"fdg-pet","kind":"technology","name":"FDG PET","route":"/technologies/fdg-pet/"},{"id":"pet","kind":"technology","name":"PET (positron emission tomography)","route":"/technologies/pet/"},{"id":"pet-ct","kind":"technology","name":"PET/CT","route":"/technologies/pet-ct/"},{"id":"sstr-pet","kind":"technology","name":"Somatostatin receptor PET (68Ga/64Cu-DOTATATE)","route":"/technologies/sstr-pet/"}],"target":[{"id":"sstr2","kind":"target","name":"Somatostatin receptor 2","route":"/targets/sstr2/"}],"drug":[{"id":"ryz101","kind":"drug","name":"Actinium-225 DOTATATE","route":"/drugs/ryz101/"},{"id":"fludeoxyglucose-f18","kind":"drug","name":"Fludeoxyglucose F-18 (FDG)","route":"/drugs/fludeoxyglucose-f18/"},{"id":"ga68-dotatate","kind":"drug","name":"Gallium-68 DOTATATE (and Cu-64 DOTATATE)","route":"/drugs/ga68-dotatate/"}]}}