{"entity":{"id":"krenning-score","kind":"term","name":"Krenning score","aka":[],"tldr":"A 0-to-4 scale doctors use to describe how strongly a tumour lights up on a somatostatin receptor scan, by comparing it with the normal liver and spleen. A higher score generally means the tumour is a good candidate for peptide receptor radionuclide therapy.","summary":"The Krenning score is a five-point visual grading system (0-4) developed for planar and SPECT imaging with 111In-pentetreotide (OctreoScan), which grades tumour uptake of a somatostatin receptor tracer against two internal reference tissues: normal liver (grades 1-3) and spleen or kidney (grade 4). Grade 0 is no uptake; grade 1 is uptake below liver; grade 2 is uptake equal to or slightly less than liver; grade 3 is uptake greater than liver; grade 4 is uptake greater than spleen or kidney. The NETTER-1 trial required tumour uptake at least equal to normal liver (Krenning grade 2 or above) for enrolment, and a score greater than 2 is the practical threshold most centres use when selecting patients for PRRT with lutetium-177 dotatate.\n\nThe score has been extrapolated to gallium-68 and copper-64 DOTATATE PET/CT as a \"modified Krenning score\", but the correlation between the original scintigraphy-derived score and the PET-derived score is limited: PET is more sensitive, is acquired around one hour after injection rather than 24 hours, and tends to grade the same lesion higher. For lesions larger than 2 cm the modified score is considered more reliable; centres should state which imaging method and which reference organ underlie a reported grade.\n\nThe score is lesion-level and visual rather than quantitative, so heterogeneous disease (some lesions with low uptake alongside others with high uptake) requires reporting each discordant lesion separately rather than a single summary number, since a single index-lesion grade can misrepresent overall receptor status across the body.","asOf":"2026-09-22","links":[{"label":"Radiopaedia: Krenning score of neuroendocrine tumour uptake","url":"https://radiopaedia.org/articles/krenning-score-of-neuroendocrine-tumour-uptake?lang=us"},{"label":"Somatostatin receptor imaging and theranostics: current practice and future prospects (JNM/PMC, 2021)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC9364764/"}],"tags":["scoring system","SSTR imaging","PRRT eligibility"],"related":["ga68-dotatate","sstr-pet","prrt","itm-11","lutathera","neuroendocrine","netter-1","ga-68","in-111","cu-64","lu-177"],"indications":[],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"category":"imaging"},"route":"/terms/krenning-score/","neighbours":{"drug":[{"id":"itm-11","kind":"drug","name":"177Lu-edotreotide","route":"/drugs/itm-11/"},{"id":"ga68-dotatate","kind":"drug","name":"Gallium-68 DOTATATE (and Cu-64 DOTATATE)","route":"/drugs/ga68-dotatate/"},{"id":"lutathera","kind":"drug","name":"Lutetium-177 dotatate","route":"/drugs/lutathera/"}],"technology":[{"id":"prrt","kind":"technology","name":"Peptide receptor radionuclide therapy (PRRT)","route":"/technologies/prrt/"},{"id":"sstr-pet","kind":"technology","name":"Somatostatin receptor PET (68Ga/64Cu-DOTATATE)","route":"/technologies/sstr-pet/"}],"indication":[{"id":"neuroendocrine","kind":"indication","name":"Neuroendocrine tumours","route":"/indications/neuroendocrine/"}],"trial":[{"id":"netter-1","kind":"trial","name":"NETTER-1","route":"/trials/netter-1/"}],"isotope":[{"id":"cu-64","kind":"isotope","name":"Copper-64","route":"/isotopes/cu-64/"},{"id":"ga-68","kind":"isotope","name":"Gallium-68","route":"/isotopes/ga-68/"},{"id":"in-111","kind":"isotope","name":"Indium-111","route":"/isotopes/in-111/"},{"id":"lu-177","kind":"isotope","name":"Lutetium-177","route":"/isotopes/lu-177/"}],"term":[{"id":"tumour-to-background-ratio","kind":"term","name":"Tumour-to-background ratio (TBR)","route":"/terms/tumour-to-background-ratio/"}]}}