What does increased FDG uptake observed on a PET-CT scan mean? Does it definitely indicate cancer?

Question

Mit jelent a PET-CT-n látott fokozott FDG-halmozás? Biztosan rákot jelent?

Accepted Answer

The 18F-FDG used during a PET-CT examination is a glucose analogue (fluorodeoxyglucose); therefore, increased FDG accumulation indicates increased glucose metabolism, or hypermetabolism, of the given tissue. This phenomenon does not definitively signify a tumour or a malignant cancerous lesion. Although malignant tumours frequently exhibit intense FDG uptake during staging and therapy response assessment due to their elevated glucose consumption, numerous non-neoplastic processes can also cause marked accumulation. These include active infections (such as tularaemia or spondylodiscitis), inflammatory conditions (such as mediastinal anthracosis, pericardial inflammation associated with reactive mesothelial proliferation, epididymo-orchitis, or vasculitis), as well as other benign tissue reactions (such as foreign-body-induced abscess, round atelectasis, or an oesophageal retention cyst). Consequently, increased FDG uptake detected on a PET-CT report cannot be considered a histological diagnosis on its own; confirming or ruling out malignancy requires the combined evaluation of the clinical presentation, laboratory results, other imaging modalities, and, if necessary, histological sampling (biopsy). Quantitative parameters, such as the maximum standardised uptake value (SUVmax) or the tumour-to-blood background ratio (TBR), can assist in the probabilistic differentiation between malignant and benign lesions, as significantly higher values are often measured in malignant processes; however, due to overlaps, absolute SUV values alone do not guarantee the presence of a malignancy. EBUS-guided Cryobiopsy-Proven Anthracotic Mediastinal Lymph Node Mimicking Malignancy on FDG PET-CT: A Case Report.: https://pubmed.ncbi.nlm.nih.gov/42621652 Hepatic FDG Avidity From a Migrating Gastric Foreign Body: A PET/CT Pitfall.: https://pubmed.ncbi.nlm.nih.gov/42080620 Differentiating lymphoma progression from benign lesions: features of incident [¹⁸F]FDG-avid foci on interim and end-of-treatment PET/CT.: https://pubmed.ncbi.nlm.nih.gov/41982531 Fluorodeoxyglucose (FDG)-Avid Pericardial Effusion With Reactive Mesothelial Proliferation Mimicking Malignancy.: https://pubmed.ncbi.nlm.nih.gov/42220718 The role of 18F-FDG PET/CT in spinal infections: A comprehensive diagnostic tool.: https://pubmed.ncbi.nlm.nih.gov/42232200 A Case of Esophageal Retention Cyst with High Fluorodeoxyglucose Uptake on PET/CT Scan.: https://pubmed.ncbi.nlm.nih.gov/40746981 The role of ¹⁸F-FDG PET/CT in patients with serous cavity effusion of undetermined origin: a retrospective clinical study.: https://pubmed.ncbi.nlm.nih.gov/40416606 Diagnostic Dilemma of Rounded Atelectasis in the Left Lower Lobe Showing High Uptake of 18F-Fluorodeoxyglucose: A Surgical Conundrum.: https://pubmed.ncbi.nlm.nih.gov/40416114 Inflammatory Mimicry: Epididymo-orchitis Masquerading as Malignancy on [18F]-FDG PET/CT Imaging.: https://pubmed.ncbi.nlm.nih.gov/40291349 ¹⁸F-FDG PET/CT Findings in Glandular Tularemia.: https://pubmed.ncbi.nlm.nih.gov/40361977 Role of 18F-FDG PET/CT in assessing systemic involvement in ANCA-associated vasculitis.: https://pubmed.ncbi.nlm.nih.gov/40111549 18F-FDG PET and PET/CT in the Evaluation of Cancer Treatment Response: https://doi.org/10.2967/jnumed.108.054205 PMID 19139187: https://pubmed.ncbi.nlm.nih.gov/19139187/

What does increased FDG uptake observed on a PET-CT scan mean? Does it definitely indicate cancer?

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