PET-CT is a combination of cross-sectional anatomic information provided by CT and the metabolic information provided by positron emission tomography (PET).
PET is most commonly performed with 2-[F-18]fluoro-2-deoxy-D-glucose (FDG). F-18 is an unstable radioisotope and has a half-life of approximately 110 minutes.
The indications for Fluorine-18 fluorodeoxyglucose (FDG) PET-CT imaging include:
- staging of cancer which potentially can be treated radically (e.g. small cell lung cancer)
- establish baseline staging before commencing treatment (e.g. GIST)
- evaluation of an indeterminate lesion (solitary pulmonary nodule)
- assessing response to therapy
- evaluation of suspected disease recurrence, relapse and/or residual disease (e.g. lymphoma, testicular seminoma)
- to guide a biopsy (e.g. pleural biopsy for mesothelioma)
PET-CT can also be used as a problem-solving tool:
- occult primary lesion (e.g. non-metastatic manifestation of neoplastic disease)
- evaluation of suspected recurrence in patients with equivocal conventional imaging
- evaluation of residual disease in patients with treated differentiated thyroid carcinoma and treated medullary thyroid carcinoma with negative/equivocal conventional imaging
- prior to radical nodal resection in patients with metastatic melanoma
- suspected malignant transformation in plexiform neurofibromata (neurofibromatosis type 1)
- differentiate between radiation-induced necrosis and tumour recurrence (e.g. primary CNS malignancy)
- 1. Clinical Indications for PET/CT. NHS PET/CT Diagnostic Imaging Service Group.
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