Diagnostic Imaging Pathways - Common Procedures
Positron Emission Tomography (PET)
Positron Emission Tomography utilises short acting, positron emitting isotopes to investigate a number of disease processes. The most commonly used agent is fluorodeoxyglucose (FDG). The positron emitting isotope fluorine-18 is substituted for a hydroxyl group in the glucose molecule. FDG uptake and subsequent retention is a marker of cellular glycolytic activity. The higher metabolic activity of tumours and their preference for glucose as an energy substrate leads to the high sensitivity and specificity of this agent in oncology, which is the main area of use. Combined PET CT scanners are gradually replacing the dedicated PET scanner, and combined imaging will soon be the standard in PET imaging. Many other PET radiopharmaceuticals are available which can be used to look at various biological processes.
The current reimbursable indications in Australia are:
- Primary staging of non small cell lung carcinoma where curative surgery or radiotherapy is planned
- Solitary pulmonary nodule where the lesion is considered unsuitable for transthoracic FNAB, or where pathological characterisation has failed.
- Evaluation of apparently limited metastatic disease, where surgical resection is planned
- Staging of newly diagnosed or previously untreated Hodgkin’s or non-Hodgkin’s lymphoma, evaluation of a residual mass after treatment, and restaging of suspected recurrent or residual disease
- Staging of proven oesophageal carcinoma, where curative surgery or chemoradiation is planned.
- Staging of proven gastric carcinoma, where curative surgery is planned.
- Performed in a symptomatic patient for the evaluation of a residual structural lesion, after definitive therapy for colorectal carcinoma.
- Evaluation of apparently isolated liver or pulmonary metastases following previous therapy for colorectal carcinoma, where surgical resection is planned
- Evaluation of epithelial ovarian carcinoma with suspected tumour recurrence following initial therapy, based on equivocal anatomical imaging findings or an elevation of CA-125.
- Primary staging of proven carcinoma of the uterine cervix, prior to planned radical radiation therapy or combined modality therapy
- To guide biopsy of a suspected bone or soft tissue sarcoma, where structural imaging suggests lesional heterogeneity.
- Staging of biopsy-proven bone or soft tissue sarcoma being considered for resection of the primary or limited metastatic disease.
- Evaluation of suspected residual or recurrent sarcoma on structural imaging after definitive therapy
- Suspected primary brain tumour to guide surgical biopsy of the lesion and to assist in treatment planning.
- Evaluation of a residual structural brain lesion based on anatomical imaging findings, after definitive therapy for glioma
- Refractory epilepsy which is being evaluated for surgery, where results of standard assessment are inconclusive for localisation of the epileptogenic focus
- Evaluation of ischaemic heart disease and impaired left ventricular function, where revascularisation surgery is being considered and standard myocardial viability tests are negative or equivocal for ischaemia
- Primary staging of carcinoma of the head and neck.
- Further investigation of suspected residual or recurrent carcinoma of the head and neck.
- Evaluation of metastatic squamous cell carcinoma involving cervical nodes from an unknown primary site.
- Follow-up of a cancer shown to be FDG positive to assess response to treatment or possible tumour recurrence.
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|Positron Emission Tomography (PET) Scan (May 2009)|