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Positron emission tomography (PET) is an exact, non-invasive
technique for studying the body's biochemistry. The patient is
injected with a positron-emitting radioisotope of a biologically
active substance -- for oncological investigations,
fluorodeoxyglucose (FDG) (2-deoxyglucose labelled with the
positron emitter fluorine 18) is used.1,2 FDG is actively
concentrated in cancer cells, and the PET camera detects the location
of the FDG by registering the ejection of positrons from the nuclei of
fluorine 18 atoms. As the positrons are ejected they collide with
electrons; both particles annihilate and emit two 511 keV gamma rays
at 180º to each other. Rings of detectors in PET cameras register these
signals and the resulting images of particular organs, or the whole
body, are displayed in three dimensions. Thus, PET can reveal the
presence of cancer by recording an increased rate of glucose
metabolism before any of the structural changes detectable by
ultrasound, radiography, computed tomography (CT) and magnetic
resonance imaging (MRI) have occurred.
The history of PET in Australia is given in Box 1. Recognition of the
utility of PET, particularly in cancer management, is reflected in
its expanding applications around the world, and in the proportion of
papers on PET (rising from 10% to 36%) presented at annual meetings of
the US Society of Nuclear Medicine.3 The majority of these papers
relate to its applications in oncology. Similarly, most clinical PET
studies performed in Australia (over 80%) have been for cancer
management.4
Box 2 gives a summary (adapted from
Valk5) of the current role of PET in
cancer management.
Although these overseas studies demonstrate the superior
diagnostic accuracy of PET in a wide range of applications in
oncology, the article in this issue of the Journal by Hicks et
al6
is the first extensive Australian report of the use
of PET. The contributions of PET to patient management in oncology
reported by Hicks and colleagues are similar to those recorded in the
international literature.
Hicks and colleagues did not assess cost-effectiveness as part of
their audit of PET studies, but studies in other countries have
provided a large body of evidence of the cost-effectiveness of PET in
oncology. However, Valk emphasises that, while there are adequate
cost-effectiveness data on diagnosis of pulmonary nodules and
mediastinal staging of lung cancer, cost-effectiveness data for the
use of PET in other conditions are incomplete.7 Cost-effectiveness
studies have demonstrated that the benefits of PET include avoidance
of unnecessary imaging procedures (radiography, CT, and MRI) and
biopsies, as well as prevention of unnecessary surgery and
hospitalisation.7-9
Influenced by the findings of diagnostic accuracy and
cost-effectiveness, the US government has now included the oncology
applications for PET studies detailed below among its Medicare
reimbursement categories:
- Characterisation of
solitary pulmonary nodule; and initial staging of non-small-cell
carcinoma of the lung (since January 1998); and
- Colorectal cancer recurrence or metastasis; lymphoma staging and
characterisation; melanoma recurrence or metastasis (since July
1999).10
In Australia, it is time to consider making PET available at
additional sites, both to improve medical outcomes for a greater
number of patients and to obtain our own cost-effectiveness data.
Essential to this process are:
Fluorine-18 deoxyglucose (FDG) supply: In the past decade,
Australia has made a multimillion dollar investment in cyclotrons --
the National Medical Cyclotron (NMC) in Sydney, operated by the
Australian Nuclear Science and Technology Organisation (ANSTO),
and two small cyclotrons in Melbourne. These cyclotrons can supply
enough FDG to meet the present and immediate future needs of all
capital cities except Perth and Darwin. If PET continues to expand, it
may be necessary to install further regional cyclotrons.
Acceptable instrumentation: The bulk of the evidence
used by expert committees in the United States and Australia to
determine existing reimbursement policies in PET in oncology came
from PET studies using scanners equipped with bismuth germanate
crystals (BGO). PET centres at Royal Prince Alfred Hospital and the
Austin and Repatriation Medical Centre are equipped with BGO
cameras, which remain the reference standard for FDG PET oncology
studies. Further studies on cost-effectiveness need to be based on
data obtained using comparable instruments. A range of instruments
claiming similar performance exists, and there is an ongoing need for
these to be evaluated.
Accredited PET staff (physicians, scientists,11,12
technologists): Australia has a number of PET-trained physicians,
scientists and technologists. This pool of expertise will need to be
expanded and appropriate accreditation guidelines defined and
implemented.
Appropriate location of PET services: Delivery of
advanced oncology therapy is centred predominantly in major
hospitals which have comprehensive diagnostic services (eg,
radiography, CT, MRI, nuclear medicine), a range of other
specialties and radiation oncology planning and treatment
services. The oncological dominance of clinical PET usage patterns
automatically proposes centres such as these as logical sites for the
diffusion of PET.
Ongoing evaluation: Diffusion of PET services should be
carried out in conjunction with the established, transparent
evaluation processes. The oncology stakeholders, including
patient advocacy groups, should be involved in the formulation and
implementation of protocols. Liaison with the Medical Services
Advisory Committee, the federal Department of Health and Aged Care
and State and Territory health departments is essential. The Federal
Department of Health and Aged Care is currently conducting a review of
PET with input from a Medical Services Advisory Committee PET working
party and involving existing PET providers. In addition, NSW and
Victoria are conducting their own reviews of PET services.
As well as demonstrating clinical utility, the study of Hicks et al
shows the advantages that flow from locating PET facilities in major
oncology referral centres. The model for the role of PET suggested
here proposes the collocation of PET services in the nuclear medicine
departments of comprehensive refer
ral hospitals which have
existing regional oncology services. The advantages of this
proposal are that PET is located where the greatest number of oncology
patients can benefit from its clinical accuracy, and further
large-scale evaluations of its cost effectiveness can be
undertaken.
John G Morris, AO
Professor of Clinical Medicine
Australian Nuclear Medicine and PET Consultants, Sydney, NSW
- Sokoloff L, Reivich M, Kennedy C, et al. The [14C] deoxyglucose
method of local cerebral glucose utilisation: Theory, procedure,
and normal values in the conscious and anaethestised albino rat. J
Neurochem 1977; 28: 897-916.
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Som P, Atkins HL, Bandoypadhyay D, et al. A fluorinated glucose
analog, 2-fluoro-2-deoxy-D-glucose (F-18): non-toxic tracer for
rapid tumor detection. J Nucl Med 1980; 21: 670-675.
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Proceedings of the 46th Annual Meeting of the Society of Nuclear
Medicine, Los Angeles, California, 1999. J Nucl Med 1999; 40
(Suppl): 5.
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Commonwealth Department of Health and Aged Care (Diagnostics and
Technology Branch). Review of positron emission tomography (PET).
Canberra: The Department, July 1999.
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Valk PE. Effect of FDG-PET on patient management and cost. Handout
book. Reston, Va (USA): Society of Nuclear Medicine, 1999: 200-204.
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Hicks RJ, Binns DS, Fawcett ME, et al. Positron emission tomography
(PET): experience with a large-field-of-view three-dimensional
PET scanner. Med J Aust 1999; 171: 529-532.
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Valk PE, Pounds TR, Tesar TD, et al. Cost-effectiveness of PET in
clinical oncology. Nucl Med Biol 1996; 23: 737-743.
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Lowe VJ, Fletcher JW, Gobar L, et al. Prospective evaluation of
positron emission tomography in lung nodules. J Clin Oncol
1998; 16: 1075-1084.
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Gambhir SS, Hoh CK, et al. Decision tree sensitivity analysis for
cost-effectiveness of FDG-PET in the staging and management of
non-small-cell lung carcinoma. J Nucl Med 1996; 37:
1428-1436.
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HCFA expands Medicare coverage of PET. J Nucl Med 1999; 50:
23N.
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Bailey DL, Miller MP, Spinks TJ, et al. Experience with fully 3D PET
and implications for future high-resolution 3D tomographs. Phys
Med Biol 1998; 43: 777-786.
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Hutton B. Emerging clinical applications of quantitative
emission computed tomography. In: Pham B, Braun M, Maeder AJ, Eckert
MP, editors. New approaches in medical image analysis, 1999.
Proceedings of SPIE (International Society of Optical Engineering)
1999; 3747: 57-76. (ISBN 0-8194-3229-6.)
©MJA 1999
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Other articles have cited this article:
 Robert E Ware, Hilton W Francis and Kenneth E Read. The Australian Government’s Review of Positron Emission Tomography: evidence-based policy-making in action Med J Aust 2004; 180 (12): 627-632. [Healthcare] <http://www.mja.com.au/public/issues/180_12_210604/war10444_fm.html>
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