 Abstract of the lecture presented at the 12th ASEAN Association of Radiology Congress, Sep 2004 by Professor Rodney J Hicks, Director, Centre for Molecular Imaging, the Peter MacCallum Cancer Centre, Melbourne, Australia
Although first implemented as an imaging technique more than 25 years ago, PET scanning has only recently become a mainstream diagnostic imaging modality. The dramatic growth in clinical PET over the past decade has been fuelled primarily by the development of whole body imaging capability with its concomitant specific and clear advantages for oncological assessment.
Oncology applications are the now the dominant referral indication for PET throughout the world, representing more than 90% of cases in many facilities. The high contrast achieved between cancer deposits and most normal tissues when the glucose analogue, F-18 fluorodeoxyglucose (FDG), is used as a PET tracer provides excellent sensitivity for many types of malignancy but limits the ability of PET to determine the structural relations of these deposits. Furthermore, since physiological uptake or secretion of FDG occurs in relationship to normal tissues, patterns of uptake become important in differentiating disease from normal processes and avoiding false positive results.
Correlation of structural imaging results from CT or MRI with FDG PET findings has been shown to improve the overall diagnostic accuracy of PET and to be of vital importance for T-staging. Although direct visual comparison is an inexpensive and helpful process, it can remain difficult to relate structural findings to metabolic images. Software co-registration programs suffer from similar difficulties. An alternative approach was developed in the late 1990’s utilising “hardware fusion”. By contemporaneously acquiring both PET and CT images with the patient in a constant and known position, direct co-registration of both data volumes was made possible. The hybrid PET/CT devices are now available commercially from several manufacturers.
The first PET/CT device in the Asia-Oceania region was installed at the Peter MacCallum Cancer Centre in 2001. Over 5000 scans have been performed using this scanner. Our experience suggests that this technology will become a routine part of the diagnostic armamentarium because of its superior performance compared to other techniques used in cancer staging, including both stand-alone PET and multi-slice CT. This experience is supplemented by a growing body of evidence regarding the superior diagnostic capability of PET/CT compared to PET. In particular, PET/CT has advantages in regions of complex anatomy such as the neck and epigastrium and in relationship to organs or structures that have high physiological uptake, including the bowel and bladder. This presentation will focus on the diagnostic impact of PET in oncology.
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