Clinical imaging of cancer metastasis

Tumour imaging is an essential part of the practice of oncology, with a cru cial role in screening programmes and in diagnosis and staging of establish ed disease. Furthermore, the assessment of tumour size by imaging, usually with computer tomography (CT) scanning, is a key component in determining t he tumour response to therapy both in clinical trials and in daily oncology practice. Techniques such as CT, ultrasound (US) and magnetic resonance im aging (MRI) provide high resolution anatomical images with detailed structu ral information. However, these imaging modalities yield limited functional information on the tumour tissues and often cannot distinguish residual di sease from non-viable or necrotic tumour masses, nor can they detect minima l residual disease. In contrast, radiopharmaceutical imaging and, in partic ular, positron emission tomography (PET) can give some functional informati on about the underlying tissues. The possibility of refining these techniqu es and also the emergence of newer imaging modalities that call detect chan ges in cancers at the physiological, cellular or molecular levels, gives ri se to the notion that these methods will have implications for drug develop ment strategies and also future clinical management. In this review, we bri efly discuss the current role of imaging in clinical practice, describe som e of the advances in imaging modalities currently undergoing evaluation, an d speculate on the future role of these techniques in developmental therape utics programmes. (C) 2000 Elsevier Science Ltd. All rights reserved.