New imaging techniques in gastrointestinal cancer.

Impressive advances in both anatomic and functional imaging of gastrointestinal tumors have been made in recent years, with several interesting studies appearing this past year. Increasingly, different imaging modalities have been used in combination and have shown complementation and improved accuracy. Improvements in detecting and defining local versus extended sites of cancer in various gastrointestinal organs have been made by conventional methods and by newer functional tests, including positron-emission tomography, receptor scintigraphy, and radioimmunodetection. With the US Food and Drug Administration approval of the first antibody-based cancer imaging agent, a new class of biologic imaging agents is coming of age in oncology and will likely experience the most use in management of colorectal cancer, permitting improved staging and disclosure of occult disease. In addition to gamma camera imaging, these radioactive biologic targeting agents hold promise for positron-emission tomography scanning and for cancer radioimmunotherapy.