Imaging jumps ahead with PETT.

Abstract

While conventional tomography gives anatomic images, this new technique provides a look at local metabilic and physiological functions in tissues. It is noninvasive, makes use of physiological biochemicals, can detect small metabolic changes, and has a resolving power approaching that of currently used tomographic scanners. The procedure is called positron emission transaxial tomography (PETT) and while still a research tool, it is already offering valuable insignts into normal and disease processes. The standard computed tomograph transmits x-rays through tissue, and differential absorption of these rays forms the image, giving a static look at organs of the body. With PETT, positron-emitting isotopes are incorporated into natural biochemical substances such as glucose (or its analogue, deoxyglucose (DOG)), ammonia, fatty acids, or catecholamines, which are then administered to the subject. Localization of these isotope-containing chemicals with the tomograph can show how they are transported in the body, where they are taken up into tissues, and how quickly they are metabolized. Thus, PETT provides dynamic information about body functions that complements the morphological data derived from standard transmission computed tomographic (TCT) scanning.