ABSTRACT
As is described by other authors in this volume, the use of radiolabeled ligands which bind specifically to a variety of cell-surface and cytosolic receptors is of great and increasing importance. This is particularly so when the target-organ/whole-body uptake ratio of the ligand is sufficiently large to allow for in vivo imaging studies. Such imaging would be especially valuable, first, because of the well-documented changes which take place in various receptor systems during disease (e.g., in diabetes, Huntington’s chorea, Alzheimer’s dementia, and parkinsonism 1-4 ); second, because of the tremendous potential for the use of radiolabeled antibodies and endocrine hormone analogues for the detection and characterization of tumors; 5-7 third, because of the promise of “physiological tomography” 8-12 which will allow noninvasive studies to be made of local metabolism, drug pharmacology, and other dynamic aspects of biochemical interactions, using ligands labeled with gamma- or positron-emitting isotopes. It is also worth noting that questions have been raised recently 13 about the ambiguity of [201]-Thallium redistribution studies of myocardial infarction caused by the interaction of perfusion-dependent and uptake-dependent processes.
