Biomedical Imaging: Principles and Applications

Chapter 7

Tracer Imaging

Rainer Hinz

Wolfson Molecular Imaging Centre, University of Manchester, Manchester, UK

7.1 Introduction

The Nobel Prize in Chemistry 1943 was awarded to George de Hevesy for his work on the use of isotopes as tracers in the study of chemical processes. This was just 8 years after the first radioindicator study in life sciences with a manmade radionuclide was reported (Chievitz and Hevesy, 1935). Since then, the use of the tracer principle has provided a wealth of knowledge about the biochemical pathways in living organisms. In particular, combination with imaging, that is, the recording of spatial and temporal distributions of radiolabeled molecules within the body, has made it possible to quantitatively acquire parameters such as blood flow, rates of metabolism, or receptor binding to describe physiological processes.

In the first tracer studies, only crude spatial information about radioactive source distributions was available by positioning a single detector at various locations around the subject. In 1950, Benedict Cassen invented the rectilinear scanner. This device produced planar images by mechanically scanning a detector in a rasterlike pattern over the area of interest. However, because of the sequential nature of the scanning, this technique required very long imaging times.

By 1952, Hal Anger completed the first prototype of a pinhole camera with a photographic plate. In late 1956, he developed the design now seen in current “Anger camera” systems ...