ABSTRACT
Since its inception, nuclear medicine imaging has always been known as a functional imaging technique rather than an anatomical imaging method. Three-dimensional images obtained from SPECT or PET devices depict the accumulation of radiopharmaceutical by specific cells, thus representing cellular function (see Figure 14.1a). As a result, these images lack the spatial information and instant recognition of other medical imaging techniques such as x-ray CT or MRI. The underlying information conveyed to an educated reader, however, is substantial as the distribution of radiopharmaceu-tical within the body provides physiological information about the body rather than strictly anatomical information. Nuclear medicine images often provide an early glimpse into disease progression as physiological changes occur prior to structural changes appearing. Even so, nuclear medicine has long been described as “unclear” medicine due to the fact that images typically lack any readily identifiable landmark information such as bones or lungs. In fact, an ideal nuclear medicine should contain no anatomical information whatsoever but rather depict the highly specific uptake of radio-tracer in certain cell types. Admittedly, the lack of structural information may introduce some difficulties in localizing disease or framing the extent of disease. In order to provide some measure of anatomical structure and to correlate the radiopharmaceutical distribution with anatomy, numerous methods have been used.
