There are various ways of thinking about diagnostic imaging and nuclear medicine. If the reason for imaging the patient is to determine the presence of disease, then there are at least two possible strategies. One is to do the most complicated examination that will give a complete set of results on all patients. The other is to start with a simple examination and hope to categorize patients, perhaps into certain abnormals and all others, or even into abnormals, indeterminates, and normals. Then a subsequent, more complex examination is used to determine if there are more abnormals, or perhaps how abnormal they are. If the reason for imaging the patient is to collect a set of data that will be compared with results from that patient at a later time and with a range of normal results from all patients, then the least complex method possible for collecting the information should be used in a regular and routine fashion so that the comparison are possible.
In the former setting, where the complexity of the examination may have to be changed after the initial results are seen, in order to take full advantage of the dose of radioactive material that has been given to the patient, it is sensible to have the equipment available that will be able to perform the more complex examination and not to confine the equipment available to that capable of doing only the simple first examination. For this reason and because for some organs, such as the brain, the first examination is a SPECT examination, the new Anger cameras being sold today are mostly capable of doing rotating SPECT. The added necessities that SPECT brings to the instrument specifications are of degree: better stability, uniformity, and resolution. Thus they do not obviate the use of the equipment for planar imaging but rather enhance it. In the setting of performing only the examination necessary to define the disease, the Anger SPECT camera can be used for plane projection imaging and afterward for SPECT to further refine the examination. There are settings in which a planar camera will be purchased because of the simplicity of all the examinations (as in a very large laboratory that can have specialized instruments, a thyroid practice, or in the developing countries), but in the small- to medium-sized nuclear medicine practice, the new cameras being purchased are all SPECT-capable.
Nuclear medicine studies are generally less expensive than x-ray computed tomography or magnetic resonance imaging and more so than planar x-ray or ultrasound imaging. The general conduct of a nuclear medicine laboratory is more complex than these others because of the radioactive materials and the accompanying regulations. The specialty is practice both in clinics and in hospitals, but again, the complication imposed by the presence of the radioactive materials tips the balance of the practices toward the hospital. In that setting the practitioners may be imagers with a broad range of studies offered or cardiologists with a concentration on cardiac studies. Thus the setting also will determine what kind of instrument is most suitable.
