<qa>  What is the strength of biochemical imaging methods?In general, diagnostic imaging can address two issues: structure and function. One can either view structures in the body and image anatomy using structural imaging modalities such as plain film radiography X-ray, Computerized Tomography CT and Magnetic Resonance Imaging MRI, or one can view chemical processes and image biochemistry and function using biochemical imaging modalities such as Planar and Single Photon Emission Computerized Tomography SPECT imaging and Positron Emission Tomography PET. The strength of the biochemical imaging methods is in distinguishing tissues according to metabolism rather than structure. 