Multimodality imaging: beyond PET/CT and SPECT/CT.

Multimodality imaging with positron emission tomography/computed tomography (PET/CT) and single-photon emission computed tomography (SPECT)/CT has become commonplace in clinical practice and in preclinical and basic biomedical research. Do other combinations of imaging modalities have a similar potential to impact medical science and clinical medicine? Presently, the combination of PET or SPECT with magnetic resonance imaging (MRI) is an area of active research, while other, perhaps less obvious combinations, including CT/MRI and PET/optical also are being studied. In addition to the integration of the instrumentation, there are parallel developments in synthesizing imaging agents that can be viewed by multiple imaging modalities. Is the fusion of PET and SPECT with CT the ultimate answer in multimodality imaging, or is it just the first example of a more general trend toward harnessing the complementary nature of the different modalities on integrated imaging platforms?