Learning Objectives: 1) Describe the technology involved with the two principal methods of image fusion including dual modality machines such as PET/CT and SPECT/CT and post acquisition/software based image registration and fusion. 2) Identify the technological and clinical advantages and disadvantages of each approach to image fusion. 3) Describe the diagnostic advantages of fused images in terms of lesion conspicuity, clarification of complex findings from different modalities, and confidence of interpretation. Disclosure: (M.P.S. is on Elgems advisory board.)