Professor Saltzman continues his discussion of biomedical imaging technology. Magnetic resonance imaging (MRI) is introduced as an alternate form of imaging, which does not use ionizing radiation yet can provide detailed structure of the body. Functional MRI (fMRI) has a different application from traditional MRI. It can be used to measure oxygen consumption (tissue metabolic rate), and is an important tool in deciphering brain function. Third, ultrasound imaging is another imaging technique that can detect motion by translating sound wave reflections into structural images at fast timescale. Finally, examples of nuclear imaging and advances in light microscopy are discussed.