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Medical Imaging Modalities

quite distinct medical imaging modalities: diagnostic ultrasound, magnetic resonance imaging (MRI), positron-emission tomography (PET), and cardiac electrical imaging. The imaging physics are quite varied-scattering of incident acoustic energy, relaxation of magnet spin, spontaneous emission of nuclear particles, and passive measurement of low-frequency (quasi-static) electrical potentials. Two of the modalities generally image anatomy (ultrasound and MRI, although functional MRI imaging is a current topic of research) and two image active functioning of the tissue (metabolic activity, in PET, and spatio-temporal changes in electrical potential distribution in the heart, in cardiac electrical imaging). The goal of each article is to present: 1. the physical model behind the mo-