What Are Single Photon Emission Tomography, Ultrasound Imaging, Computed Tomography and Magnetic Resonance Imaging?
Single photon emission tomography (SPET) is a functional diagnostic technique similar to PET that is based on the use of radionuclides decaying by emitting photons rather than positrons. Photons are quanta of electromagnetic radiation. This technique is less accurate and less costly than PET. On the other hand, ultrasound imaging (USI), computed tomography (CT) and magnetic resonance imaging (MRI) are medical diagnostic techniques that give anatomical or structural images of tissues, organs, parts of the body and the whole body. USI is based on reflection of high energy sound waves from tissues, CT on absorption of low energy X-rays in tissues, and MRI on perturbation of aligned magnetic moments of atomic nuclei in tissues with radiofrequency waves. In most cases, PET gives images that are superior to those obtained by USI, CT and MRI. But, a PET scan is more expensive than an USI, CT or MRI scan. Today, there are scanners providing PET and CT in the same session, immediately one after
