Sectional anatomy is a subject of anatomy wherein the focus is on studying regions instead of systems. It helps to view a part of the body in different dimensions, which helps in creating three-dimensional (3D) images of the body parts. Sectional views of body are obtained using imaging techniques such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT). PET is a functional imaging technique that utilizes safe injectable radioactive chemicals called radiotracers. It helps in visualizing and measuring alterations in metabolic processes and other physiological functions such as absorption, blood flow and regional chemical composition. On the other hand, SPECT is a tomographic imaging technique that uses gamma rays that can be detected by the CT scanner. The gamma ray emission is collected by the computer systems and the CT cross-sections are displayed. The computer then generates the three-dimensional image of the body part. This book explores all the important aspects of PET and SPECT imaging in the present day. Those in search of information to further their knowledge will be greatly assisted by it.