Positron emission tomography (PET) uses small amounts of radioactive materials called radiotracers, a special camera and a computer to help evaluate your organ and tissue functions. By identifying body changes at the cellular level, PET may detect the early onset of disease before it is evident on other imaging tests.

http: www.einstein.yu.edu - This introductory chapter of Dr. Michael Lipton s MRI course covers the basic technology of MRI, including signal intensity, contrast resolution and spatial resolution. Dr. Lipton is associate professor radiology ......

course covers the essentials of image reconstruction used for x-ray based imaging, here the example of computed tomography.