I have briefly explained magnetic resonance imaging before and so it is advisable to read this previous article first. One of the other common methods of biological scanning is nuclear imaging. Despite gamma rays notorious nature, radioisotopes that give off gamma rays are the safest to ingest as gamma rays tendency to pass through concrete means that it will definitely pass thorough the body and allow an exterior detector to get a look at where the rays are coming from. MRI allows for good detail and contrast for the different parts of the body while γ-imaging allows for targeted parts of the body to be observed based on manipulating where the gamma source will end up.
By using electromagnetic radiation and a varying magnetic field a radioactive tracer can be polarised and have its spin quantum number given specific values. This means that the gamma radiation given off can be detected and formed into an image not by a radiation camera but by a single radiation detector. The polarisation and spin effect is identical to what occurs in water molecules in MRI and the similarities to nuclear imaging is clear. This new method combines the best parts of both the originals and was able to detect 8.7 μg (8.7×10−9 kg) of Xe-131m in a model glass cell. This means 4 × 1013 atoms had information taken from them, if this was standard MRI and water had to be used it would have been in the region of 1024 water molecules that needed to be imaged. This method opens up new possibilities when it comes to radioactive tracers and the precise imaging of the human body.