Photoacoustic imaging
Photoacoustic imaging is one of the latest breakthroughs in the world of medicine. It offers great promise as a diagnostic tool for doctors. At this point it remains confined largely to laboratories mainly because the hospitals don't have the necessary equipment. However eventually photoacoustic imaging will likely become commonplace. Mainly because of all the advantages that it offers.
Photoacoustic imaging is very much on the cutting edge of modern medicine. The basic idea is that by using a laser pulse in the area that you are interested in looking at you will heat the tissue slightly. This heat will then generate high frequency sound waves as the result of the photoacoustic effect. This simply means that as the tissue get heated it will expand slightly and this will cause a pressure wave which gets transmitted as sound. These sound waves are at a frequency that is to high for people to hear. However a detector can be made to capture these waves. The slight differences in frequency of the waves will show the different areas of the internal structure. This can all be put together to create a picture.
The idea of using sound waves to create a picture of the inside of the body isn't new ultrasound has been doing that for years. However the great flaw with ultrasound is that it requires that the sound be made internally by your body. This is great for things like looking at a fetus in the womb or looking at your heart but it doesn't really do much for allowing doctors to see areas that aren't producing a sound. Photoacoustic imaging allows them to use a laser to create the sound that they need greatly enhancing what can be seen.
The great advantage that photoacoustic imaging has over other forms of medical imaging is that it can give a much clearer picture than any other technique. This is because you can get a much better contrast between what you are looking at and the background. All imaging is based on the idea of optical absorption. This is simply that different materials will absorb radio or light waves to a greater or lesser extent. These differences are what allow them to show up differently on the monitor. The problem with most medical imaging techniques is that optical absorption has to be observed indirectly. This isn't the case with photoacoustic imaging, the heat from the laser allows for direct viewing of optical absorption giving a much clearer picture.
At this point photoacoustic imaging remains largely experimental. It is used mainly by research laboratories. While there are clearly benefits to be had for using it as a diagnostic tool at this point very few hospitals have the required equipment. Over time this will change but it will take quite some time. The required equipment is very expensive.