Computer Enhanced ElectroEncephaloGram:
This test measures the electrical activity of the brain which is then interpreted by a computer to be shown as an image. A series of these tests of over time can show the shunted areas of my brain and their growth.
These pictures are from the internet, it's not my brain, and the readouts they use to show me where slightly different in format.
Magnetic Resonance Imaging:
While the CEEEG looks at electrical impulses, the MRI looks at the physical structure of my brain. While it was said to me specifically, I suspect this test is for early detection of any potential tumors or anomalies brought on by the experimental medicines. Also, I know that MS causes very distinct detectible physical changes in the brain, perhaps CDS does as well. Again, the picture below is not my brain, just an example of what an MRI readout looks like (according to the net, I've never gotten to see one of my MRIs displayed.
Note: Some time after I wrote the above I did get to see the 'films' of one of my MRIs. It did look a lot like the example below except there were 5 pages, showing 180 cross sections. What I remember most is that there were a lot of small, and a couple not so small, completely black areas. When I run across a memory I can no longer access, I picture - a refer - to it as being in one of the black holes.
Positron emission tomography:
Positron emission tomography (PET) is a nuclear medicine imaging technique which produces a three-dimensional image or picture of functional processes in the body. The system detects pairs of gamma rays emitted indirectly by a positron-emitting radionuclide (tracer), which is introduced into the body on a biologically active molecule. Images of tracer concentration in 3-dimensional space within the body are then reconstructed by computer analysis. In modern scanners, this reconstruction is often accomplished with the aid of a CT X-ray scan performed on the patient during the same session, in the same machine.
If the biologically active molecule chosen for PET is FDG, an analogue of glucose, the concentrations of tracer imaged then give tissue metabolic activity, in terms of regional glucose uptake. Although use of this tracer results in the most common type of PET scan, other tracer molecules are used in PET to image the tissue concentration of many other types of molecules of interest.
Neurology: PET neuroimaging is based on an assumption that areas of high radioactivity are associated with brain activity. What is actually measured indirectly is the flow of blood to different parts of the brain, which is generally believed to be correlated, and has been measured using the tracer oxygen-15. However, because of its 2-minute half-life O-15 must be piped directly from a medical cyclotron for such uses, and this is difficult. In practice, since the brain is normally a rapid user of glucose, and since brain pathologies such as Alzheimer's disease greatly decrease brain metabolism of both glucose and oxygen in tandem, standard FDG-PET of the brain, which measures regional glucose use, may also be successfully used to differentiate Alzheimer's disease from other dementing processes, and also to make early diagnosis of Alzheimer's disease. The advantage of FDG-PET for these uses is its much wider availability. PET imaging with FDG can also be used for localization of seizure focus: A seizure focus will appear as hypometabolic during an interictal scan. Several radiotracers (i.e. radioligands) have been developed for PET that are ligands for specific neuroreceptor subtypes such as [11C] raclopride and [18F] fallypride for dopamine D2/D3 receptors, [11C]McN 5652 and [11C]DASB for serotonin transporters, or enzyme substrates (e.g. 6-FDOPA for the AADC enzyme). These agents permit the visualization of neuroreceptor pools in the context of a plurality of neuropsychiatric and neurologic illnesses.