Biomedical Engineering Reference
In-Depth Information
FIGURE 9.1
Example of PET-FDG brain images shown as transverse, coronal, and sagittal cuts. Although
these are primarily functional tomograms, some anatomical structures are visible and this
facilitates the application of automated and visual interactive registration techniques.
FIGURE 9.2
Example of C-11-Methionine (top) and F-18-DOPA (bottom) PET studies. Compared to
Figure 9.1, much less anatomical detail is visible. These images are, however, extremely
helpful for delineating pathologic areas caused by tumors (arrow, top row) or the evaluation
of the dopaminergic system (arrow, bottom row). This type of image is a challenge for image
registration algorithms, but can have high diagnostic utility.
shows such an example in which C-11-methionine was used to detect increased
protein synthesis indicating areas where tumor tissue develops. Compared
with the tumor region, C-11-methionine uptake in the remaining brain tissue is
considerably lower. There are no clear outlines of the cortex or other structures
as with FDG, rendering the identification of landmarks more difficult.
A similar situation is found using 6-[
18
F]-fluoro-L-DOPA to study the pre-
synaptic dopaminergic system. There is a clear concentration of the tracer accu-
mulation in the center structures of the brain (i.e., striatum) as shown in Figure 9.2
(bottom), with some nonspecific binding of the tracer in the remaining brain
tissue. Again, the outline of the outer brain surface is rather limited and not as
