Biomedical Engineering Reference
In-Depth Information
FIGURE 12.7: (See color insert.) Combined FMT and MRI imaging.
Examples of fluorescence imaging using a cathepsin B-activatable imaging
probe. (a) and (b), Enzyme activity in a 9L glioma model in a live mouse.
The image in (a) is superimposed onto an MRI image shown separately in (b)
with gadolinium enhancement of the glioma28. (c), In vitro FRI of the axial
brain section corresponding to the MR and FMT images. The tumor position
is indicated by the arrow. (From [29].)
segmented in different regions first, and the segment boundaries are used as
prior information for calculation of the optical property map. An example of
pre-clinical combined FMT and MRI imaging is illustrated in Figure 12.7. In
this experiment the FMT image of a brain tumor was superimposed on the
corresponding MRI image. The new generation of hybrid optical tomography
and MRI systems in which the instrumentation is fully integrated [56] consist
of an MRI scanner with laser diodes at one or more wavelengths for optical
illumination guided into the MRI coil using fibers.
12.3.2.2 FMT-XCT
A very promising hybrid approach is the combination of free-space fluo-
rescence tomography instrumentation with X-ray CT. Figures 12.8 and 12.9
show results of an experiment performed with a nude mouse with lung tu-
mors. FMT and XCT data were coregistered and later combined in this case.
Due to the similar configuration characteristics, these modalities are ideal for
combination into one single system.
An example of a hybrid FMT-XCT system is schematically represented in
Figure 12.10 [46]. In this setup, free-space FMT instrumentation is mounted
on the same rotating gantry as the X-ray CT components. The X-ray com-
ponents consist of an X-ray source and an X-ray detector. The FMT instru-
mentation includes a CCD camera coupled to a macro lens and diode laser
sources, placed orthogonal to the X-ray source-detector axis. The FMT instru-
mentation needs to be protected from radiation using shielding. In front of the
CCD camera lens a filter wheel is positioned, which includes a lead filter for
radiation shielding during X-ray exposure, and different combinations of fil-
 
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