Biomedical Applications of Emission Tomography - Correction Techniques in Emission Tomography - page 19

FIGURE 2.2: (See color insert.) Longitudinal BLI analysis of the growth
of subcutaneous brain tumors. CD1 nu/nu mice were injected twice with 1*10 6
human U87EGFR glioma cells that stably express rey luciferase. At dif-
ferent days post tumor implantation the tumor volume was measured with the
help of a caliper (A); tumor volume = 0.52 length width 2 ). Furthermore,
tumor activity was assessed by BLI measurements 10 min after intraperitoneal
injection of 2 mg D-luciferin using the IVIS spectrum system (Caliper Life Sci-
ences). Serial BL images displayed in pseudocolors superimposed to a white
light image show tumor growth of two subcutaneous tumors at the left and
right back region (C). BLI signals that arise from the tumors were quantified
(B) (gray: left tumor, black: right tumor) to assess viable tumor volumes.

tion of luciferase expression with tumor volume as measured by, for example,
caliper measurement [16] or MRT [19], has been observed. Figure 2.2 shows
the use of the luciferase reporter gene for studying the spontaneous growth
of subcutaneous tumors in individual mice over time. Precise algorithms for
translating 2D bioluminescence signals into measures of cell numbers and pro-
viding 3D images remain a huge challenge in optical imaging due to scatter
and attenuation of light in tissue.

2.4.3.2 Dynamic PET in pharmakodynamic studies

A unique feature of PET in small animals is the dynamic assessment of
radioactivity distribution in the whole animal to assess pharmakodynamics.
An example of using this approach to assess quantitatively the nerve function
in murine hearts is given here. For the function of the heart, the sympa-
thetic nervous system is as important as the perfusion or myocardial contrac-
tility. In heart failure and arrhythmias, activity of the sympathetic nervous
system is impaired; the quantitative study of nerve function at the heart is