Biomedical Engineering Reference
In-Depth Information
Fig. 4
Bioluminescence and l uorescence imaging of a mouse with a luciferase-expressing renal
carcinoma tumor at er injection of luciferin (let ). h e signal colocalizes with the l uorescence
signal at er IV injection of α
v
β
3
-targeted quantum dot, a semiconductor nanocrystalloid particle
with bright l uorescence (right). With permission from Mulder (2008).
then be used to detect signal (Ntziachristos 2006).
In vivo
immunol uorescence
microscopy and intravital microscopy can allow probe specii city to be determined
in vivo
, non-invasive l uorescence transillumination, whereby light at an excitation
wavelength is shone through the tissue and the l uorescence emitted is recorded
on the other side with a highly sensitive charge-coupled device camera, has only
more recently been described, and optical tomography uses light measurements
collected at the tissue boundary to create a 3D reconstruction of l uorophore
distribution.
Currently
l uorescence
imaging is limited to small animal studies, since the
limited penetration depth of the optimal signal currently limits the use of this
technique in everyday practice. Microscopic resolution can be obtained using
invasive techniques, and sub-millimeter resolution can be achieved using
l uorescence molecular tomography (Graves
et al.
2003), which uses the deep
tissue penetration ability of near infra-red l uorescent light (Nahrendorf
et al.
2008).
Ts o u r k a s
et al
. (2005) constructed a novel monocrystalline nanoparticle
consisting of an iron oxide core and an animated cross-linked dextran coating.
Cy5.5 l uorochrome was then attached to the particle to enable near-infra red
l uorescent imaging. Monoclonal antibodies to VCAM-1 were then added to
allow specii c targeting of the protein's expression on murine endothelium using
intravital l uorescence microscopy and MRI. A similar particle has been used by
Funovics
et al.
(2005) to detect E-selectin expression in mouse lung carcinoma.
In the future, optical imaging promises to shed further insights into the
mechanisms of disease. For example, Walls
et al.
(2008) used optical projection
tomography of the ubiquitous vascular marker PECAM-1 to analyze vascular
development in the mouse embryo. Analysis of the vascular tree at separate stages
of development provided new information regarding the normal development of
several dif erent areas of the vascular tree. In a further example using l uorochromes
