Biomedical Engineering Reference
In-Depth Information
high resolution and monitoring patients over time intervals. Performing this through skin biopsies (or
ultimately through a true virtual biopsy using only backward detection) would be much less invasive
than performing unpleasant bone biopsies. Analogously, women at high risk for cancer could be moni-
tored every several years through a combination of a laparascope and endoscope.
We have stressed that the overall approach is generally in terms of analyzing the ECM in dis-
eased tissues; there remain challenges in making the scheme practical. However, we believe these
can be overcome. Currently, we measure the bulk optical properties through integrating spheres and
rotating goniometers. There are not simple measurements and can obviously only be performed on
ex vivo
tissues. However, recently, Jacques presented a method using reflectance confocal microscopy
to measure local optical properties [47]. The Jacque and Campagnola labs used this approach in clas-
sifying normal and oim skin tissues. This method could be ultimately implemented
in vivo
through a
microendoscope, given the rapid advances in fiber optics and miniaturized scanning being developed
in several labs. Our method of measuring the SHG directionality also cannot be implemented directly
in vivo
. However, we suggest both the
F/B
and attenuations method can be performed in the back-
ward collection geometry and would yield all the same data as shown here in the forward case. For
attenuation, this is straightforward, although the signal levels would be smaller. For the directional
measurements, devices we envision that a multiple probe scheme could be constructed where the
same information could be extracted. Recently, Brown showed how the
F/B
could be extracted using
a single objective [48]. We note that the directional measurements could be applied to
ex vivo
biopsies
of more accessible epithelial tissues such as skin and breast, where ECM remodeling also accompanies
carcinogenesis.
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