Biomedical Engineering Reference
In-Depth Information
These Raman breast studies have demonstrated the potential of the tech-
nique for sampling and identifying disease processes on excised tissue sec-
tions. Although this would be a helpful tool it is yet to be realised for clin-
ical decision making. If the performance of the DCIS model can be carried
forward to more extensive population-based diagnostic models then the use
of an automated Raman DCIS classification tool would allow histopatholo-
gists to reliably utilise the DCIS pathology to provide a prediction of likely
carcinoma development, and therefore drive critical clinical decision making
[99].
The biochemical changes that occur during carcinogenesis are thought
to be a gradual continuum from normal to malignant; therefore, a means of
detecting pre-malignancies within these tissues could be achieved by detecting
the biochemical changes that are associated with disease progression before
the actual progression has occurred. To date direct analysis of the biochemical
information in the spectra has been rarely exploited. This has been performed
in breast [100] using tissue-derived constituents or urological and oesophageal
tissues [21, 67] using pure chemical standards.
Even though there is great potential for future molecular diagnostics and
potential prognostication; the greatest early breakthrough for clinical detec-
tion and diagnosis is likely to come from a tool which can be used during
screening to minimise false results and identify disease-specific tissue compo-
sition changes. This is proving to be feasible as an adjunct to mammogra-
phy possible by using the novel developments in deep Raman techniques. An
overview of progress to date is provided below.
13.4 Deep Raman for Diagnostics in Solid Organs
There is great diculty in accurate diagnosis and detection of malignancies
in solid organs such as the breast and prostate. Screening programmes by
their nature often result in a high false-positive rate for detection of any
'abnormality'. This leads to a high negative biopsy rate from targeting these
'abnormalities'. There are many negative aspects for the patient of a false-
positive diagnosis, from anxiety to risk of infection and the costs to the health
community are huge.
A significant problem for those interested in the use of Raman spectroscopy
for in vivo measurements of biological tissue is that the collected Raman sig-
nal decreases when probing at greater tissue depth. This causes the surface
Raman signal and any accompanying fluorescence to be significantly stronger
than the sub-surface Raman signal. A series of early collaborative technolog-
ical developments at the Rutherford Appleton Laboratory in the UK have
made Raman spectral probing of gradually increasing depths within tissue
become a reality [101-103]. This field is rapidly developing and further details
regarding the evolution of deep probing Raman techniques are outlined in
Chap. 3.
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