Biomedical Engineering Reference
In-Depth Information
Fig. 8.6.
Beam delivery instruments. The OCT beam can be delivered through a
number of new or modified optical instruments including (
a
) surgical and research
microscopes, (
b
) hand-held probes and laparoscopes, (
c
) fiber-optic catheters, and
(
d
) optical needle-probes
with endoscopy, the 1 mm diameter catheter can be inserted through the work-
ing channel of the endoscope for simultaneous OCT and video imaging [31].
Similar catheters have been used to image plaques within the living human
coronary arteries [33]. Minimally invasive surgical procedures utilize laparo-
scopes, which are long, thin, rigid optical instruments to permit video-based
imaging within the abdominal cavity. Laparoscopic OCT imaging has been
demonstrated by passing the OCT beam through the optical elements of a
laparoscope [27,32]. Deep solid-tissue imaging is possible with the use of fiber-
needle probes [28]. Small (400
m diameter) needles housing a single optical
fiber and micro-optic elements have been inserted into solid tissues and ro-
tated to acquire OCT images. Recently, microfabricated micro-electro-optical-
mechanical systems (MEOMS) technology has been used to miniaturize the
OCT beam scan mechanism [53].
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8.6 Spectroscopic Optical Coherence Tomography
Spatially distributed spectroscopic information can be extracted from the tis-
sue specimen using spectroscopic OCT (SOCT) algorithms and techniques
[54-57] (Fig. 8.7). In structural OCT imaging, the amplitude of the envelope
of the field autocorrelation is acquired and used to construct an image based on
the magnitude of the optical backscatter at each position. Spectral information
