Presidential Greeting - American Society for Laser Medicine and ...

etween the fiber diameters. The ablation effect observed were
similar to the microsecond pulsed CO 2 laser; tissue water is
effectively turned to explosive hot vapour that is expelled from the
imploding channel leaving some residual thermal energy behind
depending on pulse length.
Conclusion: Fiber delivered Erbium lasers can provide
controlled soft tissue cutting using pulse lengths in the ms toms
range to control the thermal residual depending on the
application.
#20
REGULATORY PERSPECTIVE OF OPTICAL
IMAGING DEVICES: TECHNOLOGY,
INDICATIONS, AND FUTURE CHALLENGES
Kejing Chen, Richard Felten, Long Chen, Neil
Ogden
Office of Device Evaluation, Food and Drug Administration,
Silver Spring, MD
Background: Medical imaging is a rapidly developing area that
provides novel diagnostic information and/or facilitates image
guided therapy to areas of interest. Optical imaging devices, when
used in conjunction with minimally invasive endoscopes, collect
reflected, scattered, laser-induced fluorescent, and other light
signals in the ultraviolet, visible and near-infrared spectra. Based
on the collected signal, images are constructed to reveal tissue
structure information at microscopic level. Contrast to other
imaging methods, optical imaging could yield high spatial
resolution near the mm scale.
Study: In the past, the FDA has cleared a number of optical
imaging devices, which are currently used in clinical practice,
through the Premarket Notification process as Class-II Medical
Devices. Due to the evolution of new technology associated with
the development of optical imaging devices, there now exist
challenges, from the regulatory perspective, in the following
areas:
Results: (1) The sensitivity and specificity of optical imaging
devices to detect the claimed diseased lesions. (2) The output
readability of some optical imaging devices may be in the form of
action spectrum or numerical readout, which although still
yielding structure information is unconventional for the reading
practice of many health practitioners. (3) The use of contrast
agents to improve the contrast resolution. While most optical
imaging only requires device technology to produce images, the
concurrent use of contrast enhancing agents may improve the
image qualities, particularly for laser induced fluorescence
imaging systems. The advancement of imaging contrast agents
has been historically outpaced by that of imaging devices and a
number of such imaging drugs have been off-label used with
imaging devices in medical practice.
Conclusion: In this presentation, we review the optical imaging
literature, identify its cleared clinical beneficial effects,
summarize the regulatory status, and analyze the regulatory
challenges that might be important for bridging the academic
development and marketing delivery of optical imaging devices.
#21
American Society for Laser Medicine and Surgery Abstracts 7
IN VIVO IMAGING OF KIDNEY
MICROVASCULATURE USING DOPPLER
OPTICAL COHERENCE TOMOGRAPHY
Jerry Wierwille, Jeremiah Wierwille,
Peter Andrews, Maristela Onozato, Yu Chen
College Park, MD; Washington, DC
Background: Doppler optical coherence tomography (DOCT) is
an extension of OCT that detects phase shifts in backscattered
light resulting from contact with moving scatterers. DOCT
enables detection of blood flow in vivo. DOCT is potentially very
useful in a clinical setting having high resolution ( 10–20 mm)
and the ability to be miniaturized into handheld devices or
endoscopic probes. While the imaging depth of DOCT is limited to
2 mm, we have shown that this penetration is sufficient for
imaging of the kidney hemodynamics in the superficial cortical
region.
Study: To image the kidney in vivo, Munich-Wistar rats (n ¼ 3)
were anesthetized and the kidney exposed beneath a swept-source
microscope (?0 ¼ 1,300 nm). Many glomeruli were easily identified
by scanning the surface of the kidney, capturing 3D DOCT
volumetric data sets at each location. The Doppler signal at each
en face plane was integrated over its respective area as a measure
of glomerular blood flow. Flow histograms were also extracted for
each distinct Doppler signal that could be isolated. To test changes
in physiological blood flow, mannitol and angiotensin II were
administered intravenously to induce and increases and decreases
in glomerular flow, respectively.
Results: Individual blood flow patterns were readily visible by
DOCT. 3D reconstructions of these images provided an enhanced
visualization of the blood flow throughout the capillary network in
the glomeruli. An increase in glomerular blood flow was observed
following injection of mannitol and a decrease was observed
following injection of angiotensin II. These observations were
confirmed to be significant after calculating and comparing the
glomerular blood flow affected by each drug.
Conclusion: DOCT is able to determine different directional flow
patterns in glomerular capillaries and to detect changes in these
patterns blood flow in real-time. We conclude that DOCT may be
helpful in monitoring the status of glomerular blood flow in the
clinical setting.
#22
MULTIMODAL OPTICAL IMAGING FOR
DETECTING BREAST CANCER
Rakesh Patel, Ashraf Khan, Robert Quinlan,
Anna Yaroslavsky
University of Massachusetts Lowell, Lowell, MA;
UMass Memorial Healthcare, Inc., Worcester, MA
Background: Re-excision is required in up to 60% cases of breast
conserving surgeries, as most are performed without
intraoperative margin control. Real-time mapping of cancer
margins during surgeries would be indispensible. The long-term
goal of this research is to improve the quality of life and survival in
patients with breast cancer. We seek to improve the surgeon’s
ability to distinguish breast tissue from tumor over wide-fields
and on microscopic scale at the margin.
Study: At the initial stage of the project, we are testing the
combination of wide-field and high-resolution multimodal
imaging, that is, polarization, reflectance and fluorescence
imaging for detecting breast cancer. Fresh excess breast cancer
tissue is collected from surgeries and subsequently imaged and
processed for H&E histopathology. Then the histological slides are
digitized and compared side-by-side with the multimodal optical
images.
Results: We have acquired high resolution confocal and
polarization images of breast cancer tissue and correlated these
images to the digitized corresponding H&E histopathology. We