Surgical resection of pancreatic cancer represents the only chance of cure and long-term survival in this common disease. Unfortunately, determination of a cancer-free margin at surgery is based on one or two tiny frozen section biopsies, which is far from ideal. Not surprisingly, cancer is usually left behind and is responsible for metastatic disease. We demonstrate a method of receptor-targeted imaging using peptide ligands, lipid microbubbles, and multiphoton microscopy that could lead to a fast and accurate way of examining the entire cut surface during surgery. Using a plectin-targeted microbubble, we performed a blinded in-vitro study to demonstrate avid binding of targeted microbubbles to pancreatic cancer cells but not noncancerous cell lines. Further work should lead to a much-needed point-of-care diagnostic test for determining clean margins in oncologic surgery.
We have developed a compact dual-view endoscopic probe without field obscuration to address the need of simultaneously observing forward and backward fields of view (FOVs) in the colon. The objective is compact with the forward-view and rear-view optical paths sharing the same optical elements. The compact objective is new in that no FOV is blocked. The illumination for forward-view imaging is provided by the cylindrical light guide and backward illumination is achieved with a reflector. We have designed, prototyped, and tested the endoscope by comparing it to a standard clinical colonoscope. We will discuss the system concept, objective design, fabrication of the freeform lens, and test results.
Colonoscopy is the preferred procedure for the detection, biopsy and removal of neoplastic lesions of the colon. It is
estimated that about 14 million colonoscopies will have been performed in the US in 2014. The number of patients
undergoing colonoscopy worldwide is also increasing, however, the procedure is far from perfect and recent studies have
questioned its impact on colon cancer prevention, particularly in the proximal colon. Whereas standard endoscopes are
designed to provide a view of a cylindrical lumen, the colon is not a simple hollow tube, but a tortuous organ with many
folds that can prevent polyps from being seen. Poor color contrast of some flat lesions also make detection more
difficult. A number of techniques have been developed to increase the surface area of the colon viewed, from
accessories that can be used with existing colonoscopes to new endoscopy systems. Methods to improve lesion contrast
are also being developed. The ideal device should not only maximize the surface of the colon viewed and improve
lesion contrast to aid detection, but should do so inexpensively and without increasing the complexity and duration of the
procedure. Healthcare reform will soon require endoscopists to report the quality of their procedures, as measured by
individual rates of adenoma detection. Therefor the need to develop new devices that improve lesion detection is
profound, but for any product to be clinically assimilated, it needs to be easy to use and affordable.
The accepted screening technique for colon cancer is white light endoscopy. While most abnormal growths (lesions) are detected by this method, a significant number are missed during colonoscopy, potentially resulting in advanced disease. Missed lesions are often flat and inconspicuous in color. A prototype ultraviolet spectral imager measuring autofluorescence (AF) and reflectance has been developed and applied in a study of 21 fresh human colon surgical specimens. Six excitation wavelengths from 280 to 440 nm and formulaic ratio imaging were utilized to increase lesion contrast and cause neoplasms to appear bright compared to normal tissue. It was found that in the subset of lesions which were most difficult to visualize in standard color photographs [low contrast lesions, (LCLs)] a ratio image (F340/F440) of AF images excited at 340 and 440 nm produced extraordinary images and was effective in about 70% of these difficult cases. Contrast may be due to increased levels of reduced nicotinamide adenine dinucleotide, increased hemoglobin absorption, and reduced signal from submucosal collagen. A second successful ratio image (R480/R555) combined two reflectance images to produce exceptional images especially in particular LCLs where F340/F440 was ineffective. The newly discovered ratio images can potentially improve detection rate in screening with a novel AF colonoscope.
The design and implementation of a compact multiple-image Fourier transform spectrometer (FTS) is presented. Based on the multiple-image FTS originally developed by A. Hirai, the presented device offers significant advantages over his original implementation. Namely, its birefringent nature results in a common-path interferometer which makes the spectrometer insensitive to vibration. Furthermore, it enables the potential of making the instrument ultra-compact, thereby improving the portability of the sensor. The theory of the birefringent FTS is provided, followed by details of its specific embodiment. A laboratory proof of concept of the sensor, designed and developed at the Optical Detection Lab, is also presented. Spectral measurements of laboratory sources are provided, including measurements of light-emitting diodes and gas-discharge lamps. These spectra are verified against a calibrated Ocean Optics USB2000 spectrometer. Other data were collected outdoors and of a rat esophagus, demonstrating the sensor’s ability to resolve spectral signatures in both standard outdoor lighting and environmental conditions, as well as in fluorescence spectroscopy.
Research requiring the murine pancreatic duct to be imaged is often challenging due to the
difficulty in selectively cannulating the pancreatic duct. We have successfully catheterized the
pancreatic duct through the common bile duct in severe combined immune deficient (SCID)
mice and imaged the pancreatic duct with gas filled lipid microbubbles that increase ultrasound
imaging sensitivity due to exquisite scattering at the gas/liquid interface. A SCID mouse was
euthanized by CO2, a midline abdominal incision made, the common bile duct cut at its
midpoint, a 2 cm, 32 gauge tip catheter was inserted about 1 mm into the duct and tied with
suture. The duodenum and pancreas were excised, removed in toto, embedded in agar and an
infusion pump was used to instill normal saline or lipid-coated microbubbles (10 million / ml)
into the duct. B-mode images before and after infusion of the duct with microbubbles imaged the
entire pancreatic duct (~ 1 cm) with high contrast. The microbubbles were cavitated by high
mechanical index (HMI) ultrasound for imaging to be repeated. Our technique of catheterization
and using lipid microbubbles as a contrast agent may provide an effective, affordable technique
of imaging the murine pancreatic duct; cavitation with HMI ultrasound would enable repeated
imaging to be performed and clustering of targeted microbubbles to receptors on ductal cells
would allow pathology to be localized accurately. This research was supported by the
Experimental Mouse Shared Service of the AZ Cancer Center (Grant Number P30CA023074,
NIH/NCI and the GI SPORE (NIH/NCI P50 CA95060).
Detection of flat neoplasia is a major challenge in colorectal cancer screening, as missed lesions can lead to the development of an unexpected 'incident' cancer prior to the subsequent endoscopy. The use of a tryptophan-related autofluorescence has been reported to be increased in murine intestinal dysplasia. The emission spectra of cells isolated from human adenocarcinoma and normal mucosa of the colon were studied and showed markedly greater emission intensity from cancerous cells compared to cells obtained from the surrounding normal mucosa. A proto-type multispectral imaging system optimized for ultraviolet macroscopic imaging of tissue was used to obtain autofluorescence images of surgical specimens of colonic neoplasms and normal mucosa after resection. Fluorescence images did not display the expected greater emission from the tumor as compared to the normal mucosa, most probably due to increased optical absorption and scattering in the tumors. Increased fluorescence intensity in neoplasms was observed however, once fluorescence images were corrected using reflectance images. Tryptophan fluorescence alone may be useful in differentiating normal and cancerous cells, while in tissues its autofluorescence image divided by green reflectance may be useful in displaying neoplasms.
In surgical treatment of pancreatic cancers, the effectiveness of the procedures largely depends on the ability to
completely and precisely remove the malignant tumors. We present the ex-vivo use of oblique incidence diffuse
reflectance spectroscopy (OIRDS) to detect and differentiate normal from neoplastic tissue. An OIRDS probe has been
constructed to provide scattering and absorption information of the pancreatic tissue. To reveal the physiological origin
of the difference in these optical signatures, the optical scattering coefficients were extracted along the pancreatic duct
with 1-cm spacing. Experimental results show that OIDRS was able to successfully determinate the tumor margins
based on the higher optical scattering on malignant tissue.