Publications by authors named "Vivian W Hou"

3 Publications

  • Page 1 of 1

Intact and Isolated Human Cadaveric Coronary Artery Perfusion Models to Facilitate Research and Education Regarding Coronary Anatomy and Pathology.

J Invasive Cardiol 2019 Sep 15;31(9):272-277. Epub 2019 Jun 15.

University of Washington, 1959 NE Pacific Street, Box 356422, Seattle, WA 98195 USA.

Cadaveric tissue-perfusion models are well established in the fields of structural heart and peripheral vascular disease; however, less consideration has been given toward coronary artery disease despite comparable prevalence and morbidity. Two tissue-perfusion models were developed to address this need. The first, an intact heart model, allows simulation of percutaneous coronary interventional procedures. The second focuses upon isolated arteries, allowing quantification of simulated procedures. Both models were applied for clinical training and for investigations into medical device behavior. The manner of preparation facilitates access to clinically relevant disease, thus providing a platform to further research on coronary artery disease.
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September 2019

Target-to-background enhancement in multispectral endoscopy with background autofluorescence mitigation for quantitative molecular imaging.

J Biomed Opt 2014 ;19(7):76014

University of Washington, Department of Mechanical Engineering, Seattle, Washington 98195, United States.

Fluorescence molecular imaging with exogenous probes improves specificity for the detection of diseased tissues by targeting unambiguous molecular signatures. Additionally, increased diagnostic sensitivity is expected with the application of multiple molecular probes. We developed a real-time multispectral fluorescence-reflectance scanning fiber endoscope (SFE) for wide-field molecular imaging of fluorescent dye-labeled molecular probes at nanomolar detection levels. Concurrent multichannel imaging with the wide-field SFE also allows for real-time mitigation of the background autofluorescence (AF) signal, especially when fluorescein, a U.S. Food and Drug Administration approved dye, is used as the target fluorophore. Quantitative tissue AF was measured for the ex vivo porcine esophagus and murine brain tissues across the visible and nearinfrared spectra. AF signals were then transferred to the unit of targeted fluorophore concentration to evaluate the SFE detection sensitivity for sodium fluorescein and cyanine. Next, we demonstrated a real-time AF mitigation algorithm on a tissue phantom, which featured molecular probe targeted cells of high-grade dysplasia on a substrate containing AF species. The target-to-background ratio was enhanced by more than one order of magnitude when applying the real-time AF mitigation algorithm. Furthermore, a quantitative estimate of the fluorescein photodegradation (photobleaching) rate was evaluated and shown to be insignificant under the illumination conditions of SFE. In summary, the multichannel laser-based flexible SFE has demonstrated the capability to provide sufficient detection sensitivity, image contrast, and quantitative target intensity information for detecting small precancerous lesions in vivo.
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February 2015

Mapping surgical fields by moving a laser-scanning multimodal scope attached to a robot arm.

Proc SPIE Int Soc Opt Eng 2014 Feb 12;9036. Epub 2014 Mar 12.

Human Photonics Lab, Dept. of Mechanical Engineering, Univ. of Washington, Seattle, WA 98195.

Endoscopic visualization in brain tumor removal is challenging because tumor tissue is often visually indistinguishable from healthy tissue. Fluorescence imaging can improve tumor delineation, though this impairs reflectance-based visualization of gross anatomical features. To accurately navigate and resect tumors, we created an ultrathin/flexible, scanning fiber endoscope (SFE) that acquires reflectance and fluorescence wide-field images at high-resolution. Furthermore, our miniature imaging system is affixed to a robotic arm providing programmable motion of SFE, from which we generate multimodal surface maps of the surgical field. To test this system, synthetic phantoms of debulked tumor from brain are fabricated having spots of fluorescence representing residual tumor. Three-dimension (3D) surface maps of this surgical field are produced by moving the SFE over the phantom during concurrent reflectance and fluorescence imaging (30Hz video). SIFT-based feature matching between reflectance images is implemented to select a subset of key frames, which are reconstructed in 3D by bundle adjustment. The resultant reconstruction yields a multimodal 3D map of the tumor region that can improve visualization and robotic path planning. Efficiency of creating these 3D maps is important as they are generated multiple times during tumor margin clean-up. By using pre-programmed motions of the robot arm holding the SFE, the computer vision algorithms are optimized for efficiency by reducing search times. Preliminary results indicate that the time for creating these multimodal maps of the surgical field can be reduced to one third by using known trajectories of the surgical robot moving the image-guided tool.
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February 2014