Zhimin Han

Biomedical Engineering

PhD Defense

Date: December 9, 2015 (Wednesday)

Time: 8:00 pm (Beijing) / 7:00 am (Atlanta)

Location: 

New 1st COE Building,Room 210 (PKU campus at Beijing) 

U.A. Whitaker Building, Mclnitre Conf. Room (GT campus at Atlanta)

Advisor:

Tianyu Xie,    PhD,    Department of Biomedical Engineering,    Peking University

May D. Wang,   PhD,     Department of Biomedical Engineering,   Georgia Institute of Technology & Emory University

Committee Members:

Peng Xi,      PhD,        Department of Biomedical Engineering,   Peking University

Changhui Li,   PhD,         Department of Biomedical Engineering,   Peking University

Hongen Liao,   PhD,         Medical School,                  Tsinghua University

Shuxiang Dong,  PhD,        Department of Materials Engineering,    Peking University

Hyperspectral Endoscopy Imaging: System Development, Clinical Evaluation, and Further Application

Hyperspectral (HS) imaging originated from remote sensing field combines spectral measurement of a pixel with 2D imaging technology. It is capable to provide a series of images containing both spectral and spatial information, and has been widely used in medical domain for diagnosis and surgery guidance. However, most researches on medical HS imaging are focused on ex-vivo biopsy or skin and oral mucosa. The study on HS imaging regarding in-vivo disease lags far behind. Especially, cancers on esophagus, stomach, and colon lead to many deaths. In-vivo HS imaging applied on digestive diseases provides opportunities for early-detection and early-therapy, which could increase survival rate significantly. In this thesis, we developed a novel flexible HS endoscope system. It is capable to acquire a series of HS images in vivo in a non-contact way among the wavelength range of 405 – 665 nm. Twenty-eight sequential narrowband interference filters are mounted in two motorized filter wheels positioned in the optical path of light source, and generates narrowband illumination. The filter wheels are driven by Geneva Mechanism, and this dispersive device is the major innovative part for this system, with authorized patents. We evaluated this system in clinic. First, we got ethics approval for clinical trials. Then, we obtained HS images regarding GI diseases inside patients’ bodies using this system. As far as we know, there is no such in-vivo image data reported in previous literature. Thus using these HS images, we built a dataset for gastrointestinal (GI) mucosa, including both normal tissues and disease tissues on different organs. Next, we analyzed some typical HS images tentatively. The method of Contrast Calculation, Dependence of Information, and Recursive Divergence are implemented to extract valuable and diagnostic information from HS images. All these results prove the effect and applicability of this new HS endoscope system, together with its potential to be used as a platform and guidance for further medical researches. To further apply these analysis results, we propose a novel endoscopy technique that could enhance the display of valuable information on images. This technique is named as Adaptive Narrow-Band Imaging (ANBI) and based on band selection of HS images of a specific disease. One case study shows that it gives higher accuracy (92.86% to 90.15%), sensitivity (97.71% to 95.14%), and specificity (89.14% to 86.29%) compared to conventional Narrow-Band Imaging (NBI).