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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Three-dimensional Vision-based Nail-fold Morphological and Hemodynamic Analysis

Cai, Yu-shan 25 July 2011 (has links)
Nailfold capillary microscopy is simple, non-invasive, no injuries and easy to observe human`s microcirculation and micro blood stream directly. Due to these advantages, it plays a significant role in diseases diagnoses, treatments and prognosis. The observation of microcirculation focuses on hand, foot naildfold, conjunctival, lingual surface and lips. Nailfold microcirculation is usually performed on the ring finger. However, when measuring the speed of blood flow, difficulty to stabilize the region of interest (ROI) is often encountered. This problem becomes more serious when the magnification of microscope increases. Fixture to stabilize finger will inevitably affect the speed of blood flow under observation. The Laser Doppler blood flow velocimetry method, is expensive, only can be used in bigger capillary or to measure the average flow velocity of lager observed area, lacking of diversified morphological features of capillary, it¡¦s precision is worse than microscopy image capture method, and because of the regular contraction and relaxation of arterioles it can only measure the local blood flow velocity, cannot describe whole details of capillary blood flow velocity, some important information of microcirculation will be ignored easily. This thesis employs computer vision technique to operate displacement compensation of microscopy image sequence to stabilize observed area and extract area of capillary. Then the morphological and hemodynamic pathology features will be derived and analyzed to evaluate the status of a person¡¦s health. Not only morphological features, e.g., length, density and color, but also hemodynamic features, e.g., blood flow velocity will be measured to assess the microcirculation in end capillary. The most significant characteristic of this project is to combine three-dimensional models reconstruction technology of computer graphic to reconstruct three-dimensional capillary models and perform the three-dimensional dynamic blood flow visualization. Thus, the capillary blood flow can be adjusted and observed in the desired orientation, magnification and viewpoint. A variety of pathologically significant features of nailfold microcirculation will be extracted in the project proposed. These features can be classified into morphological and hemodynamic features. The morphological features extracted include the number, width/height, density, arteriolar limb caliber, curved segment caliber, venular limb caliber, blood color, tortuosity, and width of the curved segment of capillaries. On the other hand, hemodynamic features including velocity, direction of blood flow will also be extracted. By integrating both morphological and hemodynamic features, the status of a person¡¦s health can be evaluated by the doctor. The novel system proposed is not only easy to operate, low-cost but also has the great potential to be utilized clinically.

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