Clustering based 3D level set method for volumetric cardiac segmentation

Sect.D Computer modeling and simulations : D-5Multi-slice CT (MSCT) provides dynamic three-dimensional (3D) volumetric data of the whole heart, and is an important medical imaging tool for diagnosis of cardiac diseases. Due to the large size of the dynamic data, manual identification, segmentation and tracking of various parts of the heart will be very labor intensive and inefficient. Alternatively, sophisticated image processing techniques, which require minimal user intervention, can be developed and employed to automate such tasks. In this work, we propose a semi-automatic clustering based 3D level set method to robustly segment the endocardium surface from cardiac MSCT images. The theory of level set defines a flexible and powerful surface which is capable of capturing the complex endocardium anatomical structure. A novel speed function for the level set method using a clustering algorithm is proposed to exploit the non-homogeneous blood pool intensity property by supporting a set of independent intensity samples. To define the intensity clusters for the blood pool region and the surrounding region, only a few lines drawn on the corresponding regions are required as user input. The segmentation result is a level set 3D surface in the whole volume space which can readily be constructed to form a spatial model. Our clustering based 3D level set method can also be used for segmenting other heart wall surfaces by performing appropriate initialization. By ex-tending to a 4D level set method, 4D (3D plus time) dynamic volumetric data could be readily processedpostprintProceedings of BME 2006 Biomedical Engineering Conference : biomedical engineering in education, research and industry, Hong Kong, 21-23 September 2006

Widely tunable wavelength exchange in anomalous-dispersion regime

We demonstrate the 10-Gb/s wavelength exchange with two pumps in the anomalous-dispersion region. Results show that performance degradation caused by Raman gain is avoided so that a nearly complete exchange can be achieved. In this letter, we also investigate the tunability of wavelength exchange for the first time to the best of our knowledge. Complete wavelength exchange is achieved with tuning range >15 nm. A bit-error rate of <10-9 is maintained with power penalties of ∼2 dB using 27-1 pseudorandom bit sequence (PRBS). © 2007 IEEE.published_or_final_versio

A comprehensive study on the dynamic range of wavelength exchange and its impact on exchanged signal performance

Effects of the incomplete signal exchange on the dynamic range performance of type II wavelength exchange (WE II, i.e. both pumps are in anomalous dispersion region) are investigated analytically and experimentally. The dynamic range here is defined as the tolerable operational range of the signal power to maintain a nearly complete WE performance. We studied the case of equal signal powers (balanced signal powers) as well as the case of unequal signal powers (imbalanced signal powers). It is demonstrated that the beating between exchanged signal and residual one and the extinction ratio degradation due to the existence of residual power at original channel is the major source of the signal quality degradation after WE II. The experimental results demonstrated dynamic range ∼17 dB with bit-error rate (BER) < 10-9 could be maintained with power penalty of <2 dB in the case of balanced signal powers. In the case of imbalanced signal powers, the dynamic range was <8 dB with the power penalty incurred of ∼2 dB in the worst case. © 2009 IEEE.published_or_final_versio

Timely thoracoscopic decortication promotes the recovery of paediatric parapneumonic empyema

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Dynamic range of wavelength exchange in highly nonlinear dispersion-shifted fiber

We investigate the signal dynamic range of wavelength exchange using 10Gb/s 231-1 PRBS. Data exchanging between two wavelengths is achieved with signal dynamic range ∼20dB. Bit-error-rate of <10-9 is maintained with power penalties of <2dB. © 2008 Optical Society of America.published_or_final_versio

Interaction Effect of Social Isolation and High Dose Corticosteroid on Neurogenesis and Emotional Behavior

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Effects of a self-management arthritis programme with an added exercise component for osteoarthritic knee : randomized controlled trial

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Performance of Wavelength Exchange in Anomalous-dispersion Region

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All-Optical NRZ-to-RZ Format Conversion based on Optical Parametric Amplifier

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