Current Issue : October - December Volume : 2014 Issue Number : 4 Articles : 6 Articles
Both respiratory and cardiac motions devastate the quality and reliability of medical imaging specifically in nuclear medicine\nimaging.Motion artifacts can be eliminated by gating the image acquisition based on the respiratory phase and cardiac contractions\nmedical imaging. Electrocardiography (ECG), 3-axis accelerometer, and respiration belt data were processed and analyzed fromten\nhealthy volunteers. Seismocardiography (SCG) is a noninvasive accelerometer-based method that measures accelerations caused\nby respiration and myocardial movements. This study was conducted to investigate the feasibility of the accelerometer-based the\nmethod in dual gating technique.The SCG provides accelerometer derived respiratory (ADR) data and accurate information about\nquiescent phases within the cardiac cycle. The correct information about the status of ventricles and atria helps us to create an\nimproved estimate for quiescent phases within a cardiac cycle. The correlation of ADR signals with the reference respiration belt\nwas investigated using Pearson correlation. High linear correlation was observed between accelerometer-based measurement and\nreference measurement methods (ECGand respiration belt). Above all, due to the simplicity of the proposedmethod, the technique\nhas high potential to be applied in dual gating in clinical cardiac positron emission tomography (PET) to obtain motion-free images\nin the future....
Active contour models are very popular in image segmentation. Different features such as mean gray and variance are selected for\ndifferent purpose. But for image with intensity inhomogeneities, there are no features for segmentation using the active contour\nmodel. The images with intensity inhomogeneities often occurred in real world especially in medical images. To deal with the\ndifficulties raised in image segmentation with intensity inhomogeneities, a new active contour model with higher-order diffusion\nmethod is proposed.With the addition of gradient and Laplace information, the active contour model can converge to the edge of\nthe image even with the intensity inhomogeneities. Because of the introduction of Laplace information, the difference scheme\nbecomes more difficult. To enhance the efficiency of the segmentation, the fast Split Bregman algorithm is designed for the\nsegmentation implementation.The performance of our method is demonstrated through numerical experiments of some medical\nimage segmentations with intensity inhomogeneities....
A novel method for characterizing and visualizing the progression of waves along the walls of the carotid artery is presented.The\nnewapproach is noninvasive and able to simultaneously capture the spatial and the temporal propagation ofwavy patterns along the\nwalls of the carotid artery in a completely automated manner. Spatiotemporal and spatiospectral 2D maps describing these patterns\n(in both the spatial and the frequency domains, resp.) were generated and analyzed by visual inspection as well as automatic feature\nextraction and classification. Three categories of cases were considered: pathological elderly, healthy elderly, and healthy young\ncases. Automatic differentiation, between cases of these three categories, was achieved with a sensitivity of 97.1% and a specificity\nof 74.5%. Two features were proposed and computed to measure the homogeneity of the spatiospectral 2D map which presents the\nspectral characteristics of the carotid artery wall�s wavymotion patternwhich are related to the physical,mechanical (e.g., elasticity),\nand physiological properties and conditions along the artery.These results are promising and confirmthe potential of the proposed\nmethod in providing useful information which can help in revealing the physiological condition of the cardiovascular system....
The intima-media thickness (IMT) of the common carotid artery (CCA) is widely used as an early indicator of cardiovascular\ndisease (CVD). Typically, the IMT grows with age and this is used as a sign of increased risk of CVD. Beyond thickness, there is\nalso clinical interest in identifying how the composition and texture of the intima-media complex (IMC) changed and how these\ntextural changes grow into atherosclerotic plaques that can cause stroke. Clearly though texture analysis of ultrasound images can\nbe greatly affected by speckle noise, our goal here is to develop effective despeckle noise methods that can recover image texture\nassociated with increased rates of atherosclerosis disease. In this study, we perform a comparative evaluation of several despeckle\nfiltering methods, on 100 ultrasound images of the CCA, based on the extracted multiscale Amplitude-Modulation Frequency-\nModulation (AM-FM) texture features and visual image quality assessment by two clinical experts. Texture features were extracted\nfrom the automatically segmented IMC for three different age groups. The despeckle filters hybrid median and the homogeneous\nmask area filter showed the best performance by improving the class separation between the three age groups and also yielded\nsignificantly improved image quality....
Objective. Sentinel node biopsy in patients with cutaneous melanoma improves staging, provides prognostic information, and leads\nto an increased survival in node-positive patients.However, frozen section analysis of the sentinel node is not reliable and definitive\nhistopathology evaluation requires days, preventing intraoperative decision-making and immediate therapy. Photoacoustic imaging\ncan evaluate intact lymph nodes, but specificity can be hampered by other absorbers such as hemoglobin. Near infrared\nmultispectral photoacoustic imaging is a new approach that has the potential to selectively detect melanin. The purpose of the\npresent study is to examine the potential ofmultispectral photoacoustic imaging to identify melanoma metastasis in human lymph\nnodes. Methods.Three metastatic and nine benign lymph nodes from eight melanoma patients were scanned ex vivo using a Vevo\nLAZR�© multispectral photoacoustic imager and were spectrally analyzed per pixel. The results were compared to histopathology\nas gold standard. Results. The nodal volume could be scanned within 20 minutes. An unmixing procedure was proposed to\nidentify melanoma metastases with multispectral photoacoustic imaging. Ultrasound overlay enabled anatomical correlation. The\npenetration depth of the photoacoustic signal was up to 2 cm. Conclusion.Multispectral three-dimensional photoacoustic imaging\nallowed for selective identification of melanoma metastases in human lymph nodes....
Nowadays manyMRI scans can give 3D volume data with different contrasts, but the observers may want to view various contrasts\nin the same 3D volume.The conventional 2D medical fusion methods can only fuse the 3D volume data layer by layer, which may\nlead to the loss of interframe correlative information. In this paper, a novel 3D medical volume fusion method based on 3D band\nlimited shearlet transform (3D BLST) is proposed. And this method is evaluated upon MRI T2? and quantitative susceptibility\nmapping data of 4 human brains. Both the perspective impression and the quality indices indicate that the proposed method has a\nbetter performance than conventional 2D wavelet, DT CWT, and 3D wavelet, DT CWT based fusion methods....
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