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Pharmacokinetic modeling of dynamic MR images using a simulated annealing based optimization

Proceedings of SPIE - The International Society for Optical Engineering 2000年 3978卷 276-283页

作者： Sawant, Amit Reece, John H. Reddick, Wilburn E. Univ of Tennessee-Memphis Memphis United States

The aim of this work was to use dynamic contrast enhanced MR image (DEMRI) data to generate `parameter images' which provide functional information about contrast agent access, in bone sarcoma. A simulated annealing based technique was applied to optimize the parameters of a pharmacokinetic model used to describe the kinetics of the tissue response during and after intravenous infusion of a paramagnetic contrast medium, Gd-DTPA. Optimization was performed on a pixel by pixel basis so as to minimize the sum of square deviations of the calculated values from the values obtained experimentally during dynamic contrast enhanced MR imaging. A cost function based on a priori information was introduced during the annealing procedure to ensure that the values obtained were within the expected ranges. The optimized parameters were used in the model to generate parameter images, which reveal functional information that is normally not visible in conventional Gd-DTPA enhanced MR images. This functional information, during and upon completion of pre-operative chemotherapy, is useful in predicting the probability of disease free survival.

关键词： Medical imaging

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Quantitative analysis for differential diagnosis of lung cancer on blood vessels connectivity using thoracic 3D CT images

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Proceedings of SPIE - The International Society for Optical Engineering 2000年 3978卷 94-101页

作者： Tanaka, Akira Tozaki, Tetsuya Kawata, Yoshiki Niki, Noboru Ohmatsu, Hironobu Kakinuma, Ryutaro Kaneko, Masahiro Eguchi, Kenji Moriyama, Noriyuki Univ of Tokushima Tokushima Japan

To diagnosis the lung cancer as to determine if it has malignant or benign nature, it is important to understand the spatial relationship among the abnormal nodule and other pulmonary organs. But the lung field has very complicated structure, so it is difficult to understand the connectivity of the pulmonary organs using Thin-section CT images. This method consists of two parts. The first is the classification of the pulmonary structure based on the anatomical information. The second is the quantitative analysis that is then applicable to differential diagnosis, such as differentiation of malignant or benign abnormal tissue.

关键词： Medical imaging

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Subband denoising technique for dynamic FDOPA-PET images

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Proceedings of SPIE - The International Society for Optical Engineering 2000年 3978卷 354-363页

作者： Lin, Kang-Ping Lin, Hong-Dun Yu, Chin-Lung Wu, Liang-Chih Liu, Ren-Shyan Chung-Yuan Univ Chung-Li Taiwan

Since the positron emission tomographic (PET) image shows the abnormal activity of brain by the different parts of the brain respond to different stimuli and the patient's response to noise, illumination, change in mental concentration, and other activity, the functional PET image data is much helpful for clinical diagnosis. However, the PET image is also a high noise image that the quality of the PET image and the diagnosis accuracy is effected by the noise. To improve the quality problem of PET image, a novel subband denoising technique is provided in this paper. The method is based on the subband transformation and the statistical features in each subbands of the PET image.

关键词： Medical imaging

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Application of a linear time invariant model in the Fourier domain to perform statistical analysis of functional magnetic resonance images

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Proceedings of SPIE - The International Society for Optical Engineering 2000年 3978卷 265-275页

作者： Rio, Daniel E. Rawlings, Robert R. Hommer, Daniel W. Natl Inst of Health Bethesda United States

A linear time invariant model is applied to functional fMRI blood flow data. This model assumes that the fMRI stochastic output sequence can be determined by a constant plus a linear filter (hemodynamic response function) of several fixed deterministic inputs and an error term, assumed stationary with zero mean and error spectrum. An on-off finger tapping experiment was performed where the subject repetitively tapped their fingers for 30 seconds and remained still for 30 seconds. Thirty three disjoint frequency bands, 3 wave numbers wide were chosen to analyze the data. At each band an F-statistical image was constructed to test (α = .05/33) whether power from the input signal induced a response in the output signal. Activation was seen at frequency .0154 Hz close to the frequency for maximum power of the input signal, .0167 Hz in the contralateral motor strip and motor cortex. In conclusion, (1) No assumptions are made about the filter. (2) Several different deterministic inputs may be applied. (3) Problems with temporal correlation are avoided by performing the statistics in the Fourier domain. (4) Testing can be performed for differences in the hemodynamic transfer function at different spatial locations under different experimental conditions.

关键词： Hemodynamics

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Separation of artery and vein in contrast enhanced MRA images

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Proceedings of SPIE - The International Society for Optical Engineering 2000年 3978卷 233-244页

作者： Lei, Tianhu Udupa, Jayaram K. Saha, Punam K. Odhner, Dewey Univ of Pennsylvania Philadelphia United States

This paper presents a near automatic process for separating vessels from background and other clutter as well as for separating arteries and veins in contrast-enhanced MR angiographic (CE-MRA) images, and an optimal method for the 3D visualization of vascular structures. The anatomic separation process utilizes fuzzy connected object delineation principles and algorithms. Its first step is the segmentation of the entire vessel structure from the background and other clutter via absolute fuzzy connectedness. Its second step is to separate artery from vein within this entire vessel structure via relative fuzzy connectedness. After `seed' points are specified inside artery and vein in the vessel-only image, the regions of the bigger aspects of artery and vein are separated in the initial iteration. Further regions are added with subsequent iterations so that the detailed aspects of artery and vein are included in later iterations. This approach has been applied to EPIX Medical Inc's CE-MRA data. 3D images/movies of vessels, arteries, and veins have been created. Shell renditions are colored differently for arteries and veins in a composite display. This approach can produce separated artery and vein images with high quality, reliability, and minimal user interaction, in a clinical setting. All case studies were performed on a Gateway Pentium PC under Linux, and the whole procedure per study was completed in a few minutes.

关键词： Angiocardiography

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Identification of atherosclerotic plaque components using cluster analysis of multispectral MR images: Comparison with histology

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Proceedings of SPIE - The International Society for Optical Engineering 2000年 3978卷 304-311页

作者： Clarke, Sharon Rutt, Brian Lucas, Alexandra Lownie, Steve Hammond, Robert Mitchell, J.Ross Robarts Research Inst London Canada

The composition of atherosclerotic lesions in the carotid arteries is believed to be an important predictor of stroke risk. Several MR contrasts may be necessary to discriminate between different plaque components, and multispectral analysis can used to integrate the information obtained from these multiple contrasts. This study presents the use of registered MR and histological images of carotid endarterectomy specimens as a tool for the quantitative assessment of maximum likelihood classification and other segmentation algorithms. Carotid endarterectomy specimens were imaged in a 1.5T GE Signa scanner. PD, T1, T2, diffusion spin echo weightings were obtained. MR images were registered with digitized images of the corresponding histology. A pathologist identified regions of collagen, calcification, cholesterol, hemorrhage on the histological images. Training and ground truth regions were selected. The accuracy of the maximum likelihood classification was assessed on a pixel by pixel basis using truth regions identified on histological images. The accuracy of multispectral analysis was calcification (73%), fibrin (68%), cholesterol (62%), fibrous plaque (53%). This technique was limited by registration inaccuracies caused by partial volume effects and histological artifacts. Despite these limitations, accuracy results were reasonable. This technique, with continued improvements, provides a framework for evaluating the accuracy of different segmentation algorithms.

关键词： Medical imaging

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Application of indicator dilution theory to time-density curves obtained from dynamic contrast images

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Proceedings of SPIE - The International Society for Optical Engineering 2000年 3978卷 457-465页

作者： Clough, Anne V. Manuel, Albert W. Haworth, Steven T. Dawson, Christopher A. Marquette Univ Milwaukee United States

Typically, indicator dilution theory is applied to time-density curves acquired from dynamic contrast images, including x-ray planar and fast CT, for determination of blood circulation parameters. The original theory developed by Zierler and now applied to image curves assumes that the time-density curves are flow-sampled, i.e. each particle of indicator is counted for a time proportional to its velocity so that particles traveling within streamlines with higher or lower flow contribute equally to the measured concentration. However, curves obtained from images are instead cross-sectionally sampled, i.e., each indicator particle is counted for a time proportional to its residence time within the ROI, (inversely proportional to its velocity), so that particles traveling within low flow streamlines contribute relatively more to the measured concentration than do particles within higher flow streamlines. We illustrate some of the potential pitfalls encountered when applying the conventional theory directly to image curves and propose a strategy for accounting for the cross-sectional error in the transit time estimate. The correction method was applied to a known simulated network system for verification and illustration of its usefulness. Finally, to illustrate its applicability, the method was implemented on experimental image curves obtained from a microfocal x-ray imaging system.

关键词： Angiography

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Volume of myocardium perfused by coronary artery branches as estimated from 3D micro-CT images of rat hearts

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Proceedings of SPIE - The International Society for Optical Engineering 2000年 3978卷 314-319页

作者： Lund, Patricia E. Naessens, Lauren C. Seaman, Catherine A. Reyes, Denise A. Ritman, Erik L. Mayo Clinic Rochester United States

Average myocardial perfusion is remarkably consistent throughout the heart wall under resting conditions and the velocity of blood flow is fairly reproducible from artery to artery. Based on these observations, and the fact that flow through an artery is the product of arterial cross-sectional area and blood flow velocity, we would expect the volume of myocardium perfused to be proportional to the cross-sectional area of the coronary artery perfusing that volume of myocardium. This relationship has been confirmed by others in pigs, dogs and humans. To test the body size-dependence of this relationship we used the hearts from rats, 3 through 25 weeks of age. The coronary arteries were infused with radiopaque microfil polymer and the hearts scanned in a micro-CT scanner. Using these 3D images we measured the volume of myocardium and the arterial cross-sectional area of the artery that perfused that volume of myocardium. The average constant of proportionality was found to be 0.15±0.08 cm3/mm2. Our data showed no statistically different estimates of the constant of proportionality in the rat hearts of different ages nor between the left and right coronary arteries. This constant is smaller than that observed in large animals and humans, but this difference is consistent with the body mass-dependence on metabolic rate.

关键词： Medical imaging

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Computer-assisted esophageal wall motion analysis from digital fluoroscopic images

Computer-assisted esophageal wall motion analysis from digit...

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Medical Imaging 2000 conference

作者： Senoo, A Shimada, M Ito, A Yagi, K Ogura, I Negishi, T Katoh, T Matsumoto, M Yoshikawa, K Tokyo Metropolitan Univ Hlth Sci Dept Radiol Technol Tokyo Japan

ISBN: (纸本)0819435953

The dynamic image recognition is applied to the robot engineering sciences. This technology (the optical flow method) was used the computer aided diagnosis of the esophageal fluoroscopy. The dynamic images were obtained by means of using digital video recorder. The motion vectors are calculated using the computer vision algorithm (the gradient based method) from these dynamic images in each pixels. The motion vectors were visualized in color images and allow images. The results showed that the motion of normal esophageal walls were mainly in the horizontal direction, whereas a large oblique direction component was observed in that of abnormal esophageal walls. The dynamic image recognition was useful in clinical study for the analysis of esophageal wall motion.

关键词： Esophagus Detection and tracking algorithms Motion analysis Calculus Optical flow Tumors Barium Fluoroscopy Diagnostics Visualization

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Imaging longitudinal cardiac strain on short-axis images using 3D-HARP

Imaging longitudinal cardiac strain on short-axis images usi...

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Medical Imaging 2000: physiology and function from multidimensional images

作者： Osman, Nael F. Sampath, Smita Prince, Jerry L. Johns Hopkins Univ Baltimore MD United States

This paper presents a new method for measuring longitudinal strain of the heart using harmonic phase magnetic resonance imaging (HARP-MRI). The heart is tagged using 1-1 SPAMM at end-diastole with tagging surfaces parallel to the imaging plane. Two image sequences are acquired for a short-axis slice with two different encodings in the direction orthogonal to the imaging plane. A method to compute a sequence of longitudinal strain estimates from this data is described.

关键词： Medical imaging

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