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Three-dimensional echocardiography paves the way toward virtual reality

ULTRASOUND IN MEDICINE AND BIOLOGY 2000年第7期26卷 1065-1074页

作者： Bruining, N Lancée, C Roelandt, JRTC Bom, N Erasmus Univ Erasmus Med Ctr Rotterdam Dept Cardiol Thoraxctr NL-3015 GD Rotterdam Netherlands Interuniv Cardiol Inst Rotterdam Netherlands

The heart is a three-dimensional (3-D) object and, with the help of 3-D echocardiography (3-DE), it can be shown in a realistic fashion. This capability decreases variability in the interpretation of complex pathology among investigators, Therefore, it is likely that the method will become the standard echocardiography examination in the future. The availability of volumetric data sets allows retrieval of an infinite number of cardiac cross-sections. This results in more accurate and reproducible measurements of valve areas, cardiac mass and cavity volumes by obviating geometric assumptions. Typical 3-DE parameters, such as ejection fraction, flow jets, myocardial perfusion and LV wall curvature, may become important diagnostic parameters based on 3-DE. However, the freedom of an infinite number of cross-sections of the heart can result in an often-encountered problem of being "lost in space" when an observer works on a 3-DE image data set. Virtual reality computing techniques in the form of a virtual heart model can be useful by providing spatial "cardiac" information, With the recent introduction of relatively low cost portable echo devices, it is envisaged that use of diagnostic ultrasound (US) will be further boosted. This, in turn, will require further teaching facilities. Coupling of a cardiac model with true 3-D echo data in a virtual reality setting may be the answer. (C) 2000 World Federation for Ultrasound in Medicine & Biology.

关键词： echocardiography three-dimensional ultrasound computer-assisted image processing magnetic position sensor freehand acquisition virtual reality

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Advanced very low bit rate video coding using preferential pattern selection algorithms

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JOURNAL OF RESEARCH AND PRACTICE IN INFORMATION TECHNOLOGY 2005年第3期37卷 285-295页

作者： Paul, M Murshed, M Monash Univ Gippsland Sch Comp & IT Churchill Vic Australia

In the context of very low bit-rate video coding, pre-defined fixed pattern representations of moving regions in blocked-based motion estimation and compensation has become increasingly attractive over H.264 as the former represents an MB by a smaller size moving region covered by the best available pattern that approximates the shape of the region more closely and hence, requiring no extra motion vector, which is not the case with the latter. But fixed set patterns sometimes fail to code efficiently for all video sequences. In this paper a novel idea of selecting a subset of best-matched patterns through preferential selection technique is developed by presenting two algorithms, Variable Pattern Selection (VPS) and Extended VPS (EVPS) for an initial pattern codebook size of 32 using a new parametric macroblock classification definition and a new similarity metric. The complexity analysis confirmed that EVPS guaranteed to be nearly six times faster than VPS, with the peak performance providing an improvement factor of nine times. The overall performance of EVPS is identical to VPS for certain parameters but on average, 0.2dB and 0.8dB better than the contemporary algorithm using fixed set patterns and Advanced Video coding standard (H.264) respectively, for the same. number of bits per frame. ACM Classification: 1.4.2 (Computing methodologies - image processing and computer vision - compression (coding)).

关键词： Computing methodologies image processing and computer vision Compression (coding) Video coding peak performance algorithms Computing Methodologies improvement factor motion vector Complexity Analysis computer-assisted image processing

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In vivo coronary artery plaque assessment with computed tomography angiography: is there an impact of iterative reconstruction on plaque volume and attenuation metrics?

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ACTA RADIOLOGICA 2017年第6期58卷 660-669页

作者： Chen, Zhongyi Boldeanu, Irina Nepveu, Simon Durand, Madeleine Chin, Anne S. Kauffmann, Claude Mansour, Samer Soulez, Gilles Tremblay, Cecile Chartrand-Lefebvre, Carl Univ Montreal Med Ctr CHUM Radiol Dept Montreal PQ Canada Univ Montreal Med Ctr CHUM Med Dept Montreal PQ Canada

Background: Coronary computed tomography angiography (CTA) allows the evaluation of coronary plaque volume and low attenuation (lipid-rich) component, for plaque vulnerability assessment. Purpose: To determine the effect of iterative reconstruction (IR) on coronary plaque volume and composition. Material and Methods: Consecutive patients without coronary artery disease were prospectively enrolled for 256-slice CT. images were reconstructed with both filtered back projection (FBP) and a hybrid IR algorithm (iDose(4), Philips) levels 1, 3, 5, and 7. Coronary plaques were assessed according to predefined Hounsfield unit (HU) attenuation intervals, for total plaque and HU-interval volumes. Results: Fifty-three patients (mean age, 53.6 years) were included. Noise was significantly decreased and signal-to-noise ratio (SNR) / contrast-to-noise (CNR) were both significantly improved at all IR levels in comparison to FBP. Plaque characterization was performed in 41 patients for a total of 125 plaques. Total plaque volume ranged from 104.4 +/- 120.7 to 107.4 +/- 128.9 mm(3) and low attenuation plaque component from 40.5 +/- 54.7 to 43.5 +/- 58.9 mm(3), with no statistically significant differences between all IR levels and FBP (P = 0.786 and P >= 0.078, respectively). Conclusion: IR improved image quality. Total and low attenuation plaque volumes were similar using either IR or FBP.

关键词： Algorithms coronary artery disease atherosclerotic plaque X-ray computed tomography (CT) computer-assisted image processing image reconstruction

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Automated and representative fascicle selection for computer-assisted morphometry of myelinated nerve fibres in peripheral nerves

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computerS IN BIOLOGY AND MEDICINE 2002年第1期32卷 1-11页

作者： Lindemuth, R Mink, D Ernzerhof, C Schimrigk, K Univ Saarland Fak Med Neurol Klin D-66421 Homburg Germany Univ Saarland Fak Med Frauenklin D-66421 Homburg Germany

We describe an algorithm that permits representative fascicle selection for sample acquisition from the entire cross-section of a nerve. We calculate the number of fascicles necessary for the acquisition of a given sample volume of nerve fibres from the image magnification, determine the scheme of intrafascicular sampling, and measure the (estimated) nerve fibre density. We start by storing the positions of all fascicles as coordinates of the microscope motor stage. We then recruit the needed fascicles from the file by calling them up out of the storage order with a constant interval, using the quotient of the total number of fascicles and the number of fascicles necessary to obtain the sample size for this purpose. The results obtained on the analysis of 40 specimens of sural and tibial nerves by means of the image analysis system IBAS are reported. (C) 2002 Elsevier Science Ltd. All rights reserved.

关键词： automated morphometry computer-assisted image processing fibre distribution fibre sampling fascicle sampling myelinated fibre peripheral nerve

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New methods for arterial diameter measurement from B-mode images

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ULTRASOUND IN MEDICINE AND BIOLOGY 1996年第1期22卷 25-34页

作者： Stadler, RW Karl, WC Lees, RS HARVARD UNIV MITDIV HLTH SCI & TECHNOLCAMBRIDGEMA BOSTON UNIV DEPT ELECT COMP & SYST ENGNBOSTONMA 02215

Arterial diameter is an important parameter of vascular physiology in vivo, Noninvasive measurements of arterial diameter can be used in the assessment of endothelium-dependent vasoreactivity (EDV) and arterial compliance, Measurements of EDV may serve for assessment of early atherosclerosis, The potential value of EDV measurements with specificity for individual subjects is a strong motivation for improvements in the ultrasonic measurement of arterial diameter, This article presents and evaluates new methods for the measurement and tracking of arterial diameter from B-mode images, B-mode images acquired in planes longitudinal to the vessel and in planes rotated slightly off of the vessel axis (''skew'') are considered, The cross-sections of arteries in these planes are modeled as parabola pairs or as ellipses, For the brachial artery, the variance of caliper-based diameter estimates (0.0139 mm(2)) is twice as large as that of elliptical-model-based diameter estimates (0.0072 mm(2)) and five times as large as parabolic-model-based diameter estimates (0.0027 mm(2)), Diameter estimates from the skew and longitudinal planes perform equivalently in limited-motion quantitative comparisons, However, diameter estimates from skew planes are less sensitive to translational motions of the artery, Also, translational motions are unambiguously represented in the skew image, thus facilitating compensatory motions of the transducer, The methods described here are relatively simple to implement and may provide adequate resolution for noninvasive assessment of EDV with individual specificity.

关键词： ultrasound computer-assisted image processing dilation atherosclerosis endothelial-derived relaxing factor arterial compliance

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ULTRASONIC 3-DIMENSIONAL RECONSTRUCTION - IN-VITRO AND IN-VIVO VOLUME AND AREA MEASUREMENT

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ULTRASOUND IN MEDICINE AND BIOLOGY 1994年第8期20卷 719-729页

作者： HODGES, TC DETMER, PR BURNS, DH BEACH, KW STRANDNESS, DE UNIV WASHINGTON MED CTRINST AFFILIATDEPT SURGVASC SURG SECTSEATTLEWA 98195

This study validates the use of an ultrasound three-dimensional reconstruction system to measure phantom and blood conduit geometry. Independently determined uniform and stenotic phantom dimensions are compared with reconstruction-based measurements. Lower extremity saphenous vein bypass graft reconstructions were performed to demonstrate clinical application. Uniform phantom independent and reconstructed volume correlation was high (r = 0.989), the average volume difference was 4.68 mm(3) and the average area difference was 0.4 mm(2). An in vitro 28% diameter reduction was detected. Stenotic bypass graft segment volume was 795 mm(3);following successful angioplasty the volume increased to 1419 mm(3). Advantages of this technique are its accuracy, the luminal information it provides and the absence of mechanical arm or acoustic transmitter limitations. We are exploring the possibility that measurement of luminal change over time may allow stenosis detection prior to hemodynamic disturbance, in an ongoing clinical saphenous vein bypass graft surveillance study.

关键词： computer-assisted image processing ULTRASONOGRAPHY HUMAN IN VITRO VASCULAR PATENCY

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Can color inhomogeneity of bruises be used to establish their age?

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JOURNAL OF BIOPHOTONICS 2011年第10期4卷 759-767页

作者： Stam, Barbara van Gemert, Martin J. C. van Leeuwen, Ton G. Teeuw, Arianne H. van der Wal, Allard C. Aalders, Maurice C. G. Univ Amsterdam Acad Med Ctr Dept Biomed Engn & Phys NL-1105 AZ Amsterdam Netherlands Univ Twente MIRA Inst Biomed Technol & Tech Med Biomed Opt Grp NL-7500 AE Enschede Netherlands Univ Twente Fac Sci & Technol NL-7500 AE Enschede Netherlands Univ Amsterdam Acad Med Ctr Child Protect Team NL-1105 AZ Amsterdam Netherlands Univ Amsterdam Acad Med Ctr Dept Pediat NL-1105 AZ Amsterdam Netherlands Univ Amsterdam Acad Med Ctr Dept Pathol NL-1105 AZ Amsterdam Netherlands

Bruises become spatially inhomogeneous during the healing process;a smaller red-blue core area, caused by hemoglobin, is surrounded by a larger yellow area, caused by bilirubin, which is enzymatically formed from hemoglobin. These two areas develop at different rates and hence carry information about the age of the bruise. We present a proof of principle demonstration that the age of bruises can be determined via an inverse procedure using a mathematical model and daily measurements of these two areas using a hyperspectral imaging system. The inaccuracy found is 2.3% for fresh bruises and 3 to 24% for bruises up to 3 days old. In conclusion, color inhomogeneity of bruises can be used to determine their age. We expect that future age determination of bruises by the inverse procedure described here, possibly also including the distribution of concentrations in the areas will open up a new phase in clinical bruise classification. [GRAPHICS] Measured and simulated hemoglobin and bilirubin areas over time.

关键词： contusion computer-assisted image processing near-infrared spectroscopy diagnostic imaging computer simulation

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Reliability of tarsal bone segmentation and its contribution to MR kinematic analysis methods

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computerIZED MEDICAL IMAGING AND GRAPHICS 2007年第7期31卷 523-530页

作者： Wolf, P. Lueehinger, R. Stacoff, A. Boesiger, P. Stuessi, E. Swiss Fed Inst Technol ETH Honggerberg HCI E451 Inst Biomech CH-8093 Zurich Switzerland Univ Zurich ETH Zurich Inst Biomed Engn CH-8092 Zurich Switzerland

The Purpose of this study was to determine the reliability of tarsal bone segmentation based on magnetic resonance (MR) imaging using commercially available software. All tarsal bones of five subjects were segmented five times each by two operators. Volumes and second moments of volume were calculated and used to determine the intra- as well as interoperator reproducibility. The results show that these morphological parameters had excellent interclass correlation coefficients (> 0.997) indicating that the presented tarsal bone segmentation is a reliable procedure and that operators are in fact interchangeable. The consequences on differences in MR kinematic analysis methods of segmentation due to repetition were also determined. It became evident that one analysis method - fitting surface point clouds - was considerable less affected by repeated segmentation (cuboid: up to 0.2 degrees, other tarsal bones Lip to OX) compared to a method using principal axes (cuboid up to 6.7 degrees, other tarsal bones up to 0.8 degrees). Thus, the former method is recommended for investigations of tarsal bone kinematics by MR imaging. (c) 2007 Elsevier Ltd. All rights reserved.

关键词： tarsus computer-assisted image processing reliability methods of MR kinematic analyses

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Automatic segmentation of hepatocellular carcinoma on dynamic contrast-enhanced MRI based on deep learning

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PHYSICS IN MEDICINE AND BIOLOGY 2024年第6期69卷 065008-065008页

作者： Luo, Xiao Li, Peiwen Chen, Hongyi Zhou, Kun Piao, Sirong Yang, Liqin Hu, Bin Geng, Daoying Fudan Univ Shanghai Peoples R China Fudan Univ Shanghai Peoples R China Chinese Acad Med Sci & Peking Union Med Coll Chinese Acad Med Sci & Peking Union MedicalCollege Dept Radiol Beijing Peoples R China Shanghai Engn Res Ctr Intelligent Imaging Crit Bra Shanghai Peoples R China Fudan Univ Inst Funct & Mol Med Imaging Shanghai Peoples R China

Objective. Precise hepatocellular carcinoma (HCC) detection is crucial for clinical management. While studies focus on computed tomography-based automatic algorithms, there is a rareness of research on automatic detection based on dynamic contrast enhanced (DCE) magnetic resonance imaging. This study is to develop an automatic detection and segmentation deep learning model for HCC using DCE. Approach: DCE images acquired from 2016 to 2021 were retrospectively collected. Then, 382 patients (301 male;81 female) with 466 lesions pathologically confirmed were included and divided into an 80% training-validation set and a 20% independent test set. For external validation, 51 patients (42 male;9 female) in another hospital from 2018 to 2021 were included. The U-net architecture was modified to accommodate multi-phasic DCE input. The model was trained with the training-validation set using five-fold cross-validation, and furtherly evaluated with the independent test set using comprehensive metrics for segmentation and detection performance. The proposed automatic segmentation model consisted of five main steps: phase registration, automatic liver region extraction using a pre-trained model, automatic HCC lesion segmentation using the multi-phasic deep learning model, ensemble of five-fold predictions, and post-processing using connected component analysis to enhance the performance to refine predictions and eliminate false positives. Main results. The proposed model achieved a mean dice similarity coefficient (DSC) of 0.81 +/- 0.11, a sensitivity of 94.41 +/- 15.50%, a precision of 94.19 +/- 17.32%, and 0.14 +/- 0.48 false positive lesions per patient in the independent test set. The model detected 88% (80/91) HCC lesions in the condition of DSC > 0.5, and the DSC per tumor was 0.80 +/- 0.13. In the external set, the model detected 92% (58/62) lesions with 0.12 +/- 0.33 false positives per patient, and the DSC per tumor was 0.75 +/- 0.10. Significance. This study developed

关键词： hepatocellular carcinoma deep learning computer-assisted image processing

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Methodological considerations in quantification of oncological FDG PET studies

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EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING 2010年第7期37卷 1408-1425页

作者： Vriens, Dennis Visser, Eric P. de Geus-Oei, Lioe-Fee Oyen, Wim J. G. Radboud Univ Nijmegen Med Ctr Dept Nucl Med NL-6500 HB Nijmegen Netherlands

This review aims to provide insight into the factors that influence quantification of glucose metabolism by FDG PET images in oncology as well as their influence on repeated measures studies (i.e. treatment response assessment), offering improved understanding both for clinical practice and research. Structural PubMed searches have been performed for the many factors affecting quantification of glucose metabolism by FDG PET. Review articles and references lists have been used to supplement the search findings. Biological factors such as fasting blood glucose level, FDG uptake period, FDG distribution and clearance, patient motion (breathing) and patient discomfort (stress) all influence quantification. Acquisition parameters should be adjusted to maximize the signal to noise ratio without exposing the patient to a higher than strictly necessary radiation dose. This is especially challenging in pharmacokinetic analysis, where the temporal resolution is of significant importance. The literature is reviewed on the influence of attenuation correction on parameters for glucose metabolism, the effect of motion, metal artefacts and contrast agents on quantification of CT attenuation-corrected images. Reconstruction settings (analytical versus iterative reconstruction, post-reconstruction filtering and image matrix size) all potentially influence quantification due to artefacts, noise levels and lesion size dependency. Many region of interest definitions are available, but increased complexity does not necessarily result in improved performance. Different methods for the quantification of the tissue of interest can introduce systematic and random inaccuracy. This review provides an up-to-date overview of the many factors that influence quantification of glucose metabolism by FDG PET.

关键词： F-18-Fluorodeoxyglucose Positron emission tomography Pharmacokinetics computer-assisted image processing Reference standards

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