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correction of rotational distortion for catheter-based en face OCT and OCT angiography

OPTICS LETTERS 2014年第20期39卷 5973-5976页

作者： Ahsen, Osman O. Lee, Hsiang-Chieh Giacomelli, Michael G. Wang, Zhao Liang, Kaicheng Tsai, Tsung-Han Potsaid, Benjamin Mashimo, Hiroshi Fujimoto, James G. MIT Dept Elect Engn & Comp Sci Cambridge MA 02139 USA MIT Elect Res Lab Cambridge MA 02139 USA Thorlabs Inc Adv Imaging Grp Newton NJ 07860 USA Vet Affairs Boston Healthcare Syst Boston MA 02130 USA Harvard Univ Sch Med Boston MA 02115 USA

We demonstrate a computationally efficient method for correcting the nonuniform rotational distortion (NURD) in catheter-based imaging systems to improve endoscopic en face optical coherence tomography (OCT) and OCT angiography. The method performs nonrigid registration using fiducial markers on the catheter to correct rotational speed variations. algorithm performance is investigated with an ultrahigh-speed endoscopic OCT system and micromotor catheter. Scan nonuniformity is quantitatively characterized, and artifacts from rotational speed variations are significantly reduced. Furthermore, we present endoscopic en face OCT and OCT angiography images of human gastrointestinal tract in vivo to demonstrate the image quality improvement using the correction algorithm. (C) 2014 Optical Society of America

关键词： Quality Improvement Fiducial Markers correction algorithm Angiography Catheters Gastrointestinal Tract optical coherence tomography

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Rules for the correction with Additional Insulin in the Case of Elevated Blood Sugar in Patients with Type 1-Diabetes

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DIABETOLOGIE UND STOFFWECHSEL 2009年第2期4卷 108-117页

作者： Schneider, S. El-Ouaghlidi, A. Haertel, I. Nauck, M. A. Diabet Zentrum Bad Lauterberg D-37431 Bad Lauterberg im Harz Germany Diabet Klin Bad Nauheim Bad Nauheim Germany

Introduction/Aim: There are experiences and recommendations for the correction of acute blood sugar elevations and for deriving correction algorithms, but only few scientific analyses. It was the aim of the present analysis to determine which correction thresholds (blood sugar value, above which a correction should be started) and correction intervals (blood sugar range, by which blood sugar is expected to be lowered with 1 additional unit of insulin) can be recommended for patients with type I diabetes. Patients/Methods: For 128 consecutive patients with type 1 diabetes treated with intensified conventional insulin regimens (51women, 77men, age 47 +/- 15y. [mean +/- SD], diabetes duration 23 +/- 14y., HbA(1c) 8.0 +/- 1.5%, BMI 24.8 +/- 4.4kg/m(2), basal insulin: NPH n = 51, NPH/Semilente n = 9, insulin glargine n = 68, insulin dose 43.1 +/- 15.01. U./d) insulin dose and correction plans including a correction algorithm were optimized during a inpatient treatment. In addition, the consequences of adding insulin for the purpose of correction were assessed by glucose measurements 4-6h later (both self monitoring and laboratory determinations). Results: The correction threshold was 144 12 (range: 121-180)mg/dl in the morning, the correction interval was 43 +/- 13 (18-100)mg/dl per I.U. This leads to a calculated blood sugar goal of (correction threshold minus 1/2 correction interval) 122 +/- 10 (96-162)mg/dl. There was a significant correlation of correction threshold and correction interval (r(2)=0.292, p<0.0001), and between daily insulin dose and correction interval (r(2)=0.219, p<0.0001). The correction interval predicted by the rule of thumb "1500[mg.I.U..dl(-1).d(-1)]/insulin dose [I.U./d]" significantly correlated to the respective value found by clinical experience (r(2)=0.276, p<0.0001). However, the estimated values were lower. When using the correction algorithm, this led to a reduction from average preprandial blood sugar values of 197 +/- 33 mg/dl (6:45a.m

关键词： insulin therapy type 1 diabetes insulin for correction correction algorithm glycaemic variation

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correction for Effect of Cold Storage on Immature Platelet Fraction

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JOURNAL OF CLINICAL LABORATORY ANALYSIS 2010年第6期24卷 431-433页

作者： Osei-Bimpong, Andrew Saleh, Mohammad Sola-Visner, Martha Widness, John Veng-Pedersen, Peter Univ Iowa Coll Pharm Iowa City IA 52242 USA Univ Iowa Coll Med Dept Pediat Iowa City IA 52242 USA Childrens Hosp Boston Div Newborn Med Boston MA USA

It is common practice to store samples and measure the immature platelet fraction (IPF) only when the initial standard complete blood count and the blood smear indicate thrombocytopenia. However, the cold storage introduces an inherent error in the %IPF. A falsely elevated %IPF carries the risk of potentially misleading the clinicians' interpretation of the thrombopoietic activity, thus hindering the clinical utility of this parameter. To address this issue, we determined the IPF% in individual blood samples from 29 adults at 0, 4, 8, 10, 12, 21, and 24 hr after the blood draw. This study demonstrated that the effect of 4 degrees C storage is linear over a 24 hr period and independent of the initial IPF%. These observations have enabled the development of a proposed algorithm for a corrected IPP%, which is equal to the uncorrected IPF% minus 1.34 times the length of time in hours of storage at 4 degrees C. The proposed correction algorithm extends the utility of this clinically important laboratory parameter. However, care should be taken not to extrapolate the algorithm significantly beyond 24 hr storage, because the experimental data only covered this range. J. Clin. Lab. Anal. 24:431-433, 2010. (C) 2010 Wiley-Liss, Inc.

关键词： storage correction IPF thrombocytopenia haematology analysis thrombopietic activity correction algorithm

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Out-of-field stray light correction in optical instruments: the case of Metop-3MI

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JOURNAL OF APPLIED REMOTE SENSING 2024年第1期18卷

作者： Clermont, Lionel Michel, Celine Univ Liege STAR Inst Ctr Spatial Liege Liege Belgium

. In high performance optical instruments, post-processing methods are employed to reduce the stray light (SL) level below what can be achieved by design. Often, algorithms are limited to SL coming from sources located inside the field of view (FOV) of the instrument;however, SL could also come from sources located outside the FOV. We describe a method for correcting out-of-field SL, in particular for the case of the Earth observation instrument Metop-3MI. The proposed approach is a variant of the in-field (IF) method developed previously. We estimate the out-of-field SL by a linear combination of the SL kernels modulated by the input scene radiance. The correction is computed for fields on a regularly spaced polar grid, providing reasonable variations of the solid angle sustained around individual fields. Compared with the case of IF SL correction, a difficulty is that the out-of-field input radiance is unknown. We implement a mirroring technique, which is shown to be effective in most situations. This method will be used to correct the in-flight data of Metop-3MI, hence providing an SL level sufficiently low to fulfill the mission requirement.

关键词： stray light out-of-field Earth observation correction algorithm

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Improved topographic correction for satellite imagery

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IEICE TRANSACTIONS ON INFORMATION AND SYSTEMS 2001年第12期E84D卷 1820-1827页

作者： Chen, F Muramoto, K Kubo, M Kanazawa Univ Grad Sch Nat Sci & Technol Div Mat & Informat Sci Kanazawa Ishikawa 9208667 Japan

An improved algorithm is developed for correcting the topographic impact on satellite imagery, First, we analyze the topography induced distortion un satellite image. It is shown that the variation of aspect can cause the obvious different distortions in the remotely sensed image, and also effect the image illumination significantly. Because the illumination is the basis for topographic correction algorithms, we consider its variation in different smi-facing aspects in calculation a correction parameter and take it as a key element in the modified correction algorithm. Then, we apply the modified correction method on the actual Landsat Thematic Mapper satellite image. The topographic correction was done in different image data with different season and different solar angle. The corrected results show the effectiveness and accuracy using this approach.

关键词： satellite imagery mountainous region topographic factor correction algorithm

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APPLICATION OF A DIGITAL SIGNAL PROCESSOR FOR correction OF SPECTROPHOTOMETRIC MEASUREMENTS

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IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT 1993年第3期42卷 778-782页

作者： MORAWSKI, RZ BENSLIMA, M MILEWSKI, MS BARWICZ, A UNIV QUEBEC DEPT ENGNTROIS RIVIERES GA9 5H7QUEBECCANADA

The results of spectrophotometric measurements are subject to systematic errors of an instrumental type which may be partially corrected provided a mathematical model of the instrumental imperfections is identified. It is assumed that this model has the form of an integral, convolution-type equation of the first kind. The correction of the results of measurements, subject to random measurement errors, consists in numerically solving this equation on the basis of these results. An algorithm of correction, based on the Tikhonov method of frequency-domain regularization, has been implemented using the digital signal processor DSP56001. The results of its application are compared with those obtained by means of the PC-MATLAB software for the same synthetic data. It is shown that a considerable gain in speed of computation is attained without significant reduction of the accuracy.

关键词： Spectrophotometry random measurement correction algorithm Mathematical Model Digital signal processors Error measure digital signals signal processor PROCESSOR Systematic errors Equation

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correction of nonlinear lateral distortions of scanning probe microscopy images

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ULTRAMICROSCOPY 2014年 136卷 86-90页

作者： Schnedler, M. Weidlich, P. H. Portz, V. Weber, D. Dunin-Borkowski, R. E. Ebert, Ph Forschungszentrum Julich Peter Grunberg Inst D-52425 Julich Germany

A methodology for the correction of scanning probe microscopy image distortions is demonstrated, It is based on the determination of displacement vectors from the measurement of a calibration sample. By moving the pixels of the distorted scanning probe microscopy image along the displacement vectors an almost complete correction of the nonlinear, time independent distortions is achieved. (C) 2013 Elsevier B.V. All rights reserved.

关键词： Scanning probe microscopy Image distortions correction algorithm Calibration

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correction of the image distortion for laser galvanometric scanning system

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OPTICS AND LASER TECHNOLOGY 2005年第4期37卷 305-311页

作者： Xie, J Huang, SH Duan, ZC Shi, YS Wen, SF Huazhong Univ Sci & Technol Rapid Mfg Ctr Sch Mech Sci & Engn Wuhan 430074 Hubei Province Peoples R China

Laser galvanometric scanning techniques are commonly used in various image display fields, such as medical imaging, laser display and material processing. The paper gives detail analyses of the image distortion involved in the galvanometric scanning. At the same time, the paper addresses the role of the correction algorithms of the image distortion. Experiment results based on SLS machine prove the efficiency of the correction algorithms. (C) 2004 Elsevier Ltd. All rights reserved.

关键词： galvanometric scanning image distortion correction algorithm

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correction of conductance measurements in non-space-clamped structures:: 1.: Voltage-gated K⁺ channels

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BIOPHYSICAL JOURNAL 2003年第6期84卷 3508-3528页

作者： Schaefer, AT Helmstaedter, M Sakmann, B Korngreen, A Bar Ilan Univ Fac Life Sci IL-52900 Ramat Gan Israel Max Planck Inst Med Res Zellphysiol Abt D-69120 Heidelberg Germany

To understand functions of a single neuron, such as propagation and generation of synaptic or action potentials, a detailed description of the kinetics and distribution of the underlying ionic conductances is essential. In voltage-clamp experiments, incomplete space clamp distorts the recorded currents, rendering accurate analysis impossible. Here, we present a simple numerical algorithm that corrects such distortions. The method performs a stepwise approximation of the conductance density at the site of a local voltage clamp. This is achieved by estimating membrane conductances in a simulation that yields simulated clamp currents, which are then fitted to the distorted recordings from the non-space-clamped structure, relying on accurately reconstructed cell morphology and experimentally determined passive properties. The method enabled accurate retrieval of the local densities, kinetics, and density gradients of somatic and dendritic channels. Neither the addition of noise nor variation of passive parameters significantly reduced the performance of the correction algorithm. The correction method was applied to two-electrode voltage-clamp recordings of K+ currents from the apical dendrite of layer 5 neocortical pyramidal neurons. The generality and robustness of the algorithm make it a useful tool for voltage-clamp analysis of voltage-gated currents in structures of any morphology that is amenable to the voltage-clamp technique.

关键词： .Korngreen conductances voltage-clamp conductance density correction algorithm

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FACET - a "Flexible Artifact correction and Evaluation Toolbox" for concurrently recorded EEG/fMRI data

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BMC NEUROSCIENCE 2013年第1期14卷 1-21页

作者： Glaser, Johann Beisteiner, Roland Bauer, Herbert Fischmeister, Florian Ph S. Univ Vienna Fac Psychol Biol Psychol Unit A-1010 Vienna Austria Med Univ Vienna High Field MR Ctr Excellence A-1090 Vienna Austria Med Univ Vienna Dept Neurol Study Grp Clin fMRI A-1090 Vienna Austria

Background: In concurrent EEG/fMRI recordings, EEG data are impaired by the fMRI gradient artifacts which exceed the EEG signal by several orders of magnitude. While several algorithms exist to correct the EEG data, these algorithms lack the flexibility to either leave out or add new steps. The here presented open-source MATLAB toolbox FACET is a modular toolbox for the fast and flexible correction and evaluation of imaging artifacts from concurrently recorded EEG datasets. It consists of an ANALYSIS, a correction and an EVALUATION framework allowing the user to choose from different artifact correction methods with various pre- and post-processing steps to form flexible combinations. The quality of the chosen correction approach can then be evaluated and compared to different settings. Results: FACET was evaluated on a dataset provided with the FMRIB plugin for EEGLAB using two different correction approaches: Averaged Artifact Subtraction (AAS, Allen et al., NeuroImage 12(2):230-239, 2000) and the FMRI Artifact Slice Template Removal (FASTR, Niazy et al., NeuroImage 28(3):720-737, 2005). Evaluation of the obtained results were compared to the FASTR algorithm implemented in the EEGLAB plugin FMRIB. No differences were found between the FACET implementation of FASTR and the original algorithm across all gradient artifact relevant performance indices. Conclusion: The FACET toolbox not only provides facilities for all three modalities: data analysis, artifact correction as well as evaluation and documentation of the results but it also offers an easily extendable framework for development and evaluation of new approaches.

关键词： correction algorithm Template Generation Artifact correction Adaptive Noise Cancellation fMRI Acquisition

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