Accurate

Distribution by Scientific Domains

Kinds of Accurate

  • highly accurate
  • order accurate
  • second-order accurate
  • very accurate

  • Terms modified by Accurate

  • accurate account
  • accurate alignment
  • accurate alternative
  • accurate analysis
  • accurate approximation
  • accurate assessment
  • accurate calculation
  • accurate characterization
  • accurate classification
  • accurate comparison
  • accurate computation
  • accurate control
  • accurate correlation
  • accurate data
  • accurate definition
  • accurate depiction
  • accurate description
  • accurate design
  • accurate detection
  • accurate determination
  • accurate diagnosis
  • accurate diagnostic test
  • accurate differentiation
  • accurate estimate
  • accurate estimation
  • accurate evaluation
  • accurate forecast
  • accurate identification
  • accurate indicator
  • accurate information
  • accurate interpretation
  • accurate knowledge
  • accurate localization
  • accurate location
  • accurate manner
  • accurate mapping
  • accurate marker
  • accurate mass
  • accurate mass data
  • accurate mass measurement
  • accurate mean
  • accurate measure
  • accurate measurement
  • accurate method
  • accurate methods
  • accurate model
  • accurate modeling
  • accurate modelling
  • accurate models
  • accurate monitoring
  • accurate only
  • accurate perception
  • accurate picture
  • accurate placement
  • accurate prediction
  • accurate predictor
  • accurate preoperative diagnosis
  • accurate procedure
  • accurate prognosis
  • accurate quantification
  • accurate quantitation
  • accurate recognition
  • accurate reconstruction
  • accurate reflection
  • accurate registration
  • accurate reporting
  • accurate representation
  • accurate response
  • accurate result
  • accurate risk assessment
  • accurate scheme
  • accurate simulation
  • accurate solution
  • accurate staging
  • accurate technique
  • accurate test
  • accurate tool
  • accurate treatment
  • accurate understanding
  • accurate value
  • accurate way

  • Selected Abstracts


    Molecular diagnostics of non-small cell lung cancer using mediastinal lymph nodes sampled by endoscopic ultrasound-guided needle aspiration

    CYTOPATHOLOGY, Issue 1 2006
    M. Al-Haddad
    Non-small cell lung cancer is a common cancer with significant mortality. Accurate and early staging of this cancer has a significant impact on outcome. Endoscopic ultrasound-guided fine needle aspiration of involved mediastinal lymph nodes is critical for staging. Several molecular markers have been identified recently in association with non-small cell carcinoma of the lung that are promising to make early detection of metastatic disease more reliable. [source]


    Measurement and data analysis methods for field-scale wind erosion studies and model validation,

    EARTH SURFACE PROCESSES AND LANDFORMS, Issue 11 2003
    Ted M. Zobeck
    Abstract Accurate and reliable methods of measuring windblown sediment are needed to con,rm, validate, and improve erosion models, assess the intensity of aeolian processes and related damage, determine the source of pollutants, and for other applications. This paper outlines important principles to consider in conducting ,eld-scale wind erosion studies and proposes strategies of ,eld data collection for use in model validation and development. Detailed discussions include consideration of ,eld characteristics, sediment sampling, and meteorological stations. The ,eld shape used in ,eld-scale wind erosion research is generally a matter of preference and in many studies may not have practical signi,cance. Maintaining a clear non-erodible boundary is necessary to accurately determine erosion fetch distance. A ,eld length of about 300 m may be needed in many situations to approach transport capacity for saltation ,ux in bare agricultural ,elds. Field surface conditions affect the wind pro,le and other processes such as sediment emission, transport, and deposition and soil erodibility. Knowledge of the temporal variation in surface conditions is necessary to understand aeolian processes. Temporal soil properties that impact aeolian processes include surface roughness, dry aggregate size distribution, dry aggregate stability, and crust characteristics. Use of a portable 2 tall anemometer tower should be considered to quantify variability of friction velocity and aerodynamic roughness caused by surface conditions in ,eld-scale studies. The types of samplers used for sampling aeolian sediment will vary depending upon the type of sediment to be measured. The Big Spring Number Eight (BSNE) and Modi,ed Wilson and Cooke (MWAC) samplers appear to be the most popular for ,eld studies of saltation. Suspension ,ux may be measured with commercially available instruments after modi,cations are made to ensure isokinetic conditions at high wind speeds. Meteorological measurements should include wind speed and direction, air temperature, solar radiation, relative humidity, rain amount, soil temperature and moisture. Careful consideration of the climatic, sediment, and soil surface characteristics observed in future ,eld-scale wind erosion studies will ensure maximum use of the data collected. Copyright 2003 John Wiley & Sons, Ltd. [source]


    Emergency Department Information System Adoption in the United States

    ACADEMIC EMERGENCY MEDICINE, Issue 5 2010
    Adam B. Landman MD
    Abstract Objectives:, The American Recovery and Reinvestment Act of 2009 incentivizes adoption of health care information technology (HIT) based on support for specific standards, policies, and features. Limited data have been published on national emergency department information systems (EDIS) adoption, and to our knowledge, no prior studies have considered functionality measures. This study determined current national estimates of EDIS adoption using both single-response rates of EDIS adoption and a novel feature-based definition and also identified emergency department (ED) characteristics associated with EDIS use. Methods:, The 2006 National Hospital Ambulatory Medical Care Survey, a nationally representative sample of ED visits that also surveyed participating EDs on EDIS, was used to estimate EDIS adoption. EDIS adoption rates were calculated using two definitions: 1) single-response,response to a single survey question as to whether the EDIS was complete, partial, or none; and 2) feature-based,based on the reported features supported by the EDIS, systems were categorized as fully functional, basic, other, or none. The relationship of EDIS adoption to specific ED characteristics such as facility type and location was also examined. Results:, Using the single-response classification, 16.1% of EDs had a complete EDIS, while 30.4% had a partial EDIS, and 53.5% had none. In contrast, using a feature-based categorization, 1.7% EDs had a fully functional EDIS, 12.3% had basic, 32.1% had other, and 53.9% had none. In multivariable analysis, urban EDs were significantly more likely to have a fully functional or basic EDIS than were rural EDs. Pediatric EDs were significantly more likely than general EDs to have other EDIS. Conclusions:, Despite more optimistic single-response estimates, fewer than 2% of our nation's EDs have a fully functional EDIS. EDs in urban areas and those specializing in the care of pediatric patients are more likely to support EDIS. Accurate and consistent EDIS adoption estimates are dependent on whether there are standardized EDIS definitions and classifications of features. To realize the potential value of EDIS for improved emergency care, we need to better understand the extent and correlates of the diffusion of this technology and increase emergency medicine engagement in national HIT policy-making. Academic Emergency Medicine 2010; 17:536,544 2010 by the Society for Academic Emergency Medicine [source]


    Pyrosequencing for detection of mutations in the connexin 26 (GJB2) and mitochondrial 12S RNA (MTRNR1) genes associated with hereditary hearing loss,

    HUMAN MUTATION, Issue 4 2002
    Alessandro Ferraris
    Abstract Hereditary hearing loss (HHL) is one of the most common congenital disorders and is highly heterogeneous. Mutations in the connexin 26 (CX26) gene (GJB2) account for about 20% of all cases of childhood deafness, and approach 50% in documented recessive cases of non-syndromic hearing loss. In addition, a single mitochondrial DNA mutation, mt1555A>G, in the 12S rRNA gene (MTRNR1), is associated with familial cases of progressive deafness. Effective screening of populations for HHL necessitates rapid assessment of several of these potential mutation sites. Pyrosequencing links a DNA synthesis protocol for determining sequence to an enzyme cascade that generates light whenever pyrophosphate is released during primer strand elongation. We assessed the ability of Pyrosequencing to detect common mutations causing HHL. Detection of the most common CX26 mutations in individuals of Caucasian (35delG), Ashkenazi (167delT), and Asian (235delC, V37I) descent was confirmed by Pyrosequencing. A total of 41 different mutations in the CX26 gene and the mitochondrial mt1555A>G mutation were confirmed. Genotyping of up to six different adjacent mutations was achieved, including simultaneous detection of 35delG and 167delT. Accurate and reproducible results were achieved taking advantage of assay flexibility and experimental conditions easily optimized for a high degree of standardization and cost-effectiveness. The standardized sample preparation steps, including target amplification by PCR and preparation of single-stranded template combined with automated sequence reaction and automated genotype scoring, positions this approach as a potentially high throughput platform for SNP/mutation genotyping in a clinical laboratory setting. Hum Mutat 20:312,320, 2002. 2002 Wiley-Liss, Inc. [source]


    Refined second order semi-analytical design sensitivities

    INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 9 2002
    H. de Boer
    Abstract Accurate and efficient calculation of second order design sensitivities in a finite element context is often difficult. The semi-analytical (SA) method is efficient and easy to implement but has accuracy problems even for first order shape design sensitivities. To overcome accuracy problems a refined semi-analytical (RSA) method has been developed for first order sensitivities. The present paper investigates the application of the RSA method to second order design sensitivities. It is found that second order RSA sensitivities are significantly more accurate than their SA counterparts. Copyright 2002 John Wiley & Sons, Ltd. [source]


    Rapid detection of metastasis of gastric cancer using reverse transcription loop-mediated isothermal amplification

    INTERNATIONAL JOURNAL OF CANCER, Issue 5 2007
    Daisuke Horibe
    Abstract Tailor-made surgeries for patients with solid malignancies have been under consideration on the basis of the development of new approaches for minor metastatic foci of malignant tumors. Accurate and reliable methods to detect metastases in biopsy specimens with certain rapidity are essential for the performance of these surgeries. The aim of this study was to develop a rapid and practical method to detect metastasis in specimens from patients with gastric carcinoma with the use of reverse transcription loop-mediated isothermal amplification (RT-LAMP) reaction, a novel technique for detecting mRNA expressions of targeted sequences with high sensitivity, specificity and rapidity under isothermal conditions. RT-LAMP primers to detect cytokeratin19 (CK19) mRNA were generated and 92 lymph nodes (LNs) obtained from 9 patients with gastric cancer were tested for tumor metastases with this technique. Among 92 LNs, 15 were metastasis-positive by routine histopathological examination. RT-LAMP reaction detected CK19 expression in all of the pathologically positive LNs and in 16 of 77 negative LNs. Nested RT-PCR assay for CK19 expression was also performed on 2 of the 9 cases including 32 LNs. The agreement rate of CK19 expression detection by RT-LAMP and RT-PCR analysis was 31/32 (97%). The RT-LAMP technique showed similar sensitivity to detect metastases as nested RT-PCR assay, with a rapidity comparable to that of intraoperative histopathological examination with frozen sectioning and hematoxylin and eosin staining. This method is expected to play an essential role in the performance of tailor-made surgeries in the near future. 2006 Wiley-Liss, Inc. [source]


    Accurate and time efficient estimation of the probability of error in bursty channels,

    INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 7 2003
    M. Stevan Berber
    Abstract A method and a technique for the probability of error estimation in digital channels with memory are developed and demonstrated. The expressions for the mean and variance of a random variable, representing a block of bits transmission in a bursty channel (channel with memory), are derived. The influence of the memory is expressed by a parameter called the memory factor. It is shown that the traditional Monte Carlo method can be applied for the probability of error estimation. In order to control the accuracy and increase the time efficiency of estimation this method is modified and a new method, called the modified Monte Carlo method, is proposed. Based on this modified method a technique of estimation with controlled accuracy is developed and demonstrated using data obtained by simulation. According to this technique the sample size is adjusted in the course of estimating procedure to give an accurate estimate of the probability of error for a minimum required time of estimation. Copyright 2003 John Wiley & Sons, Ltd. [source]


    Accurate and simple synthesis formulas for coplanar waveguides

    INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 2 2008
    Ali Akdagli
    Abstract Simple and accurate closed-form formulas obtained by using a differential evolution algorithm are presented for the synthesis of coplanar waveguides (CPW). The results of the synthesis formulas proposed in this article are compared with those of the quasi-static analysis, the synthesis formulas reported by the other researchers and also the experimental works available in the literature. The accuracy of the proposed synthesis formulas is found to be better than 0.75% for 9256 CPWs samples. 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008. [source]


    Measurement of bone blood flow using the hydrogen washout technique,part II: Validation by comparison to microsphere entrapment

    JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 6 2008
    Mikko Larsen
    Abstract Accurate and reproducible measurement of bone blood flow has important clinical and experimental applications. Hydrogen washout is simple, safe, and widely used, but its use in bone tissue has not been validated. To this end, we have compared cortical bone blood flow measurements obtained by radioactive-labeled microsphere entrapment with those from hydrogen washout. Blood flow was measured in tibial cortical bone of 12 New Zealand White rabbits by radioactive microsphere entrapment and by hydrogen washout. Besides a control group (n,=,6), four animals were treated with systemic epinephrine (0.8 g/kg/min) (group 2) and two with nitroprusside (100 g/kg/min) (group 3). Furthermore, nine femora from seven rats were isolated on their vascular pedicles and repeated bone blood flow measurements were made at each location with the hydrogen washout method to confirm reproducibility of blood flow determinations by hydrogen washout. An average flow of 2.3,,2.0 mL/min/100 g was obtained with the microsphere method and 2.0,,0.5 mL/min/100 g with the hydrogen washout method. There was a significant correlation and agreement: R2,=,0.97 (p,<,0.01). No consistent flow variations were found with systemic vasoactive drug administration. Hydrogen washout provided reproducible results and showed high sensitivity to flow changes. Hydrogen washout is both sensitive and reproducible in measuring bone blood flow. Results agree well with flow values obtained by labeled microsphere entrapment. 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:746,752, 2008 [source]


    Global Daily Reference Evapotranspiration Modeling and Evaluation,

    JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 4 2008
    G.B. Senay
    Abstract:, Accurate and reliable evapotranspiration (ET) datasets are crucial in regional water and energy balance studies. Due to the complex instrumentation requirements, actual ET values are generally estimated from reference ET values by adjustment factors using coefficients for water stress and vegetation conditions, commonly referred to as crop coefficients. Until recently, the modeling of reference ET has been solely based on important weather variables collected from weather stations that are generally located in selected agro-climatic locations. Since 2001, the National Oceanic and Atmospheric Administration's Global Data Assimilation System (GDAS) has been producing six-hourly climate parameter datasets that are used to calculate daily reference ET for the whole globe at 1-degree spatial resolution. The U.S. Geological Survey Center for Earth Resources Observation and Science has been producing daily reference ET (ETo) since 2001, and it has been used on a variety of operational hydrological models for drought and streamflow monitoring all over the world. With the increasing availability of local station-based reference ET estimates, we evaluated the GDAS-based reference ET estimates using data from the California Irrigation Management Information System (CIMIS). Daily CIMIS reference ET estimates from 85 stations were compared with GDAS-based reference ET at different spatial and temporal scales using five-year daily data from 2002 through 2006. Despite the large difference in spatial scale (point vs. ,100 km grid cell) between the two datasets, the correlations between station-based ET and GDAS-ET were very high, exceeding 0.97 on a daily basis to more than 0.99 on time scales of more than 10 days. Both the temporal and spatial correspondences in trend/pattern and magnitudes between the two datasets were satisfactory, suggesting the reliability of using GDAS parameter-based reference ET for regional water and energy balance studies in many parts of the world. While the study revealed the potential of GDAS ETo for large-scale hydrological applications, site-specific use of GDAS ETo in complex hydro-climatic regions such as coastal areas and rugged terrain may require the application of bias correction and/or disaggregation of the GDAS ETo using downscaling techniques. [source]


    Delineating melanoma using multimodal polarized light imaging

    LASERS IN SURGERY AND MEDICINE, Issue 1 2009
    Zeina Tannous
    Abstract Background and Significance Melanoma accounts for 3% of all skin cancers but causes 83% of skin cancer deaths. The first step in treatment of melanoma is the removal of the lesions, usually by surgical excision. Currently most lesions are removed without intraoperative margin control. Post-operative methods inspect 1,2% of the surgical margin and are prone to sampling errors. In this study we evaluate the use of reflectance and fluorescence polarization imaging for the demarcation of melanoma in thick fresh skin excisions. Materials and Methods Pigmented lesions clinically suspicious for melanoma were elliptically excised with proper margins. Elliptical surgical excisions were vertically bisected along the short axis of the specimen into two halves in the middle of the pigmented lesions. The vertically bisected tumor face was imaged. After that, one half of the sample was briefly stained in aqueous 2 mg/ml solution of tetracycline, whereas another half was stained in 0.2 mg/ml aqueous solution of methylene blue. Then both specimens were reimaged. Reflectance images were acquired in the spectral range between 390 and 750 nm. Fluorescence images of the tetracycline-stained tissue were excited at 390 nm and registered between 450 and 700 nm. Fluorescence of the methylene blue-stained samples was excited at 630 nm and registered between 650 and 750 nm. After imaging, the tissue was processed for standard H&E histopathology. The resulting histological and optical images were compared to each other. Results and Conclusions Our findings demonstrate that both tetracycline and methylene blue are suitable for imaging dysplastic and benign nevi. Melanoma is better delineated in the samples stained in methylene blue. Accurate and rapid delineation of melanoma in standard fresh surgical excisions appears feasible. Lasers Surg. Med. 41:10,16, 2009. 2008 Wiley-Liss, Inc. [source]


    Visual Images of America in the Sixteenth Century

    LITERATURE COMPASS (ELECTRONIC), Issue 6 2008
    Elaine Brennan
    Artists rarely accompanied sixteenth-century voyages of discovery and exploration.1 As a consequence, few first-hand visual representations of the New World were produced. Despite this, published accounts of the Americas in the sixteenth century often included illustrations. With some notable exceptions, the voyagers themselves did not supply the images, or directly supervise their publication. Accurate or not, these images, together with the texts they illustrated, contributed to the construction of the Americas in European consciousness. Only a small number of original first-hand pictorial works survive today, the most important being John White's drawings of the Algonquian Indians of Roanoke, Virginia, from 1585,86. The recent major exhibition of John White's drawings may provoke new scholarly interest in sixteenth-century visual images of the Americas, a topic which offers a rich and relatively neglected area of study.2 This article offers an introduction to the field together with some suggestions for avenues of further research.3 [source]


    Fast mapping of myocardial blood flow with MR first-pass perfusion imaging

    MAGNETIC RESONANCE IN MEDICINE, Issue 6 2008
    Thomas A. Goldstein
    Abstract Accurate and fast quantification of myocardial blood flow (MBF) with MR first-pass perfusion imaging techniques on a pixel-by-pixel basis remains difficult due to relatively long calculation times and noise-sensitive algorithms. In this study, Zierler's central volume principle was used to develop an algorithm for the calculation of MBF with few assumptions on the shapes of residue curves. Simulation was performed to evaluate the accuracy of this algorithm in the determination of MBF. To examine our algorithm in vivo, studies were performed in nine normal dogs. Two first-pass perfusion imaging sessions were performed with the administration of the intravascular contrast agent Gadomer at rest and during dipyridamole-induced vasodilation. Radiolabeled microspheres were injected to measure MBF at the same time. MBF measurements in dogs using MR methods correlated well with the microsphere measurements (R2 = 0.96, slope = 0.9), demonstrating a fair accuracy in the perfusion measurements at rest and during the vasodilation stress. In addition to its accuracy, this method can also be optimized to run relatively fast, providing potential for fast and accurate myocardial perfusion mapping in a clinical setting. Magn Reson Med, 2008. 2008 Wiley-Liss, Inc. [source]


    Changing Trends in Pacemaker and Implantable Cardioverter Defibrillator Generator Advisories

    PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 12 2002
    WILLIAM H. MAISEL
    MAISEL, W.H., et al.: Changing Trends in Pacemaker and Implantable Cardioverter Defibrillator Generator Advisories. Pacemaker and implantable cardioverter defibrillator (ICD) generator recalls and safety alerts (advisories) occur frequently, affect many patients, and are increasing in number and rate. It is unknown if advances in device technology have been accompanied by changing patterns of device advisory type. Weekly FDA Enforcement Reports from January 1991 to December 2000 were analyzed to identify all advisories involving pacemaker and ICD generators. This article represents additional analysis of previously cited advisories and does not contain additional recalls or safety alerts over those that have been previously reported. The 29 advisories (affecting 159,061 devices) from the early 1990s (1991,1995) were compared to the 23 advisories (affecting 364,084 devices) from the late 1990s (1996,2000). While the annual number of device advisories did not change significantly, ICD advisories became more frequent and a three-fold increase in the number of devices affected per advisory was observed. The number of devices affected by hardware advisories increased three-fold, due primarily to a 700-fold increase in electrical/circuitry abnormalities and a 20-fold increase in potential battery/capacitor malfunctions. Other types of hardware abnormalities (defects in the device header, hermetic seal, etc.) became less common. The number of devices recalled due to firmware (computer programming) abnormalities more than doubled. The remarkable technological advances in pacemaker and ICD therapy have been accompanied by changing patterns of device advisory type. Accurate, timely physician and patient notification systems, and routine pacemaker and ICD patient follow-up continue to be of paramount importance. [source]


    Parents' Beliefs About Condoms and Oral Contraceptives: Are They Medically Accurate?

    PERSPECTIVES ON SEXUAL AND REPRODUCTIVE HEALTH, Issue 2 2004
    Marla E. Eisenberg
    CONTEXT: Parents are encouraged to be the primary sex educators for their children; however, little is known about the accuracy of parents' views about condoms and oral contraceptives. METHODS: Telephone surveys using validated measures provided data on beliefs about the effectiveness, safety and usability of condoms and the pill among 1,069 parents of 13,17-year-olds in Minnesota and Wisconsin in 2002. Pearson chi-square tests and multivariate logistic regression models were used to compare beliefs according to sex, age, race, religion, education, income and political orientation. RESULTS: Substantial proportions of parents underestimated the effectiveness of condoms for preventing pregnancy and sexually transmitted diseases (STDs). Only 47% believed that condoms are very effective for STD prevention, and 40% for pregnancy prevention. Fifty-two percent thought that pill use prevents pregnancy almost all the time; 39% thought that the pill is very safe. Approximately one-quarter of parents thought that most teenagers are capable of using condoms correctly; almost four in 10 thought that most teenagers can use the pill correctly. Fathers tended to have more accurate views about condoms than mothers did; mothers' views of the pill were generally more accurate than fathers'. Whites were more likely than nonwhites to hold accurate beliefs about the pill's safety and effectiveness; conservatives were less likely than liberals to hold accurate views about the effectiveness of condoms. CONCLUSION: Campaigns encouraging parents to talk with their teenagers about sexuality should provide parents with medically accurate information on the effectiveness, safety and usability of condoms and the pill. [source]


    Molecular characterization of swine leucocyte antigen class II genes in outbred pig populations

    ANIMAL GENETICS, Issue 4 2010
    C.-S. Ho
    Summary The highly polymorphic swine leucocyte antigen (SLA) genes are among the most important determinants of swine immune responses to disease and vaccines. Accurate and effective SLA genotyping methods are required to understand how SLA gene polymorphisms affect immunity, especially in outbred pigs with diverse genetic backgrounds. In this study, we present a simple and rapid molecular-based typing system for characterizing SLA class II alleles of the DRB1, DQB1 and DQA loci. This system utilizes a set of 47 sequence-specific PCR primers developed to differentiate alleles by groups that share similar sequence motifs. We applied this typing method to investigate the SLA class II diversity in four populations of outbred pigs (n = 206) and characterized a total of 19 SLA class II haplotypes, six of which were shared by at least three of the sampled pig populations. We found that Lr-0.1 (DRB1*01XX,DQB1*01XX,DQA*01XX) was the most prevalent haplotype with a combined frequency of 16.0%, followed by Lr-0.2 (DRB1*02XX,DQB1*02XX,DQA*02XX) with 14.6% and Lr-0.15b (DRB1*04XX,DQB1*0202,DQA*02XX) with 14.1%. Over 70% of the pigs (n = 147) had at least one copy of one of these three haplotypes. The PCR-based typing system described in this study demonstrates a reliable and unambiguous detection method for SLA class II alleles. It will be a valuable tool for studying the influence of SLA diversity on various immunological, pathological and physiological traits in outbred pigs. [source]


    Resection of liver metastases from colorectal cancer: does preoperative chemotherapy affect the accuracy of PET in preoperative planning?

    ANZ JOURNAL OF SURGERY, Issue 5 2009
    Sam Adie
    Abstract Background:, Preoperative scanning for hepatic colorectal metastases surgery remains a challenge, especially in the age of preoperative chemotherapy, which has marked biochemical and physical effects on the liver. Integrated fluoro-deoxyglucose positron emission tomography and computed tomography (FDG-PET/CT) has applications for detecting extrahepatic disease. The aim of the present study was to investigate FDG-PET/CT as a preoperative planning tool for detecting liver lesions in patients with and without preoperative chemotherapy. Methods:, Patients who had resection of hepatic colorectal metastases between January 2004 and June 2006 were included. Patients were divided into those who received preoperative chemotherapy and those who did not. Malignant hepatic lesions found on each scan were compared with those found on histopathology, intraoperative examination and/or intraoperative ultrasound. Accurate scans (scan lesions corresponded to true lesions), false positives (scan lesions detected at least one non-lesion) and false negatives (scan lesions missed at least one true lesions) were recorded. Results were also compared on a per lesion basis. Results:, A total of 21 patients had preoperative FDG-PET/CT scans with preoperative chemotherapy and 53 without. Accurate tests were six (29%) for the chemotherapy group versus 28 (53%) for the non-chemotherapy group (P= 0.06). Notably, there were 11 (52%) underestimations in the chemotherapy group versus 18 (34%) in the non-chemotherapy group. A total of 1.7 lesions were missed per patient in the chemotherapy group versus 0.7 in those who did not receive chemotherapy. Conclusion:, Preoperative assessment with FDG-PET/CT is not useful for hepatic colorectal metastases, particularly when preoperative chemotherapy is used, with a trend towards underestimation of lesions. [source]


    HP36P DOES NEO-ADJUVANT CHEMOTHERAPY AFFECT THE ACCURACY OF HELICAL CT AND CT PORTOGRAPHY FOR PRE-OPERATIVE PLANNING IN HEPATIC COLORECTAL METASTASES?

    ANZ JOURNAL OF SURGERY, Issue 2007
    S. Adie
    Purpose Pre-operative scanning for hepatic colorectal metastases surgery remains a challenge, especially in the age of neo-adjuvant chemo, which has marked biochemical & physical effects on the liver. We investigated helical CT and CT portography as pre-op planning tools. Methodology All patients who had resection of hepatic colorectal metastases between Jan 2004 and June 2006 were included. Patients were divided into those who received neo-adjuvant chemo and those who did not. The number of malignant hepatic lesions found on each scan was compared with those found on histopathology & intra-op ultrasound/examination. Accurate scans (scan lesions = true lesions), over-estimations (scan lesions > true lesions) and under-estimations (scan lesions < true lesions) were recorded. Results 25 patients had pre-op CT portography with neo-adjuvant chemo and 63 without. Accurate scans on a per-patient basis were 2 (8%) for the chemo group vs. 27 (43%) for the non-chemo group, p < 0.002. Notably, there were 17 (68%) over-estimates in the chemo group vs. 25 (40%) in the non-chemo group. There were 6 (24%) vs. 11 (17%) under-estimates respectively. 23 patients had pre-op helical CT with neo-adjuvant chemo and 64 without. Accurate scans on a per-patient basis were 7 (30%) for the chemo group vs. 26 (41%) in the non-chemo group, p = 0.388. There were 8 (35%) over-estimates in the chemo group vs. 12 (19%) in the non-chemo group. There were 8 (35%) vs. 26 (41%) under-estimates respectively. Conclusion While CT portography is useful for detecting occult hepatic metastases, there is evidence that over-estimation of disease is a problem, particularly when neo-adjuvant chemo was used. Helical CT also shows this trend although to a lesser extent. [source]


    Pharmacokinetics of luteolin and tetra-acetyl-luteolin assayed by HPLC in rats after oral administration

    BIOMEDICAL CHROMATOGRAPHY, Issue 8 2010
    Xiujie Chen
    Abstract Accurate and reproducible HPLC methods were developed and validated for the determination of concentrations of luteolin (LT) and tetra-acetyl-luteolin (TALT) in rat plasma. HPLC analyses were performed on an Agilent TC-C18 column protected by a guard Agilent Zorbax Eclipse Plus. The mobile phase for LT was a binary mixture of acetonitrile,water (40:60, v/v) containing 0.5% phosphoric acid at a flow rate of 1.0,mL/min, and that for TALT was a binary mixture of methanol,water (70,:,30, v/v) containing 0.5% glacial acetic acid at the same flow rate. The UV detection wavelength for both analytes was set at 350,nm. The calibration curve was linear over the range of 40,1800,ng/mL, the lower limit of quantitation was 40,ng/mL and the lower limit of detection was 20,ng/mL for both LT and TALT. The intra- and inter-day precision (RSD) values for all samples were within 7.9%. The concentration,time curves of LT and TALT after oral administration (30,mg/kg) were both fitted to a two-compartment model. The pharmacokinetic characteristics of TALT were better than that of LT in the maximum plasma concentration (Cmax) and the area under the concentration,time curve (AUC). Copyright 2010 John Wiley & Sons, Ltd. [source]


    Nonoverlapping Clusters: Approximate Distribution and Application to Molecular Biology

    BIOMETRICS, Issue 2 2001
    Xiaoping Su
    Summary. An approach is developed for the screening of genomic sequence data to identify gene regulatory regions. This approach is based on deciding if putative transcription factor binding sites are clustered together to a greater extent than one would expect by chance. Given n events occurring on an interval of width L (L base pairs), an r:w cluster is defined as r+ 1 consecutive events all contained within a window of length wL. Accurate and easily computable approximations are derived for the distribution of the number of nonoverlapping r:w clusters under the model that the positions of the n events have a uniform distribution. Simulations demonstrate that these approximations have greater accuracy than existing methods. The approximation is applied to detect erythroid-specific regulatory regions in genomic DNA sequences, first in an artificial case where r is specified a priori and then as part of an exploratory approach. [source]


    Epithelial cell proliferative activity and oral cancer progression

    CELL PROLIFERATION, Issue 2002
    P. J. Thomson
    Abstract. Accurate, predictive assessment of the behaviour and progression of oral cancers and precancers remains elusive in clinical practice. Archival tissue specimens from 10 previously treated patients with oral lesions of known clinical outcome (3 years post-treatment) were re-examined histopathologically, and proliferative cell labelling indices (LIs) determined for Ki67, cyclin A and histone mRNA cell cycle markers. While histone mRNA labelling ultimately proved unreliable, both Ki67 and cyclin A LIs demonstrated a clear trend for enhanced labelling to occur in increasingly dysplastic and neoplastic tissue, with particular emphasis on suprabasal labelling in abnormal tissue. Perhaps of greatest significance was the observation of increased LIs and suprabasal labelling in lesions with poor clinical outcome, such as patients developing recurrent disease or cervical lymph node metastasis. Measurement of cell proliferative activity in individual oral epithelial dysplastic lesions or invasive squamous cell carcinomas may thus provide unique, predictive information on clinical outcome. [source]


    Elastic Potential Grids: Accurate and Efficient Representation of Intermolecular Interactions for Fully Flexible Docking

    CHEMMEDCHEM, Issue 8 2009
    Sina Kazemi
    Potential fields represented by irregular, deformable 3D grids provide an accurate and efficient lookup table function for evaluating intermolecular interactions in docking algorithms that consider target flexibility. Target movements can be translated into appropriate displacements of grid intersection points in a binding site region if the irregular deformable 3D grid is modeled as a homogeneous linear elastic body. [source]


    Analytical inverse kinematics with body posture control

    COMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 2 2008
    Marcelo Kallmann
    Abstract This paper presents a novel whole-body analytical inverse kinematics (IK) method integrating collision avoidance and customizable body control for animating reaching tasks in real-time. Whole-body control is achieved with the interpolation of pre-designed key body postures, which are organized as a function of the direction to the goal to be reached. Arm postures are computed by the analytical IK solution for human-like arms and legs, extended with a new simple search method for achieving postures avoiding joint limits and collisions. In addition, a new IK resolution is presented that directly solves for joints parameterized in the swing-and-twist decomposition. The overall method is simple to implement, fast, and accurate, and therefore suitable for interactive applications controlling the hands of characters. The source code of the IK implementation is provided. Copyright 2007 John Wiley & Sons, Ltd. [source]


    An augmented reality system to guide radio-frequency tumour ablation

    COMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 1 2005
    S. Nicolau
    Abstract Radio-frequency ablation is a difficult operative task that requires a precise needle positioning in the centre of the pathology. This article presents an augmented reality system for hepatic therapy guidance that superimposes in real-time 3D reconstructions (from CT acquisition) and a virtual model of the needle on external views of a patient. The superimposition of reconstructed models is performed with a 3D/2D registration based on radio-opaque markers stuck on to the patient's skin. The characteristics of the problem (accuracy, robustness and time processing) led us to develop automatic procedures to extract and match the markers and to track the needle in real time. Experimental studies confirmed that our algorithms are robust and reliable. Preliminary experiments conducted on a human abdomen phantom showed that our system is highly accurate (needle positioning error within 3,mm) and enables the surgeon to reach a target in less than 1 minute on average. Our next step will be to perform an in vivo evaluation. Copyright 2005 John Wiley & Sons, Ltd. [source]


    Java applet on computation of thermodynamic properties of steam and R134a refrigerant

    COMPUTER APPLICATIONS IN ENGINEERING EDUCATION, Issue 4 2003
    F. L. Tan
    Abstract This paper describes the application of Java programming on the computation of thermodynamic properties of steam and the HFC-134a, 1,1,1,2-tetrafluoroethane (R134a) refrigerant through the Java applets. The Java applets can compute thermodynamic properties of steam and R134a refrigerant, such as specific volume, internal energy, enthalpy, and entropy in the phases of saturated mixture, compressed liquid, and superheated vapor. The calculated values are accurate compared to the standard reference properties tables for steam and refrigerant. 2004 Wiley Periodicals, Inc. Comput Appl Eng Educ 11: 211,225, 2003; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.10049 [source]


    Reconstructing head models from photographs for individualized 3D-audio processing

    COMPUTER GRAPHICS FORUM, Issue 7 2008
    M. Dellepiane
    Abstract Visual fidelity and interactivity are the main goals in Computer Graphics research, but recently also audio is assuming an important role. Binaural rendering can provide extremely pleasing and realistic three-dimensional sound, but to achieve best results it's necessary either to measure or to estimate individual Head Related Transfer Function (HRTF). This function is strictly related to the peculiar features of ears and face of the listener. Recent sound scattering simulation techniques can calculate HRTF starting from an accurate 3D model of a human head. Hence, the use of binaural rendering on large scale (i.e. video games, entertainment) could depend on the possibility to produce a sufficiently accurate 3D model of a human head, starting from the smallest possible input. In this paper we present a completely automatic system, which produces a 3D model of a head starting from simple input data (five photos and some key-points indicated by user). The geometry is generated by extracting information from images and accordingly deforming a 3D dummy to reproduce user head features. The system proves to be fast, automatic, robust and reliable: geometric validation and preliminary assessments show that it can be accurate enough for HRTF calculation. [source]


    Gradient-based Interpolation and Sampling for Real-time Rendering of Inhomogeneous, Single-scattering Media

    COMPUTER GRAPHICS FORUM, Issue 7 2008
    Zhong Ren
    Abstract We present a real-time rendering algorithm for inhomogeneous, single scattering media, where all-frequency shading effects such as glows, light shafts, and volumetric shadows can all be captured. The algorithm first computes source radiance at a small number of sample points in the medium, then interpolates these values at other points in the volume using a gradient-based scheme that is efficiently applied by sample splatting. The sample points are dynamically determined based on a recursive sample splitting procedure that adapts the number and locations of sample points for accurate and efficient reproduction of shading variations in the medium. The entire pipeline can be easily implemented on the GPU to achieve real-time performance for dynamic lighting and scenes. Rendering results of our method are shown to be comparable to those from ray tracing. [source]


    A Screen Space Quality Method for Data Abstraction

    COMPUTER GRAPHICS FORUM, Issue 3 2008
    J. Johansson
    Abstract The rendering of large data sets can result in cluttered displays and non-interactive update rates, leading to time consuming analyses. A straightforward solution is to reduce the number of items, thereby producing an abstraction of the data set. For the visual analysis to remain accurate, the graphical representation of the abstraction must preserve the significant features present in the original data. This paper presents a screen space quality method, based on distance transforms, that measures the visual quality of a data abstraction. This screen space measure is shown to better capture significant visual structures in data, compared with data space measures. The presented method is implemented on the GPU, allowing interactive creation of high quality graphical representations of multivariate data sets containing tens of thousands of items. [source]


    A Semi-Lagrangian CIP Fluid Solver without Dimensional Splitting

    COMPUTER GRAPHICS FORUM, Issue 2 2008
    Doyub Kim
    Abstract In this paper, we propose a new constrained interpolation profile (CIP) method that is stable and accurate but requires less amount of computation compared to existing CIP-based solvers. CIP is a high-order fluid advection solver that can reproduce rich details of fluids. It has third-order accuracy but its computation is performed over a compact stencil. These advantageous features of CIP are, however, diluted by the following two shortcomings: (1) CIP contains a defect in the utilization of the grid data, which makes the method suitable only for simulations with a tight CFL restriction; and (2) CIP does not guarantee unconditional stability. There have been several attempts to fix these problems in CIP, but they have been only partially successful. The solutions that fixed both problems ended up introducing other undesirable features, namely increased computation time and/or reduced accuracy. This paper proposes a novel modification of the original CIP method that fixes all of the above problems without increasing the computational load or reducing the accuracy. Both quantitative and visual experiments were performed to test the performance of the new CIP in comparison to existing fluid solvers. The results show that the proposed method brings significant improvements in both accuracy and speed. [source]


    Sparse points matching by combining 3D mesh saliency with statistical descriptors

    COMPUTER GRAPHICS FORUM, Issue 2 2008
    U. Castellani
    Abstract This paper proposes new methodology for the detection and matching of salient points over several views of an object. The process is composed by three main phases. In the first step, detection is carried out by adopting a new perceptually-inspired 3D saliency measure. Such measure allows the detection of few sparse salient points that characterize distinctive portions of the surface. In the second step, a statistical learning approach is considered to describe salient points across different views. Each salient point is modelled by a Hidden Markov Model (HMM), which is trained in an unsupervised way by using contextual 3D neighborhood information, thus providing a robust and invariant point signature. Finally, in the third step, matching among points of different views is performed by evaluating a pairwise similarity measure among HMMs. An extensive and comparative experimental session has been carried out, considering real objects acquired by a 3D scanner from different points of view, where objects come from standard 3D databases. Results are promising, as the detection of salient points is reliable, and the matching is robust and accurate. [source]