CiteULike: Tag measurement

Quantification of superparamagnetic iron oxide (SPIO)-labeled cells using MRI

Ali Rad — 2007-07-26T12:12:29-00:00

Journal of Magnetic Resonance Imaging, Vol. 26, No. 2. (2007), pp. 366-374.

To show the feasibility of using magnetic resonance imaging (MRI) to quantify superparamagnetic iron oxide (SPIO)-labeled cells.Lymphocytes and 9L rat gliosarcoma cells were labeled with ferumoxides-protamine sulfate complex (FE-PRO). The cells were labeled efficiently (more than 95%) and the iron concentration inside each cell was measured by spectrophotometry (4.77-30.21 pg). Phantom tubes containing different numbers of labeled or unlabeled cells, as well as different concentrations of FE-PRO, were made. In addition, labeled and unlabeled cells were injected into fresh and fixed rat brains.Cellular viability and proliferation of labeled and unlabeled cells were shown to be similar. T2-weighted images were acquired using 7T and 3T MRI systems, and R2 maps of the tubes containing cells, free FE-PRO, and brains were made. There was a strong linear correlation between R2 values and labeled cell numbers, but the regression lines were different for the lymphocytes and gliosarcoma cells. Similarly, there was strong correlation between R2 values and free iron. However, free iron had higher R2 values than the labeled cells for the same concentration of iron.Our data indicate that in vivo quantification of labeled cells can be done by careful consideration of different factors and specific control groups. J. Magn. Reson. Imaging 2007. © 2007 Wiley-Liss, Inc.

Assessment of tumor oxygenation by electron paramagnetic resonance: principles and applications

Bernard Gallez — 2006-07-20T06:53:13-00:00

NMR in Biomedicine, Vol. 17, No. 5. (2004), pp. 240-262.

This review paper attempts to provide an overview of the principles and techniques that are often termed electron paramagnetic resonance (EPR) oximetry. The paper discusses the potential of such methods and illustrates they have been successfully applied to measure oxygen tension, an essential parameter of the tumor microenvironment. To help the reader understand the motivation for carrying out these measurements, the importance of tumor hypoxia is first discussed: the basic issues of why a tumor is hypoxic, why these hypoxic microenvironments promote processes driving malignant progression and why hypoxia dramatically influences the response of tumors to cytotoxic treatments will be explained. The different methods that have been used to estimate the oxygenation in tumors will be reviewed. To introduce the basics of EPR oximetry, the specificity of in vivo EPR will be discussed by comparing this technique with NMR and MRI. The different types of paramagnetic oxygen sensors will be presented, as well as the methods for recording the information (EPR spectroscopy, EPR imaging, dynamic nuclear polarization). Several applications of EPR for characterizing tumor oxygenation will be illustrated, with a special emphasis on pharmacological interventions that modulate the tumor microenvironment. Finally, the challenges for transposing the method into the clinic will also be discussed. Copyright © 2004 John Wiley & Sons, Ltd.

A simple method for measuring interstitial fluid pressure in cancer tissues

Ugur Ozerdem — 2007-07-27T10:30:34-00:00

Microvascular Research, Vol. 70, No. 1-2. (July 2005), pp. 116-120.

A novel procedure using a polyurethane transducer-tipped catheter (Millar) is described that allows reliable measurement of interstitial fluid pressure (IFP) in cancer tissues. Before and after each use, the transducer is calibrated at 37[degree sign]C by a water column. After calibration, the transducer is passed through the lumen of a surgical needle. The sensor is kept in the lumen of the needle during penetration into the tumor. The sensor tip is then introduced into the center core of the tumor as the needle sleeve is withdrawn from the tumor surface. Our new technique is simple and provides IFPs equal to those provided by the well-established, wick-in-needle technique. Using our new technique, we compared IFP in skin melanoma grafts in NG2 knockout and wild-type mice. Knocking out NG2 proteoglycan on vasculogenic and angiogenic pericytes reduced interstitial fluid pressure in melanoma from +4.9 cm H2O to -0.4 cm H2O (P = 0.0054 Mann-Whitney U test).

Roadless Space of the Conterminous United States

Raymond Watts — 2007-05-04T09:09:11-00:00

Science, Vol. 316, No. 5825. (4 May 2007), pp. 736-738.

Roads encroaching into undeveloped areas generally degrade ecological and watershed conditions and simultaneously provide access to natural resources, land parcels for development, and recreation. A metric of roadless space is needed for monitoring the balance between these ecological costs and societal benefits. We introduce a metric, roadless volume (RV), which is derived from the calculated distance to the nearest road. RV is useful and integrable over scales ranging from local to national. The 2.1 million cubic kilometers of RV in the conterminous United States are distributed with extreme inhomogeneity among its counties. 10.1126/science.1138141

Accuracy of T1 measurements at high temporal resolution: Feasibility of dynamic measurement of blood T1 after contrast administration

Jie Zheng — 2006-09-13T08:17:34-00:00

Journal of Magnetic Resonance Imaging, Vol. 10, No. 4. (1999), pp. 576-581.

The purpose of this work was to optimize a technique to measure blood T1 dynamically after contrast agent administration with a high temporal resolution. This technique uses a 90° prepared gradient-echo sequence and has a temporal resolution of one T1 measurement per cardiac cycle. The non-ideal excitation slice profiles on the estimation of T1 were evaluated by theoretical simulations and used to obtain corrected blood T1 values. The technique was validated on phantom and in vivo pig studies, which demonstrated significant improvement on the accuracy of the dynamic T1 measurement method after slice profile correction. This technique may find important applications in studying the dynamic blood T1 after injection of various contrast agents. J. Magn. Reson. Imaging 1999;10:576-581. © 1999 Wiley-Liss, Inc.

Comparison of diameter and perimeter methods for tumor volume calculation.

AG Sorensen — 2007-07-06T07:36:21-00:00

J Clin Oncol, Vol. 19, No. 2. (15 January 2001), pp. 551-557.

PURPOSE: Lesion volume is often used as an end point in clinical trials of oncology therapy. We sought to compare the common method of using orthogonal diameters to estimate lesion volume (the diameter method) with a computer-assisted planimetric technique (the perimeter method). METHODS: Radiologists reviewed 825 magnetic resonance imaging studies from 219 patients with glioblastoma multiforme. Each study had lesion volume independently estimated via the diameter and perimeter methods. Cystic areas were subtracted out or excluded from the outlined lesion. Inter- and intrareader variability was measured by using multiple readings on 48 cases. Where serial studies were available in noncystic cases, a mock response analysis was used. RESULTS: The perimeter method had a reduced interreader and intrareader variability compared with the diameter method (using SD of differences): intrareader, 1.76 mL v 7.38 mL (P < .001); interreader, 2.51 mL v 9.07 mL (P < .001) for perimeter and diameter results, respectively. Of the 121 noncystic cases, 23 had serial data. In six (26.1%) of those 23, a classification difference occurred when the perimeter method was used versus the diameter method. CONCLUSION: Variability of measurements was reduced with the computer-assisted perimeter method compared with the diameter method, which suggests that changes in volume can be detected more accurately with the perimeter method. The differences between these techniques seem large enough to have an impact on grading the response to therapy.

Measurement of liver fat content using selective saturation at 3.0 T

Scott Cotler — 2007-04-04T15:48:08-00:00

Journal of Magnetic Resonance Imaging, Vol. 25, No. 4. (2007), pp. 743-748.

To validate an MRI technique for measuring liver fat content by calibrating MRI readings with liver phantoms and comparing MRI measurements in human subjects with estimates of liver fat content on liver biopsy specimens.The MRI protocol consisted of fat and water imaging by selective saturation using a 3.0-T scanner. A water phantom and liver phantoms were scanned before each of 10 human subjects who underwent a liver biopsy to assess for nonalcoholic fatty liver disease (NAFLD). Liver fat content in human subjects was derived from a calibration curve generated by scanning the phantoms. Liver fat was also estimated by optical image analysis and pathologists' assessment of histologic sections.MRI measurements of the liver phantoms were highly reproducible. Measurements of liver fat content in human subjects made by MRI in two areas of the liver were strongly correlated (r = 0.98, P < 0.001). MRI measurements were highly associated with estimates of liver fat content made by optical image analysis (r = 0.96, P < 0.001) and with estimates made by the pathologists (r = 0.93, P < 0.001).We validated a technique for quantifying liver fat content based on selective fat and water imaging. The technique is accurate and reproducible and provides a noninvasive method to obtain serial measurements of liver fat content in human subjects. J. Magn. Reson. Imaging 2007. © 2007 Wiley-Liss, Inc.

On gray scale image measurements : II. Surface area and volume

David Eberly — 2005-11-07T22:22:52-00:00

CVGIP: Graphical Models and Image Processing, Vol. 53, No. 6. (November 1991), pp. 550-562.

We introduce methods for approximating area of a surface and volume of a region whose boundary is a closed surface where the data are taken from a 3-dimensional lattice of gray scale values. The methods require construction of unit normal vectors for the sampled surface points. The volume can be approximated by using these normal vectors in the divergence theorem from calculus. Two major advantages for this new method are that no geometric ordering of data points is required and that the algorithms are easily implemented. We compare the method to standard algorithms for measuring surface area and volume, using both artificially created data and actual data obtained from a computed tomography scanner.

On gray scale image measurements : I. Arc length and area

David Eberly — 2005-11-07T22:21:43-00:00

CVGIP: Graphical Models and Image Processing, Vol. 53, No. 6. (November 1991), pp. 538-549.

We investigate methods for approximating the arc length of a planar curve and the area of a region whose boundary is a closed curve where the data are taken from a rectangular lattice of gray scale values. The commonly used sample-count method is a simple idea. Arc length is estimated by counting pixels along the curve. Typically the relative error is larger than desired. Area is estimated by counting interior pixels. The relative error is usually smaller than that for arc length, but identifying interior pixels may be a difficult geometric problem and adds computational overhead. The sample-distance methods for measuring arc length is also standard. This method requires the curve pixels to be ordered geometrically. The distances between consecutive pixels are summed to give an estimate of arc length. Although the relative errors are small, the required geometric ordering adds complexity to the problem. We introduce the sample-normal method for estimating arc length and area from gray level data. This method requires construction of unit normal vectors for the sampled curve points. Local estimates of arc length at the pixels are made from the normal vectors. The area can be approximated by using the normal vectors in the divergence theorem from calculus. Two major advantages for this method are that no geometric ordering of data points is required and that the algorithms are easily implemented. We compare the sample-normal method to the sample-count and sample-distance methods using both artificially created data and actual 8-bit digital images.

In vivo MRI volumetric measurement of prostate regression and growth in mice

Kent Nastiuk — 2007-07-25T05:50:00-00:00

BMC Urology, Vol. 7 (24 July 2007), 12.

Quantitative assessment of blood flow, blood volume and blood oxygenation effects in functional magnetic resonance imaging

Peter van Zijl — 2007-07-20T15:24:07-00:00

Nat Med, Vol. 4, No. 2. (February 1998), pp. 159-167.

Accurate and sensitive measurements of magnetic susceptibility using echo planar imaging

Asa Carlsson — 2007-07-26T12:30:06-00:00

Magnetic Resonance Imaging, Vol. 24, No. 9. (November 2006), pp. 1179-1185.

Susceptibility differences are common causes for artifacts in magnetic resonance (MR); therefore, it is important to choose phantom materials in a way that these artifacts are kept at a minimum. In this study, a previously proposed MR imaging (MRI) method [Beuf O, Briguet A, Lissac M, Davis R. Magnetic resonance imaging for the determination of magnetic susceptibility of materials. J Magn Reson 1996; Series B(112):111-118] was improved to facilitate sensitive in-house measurements of different phantom materials so that such artifacts can more easily be minimized. Using standard MRI protocols and distilled water as reference, we measured magnetic volume susceptibility differences with a clinical MR system. Two imaging techniques, echo planar imaging (EPI) and spin echo, were compared using liquid samples whose susceptibilities were verified by MR spectroscopy. The EPI sequence has a very narrow bandwidth in the phase-encoding direction, which gives an increased sensitivity to magnetic field inhomogeneities. All MRI measurements were evaluated in two ways: (1) manual image analysis and (2) model fitting. The narrow bandwidth of the EPI made it possible to detect very small susceptibility differences (equivalent susceptibility difference, [Delta][chi]e>=0.02 ppm), and even plastics could be measured. Model fitting yielded high accuracy and high sensitivity and was less sensitive to other image artifacts as compared with manual image analysis.

MediaPlayer™ versus RealPlayer™: a comparison of network turbulence

Mingzhe Li — 2006-07-07T23:21:14-00:00

(2002), pp. 131-136.

Why is the internet traffic bursty in short time scales?

Hao Jiang — 2006-04-17T16:41:28-00:00

SIGMETRICS Perform. Eval. Rev., Vol. 33, No. 1. (June 2005), pp. 241-252.

The kinesin Eg5 drives poleward microtubule flux in Xenopus laevis egg extract spindles.

DT Miyamoto — 2005-12-31T21:33:17-00:00

J Cell Biol, Vol. 167, No. 5. (6 December 2004), pp. 813-818.

Although mitotic and meiotic spindles maintain a steady-state length during metaphase, their antiparallel microtubules slide toward spindle poles at a constant rate. This "poleward flux" of microtubules occurs in many organisms and may provide part of the force for chromosome segregation. We use quantitative image analysis to examine the role of the kinesin Eg5 in poleward flux in metaphase Xenopus laevis egg extract spindles. Pharmacological inhibition of Eg5 results in a dose-responsive slowing of flux, and biochemical depletion of Eg5 significantly decreases the flux rate. Our results suggest that ensembles of nonprocessive Eg5 motors drive flux in metaphase Xenopus extract spindles.

An introduction to quantum filtering

Luc Bouten — 2007-11-14T04:19:27-00:00

(30 Jan 2006)

This paper provides an introduction to quantum filtering theory. An introduction to quantum probability theory is given, focusing on the spectral theorem and the conditional expectation as a least squares estimate, and culminating in the construction of Wiener and Poisson processes on the Fock space. We describe the quantum Itô calculus and its use in the modelling of physical systems. We use both reference probability and innovations methods to obtain quantum filtering equations for system-probe models from quantum optics.

Everett and Structure

David Wallace — 2006-04-01T11:16:52-00:00

(22 Jul 2005)

I address the problem of indefiniteness in quantum mechanics: the problem that the theory, without changes to its formalism, seems to predict that macroscopic quantities have no definite values. The Everett interpretation is often criticised along these lines and I shall argue that much of this criticism rests on a false dichotomy: that the macroworld must either be written directly into the formalism or be regarded as somehow illusory. By means of analogy with other areas of physics, I develop the view that the macroworld is instead to be understood in terms of certain structures and patterns which emerge from quantum theory (given appropriate dynamics, in particular decoherence). I extend this view to the observer, and in doing so make contact with functionalist theories of mind.

Conceptualization and measurement of assistive technology usability

Sajay Arthanat — 2008-04-23T10:21:22-00:00

Disability and Rehabilitation: Assistive Technology, Vol. 2, No. 4. (2007), pp. 235-248.

Background. The concept of product usability has been discussed in several areas of product research and development. Usability, within the realm of assistive technology (AT) devices, determines how effectively and efficiently AT users with disabilities can function in different contexts and environments. Objective. This article conceptualizes and proposes the significance of AT usability and its measurement in entirety from a human factors perspective. Conceptual models that characterize the interaction of the AT user, the AT device, the context and the involved activity is considered to be the hallmark of measurement of AT usability. On that basis, the article highlights the methodology and the initial progress of the development of an AT outcome tool, the Usability Scale for Assistive Technology (USAT), to measure self reported degree of AT usability. Methodology. In order to identify usability indicators for measurement, a qualitative study was conducted by exploring the experiences of AT users. Ten participants who used either wheeled mobility or computer based AT devices were interviewed with questions based on the theme of a usability framework. Results. The coded interview data generated more than 800 usability indicators specific to the two categories of AT devices. These indicators were mapped to a generic usability criteria list for construction of the USAT-Wheeled Mobility and the USAT-Computer Access. Implications. The USAT, when developed, is projected to be valid and useful for AT outcomes research as well as clinical practice. The use of the USAT will enable researchers and clinicians to comprehensively identify factors that underlie effectiveness and efficiency in AT device use and establish intervention protocols to optimize user-AT interaction.

Evaluation of the Sitting Assessment Test for Children with Neuromotor Dysfunction as a Measurement Tool in Cerebral Palsy

Virginia Knox — 2006-09-14T10:17:22-00:00

Physiotherapy, Vol. 88, No. 9. (September 2002), pp. 534-541.

SummaryThe sitting assessment test for children with neuromotor dysfunction measures quality of independent sitting ability across four areas: proximal stability, postural tone, postural alignment, and balance. It was used to measure change in a child with spastic diplegia, who attended for a block of physiotherapy at the Bobath Centre, an outpatient treatment centre for children with cerebral palsy. Following therapy, the patient was observed to sit for longer and was able to reach further without losing her balance. Proximal stability and balance in sitting had improved as measured by SACND. This measure can provide objective information regarding sitting ability in children with neuromotor disabilities and proved sensitive to change over a short period of time in this patient.

Software Usability Metrics and Methods

Patricia Chalmers — 2008-01-02T17:15:27-00:00

Human-Computer Interaction – INTERACT 2007 (2007), pp. 710-711.

Potential customers usually want to know how they will benefit if they hire a usability professional, and they may want numbers to measure those benefits, or calculate a return on investment. However, many professionals become confused when customers ask them to measure the usability of a software application, software program, web site, or other software product. In order to clarify the process of measuring usability, this tutorial first offers a definition of software usability metrics, gives examples of usability metrics, and reviews reasons for usability metrics. Next, the tutorial steps through the process of deciding what metrics and methods to use as well as when, where, and how to use them.

Designing a performance measurement system: A case study

Clemens Lohman — 2007-06-25T06:47:28-00:00

European Journal of Operational Research, Vol. 156, No. 2. (16 July 2004), pp. 267-286.

Performance measurement (PM) by means of local performance indicators (PIs) is developing into performance management at a company-wide scale. But how should PIs at various levels in the organization be incorporated into one system that can help managers, working at levels that range from operational to strategic? How do we convince potential users and obtain their support when starting to develop such a system? How can we aggregate PIs? How do we present results? This paper addresses these and related questions. It is based on a case study carried out at the European Operations department of Nike, a company producing and selling sportswear worldwide. The study resulted in a prototype system that basically is a balanced scorecard tailored to the needs of the company. The empirical findings differ in some ways from the literature on developing performance measurement systems (PMSs) in Operations. Discussing these differences provides new theoretical and practical insights. They relate to the role of parallel initiatives for PM, the role of standardized metrics, the continuous improvement of PMSs, and the normalization and aggregation of measures. Our findings suggest that developing PMSs should to a large extent be understood as a co-ordination effort rather than a design effort. The lessons learned cannot have universal validity, but may be helpful in similar kinds of initiatives.

The Role of the Learning Community in the Development of Discipline Knowledge and Generic Graduate Outcomes

Calvin Smith — 2006-02-08T06:08:26-00:00

Higher Education, Vol. 51, No. 2. (March 2006), pp. 259-286.

Information and its Metric

JP Crutchfield — 2006-11-15T14:52:29-00:00

(1990), pp. 119-130.

Information is taken as the primary physical entity from which probabilities can be derived. Information produced by a source is defined as the class of sources that are recoding- equivalent. Shannon entropy is one of a family of formal Renyi information measures on the space of unique sources. Each of these measures quantifies the volume of the source’s recoding-equivalence class. A space of information sources is constructed from elements each of which is the class of recoding-equivalent, but otherwise unique sources. The norm in this space is the source entropy. A measure of distance between information sources is derived from an algebra of measurements. With this, the space of information sources is shown to be a metric space whose logic is described by a metric lattice. Applications of the information metric to quantum informational uncertainty and to information densities in multicomponent dynamical systems are outlined.

Loss and Delay Measurements of Internet Backbones

Athina Markopoulou — 2008-05-13T22:41:56-00:00

Computer Communications, Vol. 29, No. 10. (19 June 2006), pp. 1590-1604.

As the Internet evolves into a universal network for all communication needs, it has to stand up to the high quality standards of traditional networks, such as the telephone network for voice communications. Multimedia applications are particularly sensitive to various impairments introduced by IP networks, such as packet loss, delay and delay jitter. In this paper, we study loss and delay measurements taken over the Internet and we provide a detailed characterization thereof. We focus on wide-area backbone networks, which constitute an important part of long-distance communication. Our study is based on a rich data set that provides valuable insights into the behavior of Internet backbones today, and in particular into how they affect multimedia traffic. We find that most of the problems observed seem more related to reliability, network protocols and router operation rather than to traffic load and traditional quality-of-service issues. Furthermore, the characterization and modeling of packet loss, delay and delay jitter can be used by the research community as input to various problems related to the design and evaluation of network- and application-layer mechanisms.

End-to-end available bandwidth: measurement methodology, dynamics, and relation with TCP throughput

Manish Jain — 2007-10-31T13:38:01-00:00

SIGCOMM Comput. Commun. Rev., Vol. 32, No. 4. (October 2002), pp. 295-308.

Measurements of a wireless link in an industrial environment using an IEEE 802.11-compliant physical layer

A Willig — 2007-01-04T15:01:03-00:00

Industrial Electronics, IEEE Transactions on, Vol. 49, No. 6. (2002), pp. 1265-1282.

The design and simulation of coding schemes, medium access control (MAC), and link-layer protocols for future industrial wireless local area networks can be supported by some understanding of the statistical properties of the bit error patterns delivered by a wireless link (which is an ensemble of transmitter, channel, receiver, modems). The authors present results of bit error measurements taken with an IEEE 802.11-compliant radio modem in an industrial environment. In addition to reporting the most important results, they draw some conclusions for the design of MAC and link-layer protocols. Furthermore, they show that the popular Gilbert/Elliot model and a modified version of it are a useful tool for simulating bit errors on a wireless link, despite their simplicity and failure to match certain measured statistics.

An analysis of Internet chat systems

Christian Dewes — 2006-01-05T01:15:52-00:00

(2003), pp. 51-64.

Identifying IPv6 network problems in the dual-stack world

Kenjiro Cho — 2006-04-11T15:53:16-00:00

(2004), pp. 283-288.

Link-level measurements from an 802.11b mesh network

Daniel Aguayo — 2005-11-15T20:48:51-00:00

Vol. 34, No. 4. (October 2004), pp. 121-132.

Characterizing a spam traffic

Luiz Gomes — 2006-10-26T15:35:13-00:00

(2004), pp. 356-369.

Spatio-temporal modeling of traffic workload in a campus WLAN

Félix Hernández-Campos — 2007-07-11T12:43:23-00:00

(2006)

Long-distance 802.11b links: performance measurements and experience

Kameswari Chebrolu — 2006-10-24T11:55:09-00:00

(2006), pp. 74-85.

Internet traffic classification using bayesian analysis techniques

Andrew Moore — 2006-04-14T09:13:14-00:00

Vol. 33, No. 1. (June 2005), pp. 50-60.

Measurements of a distributed file system

Mary Baker — 2005-09-20T20:31:06-00:00

Vol. 25, No. 5. (October 1991), pp. 198-212.

Measuring CPU Overhead for I/O Processing in the Xen Virtual Machine Monitor

Ludmila Cherkasova — 2006-01-14T17:38:34-00:00

USENIX 2005 Annual Technical Conference, General Track (2005), pp. 387-390.

Virtual Machine Monitors (VMMs) are gaining popularity in enterprise environments as a software-based solution for building shared hardware infrastructures via virtualization. In this work, using the Xen VMM, we present a light weight monitoring system for measuring the CPU usage of different virtual machines including the CPU overhead in the device driver domain caused by I/O processing on behalf of a particular virtual machine. Our performance study attempts to quantify and analyze this overhead for a set of I/O intensive workloads.

The mismeasurement of science

Peter Lawrence — 2007-08-17T20:25:29-00:00

Current Biology, Vol. 17, No. 15. (7 August 2007), pp. R583-R585.

Why soccer players are smarter than scientists

Vincent Walsh — 2008-02-27T13:30:30-00:00

Nature Neuroscience, Vol. 11, No. 3., pp. 241-241.

Quantum Nondemolition Measurements of Harmonic Oscillators

Kip Thorne — 2007-10-19T00:24:25-00:00

Physical Review Letters, Vol. 40, No. 11. (13 March 1978), 667.

The complex amplitude X 1 + i X 2 ≡( x + ip / m ω) e i ω t of a harmonic oscillator is constant in the absence of driving forces. Although the uncertainty principle forbids precise measurements of X 1 and X 2 simultaneously (Δ X 1 Δ X 2 > ~ℏ / 2 m ω); X 1 alone can be measured precisely and continuously ("quantum nondemolition measurement"). Examples are given of measuring systems that do this job. Such systems might play a crucial role in gravitational-wave detection and elsewhere.

Parent visual analogue scale ratings of children's pain do not reliably reflect pain reported by child.

AM Kelly — 2005-08-04T22:52:49-00:00

Pediatr Emerg Care, Vol. 18, No. 3. (June 2002), pp. 159-162.

OBJECTIVES: To determine whether parent and child visual analogue scale (VAS) scores for the pain associated with acute conditions in the child agree sufficiently for these methods of measurement to be considered interchangeable in pain and analgesia research. DESIGN: This was a prospective, two-group, repeated measures, blinded study in an urban pediatric emergency department. Children aged 8 to 15 years seeking treatment for painful conditions and the parents of these children were asked to rate the child's pain independently using a VAS on as many as four occasions at 20-minute intervals. Both participants were blinded to their previous rating and the rating of the other participant. The main outcome measure was the correlation of child and parent VAS pain scores by Pearson correlation and bias plot (Bland-Altman) analysis of agreement between tests. RESULTS: Seventy-eight child-parent sets participated, yielding 289 VAS pain score comparison pairs for evaluation. The correlation between child and parent VAS pain scores was 0.63 (95% CI, 0.56-0.70). Bias plot analysis revealed a bias of 5% and 95% limits of agreement from -38 to +47 mm. The degree of difference between child and parent scores was variable, but there was an increasing tendency for parents to underestimate the child's pain when the child recorded VAS pain scores at the higher end of the scale. CONCLUSIONS: Parents' VAS score ratings of their children's pain correlate only moderately with the children's VAS pain scores and show poor levels of agreement. The difference between the measures is variable and appears to be more marked when the child reports a higher VAS score. This research raises doubt about whether parental rating of a child's pain is an appropriate surrogate marker in pediatric pain and analgesia research.

New method for measuring young children's self-report of fear and pain.

PJ Carpenter — 2005-08-04T22:39:05-00:00

J Pain Symptom Manage, Vol. 5, No. 4. (August 1990), pp. 233-240.

The purposes of this paper are (a) to describe the conceptual development of the Children's Global Rating Scale (CGRS), a technique for measuring young children's self-report of such constructs as pain and fear that was designed to address the methodological limitations of existing techniques, and (b) to report the findings of a study investigating the convergent and predictive validity of the CGRS in a sample of children undergoing an invasive medical procedure. Anticipatory procedural distress in 145 children between the ages of 4 and 8 was assessed in outpatient phlebotomy using three independent rating sources: children, parents, and a trained clinical observer. Phlebotomists' ratings as to whether or not children's distress during the actual procedure extended the time it usually takes to perform the procedure was used as the outcome criterion in a discriminate analysis in determining the degree to which anticipatory ratings would predict actual clinical distress during the medical procedure. Results provide preliminary support for the convergent and predictive validity of the CGRS revealing significant correlations with the other independent measures of children's anticipatory distress and also revealed that the CGRS was one of the significant variables in predicting children who extended and did not extend the medical procedure.

Do childhood anxiety measures measure anxiety?

Sean Perrin — 2005-08-04T22:31:48-00:00

Journal of Abnormal Child Psychology (Historical Archive), Vol. 20, No. 6. (December 1992), pp. 567-578.

The Koala Fear Questionnaire: a standardized self-report scale for assessing fears and fearfulness in pre-school and primary school children

Peter Muris — 2005-08-04T22:27:36-00:00

Behaviour Research and Therapy, Vol. 41, No. 5. (May 2003), pp. 597-617.

The Koala Fear Questionnaire (KFQ) is a standardized self-report scale for assessing fears and fearfulness in children aged between 4 and 12 years. The current article presents six studies which examined the reliability and validity of the KFQ. Study 1 (N=108) demonstrated that the visual fear scales of Koala bears as employed in the KFQ are highly comparable to the standard 3-point scales that are used in other childhood fear measures. Study 2 (N=163) provided support for the convergent validity of the KFQ in a sample of 8- to 14-year-old children. That is, the scale correlated substantially with alternative measures of childhood fear and anxiety. Study 3 (N=189) showed that the KFQ possesses good internal consistency and test-retest stability in a group of 8- to 11-year-old children. The results of Studies 4 (N=129) and 5 (N=176) indicated that the KFQ is suitable for children aged 4 to 6 years and demonstrated that the psychometric properties of the scale in younger children are highly similar to those obtained in older children. Study 6 (N=926) showed that the factor structure of the KFQ was theoretically meaningful: although the data clearly pointed in the direction of one factor of general fearfulness, spurs of the commonly found five-factor solution of childhood fear were found in the KFQ. Altogether, the KFQ seems to be a valuable addition to the instrumentarium of clinicians and researchers who are working with fearful and anxious children.

Validation of a Facial Image Scale to assess child dental anxiety.

H Buchanan — 2005-08-04T22:24:34-00:00

Int J Paediatr Dent, Vol. 12, No. 1. (January 2002), pp. 47-52.

OBJECTIVE: To examine the validity of a scale that uses faces as an indicator of children's dental anxiety. SETTING: Department of Child Dental Health waiting room, Newcastle Dental Hospital. SUBJECTS AND METHODS: 100 children (aged 3-18 years) completed the Facial Image Scale (FIS) and the Venham Picture Test (VPT) in the dental hospital waiting room. RESULTS: A strong correlation (0.7) was found between the two scales, indicating good validity for the FIS. Findings also showed that a small, but significant, number of children are anxious in the dental context. CONCLUSION: The findings suggest that the FIS is a valid means of assessing child dental anxiety status in a clinical context.

Self-report measurements of dental anxiety and fear in children: a critical assessment.

IH Aartman — 2005-08-04T22:19:40-00:00

ASDC J Dent Child, Vol. 65, No. 4. (g 1998)

This article reviews self-report measurements frequently used to assess dental anxiety in children. The main focus is on their reliability and validity. For this purpose correlations between the reviewed measurements and other measurements of dental fear in children are considered, as well as their possible ambiguity with respect to scoring procedures and their ability to discriminate between fearful and non-fearful children. Results show that all three questionnaires discussed are open to criticism. It is concluded that of the self-report measurements, the Children's Fear Survey Schedule-Dental Subscale (CFSS-DS) is to be preferred to both Corah's Dental Anxiety Scale (DAS) and the Venham Picture Test (VPT). The reasons for this are the following: the CFSS-DS covers more aspects of the dental situation; it measures dental fear more precisely than the other scales; normative data are available on this scale; and it has slightly superior psychometric properties.

The visual analog scale allows effective measurement of preoperative anxiety and detection of patients' anesthetic concerns.

CH Kindler — 2005-08-04T21:45:10-00:00

Anesth Analg, Vol. 90, No. 3. (March 2000), pp. 706-712.

The advent of managed care, reduction of costs, and advances in medical technology place increasing demands on anesthesiologists. Preoperative anxiety may go unnoticed in an environment that stresses increased productivity. The present study compares different methods for measuring preoperative anxiety, identifies certain patient characteristics that predispose to high anxiety, and describes the quantity and quality of anxiety that patients experience preoperatively. Seven hundred thirty-four patients participated in the study. We assessed aspects of anxiety by means of visual analog scales (VAS) and the State Anxiety Score of the Spielberger State-Trait Anxiety Inventory (STAI). The mean STAI anxiety score was 39 +/- 1 (n = 486) and the mean VAS for fear of anesthesia was 29 +/- 1 (n = 539). Patients feared surgery significantly more than anesthesia (P < 0.001). The VAS measuring fear of anesthesia correlated well with the STAI score (r = 0.55; P < 0.01). Young patients, female patients, and patients with no previous anesthetic experience or a previous negative anesthetic experience had higher anxiety scores. Patients worried most about the waiting period preceding surgery and were least concerned about possible awareness intraoperatively. Factor analysis of various anxiety items showed three distinct dimensions of fear: 1) the fear of the unknown 2) the fear of feeling ill, and 3) the fear for one's life. Among these dimensions, fear of the unknown correlated highest with the anxiety measuring techniques STAI and VAS. The simple VAS proved to be a useful and valid measure of preoperative anxiety. IMPLICATIONS: The study of qualitative aspects of anxiety reveals three distinct dimensions of preoperative fear: fear of the unknown, fear of feeling ill, and fear for one's life. Groups of patients with a higher degree of preoperative anxiety and their specific anesthetic concerns can be identified using the visual analog scale.

Self-report measures for use with children: a review and comment.

JH Beitchman — 2005-08-04T21:28:57-00:00

J Clin Psychol, Vol. 44, No. 4. (July 1988), pp. 477-490.

This article underscores the need for self-report instruments for children to complement the teacher and parent questionnaires traditionally used to assess various aspects of children's psychological lives. Some of the problems inherent in using teachers, parents, and children as informants are delineated. Many self-report instruments, in particular those that are used to assess children's self-concept, anxiety, depression, and personality, are reviewed. The Children's Self-Report Questionnaire (SRQ) was designed to assist in the diagnosis and detection of psychological deviance in 7- to 12-year-old children. The SRQ is easily administered, has broadly based norms, and has acceptable reliability and validity. The SRQ can be used as an aid to both research and clinical assessment and may provide insight into the inner world of the child.

An observationally based rating scale for affective symptomatology in child psychiatry.

Y Kaminer — 2005-08-04T21:20:54-00:00

J Nerv Ment Dis, Vol. 178, No. 12. (December 1990), pp. 750-754.

There is growing dissatisfaction with current methods for rating affective symptoms in children. We report findings from a preliminary psychometric study of an alternative approach, that of direct observational ratings. The Emotional Disorders Rating Scale (EDRS) is an observation-based instrument containing 59 items divided into eight subscales. The results of this study indicate that measurement of nonverbal components of affective symptoms in children is feasible. Interrater reliability and internal consistency of the EDRS subscales were high. The EDRS also has potential as a measurement of state-related changes in affective behavior and as a technique for examining treatment response.

Developmental differences in children's use of rating scales.

CT Chambers — 2005-08-04T19:50:04-00:00

J Pediatr Psychol, Vol. 27, No. 1. (b 2002), pp. 27-36.

OBJECTIVE: To examine the effect of child age and number of response choices on children's tendency to respond at the extremes of Likert-type scales rating emotional states. METHODS: Sixty children (5-6 years, 7-9 years, 10-12 years) were randomly assigned to use either three or five response choices in providing ratings in three different task conditions. Tasks were designed to have correct choices at the midpoints of the rating scales. Children also completed a self-report feelings questionnaire. RESULTS: Results showed that younger children responded in an extreme manner when rating emotion-based, but not physical, tasks. Children's extreme scores did not vary as a function of number of response choices used. More extreme scores on the three tasks were related to more extreme scores on the feelings questionnaire. CONCLUSIONS: These results indicate that young children may respond in an extreme manner when rating emotional states. Researchers and clinicians should take this into account when interpreting children's self-reporting ratings.

Fundamental dimensional properties of the operant.

TF GILBERT — 2005-07-24T21:12:27-00:00

Psychol Rev, Vol. 65, No. 5. (September 1958), pp. 272-282.

Stereotypic route-tracing in experimentally caged songbirds correlates with general behavioural disinhibition

Joseph Garner — 2005-08-24T23:31:59-00:00

Animal Behaviour, Vol. 66, No. 4. (October 2003), pp. 711-727.

Repetitive, unvarying and apparently functionless behaviours called stereotypies are common in caged animals, but the mechanisms of cage stereotypy have remained elusive. We found that stereotypies correlate with a sign of altered brain functioning, the general disinhibition of behaviour, found in stereotyping human patients and animals treated with psychostimulants. We investigated route-tracing stereotypy in blue tits, Parus caeruleus, and marsh tits,P. palustris , caged in a behavioural research laboratory. In experiment 1, stereotypy correlated with disinhibition of responses, shown as persistent responding in extinction learning. In experiment 2a, stereotypy in blue tits correlated with repetitive sequence generation on a ‘gambling task’ that specifically measures disinhibited striatal functioning in humans and correlates with stereotypy in autistic and schizophrenic patients. In experiment 2b, the behavioural disinhibition correlated with stereotypy also affected food-storing behaviour in marsh tits, in particular their response to cache pilfering. In experiment 3, the sequencing of nonstereotypic home cage behaviour was correlated with stereotypy. Finally, changes in stereotypy induced by environmental enrichment correlated with changes in these measures of altered behavioural control. These results suggest that housing conditions that cause stereotypy thus alter many aspects of the behavioural control of caged subjects, mediated by altered striatal functioning. The implications for understanding cage stereotypies in laboratory, farm and zoo animals, and for laboratory-based behavioural experiments, are discussed. We suggest that improving housing conditions so that cage stereotypies do not develop would enhance the validity of laboratory-based behavioural research.