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PubMed2002

Millon Clinical Multiaxial Inventory (MCMI-III): the inability of the validity conditions to detect random responders.

The effectiveness of the MCMI-III Validity scale, Scale X, and the Clinical Personality Pattern scales to detect random responding is put to the test. The binomial expansion and Monte Carlo techniques were used. If the examiner is willing to interpret tests of questionable validity, then 50% of the random responders will not be detected. Scale X and the Clinical Personality Pattern scales were useless in detecting random responders.

Adult↗
PubMed2004

[Validation of a new in vivo measurement method to measure subsidence of a cemented Exeter femoral stem].

PURPOSE OF THE STUDY: Total hip arthroplasty has become one of the most common procedures in orthopedic surgery. These patients must nevertheless be followed with care due to the risk of instability. Knowledge of early migration behavior can provide an indirect assessment of implant fixation. The purpose of this work was to develop a new measurement tool for early assessment of the femoral component. MATERIAL AND METHODS: We analyzed the x-rays of ten Exeter stems (Stryker-Howmedica) implanted between 1996 and 2001 using a simple software designed to calculate the vertical subsidence of each implant. The technical precision and inter-observer reproducibility were checked. RESULTS: The software provided a precision of 0.14-0.3 millimeters. The overall precision of the technique was 1.2 millimeters. There was no statistically significant inter-observer variability. We observed a mean subsidence of 1.3+/-0.7 millimeters at six Months, followed by no further migration. DISCUSSION AND CONCLUSION: This new method was found to be reliable. It is useful for identifying implant migration at different bone-cement-implant interfaces. The time course of subsidence appears to be important to determine threshold values for failure. This tool provides an easy-to-use method for both retrospective and prospective analysis. With minor modifications of the software program, this tool can be used for other types of implants.

Adult↗
PubMed1990

Performance evaluation of contemporary spirometers.

A comprehensive evaluation of 62 spirometers from 37 different sources was performed using a two-part protocol: calibrated syringe, and dynamic waveform testing. All testing was done with ambient air. Calibrated syringe testing examined the ability of the spirometers to accurately measure the output of a 3 L calibrating syringe under varying conditions. The accuracy, FVC volume linearity, and stability of each spirometer was determined from these data. All but five of 42 spirometers accurately measured a 3 L calibrating syringe to within +/- 3 percent. Dynamic waveform testing consisted of introducing 24 standard waveforms into the spirometer from a computer-controlled air pump. The values of FVC, FEV1, and FEF25-75% were compared to the actual values for each waveform to determine a performance rating. Only 35 (56.5 percent) of the spirometers performed acceptably when measuring the 24 standard waveforms. Nine (14.5 percent) were marginal and 18 (29.0 percent) were unacceptable. Fifty-nine (95 percent) of the 62 spirometers were computerized. Software errors were found in 25 percent of the computerized systems evaluated. Although using a 3 L syringe for quality control purposes is essential, simple testing of spirometers with a 3 L calibrating syringe for validation purposes was inadequate to assess spirometer performance when compared to dynamic waveform testing. Dynamic waveform testing is essential to accurately measure and validate acceptability of spirometer system performance.

Calibration↗
PubMed2003

Assessment of facial asymmetries from posteroanterior cephalograms: validity of reference lines.

The goal of this study was to determine the ability of various horizontal and vertical reference lines to provide measurements of dentofacial asymmetries from posteroanterior (PA) cephalograms. Ten horizontal and 15 vertical reference lines, including best-fit lines and lines most commonly used in PA analysis, were tested. A model of a dry skull was devised to create 30 asymmetric positions of the maxillomandibular complex. The true transverse and vertical asymmetries were calculated based on measurements of changes in the position of 24 dental and skeletal landmarks. A PA cephalogram was obtained for each asymmetric position. The horizontal and vertical reference lines were constructed on each PA cephalogram, and measurements of transverse and vertical asymmetries were obtained relative to the individual reference lines. Linear regression analyses were used to compare the actual asymmetries with those measured cephalometrically, relative to the individual reference lines. The adjusted R(2) values for all 10 horizontal lines indicated excellent agreement between the true asymmetries and the measured vertical asymmetries. Ten vertical lines accurately represented transverse asymmetry. Vertical lines constructed between 2 midline points, with 1 point located on the lower part of the skull, were not valid. The best-fit line and all lines constructed as perpendiculars through midpoints between pairs of orbital landmarks showed excellent validity. Crista galli-anterior nasal spine and nasion-anterior nasal spine had the lowest validity and should not be used in cephalometric analysis of asymmetries. The position of anterior nasal spine will be altered in facial asymmetry involving the maxilla.

Cephalometry↗
PubMed1993

Prevalidation of computer systems regulating medical device manufacturing processes.

When developing a computer system for regulating a medical device manufacturing process, it is advisable to incorporate validation criteria in the design and development of the system from the very beginning. Quality begins at the design stage and cannot be added at a later stage of system development. In this article, the author details the step-by-step process of software development that is recommended by the United States Food and Drug Administration (FDA) and utilized by the company in its development of a prevalidated sterilizer control system. By following FDA recommendations and using an external consultant to confirm validation, a prevalidated system can be supplied to the end-user. This provides the end-user with a number of significant benefits.

Computer-Aided Design↗
PubMed2005

The validation of a new method that measures contact and flight times during vertical jump.

The aim of this study was to design and validate a vertical jump assessing system based on flight time measurements. Hence, the first phase of this study consisted of programming the software SportJumpv-1.0 and adapting a contact mat and a computer mouse in order to record the flight and contact times of a jump test. In the second phase, 9 subjects made 12 maximal and submaximal vertical single and rebound jumps. Thus 108 flight times and 36 contact times were simultaneously obtained with five different systems: ErgoJump Bosco System (PS), SportJump-v1.0 (SJ), Force Plate (FP), High-speed camera (HSC), and a Led (LED) filmed with a high-speed camera; FP was considered as the reference system. No significant differences were found either between SJ and LED, or between FP and HSC systems. SJ and LED overestimate flight time (9 ms and p < 0.001) and underestimate contact time in respect to FP values. PS underestimates flight time regarding FP values (4 ms and p < 0.01). In spite of the differences obtained between the systems, the errors found are constant. Those slightly depend on the subject's body mass for the systems that are connected to a contact mat. A high correlation between all of them was obtained (r approximately 1 and p < 0.001). The SJ system was validated for an accuracy of 500 Hz, and it was shown to be a useful tool in measuring flight and contact times during jumping. The differences and correlations found between the five systems show that it is necessary to take into account which system is being used when analyzing vertical jump performance.

Adolescent↗
PubMed2001

Gamma ray induced DNA damage in human and mouse leucocytes measured by SCGE-Pro: a software developed for automated image analysis and data processing for Comet assay.

The studies reported in this communication had two major objectives: first to validate the in-house developed SCGE-Pro: a software developed for automated image analysis and data processing for Comet assay using human peripheral blood leucocytes exposed to radiation doses, viz. 2, 4 and 8 Gy, which are known to produce DNA/chromosome damage using alkaline Comet assay. The second objective was to investigate the effect of gamma radiation on DNA damage in mouse peripheral blood leucocytes using identical doses and experimental conditions, e.g. lyses, electrophoretic conditions and duration of electrophoresis which are known to affect tail moment (TM) and tail length (TL) of comets. Human and mouse whole blood samples were irradiated with different doses of gamma rays, e.g. 2, 4 and 8 Gy at a dose rate of 0.668Gy/min between 0 and 4 degrees C in air. After lyses, cells were electrophorased under alkaline conditions at pH 13, washed and stained with propidium iodide. Images of the cells were acquired and analyzed using in-house developed imaging software, SCGE-Pro, for Comet assay. For each comet, total fluorescence, tail fluorescence and tail length were measured. Increase in TM and TL was considered as the criteria of DNA damage. Analysis of data revealed heterogeneity in the response of leucocytes to gamma ray induced DNA damage both in human as well as in mouse. A wide variation in TM and TL was observed in control and irradiated groups of all the three donors. Data were analyzed for statistical significance using one-way ANOVA. Though a small variation in basal level of TM and TL was observed amongst human and mouse controls, the differences were not statistically significant. A dose-dependent increase in TM (P<0.001) and TL (P<0.001) was obtained at all the radiation doses (2-8 Gy) both in human and mouse leucocytes. However, there was a difference in the nature of dose response curves for human and mouse leucocytes. In human leucocytes, a linear increase in TM and TL was observed up to the highest radiation dose of 8 Gy. However, in case of mouse leucocytes, a sharp increase in TM and TL was observed only up to 4 Gy, and there after saturation ensued. In human samples, the dose response of both TM and TL showed best fits with linear model (r(TM)=0.999 and r(TL)=0.999), where as in mouse, the best fit was obtained with Sigmoid (Boltzman) model. From the present data on leucocytes with increase in TM and TL as the criteria of DNA damage, it appears that mouse is relatively more sensitive to radiation damage than humans.

Adult↗
PubMed1997

An example of usability measurement in clinical software procedures.

As a consequence of the dramatic improvements achieved in information technology standards in terms of single hardware and software components, efforts in the evaluation processes have been focused on the assessment of critical human factors, such as work-flow organisation, man-machine interaction and, in general, quality of use, or usability. This trend is particularly valid when applied to medical informatics, since the human component is the basis of the information processing system in health care context. With the aim to establish an action-research project on the evaluation and assessment of clinical software procedures which constitute an integrated Hospital Information System, the authors adopted this strategy and considered the measurement of perceived usability as one of the main goals of the project itself: the paper reports the results of this experience.

Attitude of Health Personnel↗
PubMed2004

Objective evaluation of three-dimensional image registration algorithms--tools for optimization and evaluation.

OBJECTIVE: The registration of medical volume data sets plays an important role when different images or modalities are used during computer-assisted surgical procedures. Nevertheless, it is often questionable how robust and accurate the underlying algorithms really are. Therefore, the goal is to foster the establishment of methods for an objective evaluation. METHOD: To reliably calculate the accuracy of registration algorithms, a reference transformation must be known. Due to the unknown perfect registration for real clinical data, the simulation of realistic data and successive affine transformations are employed. The simulation is based on models of the respective imaging modality where the dominant physical effects are taken into account. This gives the user full control over all simulation and transformation parameters. Finally, suitable quality measures are applied which allow a systematic evaluation of image registration accuracy by comparing the known theoretical result and the transformation calculated by the algorithm under investigation. RESULTS: During the development of a new registration algorithm, the presented method proved to be a very valuable tool for optimization and evaluation of registration accuracy, since it allows objective numerical comparison of the calculated results. CONCLUSIONS: The presented method can be used during the development of algorithms for optimization and for quantitative comparison of different registration schemes. The respective software tool can automatically generate and transform simulated but realistic data. Employing suitable numerical quality measures, an objective evaluation of registration results can be easily obtained. Still, the validity of the relatively simple models has to be verified to draw reliable conclusions with respect to real data.

Algorithms↗
PubMed2005

Validating DICOM content in a remote storage model.

Verifying the integrity of DICOM files transmitted between separate archives (eg, storage service providers, network attached storage, or storage area networks) is of critical importance. The software application described in this article retrieves a specified number of DICOM studies from two different DICOM storage applications; the primary picture archiving and communication system (PACS) and an off-site long-term archive. The system includes a query/retrieve (Q/R) module, storage service class provider (SCP), a DICOM comparison module, and a graphical user interface. The system checks the two studies for DICOM 3.0 compliance and then verifies that the DICOM data elements and pixel data are identical. Discrepancies in the two data sets are recorded with the data elements (tag number, value representation, value length, and value field) and pixel data (pixel value and pixel location) in question. The system can be operated automatically, in batch mode, and manually to meet a wide variety of use cases. We ran this program on a 15% statistical sample of 50,000 studies (7500 studies examined). We found 2 pixel data mismatches (resolved on retransmission) and 831 header element mismatches. We subsequently ran the program against a smaller batch of 1000 studies, identifying no pixel data mismatches and 958 header element mismatches. Although we did not find significant issues in our limited study, given other incidents that we have experienced when moving images between systems, we conclude that it is vital to maintain an ongoing, automatic, systematic validation of DICOM transfers so as to be proactive in preventing possibly catastrophic data loss.

Computer Communication Networks↗
PubMed2001

[The measurement of anxiety through computerized content analysis--automation of the Gottschalk-Gleser Test].

The Gottschalk-Gleser Content analysis for the measurement of anxiety and hostility has proven to be a valid and reliable content analytic method for the quantification of affects in many studies. It was used world-wide, German scales have been available since 1980. Especially in the field of psychosomatic medicine a lot of research was done. The certain use of this method, however, needs an extensive training and the application takes an enormous amount of time. For these reasons a computer program for the Gottschalk-Gleser analysis was developed in English language, whereas for German texts such a program has not been available up to this date. This report describes the development of a computer based anxiety measurement method in German--the Dresden Anxiety Dictionary (Dresdner Angstwörterbuch, DAW). The DAW is designed as a category system for use with different content analytic software. The test of reliability and validity, using 160 clinical texts, shows that the DAW is a reliable and valid method that can be used in different fields.

Anxiety↗
PubMed2003

Extracting numerical data from published reports of pharmacokinetics investigations: method description and validation.

A method has been proposed for extracting numerical data when only graphical results are presented. Reports with both graphical and tabular data were identified and the graphs were electronically scanned. The coordinates of each point were read using the cross-hair facility of Adobe Photoshop 7.0. To improve the precision of these coordinates, each point was read at 1600% magnification. The agreement between the observers was almost perfect (R > 0.99). The proposed method makes possible use of data in meta-analyses that, would otherwise be discarded.

Data Interpretation, Statistical↗
PubMed2006

Analysis and computer program for rupture-risk prediction of abdominal aortic aneurysms.

BACKGROUND: Ruptured abdominal aortic aneurysms (AAAs) are the 13th leading cause of death in the United States. While AAA rupture may occur without significant warning, its risk assessment is generally based on critical values of the maximum AAA diameter (> 5 cm) and AAA-growth rate (> 0.5 cm/year). These criteria may be insufficient for reliable AAA-rupture risk assessment especially when predicting possible rupture of smaller AAAs. METHODS: Based on clinical evidence, eight biomechanical factors with associated weighting coefficients were determined and summed up in terms of a dimensionless, time-dependent severity parameter, SP(t). The most important factor is the maximum wall stress for which a semi-empirical correlation has been developed. RESULTS: The patient-specific SP(t) indicates the risk level of AAA rupture and provides a threshold value when surgical intervention becomes necessary. The severity parameter was validated with four clinical cases and its application is demonstrated for two AAA cases. CONCLUSION: As part of computational AAA-risk assessment and medical management, a patient-specific severity parameter 0 < SP(t) < 1.0 has been developed. The time-dependent, normalized SP(t) depends on eight biomechanical factors, to be obtained via a patient's pressure and AAA-geometry measurements. The resulting program is an easy-to-use tool which allows medical practitioners to make scientific diagnoses, which may save lives and should lead to an improved quality of life.

Aortic Aneurysm, Abdominal↗
PubMed1992

Possibilities of software phantoms for quality control of KBS in nuclear medicine.

The assessment of the results of a "knowledge-based system" (KBS) for quality control is a basic requirement for clinical application: Large numbers of test studies are necessary in order to cover as widely as possible the spectrum of cases to be analyzed by the KBS. The use of original patient data as test data is one possibility, but real data are provided unevenly. This is due to the set of characteristics which are relevant to the analysis. Data are available in a limited quantity only. This implies a remaining set of unvalidated cases which are not represented in the data pool. The software phantom is an approach towards systematically guided validation. It permits the generation of test data adjusted to the demands of the validation.

Artificial Intelligence↗
PubMedDate not supplied

Computerized measurement of cognitive impairment and associated neuropsychiatric dimensions.

This study aimed to cross-validate the capacity of a computer software program to detect and measure, using a measurement method applied to the content and form analysis of 5-minute speech samples, cognitive impairment and associated comorbid neuropsychiatric psychobiological dimensions in drug-abusing patients. At the University of California-Irvine (UCI) Neuropsychiatric Center, 28 drug-abusing inpatients using illegal drugs were clinically evaluated. Their scores for cognitive impairment derived by the computerized content analysis method were compared with scores derived from selected tests from the Halstead-Reitan Neuropsychological Test Battery, the computerized Automated Neuropsychological Assessment Metric Battery (ANAM), the Alzheimer's Disease Assessment Scale-Cognitive Portion, the Stroop Color and Word Test, the Symbol Digit Modalities Test, and the Controlled Oral Word Association Test. The statistical significance (P value) of the correlations of scores from these different measures with scores obtained from the computerized content analysis measures was less than .05 to .001. The comparative "hit rate," detecting cognitive impairment above the norms for each measure administered to these drug-abusing patients, for the computerized content analysis measures and some of the ANAM neuropsychological measures was 75% to 89%, and for the other neuropsychological measures, 25% to 64%. In conclusion, the computerized content analysis methodology applied to 5-minute verbal samples is a valid, rapid, easily administered measurement instrument for assessing the magnitude of cognitive impairment and comorbid neuropsychiatric dimensions.

Adolescent↗
PubMed1998

Role and use of expert systems within the clinical laboratory.

Artificial intelligence can be used, mainly in the form of knowledge based systems, for different parts of clinical laboratory activity. Most of the iterative tasks for control and validation, or for maintenance or repair of automated instruments can be assisted by specialized software. There are now specific programmes (i) for control and validation of the request, where the goal is to modify the requesting behaviour of the physician, using protocol driven requests and immediate feedback, incorporating simultaneously a check of test request redundancy, (ii) for helping in equipment trouble-shooting, (iii) for technical and biological validation because too many QC data are issued from large equipment to be checked and used properly by the technologist whilst the pathologist can be assisted for the final revision of reports and (iv) for assistance in the interpretation of laboratory reports, one of the most valuable aspects of the pathologist's participation in the patient care process.

Clinical Chemistry Tests↗
PubMed2006

Development and validation of queries using structured query language (SQL) to determine the utilization of comparison imaging in radiology reports stored on PACS.

The purpose of this research was to develop queries that quantify the utilization of comparison imaging in free-text radiology reports. The queries searched for common phrases that indicate whether comparison imaging was utilized, not available, or not mentioned. The queries were iteratively refined and tested on random samples of 100 reports with human review as a reference standard until the precision and recall of the queries did not improve significantly between iterations. Then, query accuracy was assessed on a new random sample of 200 reports. Overall accuracy of the queries was 95.6%. The queries were then applied to a database of 1.8 million reports. Comparisons were made to prior images in 38.69% of the reports (693,955/1,793,754), were unavailable in 18.79% (337,028/1,793,754), and were not mentioned in 42.52% (762,771/1,793,754). The results show that queries of text reports can achieve greater than 95% accuracy in determining the utilization of prior images.

Database Management Systems↗
PubMed2003

Independent calculations to validate monitor units from ADAC treatment planning system.

Current standards of practice are based on the use of an independent calculation to validate the monitor units (MUs) derived from a treatment planning system. The ADAC PINNACLE treatment planning system has shown discrepancies of 10% or more compared to simple independent calculations for highly contoured areas such as tangential breast and chest wall irradiation. The ADAC treatment planning system generally requires more MUs to deliver the same prescribed dose. Independent MU calculation methods are based on full phantom conditions. On the other hand, the MUs from the ADAC treatment planning system are derived using realistic phantom scatter. As such, differences exist in TMR factors, off-axis wedge factors, and the phantom scatter factor. To systematically study the discrepancies due to phantom conditions, experimental measurements were performed with various percentages of tissue missing. The agreement between the experimental measurements and ADAC calculations was found to be within 2%. Using breast field geometry, a relationship between missing tissue and the dosimetric parameters used by ADAC was developed. This relationship, when applied, yielded independent MU calculations whose values closely matched those from the ADAC treatment planning system.

Algorithms↗