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PubMed2006

Internet based multicenter study for thoracolumbar injuries: a new concept and preliminary results.

This article reports about the internet based, second multicenter study (MCS II) of the spine study group (AG WS) of the German trauma association (DGU). It represents a continuation of the first study conducted between the years 1994 and 1996 (MCS I). For the purpose of one common, centralised data capture methodology, a newly developed internet-based data collection system ( http://www.memdoc.org ) of the Institute for Evaluative Research in Orthopaedic Surgery of the University of Bern was used. The aim of this first publication on the MCS II was to describe in detail the new method of data collection and the structure of the developed data base system, via internet. The goal of the study was the assessment of the current state of treatment for fresh traumatic injuries of the thoracolumbar spine in the German speaking part of Europe. For that reason, we intended to collect large number of cases and representative, valid information about the radiographic, clinical and subjective treatment outcomes. Thanks to the new study design of MCS II, not only the common surgical treatment concepts, but also the new and constantly broadening spectrum of spine surgery, i.e. vertebro-/kyphoplasty, computer assisted surgery and navigation, minimal-invasive, and endoscopic techniques, documented and evaluated. We present a first statistical overview and preliminary analysis of 18 centers from Germany and Austria that participated in MCS II. A real time data capture at source was made possible by the constant availability of the data collection system via internet access. Following the principle of an application service provider, software, questionnaires and validation routines are located on a central server, which is accessed from the periphery (hospitals) by means of standard Internet browsers. By that, costly and time consuming software installation and maintenance of local data repositories are avoided and, more importantly, cumbersome migration of data into one integrated database becomes obsolete. Finally, this set-up also replaces traditional systems wherein paper questionnaires were mailed to the central study office and entered by hand whereby incomplete or incorrect forms always represent a resource consuming problem and source of error. With the new study concept and the expanded inclusion criteria of MCS II 1, 251 case histories with admission and surgical data were collected. This remarkable number of interventions documented during 24 months represents an increase of 183% compared to the previously conducted MCS I. The concept and technical feasibility of the MEMdoc data collection system was proven, as the participants of the MCS II succeeded in collecting data ever published on the largest series of patients with spinal injuries treated within a 2 year period.

Adolescent↗
PubMed1998

Validation of the laboratory information system.

OBJECTIVE: To present an organized and practical approach to the validation of laboratory information systems. SOURCES: Personal experience, published papers, technical manuals, and Food and Drug Administration guidelines. DATA: Validation of the laboratory information system is the continuing process of proving the system fit for its intended use, initially and over time. It consists in defining, collecting, maintaining, and independently reviewing evidence that the system will perform consistently according to specification. Validation is tedious, difficult, and costly, but it must be done to assure that the system is fit for use and is working according to specification. In addition to professional and licensing bodies, laboratories making blood products fall under the regulatory requirements of the Food and Drug Administration. The buyer of a system is responsible for verifying that the developer has complied with all regulations and that the software products are validated to an appropriate degree, that the hardware is certified to perform its designated functions, that an appropriate period of acceptance testing has been done and documented, and that the system in use performs to specification and is under control. CONCLUSION: System validation demonstrates to all concerned, inside and outside the laboratory, that the laboratory information system manages information well, with the expected accuracy and reliability, file integrity, auditability, and management control.

Clinical Laboratory Information Systems↗
PubMed2006

Improving the accuracy of BRCA1/2 mutation prediction: validation of the novel country-customized IC software.

Inherited mutations of the BRCA1/2 genes confer a significantly increased risk for breast and/or ovarian cancer development. Several models were elaborated to help genetic counsellors in selecting individuals with high probability of being mutation carriers. The IC software, a country-customized version of the Brcapro model, was recently shown to be particularly accurate in the prediction of carrier probability status in the Italian population. Here, we used our independent series of 70 breast/ovarian cancer families to analyze the performances of the IC software and compare it to widely used models, such as Brcapro and the Myriad mutation prevalence tables. Analysis of the areas under the receiver operator characteristics (ROC) curves indicated that overall the models performed well. However, the IC software and Myriad tables were more efficient in predicting mutated cases, showing a higher sensitivity (94 and 88%, respectively) and negative predictive value (NPV, 94 and 92%, respectively) compared to Brcapro (sensitivity 71 and NPV 83%). IC software also appeared particularly accurate in the identification of families belonging the low mutation risk group (<10%). Finally, most Brcapro failures occurred in the hereditary breast cancer (HBC) family subset, and in 75% of the cases, the IC software corrected them. Our data suggest that the country-customized implementation operated on the Brcapro software generated a more accurate tool for the prediction of BRCA1/2 gene mutation. Whether the IC or other country-customized models might improve BRCA1/2 mutation prediction also in non-Italian families needs to be further explored.

BRCA1 Protein↗
PubMed1990

A fully automated chromatographic peak detection and treatment software for multi-user multi-task computers.

A fully automated method is presented for the detection and integration of chromatographic peak software in which the only parameter to define is the data acquisition frequency; this has to be chosen high enough to minimize some Nyquist frequency problems. Programmed in C language, the software is used on a Unix like system (Xenix) to emphasize its automaticity. The performance of the system in liquid chromatography has been studied in respect of noise frequency and intensity. It is shown that the classical signal-to-noise ratio is obsolete for definition of the detection limit since frequency analysis allows some signal filtration; these limitations are described. An example is given of simulation with Gaussian peaks convoluted with noise characterized by its intensity and frequency distribution. The validity of the software is demonstrated for some HPLC separations.

Autoanalysis↗
PubMed1999

MABDOSE. I: Characterization of a general purpose dose estimation code.

The MABDOSE software represents a general tool to perform internal radiation dosimetry. It uses a three-dimensional lattice in which to conduct radiation transport, scoring energy deposition in discrete voxels. The dosimetry system currently relies on the same algorithm used by the MIRD committee for photon transport, and assumes local deposition of particulate energy. A mathematical description of the dosimetry system's implementation is given. Additionally, a characterization of the system with respect to memory requirements, data libraries used, and simulation timing benchmarks, is presented. Validation of the software is presented in a companion manuscript.

Antibodies, Monoclonal↗
PubMed2006

Semi-automated 3-dimensional intracardiac echocardiography: development and initial clinical experience of a new system to guide ablation procedures.

BACKGROUND: Pre-interventional three-dimensional (3D) reconstruction of the heart by CT or MRI provides important information on cardiac anatomy for electrophysiological interventions. However, updates of 3D-imaging modalities with high soft-tissue contrast are not available during ablation procedures. OBJECTIVE: We describe the development and first clinical testing of a close to real-time visualization of cardiac anatomy by intracardiac echocardiography (ICE). METHODS: An electronic phased-array 5-10 MHz ICE-catheter (AcuNav/Siemens/64 elements) was inserted via a straightened femoral vein sheath (12F) and placed in the right atrium in 5 pigs. A custom-made prototype stepper motor allowed automatic rotation around the longitudinal axis from 90 degrees to 360 degrees in 2-5 degrees steps. For every plane 2D images of a complete cardiac cycle were acquired, triggered by respiration and ECG. The ultrasound images were digitized and 3D-reconstruction was performed by a prototype software. After experimental validation the system was tested in 6 patients during electrophysiological studies. RESULTS: From a single location in the right atrium, 3D-acquisition and reconstruction of both atria and ventricles with good image quality were achieved within 3-5 minutes. Doppler-mode facilitated identification of the great vessels including the pulmonary veins and their entry into the heart. 3D-visualization of ablation catheters was also possible in all patients and pigs. CONCLUSION: Semi-automated 3D intracardiac echocardiography from a single site inside the right atrium provides the electrophysiologist with a detailed image of both atria and ventricles with repeated updates of the cardiac anatomy.

Animals↗
PubMed2006

Enantiomeric separation of omeprazole and its metabolite 5-hydroxyomeprazole using non-aqueous capillary electrophoresis.

This study demonstrates the development and validation of a non-aqueous capillary electrophoresis (NACE) method for enantiomeric determination of omeprazole and its metabolite 5-hydroxyomeprazole. Heptakis-(2,3-di-O-methyl-6-O-sulfo)-beta-cyclodextrin (HDMS-beta-CD) was chosen as the chiral selector in an ammonium acetate buffer acidified with formic acid in methanol. Parameters such as CD concentration, concentration of buffer electrolyte, voltage and temperature were studied in order to optimize both the enantioresolution and migration times. An experimental design was utilized for method optimization, using software Modde 5.0. Validation of the developed method showed good linearity, which was tested over a concentration range of 2.5-500 microM. The regression coefficients for S-omeprazole, S-5-hydroxyomeprazole, R-omeprazole and R-5-hydroxyomeprazole were between 0.996 and 0.997. The limits of detection for the four enantiomers were in the range from 45 to 51microM and the limits of quantification were between 149 and 170 microM with UV detection at 301nm. Using a reduced temperature of 16 degrees C gave improved resolution values, reproducibility and also decreased the occurrence of current loss within the capillary. RSD values for peak migration time were calculated to be between 0.41 and 1.48% using an inter-day study.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2004

Determination of stable housekeeping genes, differentially regulated target genes and sample integrity: BestKeeper--Excel-based tool using pair-wise correlations.

The stability of standard gene expression is an elementary prerequisite for internal standardisation of target gene expression data and many so called housekeeping genes with assumed stable expression can exhibit either up- or down-regulation under some experimental conditions. The developed, and herein presented, software called BestKeeper determines the best suited standards, out of ten candidates, and combines them into an index. The index can be compared with further ten target genes to decide, whether they are differentially expressed under an applied treatment. All data processing is based on crossing points. The BestKeeper software tool was validated on four housekeeping genes and 10 members of the somatotropic axis differentially expressed in bovine corpora lutea total RNA. The BestKeeper application and necessary information about data processing and handling can be downloaded on http://www.wzw.tum.de/gene-quantification/bestkeeper.html.

Animals↗
PubMed2004

Finite element solution of the steady-state Smoluchowski equation for rate constant calculations.

This article describes the development and implementation of algorithms to study diffusion in biomolecular systems using continuum mechanics equations. Specifically, finite element methods have been developed to solve the steady-state Smoluchowski equation to calculate ligand binding rate constants for large biomolecules. The resulting software has been validated and applied to mouse acetylcholinesterase. Rates for inhibitor binding to mAChE were calculated at various ionic strengths with several different reaction criteria. The calculated rates were compared with experimental data and show very good agreement when the correct reaction criterion is used. Additionally, these finite element methods require significantly less computational resources than existing particle-based Brownian dynamics methods.

Acetylcholinesterase↗
PubMed1997

Procedure for studying commutability validated by biological variation.

In the field of laboratory medicine, the two quantitative approaches designed to identify the stabilized materials that produce results that are commutable with results from patients' samples were found to differ. In commutability evaluations, the responses of each material and each method studied are specific, thus, it is vital to standardise the procedure used for determining this characteristic. We incorporated statistical components from the two described methods that seemed to be consistent, and added a new element based on biological variation, to validate the criterion of acceptability that determines whether or not a material is commutable. The three methods for studying commutability (using the confidence interval [alpha = 0.05], the +/- 2s(yx) formula, and the limit based on biological variation as acceptability criteria) were applied to creatinine results from 31 stabilised materials and serum samples analysed with seven instruments, when compared against a reference method for creatinine analysis. Over the wide range of concentrations studied, the confidence interval limit and the biological variation limit coincided in the identification of commutable materials, whereas the +/- 2s(yx) was excessively permissive at normal and low concentration levels. We therefore recommend the use of Passing-Bablok regression with its confidence interval (alpha = 0.05) in studies concerning commutability. Using this method, commutability is simple to calculate with available software and, as validated by biological variation, results are reliable.

Chromatography, High Pressure Liquid↗
PubMed2003

Methods to determine private sector payment for VA outpatient services: institutional payments to providers.

OBJECTIVES: To describe methods used to estimate hospital institutional (facility) payments for providing Veterans Health Administration (VA) outpatient services. METHODS: A series of audits compared the accuracy of outpatient coding at six VA medical centers in federal fiscal year 1999 with private sector standards. Outpatient records were processed through industry standard software to determine validity and remove inappropriate services. Private sector payments were estimated by applying average payment data from Medicare cost reports and Medicare outpatient prospective payment schedules to counts of VA services. RESULTS: Coding audits found little difference in accuracy between VA and the community. Physician visits generated the most estimated payments and deviated most from Medicare payment experience. Radiology and laboratory services were the next highest expenditure categories for both the VA and Medicare. The proportion of radiology payments in VA data was notably lower and ambulatory surgery notably higher than Medicare's experience. Within major categories, the relative rankings of VA and Medicare services were consistent. DISCUSSION: Differences in payment criteria make exact cost comparisons of hospital-based and office-based settings difficult, particularly physician visits. Two VA clinical software applications, radiology and laboratory, provide information not readily convertible to a claims format; these applications need significant changes to be used for these purposes. They understate radiology services and overstate laboratory services compared with private sector standards. In addition, the laboratory application contains inappropriate or unspecified codes that cannot be accurately valued for many reasons.

Health Care Costs↗
PubMed2007

Measurements of DNA damage on silver stained comets using free Internet software.

Silver stain offers the possibility to stain comets permanently, but up to now it was impossible to measure the majority of the comet parameters, because the distinction between head and tail was not recognised by software. Here, we report a silver staining protocol that allows the measurement of comet parameters using the free Internet software CASP. We validated the silver stain protocol by comparing the behaviour of the parameter '% DNA in tail' in silver and fluorescent stained comets. The range of % DNA in tail for different visual categories of damage in silver stained comets was similar to that reported with fluorescence staining. The range was for category 0 (no damage), <1%; category 1 (low damage), 1-25%; category 2 (medium damage), >25-45%; category 3 (high damage), >45-70%; category 4 (very high damage), >70%. The mean of % DNA in tail in silver stained comets was also similar to that reported with fluorescence staining. The mean was for category 0, 0.4+/-0.34%; category 1, 12+/-7%; category 2, 37+/-4%; category 3, 57+/-5% and category 4, 83+/-6%. Others comet parameters such as tail length, tail moment and Olive tail moment can be also measured. The silver staining protocol reported here opens new opportunities for those working in the assay without fluorescent microscope as the measurement of comet parameters using free Internet software and conventional microscope becomes possible.

Comet Assay↗
PubMed2006

Use of a non-contact 3D digitiser to measure the volume of keloid scars: a useful tool for scar assessment.

Keloid scars often fail to respond to treatment, so research into new therapeutic regimes is important. However, research is limited by a scarcity of reliable, objective scar assessment tools. The volume of a keloid scar should decrease with successful treatment. This study demonstrates the use of a non-contact 3D digitiser to measure digitally the volume of a keloid scar. The scanner was used to scan 62 keloid scars and one fine-line normal scar. The scan took approximately 9s to complete. The volume was measured using 3D reverse modelling software. A previously validated scar assessment scale was used to score the scars according to their physical parameters. A significant correlation was found between volume and the scar score (Pearson's r=0.627, p<0.001). Linear regression was also statistically significant (p<0.001, R(2)=0.44). Therefore it was possible to predict the scar score from the measured volume. This technique could allow monitoring of a patient on treatment, or comparison of treatments in a research setting. It overcomes previous problems with the measurement of scar volume as it is quantitatively objective and well-tolerated.

Adult↗
PubMed2001

Winner take all experts network for sensor validation.

The validation of sensor measurements has become an integral part of the operation and control of modern industrial equipment. The sensor under harsh environment must be shown to consistently provide the correct measurements. Analysis of the validation hardware or software should trigger an alarm when the sensor signals deviate appreciably from the correct values. Neural network based models can be used to on-line estimate critical sensor values when neighboring sensor measurements are used as inputs. The underlying assumption is that the neighboring sensors share an analytical relationship. The discrepancy between the measured and predicted sensor values may then be used as an indicator for sensor health. The proposed Winner Take All Experts (WTAE) network based on a 'divide and conquer' strategy significantly reduces the computational time required to train the neural network. It employs a growing fuzzy clustering algorithm to divide a complicated problem into a series of simpler sub-problems and assigns an expert to each of them locally. After the sensor approximation, the outputs from the estimator and the real sensor readings are compared both in the time domain and the frequency domain. Three fault indicators are used to provide analytical redundancy to detect the sensor failure. In the decision stage, the intersection of three fuzzy sets accomplishes a decision level fusion, which indicates the confidence level of the sensor health. Two data sets, the Spectra Quest Machinery Fault Simulator data set and the Westland vibration data set, were used in simulations to demonstrate the performance of the proposed WTAE network. The simulation results show the proposed WTAE is competitive with or even superior to the existing approaches.

Journal Article↗
PubMedDate not supplied

Comparison of Tc-99m sestamibi and Tl-201 gated perfusion SPECT.

BACKGROUND: To determine the interpretability of gated thallium-201 perfusion SPECT compared with that performed by use of technetium-99m sestamibi (MIBI), 33 patients with prior myocardial infarction were studied. Patients received 22 to 30 mCi (814 to 1110 MBq) MIBI at peak stress, and a 15-minute gated SPECT acquisition was begun 30 to 40 minutes thereafter. On a subsequent day gated Tl-201 SPECT was acquired for 15 minutes, 4 hours after a resting 3.5 mCi (130 MBq) injection. SPECT was performed over a 180-degree arc by use of a 90-degree angled 2-detector camera. RESULTS: Gated studies were interpreted independently by 4 experienced physicians. Study quality was graded (0 = uninterpretable to 4 = excellent). Wall motion (0 = normal to 2 = akinetic/dyskinetic) and wall thickening (0 = normal to 2 = absent) were graded for each of 10 segments viewed in orthogonal planes. Left ventricular ejection fraction (LVEF) was calculated by use of software thus far validated only for MIBI. The average count density of mid-ventricular end-diastolic short axis tomograms with sestamibi was 3.47 times greater than with thallium. Mean study quality was 3.4 for MIBI and 1.8 for thallium (P < 10(-6)). No gated MIBI SPECTs, but 2 gated thallium studies (6%) were judged uninterpretable. Among interpretable scans, interobserver agreement (Kendall statistic) in assessing wall motion was 0.73 for MIBI and 0.66 for thallium (P = .01). For assessing wall thickening, the Kendall statistic was 0.73 for MIBI and 0.69 for thallium (P = .05). Correlation (r) of LVEFs was 0.91, SEE = 6.4. CONCLUSIONS: We conclude that gated thallium SPECT is inferior to MIBI because of much poorer image quality and somewhat poorer interobserver agreement among experienced physicians. However, LVEF can be determined reliably from gated thallium SPECT.

Female↗
PubMed2005

Attenuation correction single-photon emission computed tomography myocardial perfusion imaging.

Clinicians now rely heavily on the results of single-photon emission computed tomography (SPECT) myocardial perfusion imaging for diagnosing coronary disease and for planning therapy. However, the technique is imperfect for these purposes, mainly because of technical limitations, the most prominent of which is the effect of soft-tissue attenuation on apparent tracer distribution. Providers have attempted to compensate for this by a number of indirect approaches. Recently, validated hardware and software solutions for directly correcting image data for soft-tissue attenuation have become widely available commercially. Optimal application requires an understanding of the technical details that differ somewhat from system to system, the quality control prerequisites, knowledge of the importance of the transmission map quality, and how dedicated SPECT and SPECT-computed tomography systems present different challenges. In addition, the clinical literature is expanding rapidly, including studies on diagnostic accuracy, image appearances, quantitative analysis, appropriate patients for attenuation correction, clinical utility, incremental value in relation to ECG-gating, and risk stratification.

Algorithms↗
PubMed1999

Certification of highly complex safety-related systems.

The BIA has now 15 years of experience with the certification of complex electronic systems for safety-related applications in the machinery sector. Using the example of machining centres this presentation will show the systematic procedure for verifying and validating control systems using Application Specific Integrated Circuits (ASICs) and microcomputers for safety functions. One section will describe the control structure of machining centres with control systems using "integrated safety." A diverse redundant architecture combined with crossmonitoring and forced dynamization is explained. In the main section the steps of the systematic certification procedure are explained showing some results of the certification of drilling machines. Specification reviews, design reviews with test case specification, statistical analysis, and walk-throughs are the analytical measures in the testing process. Systematic tests based on the test case specification, Electro Magnetic Interference (EMI), and environmental testing, and site acceptance tests on the machines are the testing measures for validation. A complex software driven system is always undergoing modification. Most of the changes are not safety-relevant but this has to be proven. A systematic procedure for certifying software modifications is presented in the last section of the paper.

Electronics↗
PubMed2006

Investigating the accuracy of the FLUKA code for transport of therapeutic ion beams in matter.

In-beam positron emission tomography (PET) is currently used for monitoring the dose delivery at the heavy ion therapy facility at GSI Darmstadt. The method is based on the fact that carbon ions produce positron emitting isotopes in fragmentation reactions with the atomic nuclei of the tissue. The relation between dose and beta(+)-activity is not straightforward. Hence it is not possible to infer the delivered dose directly from the PET distribution. To overcome this problem and enable therapy monitoring, beta(+)-distributions are simulated on the basis of the treatment plan and compared with the measured ones. Following the positive clinical impact, it is planned to apply the method at future ion therapy facilities, where beams from protons up to oxygen nuclei will be available. A simulation code capable of handling all these ions and predicting the irradiation-induced beta(+)-activity distributions is desirable. An established and general purpose radiation transport code is preferred. FLUKA is a candidate for such a code. For application to in-beam PET therapy monitoring, the code has to model with high accuracy both the electromagnetic and nuclear interactions responsible for dose deposition and beta(+)-activity production, respectively. In this work, the electromagnetic interaction in FLUKA was adjusted to reproduce the same particle range as from the experimentally validated treatment planning software TRiP, used at GSI. Furthermore, projectile fragmentation spectra in water targets have been studied in comparison to available experimental data. Finally, cross sections for the production of the most abundant fragments have been calculated and compared to values found in the literature.

Carbon↗