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At least 613 records · Page 34Linked to original sources
PubMed1998

The Department of Veterans Affairs integration of imaging into the healthcare enterprise using the VistA Hospital Information System and Digital Imaging and Communications in Medicine.

The United States Department of Veterans Affairs is integrating imaging into the healthcare enterprise by using the Digital Imaging and Communication in Medicine (DICOM) standard protocols. Image management is directly integrated into the VistA Hospital Information System (HIS) software and clinical database. Radiology images are acquired with DICOM and are stored directly in the HIS database. Images can be displayed on low-cost clinician's workstations throughout the medical center. High-resolution diagnostic quality multimonitor VistA workstations with specialized viewing software can be used for reading radiology images. Two approaches are used to acquire and handle images within the radiology department. Some sites have a commercial Picture Archiving and Communications System (PACS) interfaced to the VistA HIS, whereas other sites use the direct image acquisition and integrated diagnostic display capabilities of VistA itself. A small set of DISCOM services has been implemented by VistA to allow patient and study text data to be transmitted to image producing modalities and the commercial PACS, and to enable images and study data to be transferred back. DICOM has been the cornerstone in the ability to integrate imaging functionality into the healthcare enterprise. Because of its openness, it allows the integration of system components from commercial and noncommercial sources to work together to provide functional cost-effective solutions.

Computer Communication Networks↗
PubMed1982

An investigation into EEG asymmetry in young children.

Microprocessor-based equipment was designed and built which enabled on-line analysis of the EEG information to be performed. The heart of the machine is an arithmetic processing unit, used to enhance the number manipulation capability of the processor system. Data from a group of ten children were recorded on an f.m. tape recorder and this was used for a comparison between three methods of analysis. A versatile, portable EEG acquisition and processing system has been designed, implemented and tested. All results obtained so far imply that brain lateralisation is observable in children at 7 years old and there seems to be a link between degree of lateralisation and reading ability.

Child↗
PubMed2004

Sensitivity-enhanced quantitative 13C NMR spectroscopy via cancellation of 1J(CH) dependence in DEPT polarization transfers.

A scheme has been developed to eliminate virtually all signal intensity dependence on 1JCH in polarization transfers between 1H and 13C nuclei, reducing differences in signal intensity to only 1.5% over the entire natural 1JCH range. The scheme relies on the summation of time-domain data acquired with four suitably selected Delta delays so that the J dependence is essentially canceled in the final, signal-averaged free-induction decay. These Delta delays have been incorporated into the DEPT pulse sequence to create sensitivity-enhanced experiments for collecting quantitative 13C{1H} spectra. Four experiments, each with unique read pulse angles, give quantitative spectra with 200-300% more sensitivity than conventional 13C spectra acquired with inverse-gated 1H decoupling. The experiments are ideal for recording spectra with improved quantitative information or for substantially reducing the long acquisition times indicative of quantitative 13C experiments. The ability of the experiments to provide quantitative spectra was demonstrated with a simple ethylbenzene solution, however, they can easily be adapted to various applications for analysis of complex mixtures.

Journal Article↗
PubMed2004

pO(2) Polarography versus positron emission tomography ([(18)F] fluoromisonidazole, [(18)F]-2-fluoro-2'-deoxyglucose). An appraisal of radiotherapeutically relevant hypoxia.

BACKGROUND AND PURPOSE: The aim of the present study was to validate ([(18)F] fluoromisonidazole (FMISO) and [(18)F]-2-fluoro-2'-deoxyglucose (FDG) positron emission tomography (PET) for determination of radiotherapeutically relevant hypoxia by the gold standard for measuring tissue oxygenation in human tumors, the computerized polarographic needle electrode system (pO(2) histography). PATIENTS AND METHODS: Up to now, a total of 16 patients with a metastatic neck lymph node from a primary squamous carcinoma of the head and neck underwent pO(2) and PET measurements. Tumor tissue pO(2) was measured with polarographic needle electrodes using a pO(2) histograph (Eppendorf). Under CT control, the needle electrode was placed in the tumor without general or local anesthesia. To assess the biological and clinical relevance of oxygenation measurement, the relative frequency of pO(2) readings, with values < or = 2.5, < or = 5.0, and < or = 10.0 mmHg, as well as mean and median pO(2) were recorded. All PET studies were carried out using an ECAT EXACT 922/47 scanner with an axial field of view of 16.2 cm. FMISO PET consisted of one static scan of the relevant region, performed 120 min after intravenous administration. The acquisition and reconstruction parameters were as follows: 15-min emission scanning and 4-min transmission scanning with (68)Ge rod sources. FDG PET of the lymph node metastasis was performed 68 +/- 11 min after intravenous administration, applying the whole-body tool with 8-min emission scanning and 4-min transmission scanning per bed position. RESULTS: In order to detect possible relations between the different relevant polarographically measured parameters of tumor hypoxia and FMISO PET data-based oxygenation values, the Pearson correlation coefficient was calculated. Average (r > 0.5) to high correlation (r > 0.7) was found between tumor-to-muscle ratio of FMISO after 2 h and parameters of hypoxic fraction (pO(2) readings with values <or = 2.5, < or = 5.0, and < or = 10.0 mmHg as well as mean and median). No correlations could be shown between FDG PET parameters and polarographically determined tumor oxygenation status. CONCLUSION: Summarizing the FMISO uptake represents a global value for macroscopic tumor parts. As a noninvasive measurement this method seems highly feasible to evaluate the state of oxygenation in subjacent tumors.

Carcinoma, Squamous Cell↗
PubMed2003

Hepatocellular carcinoma: detection with triple-phase multi-detector row helical CT in patients with chronic hepatitis.

PURPOSE: To evaluate whether the use of two arterial phase image acquisition series, when combined with portal venous phase imaging at multi-detector row helical computed tomography (CT), would be superior enough to use of a single arterial phase image acquisition series to warrant the increased radiation dose. MATERIALS AND METHODS: Multi-detector row CT was performed in 77 patients with 140 foci of hepatocellular carcinoma (HCC). A triple-phase protocol that included an early arterial phase, a late arterial phase, and a portal venous phase was performed. Images were analyzed separately by three radiologists to document the presence and number of HCC nodules. Separate reading sessions were performed for images from the early arterial phase, images from the late arterial phase, images from both arterial phases combined, and images from all three phases. Sensitivity and positive predictive values were calculated for each reading session. RESULTS: The average sensitivity and positive predictive values, respectively, for the detection of HCC were 48.5% and 96.4% for early arterial phase images, 87.1% and 94.0% for late arterial phase images, 87.1% and 94.0% for images from both arterial phases, and 88.5% and 93.4% for images from all three phases. Analysis of images from both arterial phases together yielded no improvement in either sensitivity or positive predictive value compared with analysis of late arterial phase images alone. Analysis of the combination of late arterial and portal venous phase images resulted in the highest sensitivity value. CONCLUSION: The acquisition of images during two arterial contrast phases does not provide additional benefit over timed conventional biphasic CT technique.

Aged↗
PubMed1995

Limitations of stimulated echo acquisition mode (STEAM) techniques in cardiac applications.

Stimulated echoes are widely used for imaging functional tissue parameters such as diffusion coefficient, perfusion, and flow rates. They are potentially interesting for the assessment of various cardiac functions. However, severe limitations of the stimulated echo acquisition mode occur, which are related to the special dynamic properties of the beating heart and flowing blood. To the well-known signal decay due to longitudinal relaxation and through-plane motion between the preparation and the read-out period of the stimulated echoes, additional signal loss is often observed. As the prepared magnetization is fixed with respect to the tissue, this signal loss is caused by the tissue deformation during the cardiac cycle, which leads to a modification of the modulation frequency of the magnetization. These effects are theoretically derived and corroborated by phantom and in vivo experiments.

Blood Flow Velocity↗
PubMed2003

[New computed radiography technologies in digital radiography].

Digital radiography (DR) has become integral to modern diagnostic radiology. One of the earliest forms of DR, computed radiography (CR) using storage phosphors, has established itself as the mainstay of DR-based diagnostic imaging over the past 20 years. More recently, flat-panel DR systems based on solid state X-ray detectors with integrated, large-area, active-matrix readout electronics are promising further improvements in clinical workflow and image quality. Despite CR's longevity, innovations continue to be made. New developments in CR screen technologies, like structured (needle) screens, and new scanner concepts based on line-at-a-time reading promise major improvements in image quality (comparable to that of flat-panel systems), system through-put and physical size, at a cost comparable to that of today's systems. Thus, despite the advent of flat-panel acquisition systems, there will still be an important role for CR in the foreseeable future. After a brief review of the current state of CR technology, this paper will explore several of these new CR developments and present some examples of their potential clinical impact.

Artifacts↗
PubMed2003

Molecular mechanisms of gene regulation studied by site-directed spin labeling.

The technique of site-directed spin labeling using cysteine substitution mutagenesis followed by modification of the sulfhydryl group with a nitroxide reagent is emerging as a valuable alternative for the determination of protein folds and conformational changes in a variety of systems. The incorporation of pairs of nitroxides allows determination of intramolecular distances and distance changes with a spatial resolution at the level of the backbone fold under conditions relevant to function. The methodology of electron paramagnetic resonance spectral data acquisition and interpretation is reviewed with studies on conformational changes of Tet repressor (TetR) and the human immunodeficiency virus type 1 reverse transcriptase (RT) on interaction with nucleic acid substrates or inhibitors in solution. A twisting motion of the DNA reading heads of TetR on induction by tetracycline (tc) is observed in solution by changes of the interspin distances between interacting nitroxides at positions 22/22(') or 47/47('). Spin-label side chains located near the tc-binding pocket or at position 202 indicate different conformations for the tc- and DNA-complexed repressor also in the core of the protein. Interspin distances between spin-labeled residue positions 24 and 287 in the fingers and the thumb domains of RT complexed with dsDNA or a pseudoknot RNA in solution were found to agree with the respective crystal data of the so-called open and closed conformations. For the unliganded RT a temperature-dependent equilibrium between these two states is observed.

Electron Spin Resonance Spectroscopy↗
PubMed2000

Protein identification with a single accurate mass of a cysteine-containing peptide and constrained database searching.

A method for rapid and unambiguous identification of proteins by sequence database searching using the accurate mass of a single peptide and specific sequence constraints is described. Peptide masses were measured using electrospray ionization-Fourier transform ion cyclotron resonance mass spectrometry to an accuracy of 1 ppm. The presence of a cysteine residue within a peptide sequence was used as a database searching constraint to reduce the number of potential database hits. Cysteine-containing peptides were detected within a mixture of peptides by incorporating chlorine into a general alkylating reagent specific for cysteine residues. Secondary search constraints included the specificity of the protease used for protein digestion and the molecular mass of the protein estimated by gel electrophoresis. The natural isotopic distribution of chlorine encoded the cysteine-containing peptide with a distinctive isotopic pattern that allowed automatic screening of mass spectra. The method is demonstrated for a peptide standard and unknown proteins from a yeast lysate using all 6118 possible yeast open reading frames as a database. As judged by calculation of codon bias, low-abundance proteins were identified from the yeast lysate using this new method but not by traditional methods such as tandem mass spectrometry via data-dependent acquisition or mass mapping.

Amino Acid Sequence↗
PubMed1996

Radiology information and image management system: new approach to PACS with hypermedia capabilities of personal computers.

A system for archiving patient data and images was developed, installed, and evaluated in a radiology department. The system was developed with a relational database program for use with commercially available computers linked with an Ethernet network. The main options of the system are those of a conventional radiology information system: scheduling, registration, examination execution, reporting, archives and statistics, and system administration. However, the main feature of the system is the image archiving capability. Images are associated with patient records after capture by direct acquisition of the video signal or by scanning. Only relevant pathologic images are archived and a commonly employed compression algorithm is used, reducing the total memory requirement for each case to 200-600 kbytes. The diagnosis is still made by reading the original images. The low-resolution images stored in the system have an important role in teaching and consultation and as a first-line archive. Good results have been obtained with this system, which is used by medical and nonmedical staff without any special training.

Humans↗
PubMed2005

Evidence for acquisition of Legionella type IV secretion substrates via interdomain horizontal gene transfer.

Intracellular pathogens exploit host cell functions to create a replication niche inside eukaryotic cells. The causative agent of Legionnaires' disease, the gamma-proteobacterium Legionella pneumophila, resides and replicates within a modified vacuole of protozoan and mammalian cells. L. pneumophila translocates effector proteins into host cells through the Icm-Dot complex, a specialized type IVB secretion system that is required for intracellular growth. To find out if some effector proteins may have been acquired through interdomain horizontal gene transfer (HGT), we performed a bioinformatic screen that searched for eukaryotic motifs in all open reading frames of the L. pneumophila Philadelphia-1 genome. We found 44 uncharacterized genes with many distinct eukaryotic motifs. Most of these genes contain G+C biases compared to other L. pneumophila genes, supporting the theory that they were acquired through HGT. Furthermore, we found that several of them are expressed and up-regulated in stationary phase in an RpoS-dependent manner. In addition, at least seven of these gene products are translocated into host cells via the Icm-Dot complex, confirming their role in the intracellular environment. Reminiscent of the case with most Icm-Dot substrates, most of the strains containing mutations in these genes grew comparably to the parent strain intracellularly. Our findings suggest that in L. pneumophila, interdomain HGT may have been a major mechanism for the acquisition of determinants of infection.

Amino Acid Motifs↗
PubMed1994

Effects of practice on tip-of-the-tongue states.

Tip-of-the-tongue (TOT) states were examined in relation to acquisition manipulations, using named imaginary animals (TOTimals) as targets. High levels of TOT states were found in three experiments. In the first experiment an increase in the duration of initial exposure to target material improved recall and recognition, and reduced the number of unrecalled items not in TOT states (NTOTs), but did not affect TOT levels. In Experiment 2 practice at writing target names, as compared with only reading them, improved recall performance and decreased TOT levels, but did not reduce NTOTs. Experiment 3 replicated the finding that writing during practice reduced TOT states, but did not reduce NTOTs, and also found that more frequent practice trials increased recall without affecting TOT levels. The results suggest that practice writing target names prevents TOT states by strengthening otherwise deficient phonological connections in memory, a deficiency that can cause TOT states when visual-to-lexical connections give only partial access to a target in memory. The results also demonstrate the usefulness of the TOTimal technique for testing effects of acquisition variables on TOT experiences.

Analysis of Variance↗
PubMed1997

Recombination creates novel L1 (LINE-1) elements in Rattus norvegicus.

Mammalian L1 (long interspersed repeated DNA. LINE-1) retrotransposons consist of a 5' untranslated region (UTR) with regulatory properties, two protein encoding regions (ORF I, ORF II, which encodes a reverse transcriptase) and a 3' UTR. L1 elements have been evolving in mammals for > 100 million years and this process continues to generate novel L1 subfamilies in modern species. Here we characterized the youngest known subfamily in Rattus norvegicus, L1mlvi2, and unexpectedly found that this element has a dual ancestry. While its 3' UTR shares the same lineage as its nearest chronologically antecedent subfamilies, L13 and L14, its ORF I sequence does not. The L1mlvi2 ORF I was derived from an ancestral ORF I sequence that was the evolutionary precursor of the L13 and L14 ORF I. We suggest that an ancestral ORF I sequence was recruited into the modern L1mlvi2 subfamily by recombination that possibly could have resulted from template strand switching by the reverse transcriptase during L1 replication. This mechanism could also account for some of the structural features of rodent L1 5' UTR and ORF I sequences including one of the more dramatic features of L1 evolution in mammals, namely the repeated acquisition of novel 5' UTRs.

Animals↗
PubMed2006

Reading and spelling abilities in children with severe speech impairments and cerebral palsy at 6, 9, and 12 years of age in relation to cognitive development: a longitudinal study.

Development of literacy skills was studied in six children (one male, five females) with severe speech impairments and cerebral palsy (CP). These skills were related to intellectual development, phonological abilities, and short-term memory. Three of the children were diagnosed with dystonia, and three with diplegia. They had no, or severely restricted, independent mobility (Gross Motor Function Classification System Level IV for four children and Level V for two), and severe fine motor problems, including difficulty with pointing. As they had no intelligible speech, the Bliss system was the primary communication mode. Assessments were made at approximately 6, 9, and 12 years of age. The results revealed that the children had difficulties acquiring literacy skills, although intellectual level and phonological ability predicted otherwise. Positive development during the first 3 years was followed by an arrest. A conspicuous decrease in IQ points was also found. Thus, phonological ability does not seem to have the same predictive power for literacy development in children with severe speech impairments and CP as in typically developing children. Further studies are needed to clarify the role of phonological abilities, working memory, and strategies used in literacy acquisition in these children. Such studies might also clarify the importance of articulatory abilities in early literacy acquisition.

Adolescent↗
PubMedDate not supplied

SPIO-enhanced 2D-TOF MR angiography of the portal venous system: results of an intraindividual comparison.

The purpose of this study was to investigate whether MR angiography (MRA) of the portal venous system may be improved by means of superparamagnetic iron oxides (SPIOs) during accumulation phase imaging and to study the underlying contrast mechanisms. MRA of the portal venous system was performed on 48 patients before and after intravenous injection of a new SPIO (Resovist, Schering AG, Berlin, Germany). Resovist, as a predominantly liver parenchymal darkening agent on T2-weighted MR images with uptake into the reticuloendothelial cell system, was administered intravenously by bolus injection of 8 to 12 micromol Fe/kg body weight. Patients were scanned with breath-hold coronal and axial two-dimensional (2D) time of flight (TOF) MRA (TR = 31.0 msec, TE = 9.8 msec, flip angle (FA) = 50 degrees, and 6.9-second acquisition time per section) sequences. Signal intensity values of liver parenchyma, the portal venous system, and background were obtained for quantitative analysis. The clinical relevance of additional plain and contrast-enhanced MRA studies for surgical planning was assessed by independent reading of three readers. Liver signal-to-noise ratio (SNR) significantly decreased following iv injection of Resovist; however, SNR values of the portal veins or hepatic veins did not change significantly. Visibility of the portal venous system improved significantly (tertiary branches visible: pre in 15.2% versus post in 87.0% of patients). Resovist-enhanced 2D-TOF MRA may improve planning of liver resections by better demonstrating the relationship of central liver lesions and vessels on source images. The decrease in liver SNR at a constant vessel SNR after iv injection of Resovist improves MRA of the liver. SPIO-enhanced 2D-TOF MRA scans are superior to plain 2D-TOF MRA studies and may be added for the workup of preoperative patients.

Contrast Media↗
PubMed2003

Investigation into patient doses for intravenous urography and proposed Irish diagnostic reference levels.

With the introduction of Council Directive 97/43/Euratom, all member states should establish relevant diagnostic reference levels for X-ray examinations. Diagnostic reference levels help to facilitate standardisation and optimisation within departments and attempt to reduce dose variations between hospitals. High variation of individual patient doses for plain-film examinations by up to a factor of 75 was demonstrated by a previous Irish study, which highlighted the necessity for further investigation into other examinations in Ireland. The current work aimed to establish reference values for intravenous urography (IVU) examinations, an important contributor to collective dose. Eleven Irish hospitals were randomly selected, representing 30% of the total number of hospitals. Dose-area product (DAP) readings for IVUs were recorded along with technical and procedural details. Resultant data demonstrated mean hospital and individual patient DAP variations of a factor of 4 and 58, respectively. Stepwise regression analysis demonstrated that number of images taken, method of image acquisition and patient weight were the main causal agents for dose variations recorded. A proposed diagnostic reference level of 12 Gy cm(2) was established at the level of the third-quartile value of the mean hospital DAP values. This article provides evidence of large variations in DAP values for IVU examinations. It is hoped that application of the proposed DRL of 12 Gy cm(2 )will reduce the size of these variations.

Female↗
PubMed2001

Reliability of power output measurements during repeated treadmill sprinting in rugby players.

The non-motorized treadmill system initially reported by Lakomy in 1984 has been used extensively to assess sprinting performance. However, there has been limited research into the reliability of power output measurement using such systems. The aim of this study was to design a system and protocol capable of measuring treadmill sprinting performance in rugby players and to assess the reliability of this system for measuring power output. Twenty-seven rugby players, all of whom were familiar with treadmill sprinting, performed three maximal 6 s sprints with 2 min recovery between sprints, on two occasions 1 week apart. Both tests were performed on a non-motorized Woodway tramp treadmill, interfaced to a data acquisition system. There were no significant differences (P > 0.05) between power output for repeated trials on the same day (between trials) or for repeated trials on different days (between days). Limits of agreement for maximum average power (the average of 100 readings per second) were 4+/-98 and 30+/-157 W for between trials and between days, respectively. When reported as ratio limits of agreement, these were 1.07 (*/divided 1.12) and 1.03 (*/divided 1.16), respectively. The limits of agreement for maximum instantaneous power (the highest of 100 readings per second) were 51+/-464 and 105+/-588 W for between trials and between days, respectively. When reported as ratio limits of agreement, these were 1.02 (*/divided 1.20) and 1.04 (*/divided 1.21) for between trials and between days, respectively. The coefficients of variation for all measures of power output were less than 9.3%. Hence, the treadmill system and protocol developed in this study provide a reliable measure of power output for rugby players.

Adult↗
PubMed2006

A blended learning experience for teaching microbiology.

OBJECTIVES: To create a virtual laboratory system in which experimental science students could learn required skills and competencies while overcoming such challenges as time limitations, high cost of resources, and lack of feedback often encountered in a traditional laboratory setting. DESIGN: A blended learning experience that combines traditional practices and e-learning was implemented to teach microbiological methods to pharmacy students. Virtual laboratory modules were used to acquire nonmanual skills such as visual and mental skills for data reading, calculations, interpretation of the results, deployment of an analytical protocol, and reporting results. ASSESSMENT: Learning achievement was evaluated by questions about microbiology case-based problems. Students' perceptions were obtained by assessment questionnaire. CONCLUSION: By combining different learning scenarios, the acquisition of the necessary but otherwise unreachable competences was achieved. Students achieved similar grades in the modules whose initiation was in the virtual laboratory to the grades they achieved with the modules whose complete or partial initiation took place in the laboratory. The knowledge acquired was satisfactory and the participants valued the experience.

Education, Pharmacy↗