SEARCH · PubMed Health

Results for “Resolution”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,783 records · Page 99Linked to original sources

PubMed1983

Exploration of the facial nerve canal by high-resolution computed tomography: anatomy and pathology.

A correlative study of the anatomy and the radiological appearance of the intratemporal course of the facial nerve canal was carried out. Isolated temporal bones and temporal bones of cadaver heads were examined with thin-section high-resolution computed tomography in the axial, coronal and Stenvers' projections, then sectioned with a microtome and the radiologic and anatomic images were correlated. Appropriate projections for visualization of each segment of the facial nerve canal on CT were established. The high-resolution CT Stenvers' projection proved very useful for visualization of the geniculate ganglion fossa, as also of the tympanic and mastoid segments in their full length. The high-resolution CT appearance of lesions characteristic for each segment of the facial nerve canal are presented.

Cadaver↗

PubMed1993

High-resolution 1H NMR spectroscopy of cerebrospinal fluid in spinal diseases.

Twenty-nine patients with disk herniations, 7 patients with intraspinal tumors, 4 patients with multiple sclerosis and one patient with infection by borrelia have been studied by CT, myelography and/or MR. To gain information on the metabolism of central nervous system disease (CNS), and thus, to improve diagnosis the cerebrospinal fluid (CSF) was studied in all cases using high-resolution 1H NMR spectroscopy at 360 MHz. Seventeen metabolites could be identified in CSF in addition to the usual clinical chemical parameters. As compared to a control group discrimination of tumors from inflammation was possible by means of different metabolites and/or metabolite concentration. The CSF in disk herniations differed in the concentration of acetate from the control group. In CSF of tumors, multiple sclerosis and of infection by borrelia distinct differences in the concentrations of putrescine, citrate, valine, alpha-alanine, acetate, creatinine, glucose, beta-hydroxy-butyric acid, glutamine and creatine have been observed both as compared directly and in comparison to the control group. Thus, high-resolution 1H NMR spectroscopy of CSF gives speedy information on metabolism, since a variety of metabolites, usually examined only in different tests, can be studied in one single step. Thus, high-resolution 1H NMR spectroscopy supports imaging, especially MR, as morphological changes in diseases may be differentiated by means of different metabolite profiles. This assumption needs further confirmation on a prospective study with a larger patient population.

Borrelia Infections↗

PubMed1979

Resolution of a gold latensification-elon ascorbic acid developer for Ilford L4 emulsion.

The electron-microscopical autoradiographical resolution of a gold latensification-elon ascorbic acid (GEA) developer for Ilford L4 emulsion was determined experimentally, using radioactive line sources of tritiated albumin (Heijnen and Geuze, 1977). For sections with a thickness of 62 nm (SD +/- 11), which were covered with a carbon layer about 5 nm thick and a slightly overlapping monolayer of L4 silver bromide crystals, the measured half-distance (HD) of resolution was 115 nm. This improvement in resolution, the high efficiency of the GEA developer for L4 emulsion (Wisse and Tates, 1968), and the excellent visibility of the cellular structures under the small silver grains, mean that the L4-GEA combination deserves preverence as a method for quantitative electron-microscopical autoradiography.

Ascorbic Acid↗

PubMed1981

Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches.

1. The extracellular patch clamp method, which first allowed the detection of single channel currents in biological membranes, has been further refined to enable higher current resolution, direct membrane patch potential control, and physical isolation of membrane patches. 2. A description of a convenient method for the fabrication of patch recording pipettes is given together with procedures followed to achieve giga-seals i.e. pipette-membrane seals with resistances of 10(9) - 10(11) omega. 3. The basic patch clamp recording circuit, and designs for improved frequency response are described along with the present limitations in recording the currents from single channels. 4. Procedures for preparation and recording from three representative cell types are given. Some properties of single acetylcholine-activated channels in muscle membrane are described to illustrate the improved current and time resolution achieved with giga-seals. 5. A description is given of the various ways that patches of membrane can be physically isolated from cells. This isolation enables the recording of single channel currents with well-defined solutions on both sides of the membrane. Two types of isolated cell-free patch configurations can be formed: an inside-out patch with its cytoplasmic membrane face exposed to the bath solution, and an outside-out patch with its extracellular membrane face exposed to the bath solution. 6. The application of the method for the recording of ionic currents and internal dialysis of small cells is considered. Single channel resolution can be achieved when recording from whole cells, if the cell diameter is small (less than 20 micrometer). 7. The wide range of cell types amenable to giga-seal formation is discussed.

Acetylcholine↗

PubMed1986

Prolonged halothane hepatitis. Prompt resolution of severe lesion with corticosteroid therapy.

Previous reports on halothane-induced injury have included patients treated with corticosteroids. Therapy has often been initiated before there has been the opportunity for spontaneous resolution of the process. The patient reported here developed typical acute halothane hepatitis following the second exposure to the anesthetic; she remained ill and failed to show evidence of improvement during a five-week period. Clinical improvement was noted shortly after therapy with prednisone. The laboratory studies returned to normal, and the severe morphological lesion resolved. This experience supports the use of corticosteroids in halothane-induced liver injury in the absence of prompt spontaneous resolution, since therapy appears to decrease the morbidity and hasten resolution of the process.

Chemical and Drug Induced Liver Injury↗

PubMed1985

The technique of direct multiplanar high resolution CT of the temporal bone.

The technique of direct multiplanar high resolution CT opens new possibilities for detecting even the smallest lesions of the central nervous system and its coverings. The prerequisites are: Submillimetre spatial resolution. Thin slice thickness collimation. Sufficient radiation dose to keep the noise in the image around about 1%. No waiting time between scans other than short reconstruction times, or use of rapid sequence scan procedures. Possibility to position patients and immobilize them for direct scanning of coronal and sagittal planes without significantly reducing the patient's comfort. Possibility of using optional algorithms which improve spatial resolution further (MacroView) in order to bring out very fine details. This article describes the technique we have used in order to fulfil these prerequisites and also gives a few results relating to the imaging of the facial nerve canal.

Facial Nerve↗

PubMed1994

Feasibility of high-resolution, low-dose chest CT in evaluating the pediatric chest.

Thin-section, high-resolution (1.0/1.5 mm thick slices), low-dose chest CT scans were performed in 55 infants and children. The studies were carried out with 1- and 2-s scan (data acquisition) times using a high-resolution (bone) algorithm. Although there was some motion artifact, the studies provided valuable information for evaluating diffuse parenchymal lung disease. The thin slices provided finer detail and more diagnostic information than images representing thicker sections. Most studies were performed using between 40 and 80 mAs. It is estimated that the patients' radiation exposure was 20% that of conventional high-resolution CT (HRCT) and 57% that of routine chest CT. Diagnostic HRCT scans can be obtained in infants and young children without the need for suspended respiration or specialized ultrafast CT scanners.

Adolescent↗

PubMed1997

Early resolution of Ogilvie's syndrome with intravenous neostigmine: a simple, effective treatment.

PURPOSE: Our aim was to assess the value of a parasympathomimetic drug (neostigmine) in the early resolution of acute colonic pseudo-obstruction (Ogilvie's syndrome). METHODS: A prospective study was undertaken in 18 consecutive patients (mean age, 76 (range, 31-87) years) with acute colonic pseudo-obstruction. After a varying period of conservative treatment in all cases, 16 patients with persistent, massive abdominal distention were given intravenous neostigmine. RESULTS: A rapid and satisfactory clinical and radiologic decompression of the large bowel was obtained in 12 patients (75 percent) after a single dose of the drug; another patient had complete resolution after a second dose, and the other 3 patients had only partial resolution, in one of them after a second dose of the drug. No patient required surgical decompression of the bowel. CONCLUSION: These results give support to the theory of excessive parasympathetic suppression in most cases of Ogilvie's syndrome. The treatment with intravenous neostigmine has proved very effective, preventing in many cases prolonged periods of uncomfortable and potentially hazardous conventional conservative management and avoiding surgical treatment in a consecutive series of patients.

Acute Disease↗

PubMed1999

Assessment of spatial resolution of pace mapping when using body surface potentials.

Using computer simulations and statistical methods, the resolution of pace mapping when used in combination with body surface potentials was systematically investigated. In an anatomical model of the human ventricular myocardium, pre-excitation sequences were initiated at 69 sites positioned along the atrioventricular (AV) ring and corresponding body surface potential maps (BSPMs) were calculated at 32 leads placed on the anterior torso. For each time after the onset of pre-excitation (every 4 ms to 40 ms) and each root-mean-square (RMS) noise level (5, 10, 20 and 50 microV), BSPMs were cros-correlated and the spatial resolution defined as the largest pacing site separation at which the differences in correlation coefficients were not statistically significant (level p > or = 0.05). The findings indicate that when random RMS noise of 5 microV was added to the simulated BSPMs, average spatial resolution over all 60 sites was at 20 ms after the onset of pre-excitation within 3.5 +/- 0.9 mm. The results provide theoretical evidence that statistical analysis of BSPMs obtained during pace mapping can offer improved means for subcentimetre identification of accessory pathways located along the AV ring.

Body Surface Potential Mapping↗

PubMed1994

Effects of digital resolution on characterisation of cardiac late potentials.

The effects of amplitude resolution in the signal-averaged ECG are studied in relation to the analysis of cardiac late potentials. The statistical properties of ECG signals from 22 patients after myocardial infarction were investigated in terms of amplitude distribution and noise level for the material. It was found that unbiased averaging could be achieved using a resolution greater than 10 microV. The noise levels of the bandpass-filtered individual X, Y and Z leads (range of 1-10 microV) and the vector magnitude were also investigated. Marked intra-lead differences in noise level were found, indicating that analysis based on individual leads is preferable. The effects of quantisation noise on the vector magnitude were negligible for amplitude resolutions below 5 microV. However, the additional noise contribution at 5 microV could be compensated by a moderate increase in acquisition time. The sensitivity to noise was considered when determining the endpoint of the filtered QRS complex using the vector magnitude.

Electricity↗

PubMedDate not supplied

Motor response information influence on CNV shape and resolution time.

This study systematically investigates changes in CNV waveform shape and resolution time that result from the presentation of facilitatory, inhibitory, or no motor response (MR) information simultaneously with the warning (S1) or imperative (S2) stimulus of the S1-S2-MR CNV paradigm. Analyses indicate that the simultaneous presentation of S1 and information to produce or inhibit a MR attenuates initial CNV development. Further, when the S1 information is inhibitive, CNV development is retarded throughout. The contribution of an inhibitory psychological process during CNV development is proposed. The data also indicate that CNV resolution time is not dependent on the presence of a motor response. It is suggested that CNV resolution time is indicative of psychological completion or closure.

Adolescent↗

PubMed1987

Dye-ligand chromatography for the resolution and purification of restriction endonucleases.

The resolution of restriction endonucleases from the same microorganism is conventionally achieved by lengthy fractionation protocols. We now report effective single-step procedures that exploit dye-ligand chromatography for the resolution and purification of restriction enzymes. After suitable initial screening, we demonstrated that resolution of two restriction activities can be achieved in one chromatographic step, and further purification can subsequently be effected using selected dye-adsorbents. Accordingly, we resolved in one step, Hpa I from Hpa II, Hind II from Hind III, and Sac I from Sac II. Furthermore, a three-step chromatographic procedure has been developed to purify EcoRV suitable for commercial exploitation, as judged by the "overdigestion" and "cut-ligate-recut" quality control tests.

Bacteria↗

PubMed2004

Short term arterial remodelling in the aortae of cholesterol fed New Zealand white rabbits shown in vivo by high-resolution magnetic resonance imaging - implications for human pathology.

High-resolution, non-invasive imaging methods are required to monitor progression and regression of atherosclerotic plaques. We investigated the use of MRI to measure changes in plaque volume and vessel remodelling during progression and regression of atherosclerosis in New Zealand White rabbits. Atherosclerotic lesions were induced in the abdominal aorta by balloon injury and cholesterol feeding. MR images (2D) of the abdominal aorta were acquired with cardiac and respiratory gating using a fast spin echo sequence with and without fat-suppression. In an initial study on rabbits treated for 30 weeks we imaged the aortae with a spatial resolution of 250x250 micrometers with a slice thickness of 2 mm and achieved a close correlation between MRI-derived measurements and those made on perfusion pressure-fixed histological sections (r(1) = 0.83, slope p(1) < 0.01). We subsequently imaged 18 rabbits before and periodically during 12 weeks of cholesterol feeding (progression) followed by 12 weeks on normal diet (regression). Aortic wall (atherosclerotic lesion) volume increased significantly during progression and decreased during regression. In contrast, lumen volume increased during progression and did not change during regression. In conclusion, this study confirms that non-invasive, high-resolution MRI can be used to monitor progression and regression of atherosclerosis, each within 3 months and shows, for the first time in a short-term model, that positive remodelling occurs early during progression and persists through regression of atherosclerotic lesions.

Animals↗

PubMed1998

[Noninvasive determination of coronary flow reserve with signal enhanced high resolution transthoracic Doppler color echocardiography].

UNLABELLED: The feasibility of non-invasive assessment of coronary flow reserve (CFR) in the left anterior descending artery (LAD) using echo-enhanced high-resolution transthoracic color Doppler echocardiography (TTCD) was investigated. The results were compared with the degree of coronary diameter-stenosis obtained during cardiac catheterization. CFR has proven to be useful in the selection of patients undergoing invasive treatment of coronary artery disease and in estimating their prognosis. However, CFR could only be determined in everyday practice invasively during catheterization procedures. Recent development of high-resolution TTCD allows transthoracic visualization of distal LAD and supra-apical intramyocardial perforator branches, and non-invasive measurement of CFR. CFR was determined by measuring the ratio of pulsed-wave Doppler time velocity integral during adenosine-induced hyperemia (140 micrograms/kg/min i.v.) to baseline value. If Doppler signal of LAD flow was insufficiently at basal condition, an echo enhancer (Levovist) was used. 45 patients were examined by TTCD (7 MHz B-mode, 5 MHz color Doppler, 3.5 MHz PW Doppler) after coronary angiography had been performed. Group I consisted of 15 patients without heart disease, Group II of 15 patients with 40 to 70% isolated LAD diameter stenosis, and Group III of 15 patients with > 70% LAD diameter stenosis. Peripheral LAD coronary flow at baseline condition was assessed in 40 patients (88%) using TTCD. CFR could be quantified in 36/45 patients (80%), in 18 patients without echo enhancer, and in 18 patients with echo-enhancing agent. In 9/45 patients CFR could not be assessed. CFR in Group I was 3.13 +/- 0.57, in Group II 2.23 +/- 0.20 (vs Group I p < 0.01) and in Group III 1.64 +/- 0.30 (vs Group II p < 0.02). CONCLUSION: CFR of LAD can be determined in 80% of patients by the synergistic use of high-resolution TTCD combined with intravenous given ultrasound echo-enhancing agent.

Adult↗

PubMed1999

Performance stability of SHR-2000 high resolution PET for animal research.

The performance of a high resolution positron emission tomography (PET) system SHR-2000 for animal studies was re-evaluated six years after its installation. The system employs a detector array consisting of BGO crystals that are 1.7 mm (transaxially) by 10 mm (axially) by 30 mm (deep). A block detector, which is a position-sensitive photomultiplier tube (PMT) coupled to 4 arrays of BGO crystals has been adopted to the system. There are 15 block detectors positioned to form a 35 cm diameter ring with a field of view (FOV) of 17 cm by 4.6 cm axially, giving the system a 7 slice imaging capability. For six year workload in spatial resolution (FWHM), there were approximately a 2.6% increase at tangential FOV and a 7.5% increase at radial FOV. In axial resolution (FWHM) there was almost no change. The count rate loss for the true count rate increased 1.3% at 200 kBq/ ml. The average slice sensitivity showed a decrease of approximately 4.1%, and in scatters it showed an increase of approximately 1.4%. In animal experiments, the bones of guinea pigs were clearly identified with 18F fluoride ion. These experiments show that after a six year workload, the system also maintains good performance and has good stability.

Animals↗

PubMed1997

[Characteristics of normal cross-sectional anatomy of the skin in high resolution magnetic resonance tomography].

PURPOSE: To characterize human skin qualitatively and quantitatively using high-resolution magnetic resonance tomography (MRT) and to compare skin thickness measurements from MRT and histological specimens. MATERIAL AND METHODS: The skin of 84 persons was examined by use of a 2.5 cm coil in a whole-body tomography (gradient field strength 1.5 T) at a linear resolution of 100 microns. To evaluate the ability to identify various skin structures, following an initial visual description, the signal-noise and contrast-noise ratios were analyzed and the MRT-image compared to the corresponding histological specimen. RESULTS: Using the high-resolution coil, epidermis, dermis and subcutis were discernible. Problem areas included the cheek, distal leg and foot. Reproducible measuring of skin thickness with MRT is possible, but it does not correlate well with conventional histologic measurements.

Adolescent↗

PubMed1996

[High resolution scanning electron microscopy of isolated outer hair cells].

Isolated hair cell preparations have gained wide acceptance as a model for studying physiological and molecular properties of the sensory cells involved in the hearing process. Ultrastructural details, such as stereocilia links, lateral membrane substructure or synaptic links are of crucial importance for normal sensory transduction. For this reason, we developed a high-resolution scanning electron microscopy (SEM) procedure to study the surface of isolated hair cells. Cells were mechanically and/or enzymatically separated, isolated and immobilized on cover slips by alcian blue and fixed by 2% glutardialdehyde or 1% OsO4. After dehydration, preparations were critical point-dried and sputter-coated with gold-palladium (2-4 nm). Up to 5 nm resolution was achieved. Optimal fixation kept the cells in their typical cylindrical forms. Preservation of the stereocilia and the apical plates of the outer hair cells depended strongly on the fixation process. Tip- and side-links were observed only sporadically because of the aggressive preparation procedure. The lateral plasma membranes of the cell bodies showed regular granular structures of 5-7 nm diameter at maximal magnification. The granular structure of the cell membrane seemed to correspond to putative transmembrane proteins believed to generate membrane-based motility. The remnants of the nerve endings and/or supporting cells usually covered the cell base. The preservation of the cells was better when enzymatic isolation was omitted. The technique used allowed for high resolution ultrastructural examination of isolated hair cells and, when combined with immunological labeling, may permit the identification of proteins at a molecular level.

Animals↗

PubMed2002

[CT angiography of the coronary arteries with a 16-row spiral tomograph. Effect of spatial resolution on image quality].

PURPOSE: To evaluate image quality of coronary CT angiography with retrospectively ECG-gated 16 multi-slice spiral CT (MSCT), reconstructed with 0.75 mm slice thickness for optimal spatial resolution and with 1.3 mm slice thickness, to produce spatial resolution comparable to a 4-MSCT. MATERIALS AND METHODS: Ten patients underwent coronary CT angiography with a 16-MSCT (Siemens Sensation 16, Forchheim, Germany) with 0.75 mm detector collimation. Raw helical CT data were retrospectively reconstructed using two different settings. Setting A: B20f smooth kernel, axial MPR with 1.3 mm slice thickness and 0.7 mm increment. Setting B: B35f "HeartView" medium-smooth kernel, 0.75 mm slice thickness, 0.5 mm increment. In the axial slices two regions of interest (ROIs) were placed in the area of the aortic root (AR) and more caudal in the area of the left ventricle (LV). Image noise was determined by the standard deviation of the CT numbers.Two readers determined visibility of coronary arteries by standardized maximum intensity projections (MIP) post-processing in left, right anterior and left anterior oblique projection plane from setting A and B. Each projection was rated on a five point rating scale concerning plaque delineation. Points determined for each data set were summed up and used for comparison. RESULTS: No significant difference between the CT-numbers was found for setting A and B (A: 283.0 in AR/295.9 in LV and B: 282,9 in AR/297.2 in LV; p >0.2). However, the image noise was significantly different for setting A and B (A: 4.46 in AR/1.67 in LV and B: 8.16 in AR/7.38 in LV; p <0.01). Better delineation of the coronary arteries and atherosclerotic lesions could be achieved from MIP projections in setting B compared to setting A. CONCLUSION: Higher image noise is present in coronary 16-MSCT with thin-slice reconstruction compared to simulated 4-MSCT. However the MIP-reconstructions benefit most from the higher spatial resolution.

Coronary Angiography↗