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 901 records · Page 50Linked to original sources

PubMed2005

OSEM reconstruction, associated with temporal fourier and depth-dependant resolution recovery filtering, enhances results from sestamibi and 201Tl 16-interval gated SPECT.

UNLABELLED: Gated SPECT recorded with 16 intervals determines left ventricular (LV) ejection fraction more accurately than does gated SPECT recorded with 8 intervals but produces higher image noise. This study aimed to assess the results from sestamibi and (201)Tl 16-interval gated SPECT when both signal-to-noise ratio and spatial resolution were enhanced with an original method of reconstruction. METHODS: Forty patients with coronary artery disease underwent (201)Tl and sestamibi 16-interval gated SPECT and, to be used as a reference, cardiac MRI. Assessments of global and regional LV function provided by ordered-subsets expectation maximization (OSEM) with depth-dependant resolution recovery and temporal Fourier filtering were compared with those from conventional filtered backprojection (FBP) previously optimized by screening various filter frequencies and various temporal smoothing levels. RESULTS: For both tracers, LV ejection fraction was determined best when the association of OSEM with depth-dependant resolution recovery was used alone, with temporal Fourier filtering, or with a slight 2-frame temporal smoothing: Mean absolute values of relative errors ranged from 3.2% to 3.6% (4.0%-7.9% for FBP), and coefficient correlation ranged from 0.91 to 0.93 (0.70-0.91 for FBP). Among these 3 reconstruction methods, the association of OSEM with depth-dependant resolution recovery with temporal Fourier filtering provided the highest signal-to-noise ratio, with mean increases of 54% for sestamibi and 80% for (201)Tl when compared with FBP, and the best analysis of segmental contractility, with exact agreement rates with MRI being 73% for (201)Tl and 79% for sestamibi. CONCLUSION: OSEM associated with temporal Fourier filtering and depth-dependant resolution recovery filtering enhances the LV function assessment provided by sestamibi and (201)Tl 16-interval gated SPECT and dramatically reduces image noise, a property that enhances and facilitates image interpretation.

Algorithms↗

PubMedDate not supplied

High resolution mini-gammacamera and 99mTc [HMPAO] - leukocytes for diagnosis of infection and radioguided surgery in diabetic foot.

Discovery of osteitis may be delayed because of late appearance of X-ray signs in patients with diabetic foot. Scintigraphy with labelled leukocytes is able to detect flogosis but often misses bone involvement, due to inadequate resolution of Anger camera, the commonest detector used in nuclear medicine. Radioguided surgery and biopsy with high resolution scintigraphy (HRS) started to be studied since 2000: although this method had never been tested for planning and guiding diabetic foot surgery, in our opinion it can help early diagnosis and surgical treatment of diabetic foot. Five patients with diabetic foot and suspected infection were studied with standard 99mTc [HMPAO]-leukocyte scan. In the same patients 2 mm spatial resolution HRS was performed 24 hours after administration of labelled WBC, using our inch2 field-of-view portable mini-gammacamera. Operations were done just after the 24h scan and were guided with the portable high resolution device in the four patients who showed positive scan. Scintigraphy with Anger camera and HRS were positive in four patients. HRS showed a bar-shaped radioactivity corresponding to small phalanges, close to the main inter-digital hot spot. The presence of osteitis on phalanges that had been shown by HRS was confirmed at surgery, that was successfully driven with the high resolution mini-camera. In conclusion HRS is able to diagnose early osteitis of diabetic foot and to guide diabetic foot surgery.

Diabetic Foot↗

PubMed2006

[The application of high-resolution endoscopy in non-erosive reflux disease].

OBJECTIVES: To establish the diagnosis standards of the non-erosive reflux disease (NERD) using high-resolution endoscopy. The diagnostic standards are established by observing the evolution of main endoscopic appearance of NERD with high-resolution endoscopy, in conjunction with 24 h monitoring of the pH and proton-pump inhibitor experiments. METHODS: Patients with gastroesophageal reflux disease symptoms and healthy volunteers were enrolled. All the individuals were assessed with high-resolution endoscopy and 24 h ambulatory pH monitoring. Patients with negative 24 h ambulatory pH monitoring or with positive 24 h ambulatory pH monitoring but negative endoscopic appearance were undertaken proton-pump inhibitor test. RESULTS: The individuals were divided into 3 groups: 19 in erosive esophagitis, 62 in non-erosive group, and 24 were healthy volunteers. The shapes of Z-lines are divided into 6 types: sharply circle, sparsely serration, serration, tattered, triangular extension and lingulate extension. The percentage of each type in non-erosive group was 6.5%, 6.5%, 6.5%, 11.2%, 61.2%, and 8.1% respectively. The percentage of sharply circle, sparsely serration and triangular extension Z-lines were 25.0%, 58.3% and 16.7% respectively in the control group. There were more serration, fractured, triangular extension, and tongue-like extension Z-lines in the non-erosive group than in the control group. The difference was significant (P < 0.05). The appearance of the cardia membrane below the Z-line was categorized into four types: flatted, rough, concavo-convex and villiform. In the control group, the percentage of flatted, rough and concavo-convex types were 16.6%, 54.2%, and 29.2% respectively. In the non-erosive group, cardia membrane of rough, concavo-convex and villiform shapes were 16.1%, 9.7%, and 74.2% respectively. There were more shapes of villiform types in the non-erosive group than in the control group. The difference was significant (P < 0.05). The sensitivity and specificity of high resolution endoscopic test in diagnosing NERD was 77.8% and 6/8 respectively. CONCLUSIONS: High resolution endoscopic test will raise the diagnostic rate of NERD. NERD was divided into non-erosive esophagitis and symptomatic gastroesophageal reflux disease.

Adolescent↗

PubMed2006

[DNA typing of HLA-I and II antigens with medium resolution method by DNA chip technique].

OBJECTIVE: To establish a DNA typing method for the HLA-I and II antigens in the Chinese of Han Nationality in Northern China with medium resolution method by DNA chip technique. METHODS: Corresponding primers for the sense exon fragments of HLA-A, HLA-B, HLA-DR, HLA-DQB, and HLA-DQA were designed. A DNA typing chip was made with specific medium resolution typing probes designed according to the gene frequency of HLA-I and II alleles among the Chinese of Han nationality in Northern China. Unsymmetrical PCR was used to amplify the HLA-I and II exon2 and exon3 in 30 samples from the Chinese of Han nationality in Northern China, and then the PCR products were labeled and hybridized with the probes on the chip. The typing of HLA-I and II was certified by scanning the hybridized products and analyzing them with a set of computer software. RESULTS: HLA-I and II alleles were successfully typed in 30 clinical samples. The h probes with medium resolution were able to discern 42 HLA-I and II alleles accurately. By using this chip 30 HLA-I and II alleles were distinguished and 6 new specific alleles were found. CONCLUSION: DNA typing of HLA-I and II by chip has been proven to be a high-resolution and high-specificity method. It is able to check out new alleles that can not be distinguished by other methods with the same resolution, and it is more intuitive and more suitable for clinical application.

Adult↗

PubMedDate not supplied

Pulmonary function tests, high-resolution computed tomography findings and inflammatory bowel disease.

AIM: The association between inflammatory bowel disease and pulmonary involvement has not been clearly established. The aim of this prospective study was to define the features of pulmonary function tests and high resolution computed tomography in inflammatory bowel disease patients and the relation between these and disease activity. METHOD: Fifty-two patients with inflammatory bowel disease (20 with Crohn's disease and 32 with ulcerative colitis) were enrolled. The standard pulmonary function tests and thorax high resolution computed tomography findings were investigated with respect to inflammatory bowel disease activity. Crohn's disease activity index and the Rachmilewitz endoscopic activity index for ulcerative colitis were used to assess disease activity. Medications used and smoking status were also documented. RESULTS: Among the patients with ulcerative colitis, 6.25% had an obstructive and/or restrictive ventilatory defect compared with 25% of the patients with Crohn's disease. Fifty percent of the patients with ulcerative colitis and 60% of the patients with Crohn's disease showed abnormal findings in high resolution computed tomography. Pulmonary function tests and high resolution computed tomography abnormalities did not differ significantly between Crohn's disease and ulcerative colitis. No significant difference related to inflammatory bowel disease activity was found (P > 0.05). CONCLUSION: Findings of high resolution computed tomography and the pulmonary function tests did not differ between ulcerative colitis and Crohn's disease. Bowel disease activity did not seem to affect these measurements.

Adult↗

PubMed1991

Influence of aberrant observations on high-resolution linkage analysis outcomes.

Because of the availability of efficient, user-friendly computer analysis programs, the construction of multilocus human genetic maps has become commonplace. At the level of resolution at which most of these maps have been developed, the methods have proved to be robust. This may not be true in the construction of high-resolution linkage maps (3-cM interlocus resolution or less). High-resolution meiotic maps, by definition, have a low probability of recombination occurring in an interval. As such, even low frequencies of errors in typing (1.5% or less) may influence mapping outcomes. To investigate the influence of aberrant observations on high-resolution maps, a Monte Carlo simulation analysis of multipoint linkage data was performed. Introduction of error was observed to reduce power to discriminate orders, dramatically inflate map length, and provide significant support for incorrect over correct orders. These results appear to be due to the misclassification of nonrecombinant gametes as multiple recombinants. Chi 2-Like goodness-of-fit analysis appears to be quite sensitive to the appearance of misclassified gametes, providing a simple test for aberrant data sets. Multiple pairwise likelihood analysis appears to be less sensitive than does multipoint analysis and may serve as a check for map validity.

Algorithms↗

PubMed1991

Detergent delipidation and solubilization strategies for high-resolution NMR of the membrane protein bacteriorhodopsin.

High-resolution NMR studies of bacteriorhodopsin require the availability of the detergent-solubilized protein with both high concentration and small rotational correlation time. A procedure is described for the optimized preparation of such samples. Bacteriorhodopsin was first delipidated by detergent treatment of purple membrane under nonsolubilizing conditions for the protein. The delipidated aggregated protein could then be solubilized into monomers at concentration close to millimolar by selected detergents. The solubilizing detergent had an important effect on the rotational correlation time of the protein as shown by measuring in each case the temperature-dependent stability of the protein, the size of the detergent-protein complex, and the detergent viscosity. Consistently, a strong influence of the detergent was also found on spectral resolution in 13C NMR spectra of solubilized bacteriorhodopsin labeled with [1-13C]phenylalanine. Best resolution was obtained using n-dodecylmaltoside as detergent, with which relatively narrow well resolved 13C NMR resonances were observed at 50 degrees C. It is suggested that high-resolution NMR studies performed with this detergent may contribute to the structural resolution of bacteriorhodopsin.

Bacteriorhodopsins↗

PubMed1990

Monaural and binaural time resolution ability in the aged. A psychoacoustic and electrophysiological study.

Time resolution ability is an important factor of auditory processing, especially in binaural hearing. In psychoacoustical and electrophysiological studies the time resolution of brief modulations of signal amplitude and frequency in monaural hearing, including gap detection ability, was analysed. To reveal the time resolution ability of the binaural hearing system, brief interaural modulations of signal amplitude, short changes of interaural time delay or noise coherence in broadband noise bursts were generated. The sensation levels of these short-lasting changes in the noise structure and the cortical evoked potentials were investigated in young normal hearing subjects and in the elderly. Thus age-dependent changes in monaural and binaural time resolution ability could be detected. For the monaural experiments, lengthened time constants of between 2-20 ms, depending on the degree of intensity or frequency modulation could be derived for older subjects. The binaural experiments were characterized by prolongation between 4-26 ms for short interaural signal delay changes. For both groups the time constants derived from the electrophysiological investigations were more prolonged, which might be explained by masking effects or habituation. Further electrophysiological investigations will be required to differentiate between time resolution processes of brief signal changes within the peripheral and central parts of the auditory system.

Acoustic Stimulation↗

PubMed1990

[Pulmonary lesion of paraquat poisoning on high resolution CT].

It is well known that paraquat causes severe organ-toxicity and pulmonary damage. We observed the progress of a patient who survived paraquat poisoning, and we recorded the changes in the lung by high resolution CT. The patient was a 35-year-old man who attempted suicide by paraquat (Guramoxone 100 ml) ingestion. At the time of hospitalization, there was no respiratory involvement. Five days after ingestion, an X-ray examination showed only indistinct vascularity of both lung fields, but high resolution CT showed increased density in the central part of both lung fields. According to the clinical progress after ingestion, mediastinal and subcutaneous emphysema were noted by chest X-ray examination. On the other hand, severe interstitial pneumonia progression of severe lung fibrosis with a decrease in lung volume and interstitial pulmonary emphysema in addition to mediastinal, subcutaneous emphysema were seen by high resolution CT. High resolution CT is useful for detecting morphologic change and diagnosing clinical stages. Observing the course of changes by high resolution CT is useful for deciding the course of clinical therapy, and we have no hesitation in affirming that it should be used in such cases.

Adult↗

PubMed1990

Grief resolution in hospice nurses. An exploration of effective methods.

Although there is a considerable amount of literature available on grief and grief resolution, the relevance of this information has not been adequately applied to the arena of nursing. A few studies have examined various issues impacting on nurses involved in caring for dying patients, and some have offered recommendations to facilitate grief resolution in nurses. However, these studies have primarily focused on single aspects of the nurse's involvement with dying patients/families (i.e., the nurse-patient relationship), with recommendations for strategies to facilitate grief resolution often emanating from the researchers rather than the nurses themselves. This study explored grief resolution strategies employed by hospice nurses who effectively cope with the deaths of patients. The recurring themes that emerged from the interviews with these nurses can be brought together to form a framework for better understanding of grief resolution among this unique group of individuals. Viewing these strategies in concert with one another provides a more comprehensive, holistic perspective on methods that assist nurses to effectively resolve the deaths of their patients.

Adaptation, Psychological↗

PubMed1989

High-resolution CT of the lung parenchyma.

High-resolution CT, a technique that optimizes the spatial resolution of lung parenchyma, uses thin collimation, reconstruction with a high-spatial frequency algorithm, image targeting, and sometimes increased kVp and mA settings. Performing a high-resolution CT study can provide information regarding lung morphology that cannot be obtained using conventional CT or plain radiographs. Alterations in anatomy can be identified at the level of the secondary pulmonary lobule, and although often nonspecific, in certain situations high-resolution CT findings can be diagnostic. High-resolution CT scanning is also helpful in identifying patients who have significant lung disease despite a normal chest radiograph, and in planning biopsy procedures.

Humans↗

PubMedDate not supplied

The association of psychosocial factors with the resolution of abdominal pain.

Although abdominal pain is a common presenting complaint in the family practice setting, its natural history and psychosocial associations have not been clearly described. A prospective study was conducted of 92 patients who presented with abdominal pain to the University of Iowa and Cedar Rapids Family Practice Centers between September 1982 and March 1983. Patients were given a self-administered questionnaire for measuring stress, family functioning, and psychological symptoms. All patients were followed for at least six weeks. Resolution of the pain was documented by chart audit, telephone, or mail follow-up. Two-thirds of the patients experienced resolution of their pain within six to eight weeks. The scores on the Hopkins Psychological Symptom Checklist, Family APGAR, and the Daily Hassles Stress Scale did not predict resolution of pain. Age, sex, education, occupation, and final diagnosis also did not predict resolution of pain. Marital status was not associated with pain resolution, though widowed and separated individuals more often had pain at follow-up.

Abdomen↗

PubMedDate not supplied

Computer recognition of ectocervical cells. Classification accuracy and spatial resolution.

The effect of a relaxation of the spatial resolution of images of ectocervical cells on classification accuracy by computer has been studied. The discriminatory capabilities of optical density, texture and shape features have been evaluated. Comparable computer classifications have been derived. The differences in the discriminating power of .5 and 1 mu resolution are found to be smaller than the differences corresponding to 1 and 2 mu resolution. While 2 mu resolution may be marginally acceptable in certain situations, the 4 mu resolution did not render acceptably good classification rates.

Computers↗

PubMed1986

The crystal structure of pea lectin at 3.0-A resolution.

The structure of pea lectin has been determined to 3.0-A resolution based on multiple isomorphous replacement phasing to 6.0-A resolution and a combination of single isomorphous replacement, anomalous scattering, and density modification to 3.0-A resolution. The pea lectin model has been optimized by restrained least squares refinement against the data between 7.0- and 3.0-A resolution. The final model at 3.0 A gives an R factor of 0.24 and a root mean square deviation from ideal bond distances of 0.02 A. The two monomers in the asymmetric unit are related by noncrystallographic 2-fold symmetry to form a dimer. Monomers were treated independently in modeling and refinement, but are found to be virtually identical at this resolution. The molecular structure of the pea lectin monomer is very similar to that of concanavalin A, the lectin from the jack bean. Similarities extend from secondary and tertiary structures to the occurrence of a cis-peptide bond and the pattern of coordination of the Ca2+ and Mn2+ ions. Differences between the two lectin structures are confined primarily to the loop regions and to the chain termini, which are different and give rise to the unusual permuted relationship between the pea lectin and concanavalin A protein sequences.

Concanavalin A↗

PubMed1985

Fat as a factor affecting resolution in diagnostic ultrasound: possibilities for improving picture quality.

Fat and air are the main factors affecting quality by causing interference in ultrasound. Deterioration in resolution with increasing thickness of overlapping fat has been verified experimentally. The following factors have provided better resolution in experimental studies: large aperture transducers; compound technique (good axial resolution compensates for poor lateral resolution); compression of fat and location of the fat in the focus of the transducer; large beam width of the ultrasound signal. In a clinical study with 663 patients the influence of compression and compound technique on visualisation of abdominal structures was tested with a Combison 100 real-time scanner, Combison 202 compound scanner and the Octoson system. The retroperitoneal space was not demonstrated in 66 patients. Compression with the real-time transducer improved demonstration in 50% of studies (33/66), as compared to 20% (19/66) with the compound technique. Resolution was affected by velocity errors and reflection in 30% of cases (19/66) examined with the compound technique.

Adipose Tissue↗

PubMed1985

Progress in high resolution scanning ion microscopy and secondary ion mass spectrometry imaging microanalysis.

The performance of a new high resolution scanning ion microprobe (SIM) is elucidated with regard to imaging capabilities using the ion-induced secondary electron (ISE) or secondary ion (ISI) signals, and the mass-resolved signal from a secondary ion mass spectrometry (SIMS) system. The new instrument focuses a beam extracted from a liquid metal ion source (LMIS) to a range of spot sizes reaching the 20 nm level. The probe current (1.6 pA) available at this level of lateral resolution, which approaches the theoretical resolution limits of the SIMS method, is still adequate to obtain detailed isotopic maps for surfaces rich in the elements of low ionization potential (positive ISI), or high electron affinity (negative ISI). In addition to examples of high resolution ISE and ISI images of objects displaying sufficiently small topographic detail, mass spectra and isotopic maps are shown, testing both the lateral and depth resolution attained. The latter results belong with a program of interdisciplinary research applications of the new microprobe, which include studies of e.g., the monolayer lateral distribution of intercalant in SbCl5 intercalated graphite and of silicate minerals and iron distribution in sections of chondrules and their rims (components of chondrites, a class of stony meteorites). In the biomedical field, the new microprobe finds application in e.g., the study of human renal calculi and bone. Most promising is the use of stable isotope tracers (e.g., Ca44) to unravel the dynamics of bone mineralization, as thus far shown with the in-vitro culture of the skull bone of neonatal mice.

Animals↗

PubMed1994

[Subarachnoid hemorrhage: assessment in the acute phase with angiography, with high-resolution magnetic resonance (angio-MR)].

Previous reports demonstrated that Magnetic Resonance Angiography (MRA) is a reliable means of diagnosing intracerebral aneurysms. However, in these early studies MRA was performed in patients with cerebral aneurysms already proved by intraarterial angiography. Our study was aimed at investigating the clinical feasibility and the diagnostic accuracy of high-resolution MRA in patients with acute subarachnoid hemorrhage. Twenty-five patients (15 women, 10 men) with CT diagnosis of subarachnoid hemorrhage were prospectively examined with high-resolution MRA within 24 hours of bleeding. All patients underwent intraarterial digital subtraction angiography (IA DSA) immediately after MRA examination. MRA studies were performed with a 1.5-T unit. MRA examinations of the cerebral vessels consisted of axial excitation of two 50-mm volume slabs, with 25% overlap, covering the cerebral circulation from the vertebro-basilar junction to the pericallosal artery. Pulse sequence variables were optimized to reduce voxel size (0.62 x 0.62 x 0.78) and to increase spatial resolution (160-mm FOV, 256 x 256 matrix, 0.78-mm slice thickness) while keeping S/N ratio high. The maximum intensity projection (MIP) reconstruction algorithm was used. The examination lasted nearly 20 minutes. Four MRA examinations (16%) were considered inadequate for diagnosis because of motion artifacts. High-resolution MRA detected 20 of 21 aneurysms in 17 patients, with 1 false positive and 1 false negative. Two patients had multiple aneurysms, 2 and 4 respectively, all of them detected by MRA. No cause of subarachnoid hemorrhage was found by IA DSA in 4 patients, while MRA studies were considered negative in 3 patients. Nineteen aneurysms were surgically clipped, while 2 basilar artery aneurysms were occluded by intravascular treatment. MRA and DSA findings were compared with surgical findings. Relative to IA DSA, MRA exhibited 95% sensitivity and 95% specificity. Aneurysm size ranged 2-10 mm: the smallest aneurysm detected by MRA was 2.5 mm. Anatomical and morphological agreement between MRA and IA DSA was excellent, with only slight MRA underestimation of the aneurysm size in 25% of cases and overestimation in 15% of cases. The aneurysm neck was shown by MRA in 60% and by IA DSA in 81% of cases. High-resolution MRA proved to be especially useful in complex anatomical sites where the direction of the aneurysm could be clearly demonstrated through the accurate selection of the appropriate projection angle and the careful examination of direct axial images.(ABSTRACT TRUNCATED AT 400 WORDS)

Acute Disease↗

PubMed1996

[Theoretical principles and technical realization of high resolution nuclear magnetic resonance tomography with the example of a dedicated coil system].

The theory of high-resolution magnetic resonance imaging (MRI) and the physical properties of a dedicated coil system with its clinical application are reviewed. To evaluate the spatial resolution of the system, a phantom sample was depicted by a transverse T1-weighted sequence (time of repetition 500 ms, time of echo 25 ms, 256 x 256 matrix, 3 acquisitions, field of view 25 mm2). Relative signal intensity decrease was less using the 5-cm coil, as signal intensity field distribution depends on coil diameter. The phantom appeared as an attainable resolution of 100-microns pixel width using the 2.5-cm coil. For the 5-cm coil the pixel width was 200 microns, not accomplishing clear resolution of the phantom. Coil head choice depends on the anatomic depth of the target organ. Work-up of the skin and musculoskeletal lesions is the main indication for high-resolution MRI using surface coils.

Achilles Tendon↗