Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “spatial”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 1,369 records · Page 76Linked to original sources
PubMed2002

Spatial-frequency-tuned mechanisms of the red-green channel estimated by oblique masking.

The sustained spatial-frequency-tuned (SF-tuned) mechanisms of nonoriented units were examined by means of orthogonal masking for the Red-Green (R-G) color channel, and those of oriented units by oblique masking for the achromatic channel but not for the color channels. An oblique-masking technique minimizes the artifacts that are due to spatial phase effects, local cues, spatial beats, spatial probability summation, and changing criteria. Therefore the spatial characteristics of the R-G color channel are now investigated by an oblique-masking technique and linked with my paper on orthogonal masking [J. Opt. Soc. Am. A 15, 1 (1998)]. The R-G channel was defined by the minimum-flicker and hue-cancellation techniques. A color monitor system was used to generate spatially localized (D6) vertical color test patterns [0.063-8 cycles per degree (cpd)] and sinusoidal oblique color masks (0.031-16 cpd, 1.2-60% contrasts). Color contrast sensitivity functions (CSFs), threshold elevation (TE) versus mask SF (TvSF) curves, and TE versus mask contrast (TvC) curves were measured by the method of constant stimuli with a two-interval forced-choice technique by using Powell's achromatizing lens under sustained (Gaussian, 2-s-duration) conditions. Results show the following: (1) The color CSF is a low-pass function of SF with average half-height SF of 0.7 cpd and cutoff SF of 14 cpd with the use of a color-detection criterion. (2) TvSF curves are broadly bandpass and fall into five groups, peaking at approximately 0.13, 0.5, 2, 4, and 8 cpd. The root-mean-square cone-color CSF is 3.8-5.4 times the stimulus-color CSF. (3) A "crowding effect" similar to that of the TvSF curves of the achromatic channel was also found, but the TvSF curves of the R-G channel are not sharply peaked, similar to the result for orthogonal masking. Data analysis led to the following conclusions: (1) A simple multiple-mechanism model yields one low-pass color mechanism (with average half-height SF of 0.54 cpd) and five bandpass SF-tuned color mechanisms; these six mechanisms are necessary to explain the CSF, TvSF, and TvC data simultaneously. (2) The bandpass mechanisms peaked at approximately 0.13, 0.5, 2, 4, and 8 cpd with average full bandwidths at half-heights of 3.6, 3.2, 2.1, 1.2, and 1.3 octaves, respectively. (3) Since oblique-masking color mechanisms (unlike achromatic oriented mechanisms) have broad orientation tuning under sustained conditions and there is a significant orthogonal masking, the oblique-masking color mechanisms may have contributions from both oriented and nonoriented units. (4) The high degree of similarity between the SF-tuned filters of mechanisms derived from oblique- and orthogonal-masking data suggests that most of the chromatic SF tuning is already accomplished by nonoriented units. (5) The quality of the fit to oblique- and orthogonal-masking data combined dropped enough to reject the hypothesis that the former taps the performance of only the same nonoriented mechanisms as those by the latter. Adding gain parameters that reduce the TEs for orthogonal masking gave a better fit, suggesting that orientation gains are one of the factors involved in the transformation of information from nonoriented to oriented mechanisms. However, the fit was still worse than that for oblique-(6) Since masking-alone or orthogonal-masking-alone data, suggesting that more factors may be involved. primate parvo lateral geniculate nucleus (pLGN) units behave in a fairly linear manner, the color contrast nonlinearity (which follows the linear filter) of a mechanism may be post-pLGN.

Color Perception↗
PubMed2002

Spatial frequency, phase, and the contrast of natural images.

We examined contrast sensitivity and suprathreshold apparent contrast with natural images. The spatial-frequency components within single octaves of the images were removed (notch filtered), their phases were randomized, or the polarity of the images was inverted. Of Michelson contrast, root-mean-square (RMS) contrast, and band-limited contrast, RMS contrast was the best index of detectability. Negative images had lower apparent contrast than their positives. Contrast detection thresholds showed spatial-frequency-dependent elevation following both notch filtering and phase randomization. The peak of the spatial-frequency tuning function was approximately 0.5-2 cycles per degree (c/deg). Suprathreshold contrast matching functions also showed spatial-frequency-dependent contrast loss for both notch-filtered and phase-randomized images. The peak of the spatial-frequency tuning function was approximately 1-3 c/deg. There was no detectable difference between the effects of phase randomization and notch filtering on contrast sensitivity. We argue that these observations are consistent with changes in the activity within spatial-frequency channels caused by the higher-order phase structure of natural images that is responsible for the presence of edges and specularities.

Contrast Sensitivity↗
PubMed1985

Masking of spatial-frequency discrimination.

Spatial-frequency discrimination thresholds were measured using the temporal two-alternative forced-choice procedure. A superimposed masker grating reduced discrimination threshold more than 20-fold when the spatial frequency of the masker was close to the test spatial frequency because moiré fringes provided a sensitive cue to the test grating's spatial frequency. When the effectiveness of this cue was reduced by randomly changing the frequency of the masker grating on successive presentations, masked thresholds were found to be elevated when the masker frequency was within roughly 1 octave of the test frequency. On the other hand, postadaptation thresholds were not elevated when the test frequency was close to the adapting frequency but were elevated at about twice the adapting frequency. Thus masking and adaptation have quite different effects on spatial-frequency discrimination, though their effects on contrast sensitivity are qualitatively similar. It is proposed that discrimination is determined by opponent-size processing. Adaptation elevates discrimination threshold by reducing the sensitivity of opponent elements. The masker grating elevates threshold by increasing the noise level of opponent elements, thus reducing the precision with which the visual pathway encodes spatial frequency.

Adaptation, Physiological↗
PubMed2004

Spatial navigation and hippocampal place cell firing: the problem of goal encoding.

Place cells are hippocampal neurons whose discharge is strongly related to a rat's location in the environment. The existence of such cells, combined with the reliable impairments seen in spatial tasks after hippocampal damage, has led to the proposal that place cells form part of an integrated neural system dedicated to spatial navigation. This hypothesis is supported by the strong relationships between place cell activity and spatial problem solving, which indicate that the place cell representation must be both functional and in register with the surroundings for the animal to perform correctly in spatial tasks. The place cell system nevertheless requires other essential elements to be competent, such as a component that specifies the overall goal of the animal and computes the path required to take the rat from its current location to the goal. Here, we propose a model of the neural network responsible for spatial navigation that includes goal coding and path selection. In this model, the hippocampal formation allows for place recognition, and stores the set of places that can be accessed from each position in the environment. The prefrontal cortex is responsible for encoding goal location and for route planning. The nucleus accumbens translates paths in neural space into appropriate locomotor activity that moves the animal towards the goal in real space. The complete model assumes that the hippocampal output to nucleus accumbens and prefrontal cortex provides information for generating solutions to spatial problems. In support of this model, we finally present preliminary evidence that the goal representation necessary for path planning might be encoded in the prelimbic/infralimbic region of the medial prefrontal cortex.

Action Potentials↗
PubMed2006

Spatial memory and hippocampal function in a non-foodstoring songbird, the zebra finch (Taeniopygia guttata).

Spatial memory and hippocampal function have as yet been investigated mainly in pigeons and food storing songbirds. We show here that the zebra finch, a songbird not specialized in food storing and caching, is also able to learn a spatial memory task and uses a spatial map for finding food in a 'dry water maze'. Hippocampal lesions prevent learning and retention of this spatial task. The immediate early gene (IEG) products Zenk and Fos are expressed within the hippocampus when the bird is learning the task. Spatial learning cannot be assigned to any hippocampal subregion; IEG expression within the hippocampus is patchy and seems almost arbitrarily located. The IEG activation pattern in spatial memory experiments is compared with those in other learning experiments with zebra finches.

Animals↗
PubMed2004

Selectivity for the spatial and nonspatial attributes of auditory stimuli in the ventrolateral prefrontal cortex.

Spatial and nonspatial auditory processing is hypothesized to occur in parallel dorsal and ventral pathways, respectively. In this study, we tested the spatial and nonspatial sensitivity of auditory neurons in the ventrolateral prefrontal cortex (vPFC), a cortical area in the hypothetical nonspatial pathway. We found that vPFC neurons were modulated significantly by both the spatial and nonspatial attributes of an auditory stimulus. When comparing these responses with those in anterolateral belt region of the auditory cortex, which is hypothesized to be specialized for processing the nonspatial attributes of auditory stimuli, we found that the nonspatial sensitivity of vPFC neurons was poorer, whereas the spatial selectivity was better than anterolateral neurons. Also, the spatial and nonspatial sensitivity of vPFC neurons was comparable with that seen in the lateral intraparietal area, a cortical area that is a part of the dorsal pathway. These data suggest that substantial spatial and nonspatial processing occurs in both the dorsal and ventral pathways.

Action Potentials↗
PubMed2004

Selective ablation of a class of amacrine cells alters spatial processing in the retina.

Several recent studies have suggested that the spatial tuning of retinal ganglion cells may be a more complex process than previously thought. The working hypothesis for many years was that the tuning was shaped by operations performed in the first synaptic layer of the retina, but recent work shows that operations in the second synaptic layer, involving amacrine cells, also play a significant role (Cook and McReynolds, 1998; Taylor, 1999; Flores-Herr et al., 2001). Although it is clear that amacrine cells are involved, the precise roles of the different amacrine subtypes in the many aspects of spatial tuning have not yet been established. Here we used a cell class ablation method to remove one subtype, the neuropeptide Y-expressing cells (NPY cells), and tapped into a part of the circuitry that tunes ganglion cells toward large spatial patterns (low spatial frequencies). When the subtype was ablated, ganglion cells tuned toward low spatial frequencies, both ON- and OFF-type cells, lost this preferential tuning. The effect was specific because ablation of another amacrine subtype did not produce it. Further analysis showed that the change in tuning was attributable to a decrease in the receptive field surround size of the ganglion cell. Other parameters, such as the size, strength, and asymmetry of the center and the strength of the surround, were not statistically significantly affected. These results thus show a mechanism for tuning cells to low spatial frequencies; an operation in the second synaptic layer, mediated by NPY cells, extends the surround of the ganglion cell.

Amacrine Cells↗
PubMed1996

An effect of alcohol on the distribution of spatial attention.

OBJECTIVE: Previous research on the effects of alcohol on visual performance led us to the prediction that alcohol should interfere with the distribution of visual spatial attention. This prediction was examined in two experiments that measured the effect of alcohol on reaction time (RT) for tasks that differed in visual spatial attention requirements. METHOD: In the first experiment, 48 adult volunteers (33 female) responded to either the onset or offset of one of five potential targets without alcohol to determine the relative demands on attention of stimulus onset and offset. The spatial extent of the five-target display was also varied. In the second experiment, the effect of alcohol was determined for both the onset and the offset tasks in 12 adult volunteers (nine female). RESULTS: The offset task was found to place greater demands on spatial attention as the increase in display area result in relatively greater increases in RT. Alcohol increased RT in the offset task for the larger, but not the smaller, display, and there were no significant effects of alcohol for the onset task. CONCLUSIONS: The results indicate that alcohol impairs performance on tasks that place greater demands on visual spatial attention and likely disrupts the ability to shift attention from one spatial locus to another during serial search.

Adolescent↗
PubMed2004

A spatial statistical model for landscape genetics.

Landscape genetics is a new discipline that aims to provide information on how landscape and environmental features influence population genetic structure. The first key step of landscape genetics is the spatial detection and location of genetic discontinuities between populations. However, efficient methods for achieving this task are lacking. In this article, we first clarify what is conceptually involved in the spatial modeling of genetic data. Then we describe a Bayesian model implemented in a Markov chain Monte Carlo scheme that allows inference of the location of such genetic discontinuities from individual geo-referenced multilocus genotypes, without a priori knowledge on populational units and limits. In this method, the global set of sampled individuals is modeled as a spatial mixture of panmictic populations, and the spatial organization of populations is modeled through the colored Voronoi tessellation. In addition to spatially locating genetic discontinuities, the method quantifies the amount of spatial dependence in the data set, estimates the number of populations in the studied area, assigns individuals to their population of origin, and detects individual migrants between populations, while taking into account uncertainty on the location of sampled individuals. The performance of the method is evaluated through the analysis of simulated data sets. Results show good performances for standard data sets (e.g., 100 individuals genotyped at 10 loci with 10 alleles per locus), with high but also low levels of population differentiation (e.g., FST<0.05). The method is then applied to a set of 88 individuals of wolverines (Gulo gulo) sampled in the northwestern United States and genotyped at 10 microsatellites.

Animals↗
PubMed2005

Variogram analysis of the spatial genetic structure of continuous populations using multilocus microsatellite data.

A geostatistical perspective on spatial genetic structure may explain methodological issues of quantifying spatial genetic structure and suggest new approaches to addressing them. We use a variogram approach to (i) derive a spatial partitioning of molecular variance, gene diversity, and genotypic diversity for microsatellite data under the infinite allele model (IAM) and the stepwise mutation model (SMM), (ii) develop a weighting of sampling units to reflect ploidy levels or multiple sampling of genets, and (iii) show how variograms summarize the spatial genetic structure within a population under isolation-by-distance. The methods are illustrated with data from a population of the epiphytic lichen Lobaria pulmonaria, using six microsatellite markers. Variogram-based analysis not only avoids bias due to the underestimation of population variance in the presence of spatial autocorrelation, but also provides estimates of population genetic diversity and the degree and extent of spatial genetic structure accounting for autocorrelation.

Analysis of Variance↗
PubMed2006

Spatial accessibility of primary care pediatric services in an urban environment: association with asthma management and outcome.

BACKGROUND: Disadvantaged urban children with asthma depend heavily on emergency departments (EDs) for episodic care. We hypothesized that among an urban population of children with asthma, higher spatial accessibility to primary care pediatric services would be associated with (1) more scheduled primary care visits for asthma, (2) better longitudinal asthma management, and (3) fewer unscheduled visits for asthma care. METHODS: We enrolled children aged 12 months to 17 years, inclusive, who sought acute asthma care in an urban pediatric ED. Eligibility criteria included a history of unscheduled visits for asthma in the previous year. We collected comprehensive data on each participant's asthma medical management and prior health care utilization. In addition, we calculated each participant's spatial accessibility to primary care pediatric services, reported as a provider-to-population ratio at their place of residence. Patients then were stratified by their spatial accessibility to care and compared with respect to measures of medical management and health care utilization. RESULTS: Among the 411 eligible participants, the spatial accessibility of primary care ranged from 7.4 to 350.2 full-time pediatric providers per 100,000 children <18 years of age, with a mean of 57.7 +/- 40.0. Patients in the middle and highest tertiles of spatial accessibility made significantly more scheduled visits for asthma care than patients in the lowest tertile. There were no differences among tertiles of accessibility with respect to asthma management or with respect to unscheduled visits for asthma care. CONCLUSIONS: Within this highly urban, largely disadvantaged and minority population of children with chronic asthma, patients with higher spatial accessibility to primary care services made significantly more scheduled visits for asthma care.

Adolescent↗
PubMedDate not supplied

[Spatial analysis of early neonatal mortality in the municipality of Rio de Janeiro, 1995-1996].

The objective of this study was to establish the spatial distribution of the early neonatal mortality rate (0-3 days) in the municipality of Rio de Janeiro for 1995-1996, identifying the best explanatory factors for spatial variations. By considering Rio de Janeiro's 153 neighborhoods as ecological units of analysis, socioeconomic and maternal indicators were analyzed according to place of residence. Spatial statistical analysis was performed using the Cliff & Ord methodology, appropriate for lattice data. From the 0-3 day mortality thematic map, we clearly identified two clusters of high early neonatal mortality rates. Spatial dependence was also confirmed by the statistical results of the spatial analysis. The variables that explain the clusters are the proportions of "adolescent mothers", "slum-dwellers", and "heads of households below the poverty level". Spatial statistics provided a better understanding of the geographic distribution of early neonatal mortality and suggested potential hypotheses for further investigation, which could support preventive programs and contribute to a decrease in infant mortality.

Adolescent↗
PubMedDate not supplied

Spatial modeling using mixed models: an ecologic study of visceral leishmaniasis in Teresina, Piauí State, Brazil.

Most ecologic studies use geographical areas as units of observation. Because data from areas close to one another tend to be more alike than those from distant areas, estimation of effect size and confidence intervals should consider spatial autocorrelation of measurements. In this report we demonstrate a method for modeling spatial autocorrelation within a mixed model framework, using data on environmental and socioeconomic determinants of the incidence of visceral leishmaniasis (VL) in the city of Teresina, Piauí, Brazil. A model with a spherical covariance structure indicated significant spatial autocorrelation in the data and yielded a better fit than one assuming independent observations. While both models showed a positive association between VL incidence and residence in a favela (slum) or in areas with green vegetation, values for the fixed effects and standard errors differed substantially between the models. Exploration of the data's spatial correlation structure through the semivariogram should precede the use of these models. Our findings support the hypothesis of spatial dependence of VL rates and indicate that it might be useful to model spatial correlation in order to obtain more accurate point and standard error estimates.

Analysis of Variance↗
PubMed2003

Olfactometric evaluation of spatial repellents for Aedes aegypti.

The spatial repellency responses of Aedes aegypti (L.) to deet, dehydrolinalool and linalool were evaluated using a dual port olfactometer. In the absence of human attractant mixture, each of the three chemicals resulted in activation and/or orientation of mosquitoes to the chemical source. Linalool was the most attractive compound. In the presence of human attractant mixture, activation and/or orientation of mosquitoes to each of the three chemicals was reduced. We compared reductions in mosquito responses to each of the three chemicals, in the presence of human attractant mixture, to estimate spatial repellency. As expected, lowest spatial repellency (7.3%) was observed using human attractant alone. Highest spatial repellency (33.6%) was observed using a combination of linalool and dehydrolinalool. Deet did not manifest spatial repellency, whereas linalool and dehydrolinalool alone, and in combination, exhibited spatial repellency.

Acyclic Monoterpenes↗
PubMed2004

Spatial statistical analysis of adult mosquito (Diptera: Culicidae) counts: an example using light trap data, in Redland Shire, Southeastern Queensland, Australia.

Many mosquito control agencies use carbon dioxide-baited traps as surveillance tools for adult vector populations. However, decisions regarding the number and location of trap sites and the frequency of collections are often based on logistical issues, and not on the bionomics or spatial distribution of the target species. Therefore, with the aim of providing practical information for adult mosquito surveillance programs, we used an array of 81 carbon dioxide- and octenol-baited lights traps to obtain weekly samples of adult mosquitoes in Redland Shire in southeastern Queensland, Australia. The spatial patterns of four different mosquito species were examined, and positive spatial autocorrelation in trap counts was evident for Ochlerotatus vigilax (Skuse), Coquillettidia linealis (Skuse), and Culex annulirostris Skuse, but not for the container species Ochlerotatus notoscriptus (Skuse). Of the three species that exhibited spatially correlated trap counts, the autocorrelation was greatest in Oc. vigilax at a lag distance of 0-1.5 km, with Moran's I values of 0.30-0.64. Moran's I indices were also positive and statistically significant (P < 0.05) at lag distances of 1.5-3.0 and 3.0-4.5 km on each of the 15 sampling occasions. However, at 3.0-4.5 km the Moran's I values were low, which indicated only weak spatial autocorrelation in trap counts. Universal kriging was used to estimate the numbers of each species at unsampled locations throughout the study area, and leave-one-out cross validation analyses indicated that this was a robust method for Cq. linealis and Oc. vigilax. In contrast, trap counts for the container-breeding species Oc. notoscriptus were randomly distributed and the interpolated counts were not reliable. Comparisons of weekly contour maps of adult mosquito counts indicated a consistent spatial pattern for Oc. vigilax and Cq. linealis. Particular geographic areas had consistently high or low numbers of vectors, and these patterns were stable from year to year. Definition of geographic areas with consistently high or low numbers of vectors may allow control activities to be focused in areas with the greatest risk of arbovirus transmission.

Animals↗
PubMed2006

Modeling species-habitat relationships with spatially autocorrelated observation data.

Spatial autocorrelation in wildlife observation data arises when extrinsic environmental processes and patterns that influence the spatial distribution of wildlife are themselves spatially structured, or when species are subject to intrinsic population processes, causing contagion or dispersion effects. Territoriality, Allee effects, dispersal limitations, and social clustering are examples of intrinsic processes. Both forms of autocorrelation can violate the assumptions of generalized linear regression models, resulting in biased estimation of model coefficients and diminished predictive performance. Such consequences may be avoided for extrinsic autocorrelation when autocorrelated environmental variables are available for use as model covariates, whereas intrinsic spatial autocorrelation requires an alternative modeling approach. The autologistic model provides an approach suited to the binary observations often obtained in wildlife surveys, but its performance has not been tested across widely varying sampling intensities or strengths of intrinsic spatial structure. Here we use simulated data to test the autologistic model under a range of sampling conditions. The autologistic model obtains better fits and substantially better predictive performance than the standard logistic regression model over the full range of sampling designs and intensities tested. We provide a simple Bayesian implementation of the autologistic model, which until now has not been achieved with standard statistical software alone. A step-by-step procedure is given for characterizing and modeling spatial autocorrelation in binary observation data, along with computer code for fitting autologistic models in WinBUGS, a freeware Bayesian analysis package. This approach avoids normal approximations to the pseudo-likelihood, in contrast to previous Bayesian applications of the autologistic model. We provide a sample application of the autologistic model, fitted to survey data for a gliding marsupial in southeastern Australia.

Bayes Theorem↗
PubMed2006

Beta diversity at different spatial scales: plant communities in organic and conventional agriculture.

Biodiversity studies that guide agricultural subsidy policy have generally compared farming systems at a single spatial scale: the field. However, diversity patterns vary across spatial scales. Here, we examined the effects of farming system (organic vs. conventional) and position in the field (edge vs. center) on plant species richness in wheat fields at three spatial scales. We quantified alpha-, beta-, and gamma-diversity at the microscale in 800 plots, at the mesoscale in 40 fields, and at the macroscale in three regions using the additive partitioning approach, and evaluated the relative contribution of beta-diversity at each spatial scale to total observed species richness. We found that alpha-, beta-, and gamma-diversity were higher in organic than conventional fields and higher at the field edge than in the field center at all spatial scales. In both farming systems, beta-diversity at the meso- and macroscale explained most of the overall species richness (up to 37% and 25%, respectively), indicating considerable differences in community composition among fields and regions due to environmental heterogeneity. The spatial scale at which beta-diversity contributed the most to overall species richness differed between rare and common species. Total richness of rare species (present in < or = 5% of total samples) was mainly explained by differences in community composition at the meso- and macroscale (up to 27% and 48%, respectively), but only in organic fields. Total richness of common species (present in > or = 25% of total samples) was explained by differences in community composition at the micro- and mesoscale (up to 29% and 47%, respectively), i.e., among plots and fields, independent of farming system. Our results show that organic farming made the greatest contribution to total species richness at the meso (among fields) and macro (among regions) scale due to environmental heterogeneity. Hence, agri-environment schemes should exploit this large-scale contribution of beta-diversity by tailoring schemes at regional scales to maximize dissimilarity between conservation areas using geographic information systems rather than focusing entirely at the classical local-field scale, which is the current practice.

Agriculture↗
PubMed2002

Advantages of real-time spatial compound sonography of the musculoskeletal system versus conventional sonography.

OBJECTIVE: Spatial compound sonography is a method that obtains sonographic information from several different angles of insonation and combines them to produce a single image. By reducing speckle and improving definition of tissue planes, this method can potentially improve image quality in musculoskeletal sonography. The purpose of our study was to compare real-time spatial compound sonography with conventional high-resolution musculoskeletal sonography. MATERIALS AND METHODS: Thirty-four patients underwent sonography of the musculoskeletal system for a variety of indications. All patients were evaluated using conventional high-resolution sonography and real-time spatial compound sonography performed with a 12-5-MHz multifrequency linear array transducer. Conventional images and compound images depicting the same musculoskeletal structure were obtained in pairs. A total of 118 images (59 image pairs) were randomly assorted and reviewed on a computer monitor by three experienced sonologists working independently. The reviewers were unaware of the type of images they were evaluating. Image quality was rated using a 5-point scale. The image parameters evaluated were definition of tissue planes, speckle, other noise, and image detail. RESULTS: Analysis of variance revealed that real-time spatial compound sonography significantly improved definition of soft-tissue planes, reduced speckle and other noise, and improved image detail when compared with conventional high-resolution sonography (p < 0.0001 for all evaluated parameters). CONCLUSION: Real-time spatial compound sonography significantly improved sonographic image quality in the musculoskeletal system when compared with conventional high-resolution sonography. Because musculoskeletal sonography is highly dependent on image quality and tissue-plane definition, spatial compound sonography represents an important development.

Adolescent↗