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At least 91 records · Page 5Linked to original sources
PubMed2003

Examining geographic patterns of mortality: the atlas of mortality in small areas in Spain (1987-1995).

BACKGROUND: Small-area mortality atlases have been demonstrated to be a useful tool for both showing general geographical patterns in mortality data and identifying specific high-risk locations. In Spain no study has so far systematically examined geographic patterns of small-area mortality for the main causes of death. This paper presents the main features, contents and potential uses of the Spanish Atlas of Mortality in small areas (1987-1995). METHODS: Population data for 2,218 small areas were drawn from the 1991 Census. Aggregated mortality data for 14 specific causes of death for the period 1987-1995 were obtained for each small area. Empirical Bayes-model-based estimates of age-adjusted relative risk were displayed in small-area maps for each cause/gender/age group (0-64 or 65 and over) combination using the same range of values (i.e. septiles) and colour schemes. RESULTS: The 'Spanish Atlas of Mortality' includes multiple choropleth (area-shaded) small-area maps and graphs to answer different questions about the data. The atlas is divided into three main sections. Section 1 includes the methods and comments on the main maps. Section 2 presents a two-page layout for each leading cause of death by gender including 1) a large map with relative risk estimates, 2) a map that indicates high- and low-risk small areas, 3) a graph with median and interquartile range of relative risk estimates for 17 large regions of Spain, and 4) relative-risk maps for two age groups. Section 3 provides specific information on the geographical units of analysis, statistical methods and other supplemental maps. CONCLUSION: The 'Spanish Atlas of Mortality' is a useful tool for examining geographical patterns of mortality risk and identifying specific high-risk areas. Mortality patterns displayed in the atlas may have important implications for research and social/health policy planning purposes.

Adolescent↗
PubMed1995

Cervical myelopathy caused by pseudoarthrosis between the atlas and axis associated with diffuse idiopathic skeletal hyperostosis.

STUDY DESIGN: This is a report of a patient with severe cervical myelopathy due to pseudoarthrosis between the posterior tubercle of the atlas and the spinous process of the axis, associated with diffuse idiopathic skeletal hyperostosis. Radiographs of 170 patients with neck pain were reviewed to identify lesions involving abnormal contact between the atlas and axis. OBJECTIVE: Based on an analysis of 170 radiographs, the prevalence of the reported condition was estimated. SUMMARY OF BACKGROUND DATA: A number of histologic studies on pseudoarthrosis involving the lumbar spine have been reported. In contrast, lesions between the posterior tubercle of the atlas and the spinous process of the axis have not been reported in association with cervical myelopathy. METHODS: Clinical and pathologic features of a patient with pseudoarthrosis between the posterior tubercle of the atlas and the spinous process of the axis were investigated. Radiographs of 170 Japanese patients over 40 years old were examined, and abnormal contact between the atlas and axis was classified into two groups based on the degree of spinal hyperostosis. RESULTS: Of 170 patients, 53 showed abnormal contact between the atlas and axis. The prevalence of abnormalities in the pronounced hyperostosis group (Forestier's stages II and III) was much higher than in the group with normal or slight hyperostosis. Two men had radiographic patterns showing osteophytes projecting into the spinal canal and associated with marked cervical myelopathy. CONCLUSION: In the group with pronounced hyperostosis, pseudoarthrosis or a variant can cause serious problems in the upper cervical spine that should not be overlooked.

Age Distribution↗
PubMed2003

Anatomic relationship of the internal carotid artery to the C1 vertebra: A case report of cervical reconstruction for chordoma and pilot study to assess the risk of screw fixation of the atlas.

STUDY DESIGN: A case of internal carotid artery impingement by the tip of a well-positioned C1-C2 transarticular screw is presented along with a pilot study involving radiologic and anatomic evaluation of human cadaveric specimens. OBJECTIVE: To raise awareness that the internal carotid artery may be in close proximity to the anterior aspect of the atlas and at risk of injury during placement of C1-C2 transarticular screws or C1 lateral mass screws. SUMMARY OF BACKGROUND DATA: To our knowledge, no cases of internal carotid artery injury or impingement have been reported with screw fixation of the atlas. METHODS: A case of internal carotid artery impingement by a C1-C2 transarticular screw is presented. The C1-C2 rotation appeared to place the internal carotid artery in the path of the screw, prompting a pilot study. Three fresh-frozen human cadaveric head and neck specimens were fixed in different degrees of rotation. Thin-section computed tomography of the specimens was obtained in the plane of the atlas. The frozen specimens were sectioned in the same plane as the computed tomography images. Measurements were taken to assess the location of the internal carotid artery relative to the anterior aspect of the atlas. RESULTS: Cervical rotation does not have a predictable effect on the location of the internal carotid artery. Medial angulation of a screw placed in the lateral mass of C1 appears to increase the margin of safety for the internal carotid artery. The internal carotid artery varies in location and may be within 1 mm of the ideal exit point of a bicortical transarticular screw or a C1 lateral mass screw. CONCLUSIONS: The internal carotid artery is at risk during bicortical screw fixation of the atlas. We recommend a contrast-enhanced computed tomography to assess the location of the internal carotid artery before screw fixation of the atlas.

Adolescent↗
PubMed2006

The feasibility of inserting atlas lateral mass screws via the posterior arch.

STUDY DESIGN: A total of 709 skeletally mature atlas specimens were obtained from the Hamann Todd Collection at the Cleveland Museum of Natural History. Using digital caliper, the thickness of the vertebral artery groove was measured to determine the feasibility of potential screw placement. OBJECTIVE: To determine the feasibility of screw insertion into the atlas lateral mass via the posterior arch. SUMMARY OF BACKGROUND DATA: The originally described starting point for atlas lateral mass screws, at the base of the lateral mass, can be associated with excessive bleeding and irritation of the greater occipital nerve. In order to avoid such problems, we routinely start the screw at a more cranial location on the dorsal, posterior-lateral arch of the atlas, when the anatomy permits. In cases where the arch is too small, we notch the undersurface of the arch so as to recess the screw into the notch. We undertook this cadaveric morphometric study to determine the feasibility of using such techniques in the general population. METHODS: A total of 709 atlas specimens were measured bilaterally to determine the thickness of the posterior-lateral arch at the level of the lateral mass. The presence of the ponticulus posticus was recorded as well. RESULTS: The average minimal thickness of the posterior-lateral atlas was 3.95 mm. There was a total of 157 complete and 34 incomplete ponticuli posticus. Overall, 85.2% of the specimens had a thickness greater than 3 mm, 654 (46.2%) greater than 4 mm, and 194 (13.7%) greater than 5 mm. CONCLUSIONS: Our results suggest that although only a small percentage of patients can accept a screw that is directly inserted via the posterior-lateral arch into the lateral mass, the notching technique is possible in the vast majority of patients. To our knowledge, this is the largest study to examine the possibility of using the posterior-lateral arch as the starting point for these screws. Our results suggest that alternative starting points for these screws are possible in a large percentage of the cases.

Black or African American↗
PubMed1991

Development and variation of the lateral vertebral foramen of the atlas in dogs.

Postnatal development and variation of the bony cranial border of the lateral vertebral foramen (LVF) of the atlas was studied in 96 dogs. Developmental ossification was investigated in 8 known-aged Miniature Schnauzer pups, after each atlas was prepared either as an alizarin-red stained clearing or as a dried cleaned bone. Variation was investigated in 63 atlases from mature dogs and by study of radiographs from 25 mature dogs of various breeds. The soft tissue structures passing through the LVF and attaching to its cranial border were dissected in an additional 2 embalmed and 2 fresh cadavers. In 2-week-old pups, the LVF was represented by a notch in the cranial margin of the bony arch of the atlas, with a cartilage bar completing the foramen cranially. Between 6 and 16 weeks the bar forming the cranial bony border of the LVF ossified in its preexisting cartilage anlage. In mature dogs, the LVF was present in the craniolateral aspect of the arch of the atlas and was recognized on lateral radiographs. The vertebral artery and vein, and first cervical nerve passed through the LVF and the atlantooccipital joint capsule and dorsal membrane attached to the cranial border of the LVF. In one dog the cranial border of the LVF of the atlas was incompletely ossified bilaterally. This developmental variant was compared with variations in man and other mammals, and with proatlas neural arch derivatives.

Animals↗
PubMed1983

Pseudospread of the atlas: false sign of Jefferson fracture in young children.

Jefferson fractures are rare prior to teen-age. Three young children examined after trauma exhibited the characteristic spread appearance of the atlas, but fractures were excluded radiographically and clinically. A retrospective study demonstrated a similar appearance, termed "pseudospread," in most children aged 3 months to 4 years, including over 90% during the second year. Pseudospread results from a discrepancy between the "neural" growth pattern of the atlas and the "somatic" pattern of the axis. An "atlas spread index" is defined and a normal range presented. When an atlas fracture is suggested by apparent lateral spread of the lateral atlas masses, computed tomography is useful to demonstrate an intact atlas ring.

Axis, Cervical Vertebra↗
PubMed1998

A case of cervical myelopathy with developmental canal stenosis at the level of the atlas. A case report.

The craniocervical junction is one of the most common sites of malformations. Only three cases of myelopathy due to hypoplasia of atlas have been reported previously. Among these malformations, the hypoplasia of atlas was first described by Wackenheim in 1974. Although developmental canal stenosis due to the hypoplasia of atlas seems to have a tendency of causing the cervical myelopathy, only three cases of cervical myelopathy due to this condition have been reported previously. A 77-year-old man with severe canal stenosis at the level of the atlas is reported. The clinical manifestations were 20-year history of progressive gait disturbance and paresis of both upper and lower extremities. The spinal cord was markedly compressed at the level of the atlas. The clinical manifestations improved after a resection of posterior arch of the atlas.

Aged↗
PubMed1998

[A surgical case of cervical canal stenosis caused by atlas hypoplasia in an elderly patient].

We report an 81-year-old man with hypoplastic atlas resulting in a severe stiff feeling in the bilateral shoulders, spastic tetraparesis, and hypesthesia below the C2 segment level of the spinal cord. These symptoms are compatible with compression of the high cervical cord. Neuroimaging studies revealed a narrowing of the spinal cord by compression of the hypoplastic atlas. Laminoplasty of the atlas was performed under general anesthesia, and the patient's symptoms were resolved. Operated cases of older patient's with atlas hypoplasia have been rarely reported. Laminoplasty of the atlas is a safe and useful procedure for high cervical compression due to hypoplastic atlas.

Aged↗
PubMed1999

Anatomy atlases.

Anatomy atlases are unlike other knowledge sources in the health sciences in that they communicate knowledge through annotated images without the support of narrative text. An analysis of the knowledge component represented by images and the history of anatomy atlases suggest some distinctions that should be made between atlas and textbook illustrations. Textbook and atlas should synergistically promote the generation of a mental model of anatomy. The objective of such a model is to support anatomical reasoning and thereby replace memorization of anatomical facts. Criteria are suggested for selecting anatomy texts and atlases that complement one another, and the advantages and disadvantages of hard copy and computer-based anatomy atlases are considered.

Anatomy↗
PubMed2006

Design and implementation of a web-based, database-driven histology atlas: technology at work.

At Vanderbilt University, the "Human Cell and Tissue Biology" course is a required lecture and laboratory course with 2 full-time instructors and 106 students. To address demands placed on faculty for individual attention, an interactive Web-based histology atlas was developed and implemented in January 2005. This atlas was specifically designed to complement the existing laboratory manual and to transform the manual into an interactive educational tool whereby students could view high-resolution images of histological specimens online. By utilizing a computer scripting language, interactive highlighting of histological structures was accomplished through the implementation of a simple mouse-rollover function. This computer-aided instruction software allows students to preview histological structures of interest prior to entering the laboratory, to have additional faculty-directed contact hours during laboratory, and to review material efficiently. The conversion of the originally developed static application into a database-driven tool streamlined the development and modification of the atlas while facilitating the creation of advanced features. Six weeks after launching this interactive atlas, Vanderbilt medical students logged 1,200 hr of use. Through the cooperative efforts of faculty and students, the interactive atlas evolved to meet the educational demands of medical students owing to the development and implementation of a database structure. The functionality and educational value of the interactive atlas in facilitating self-learning was ultimately measured by positive student feedback and use.

Anatomy, Artistic↗
PubMed2007

Design characteristics that affect speed of information access and clarity of presentation in an electronic neuroanatomy atlas.

Functional Neuroanatomy, an interactive electronic neuroanatomical atlas, was designed for first year medical students. Medical students have much to learn in a limited time; therefore a major goal in the atlas design was that it facilitate rapid, accurate information retrieval. To assess this feature, we designed a testing scenario in which students who had never taken a neuroanatomy course were asked to complete two equivalent tests, one using the electronic atlas and one using a comparable hard copy atlas, in a limited period of time. The tests were too long to be completed in the time allotted, so test scores were measures of how quickly correct information could be retrieved from each source. Statistical analysis of the data showed that the tests were of equal difficulty and that accurate information retrieval was significantly faster using the electronic atlas when compared with the hard copy atlas (P < 0.0001). Post-test focus groups (n = 4) allowed us to infer that the following design features contributed to rapid information access: the number of structures in the database was limited to those that are relevant to a practicing physician; all of the program modules were presented in both text and image form on the index screen, which doubled as a site map; pages were layered electronically such that information was hidden until requested, structures available on each page were listed alphabetically and could be accessed by clicking on their name; and an illustrated glossary was provided and equipped with a search engine.

Humans↗
PubMed2003

Three-dimensional maximum probability atlas of the human brain, with particular reference to the temporal lobe.

Probabilistic atlases of neuroanatomy are more representative of population anatomy than single brain atlases. They allow anatomical labeling of the results of group studies in stereotaxic space, automated anatomical labeling of individual brain imaging datasets, and the statistical assessment of normal ranges for structure volumes and extents. No such manually constructed atlas is currently available for the frequently studied group of young adults. We studied 20 normal subjects (10 women, median age 31 years) with high-resolution magnetic resonance imaging (MRI) scanning. Images were nonuniformity corrected and reoriented along both the anterior-posterior commissure (AC-PC) line horizontally and the midsagittal plane sagittally. Building on our previous work, we have expanded and refined existing algorithms for the subdivision of MRI datasets into anatomical structures. The resulting algorithm is presented in the Appendix. Forty-nine structures were interactively defined as three-dimensional volumes-of-interest (VOIs). The resulting 20 individual atlases were spatially transformed (normalized) into standard stereotaxic space, using SPM99 software and the MNI/ICBM 152 template. We evaluated volume data for all structures both in native space and after spatial normalization, and used the normalized superimposed atlases to create a maximum probability map in stereotaxic space, which retains quantitative information regarding inter-subject variability. Its potential applications range from the automatic labeling of new scans to the detection of anatomical abnormalities in patients. Further data can be extracted from the atlas for the detailed analysis of individual structures.

Adult↗
PubMed2005

Region-growing segmentation of brain vessels: an atlas-based automatic approach.

PURPOSE: To propose an atlas-based method that uses both phase and magnitude images to integrate anatomical information in order to improve the segmentation of blood vessels in cerebral phase-contrast magnetic resonance angiography (PC-MRA). MATERIAL AND METHODS: An atlas of the whole head was developed to store the anatomical information. The atlas divides a magnitude image into several vascular areas, each of which has specific vessel properties. It can be applied to any magnitude image of an entire or nearly entire head by deformable matching, which helps to segment blood vessels from the associated phase image. The segmentation method used afterwards consists of a topology-preserving, region-growing algorithm that uses adaptive threshold values depending on the current region of the atlas. This algorithm builds the arterial and venous trees by iteratively adding voxels that are selected according to their grayscale value and the variation of values in their neighborhood. The topology preservation is guaranteed because only simple points are selected during the growing process. RESULTS: The method was performed on 40 PC-MRA images of the brain. The results were validated using maximum-intensity projection (MIP) and three-dimensional surface rendering visualization, and compared with results obtained with two non-atlas-based methods. CONCLUSION: The results show that the proposed method significantly improves the segmentation of cerebral vascular structures from PC-MRA. These experiments tend to prove that the use of vascular atlases is an effective way to optimize vessel segmentation of cerebral images.

Adult↗
PubMed1996

A stereotaxic template atlas of the macaque brain for digital imaging and quantitative neuroanatomy.

A stereotaxic brain atlas of the longtailed macaque (Macaca fascicularis) is presented in a format suitable for use as a template atlas of the macaque brain. It includes most of the brain segmented to show the boundaries of landmark structures such that every point in the brain can be represented by a unique set of coordinates in three-dimensional space and ascribed unambiguously to one and only one primary structure. More than 400 structures are represented, including 360 volumetric structures, which constitute the substance of the brain, and 50 superficial features. To facilitate use with ventriculography, magnetic resonance imaging, and other noninvasive imaging techniques, the stereotaxic space is referenced to internal landmarks, viz., the anterior commissure and posterior commissure; the center of the anterior commissure at the midline is the origin of the stereotaxic axes. Reference of stereotaxis to this bicommissural space facilitates structural comparison with human brain atlases, which are commonly referenced to the biocommissural line. It also facilitates comparison of brains of different nonhuman primate species by providing a template brain against which to compare size and internal variability. Thirty-three coronal sections at 1-mm intervals from the spinomedullary junction to the rostral extreme of the caudate nucleus show most structures of the hindbrain, midbrain, and subcortical forebrain. Separately, four side views and 16 coronal sections show cortical structures. Structures are represented by outlines of their boundaries and labeled according to NeuroNames, a systematic English nomenclature of human and nonhuman primate neuroanatomy. Abbreviations are based on a protocol designed to facilitate cross-species comparisons. Instructions are provided for: (1) locating sites from the Template Atlas in the conventional stereotaxic space of an experimental animal, (2) locating sites identified by conventional stereotaxis in the Template Atlas, and (3) using the Template Atlas to collate, compare, and display image information (e.g., labeled cells, recording sites, stimulation sites, lesions) from multiple animals.

Animals↗
PubMed2005

Anatomical and electrophysiological validation of an atlas for neurosurgical planning.

Digital brain atlases can be used in conjunction with magnetic resonance imaging (MRI) and computed tomography (CT) for planning and guidance during neurosurgery. Digital atlases are advantageous, since they can be warped nonlinearly to fit each patient's unique anatomy. Two atlas-to-patient warping techniques are compared in this paper. The first technique uses an MRI template as an intermediary to estimate a nonlinear atlas-to-patient transformation. The second, is novel, and uses a pseudo-MRI volume, derived from the voxel-label-atlas, to estimate the atlas-to-patient transformation directly. Manual segmentations and functional data are used to validate the two methods.

Brain↗
PubMed1989

A computerized adjustable brain atlas.

A computerized brain atlas, adjustable to the patients anatomy, has been developed. It is primarily intended for use in positron emission tomography, but may also be employed in other fields utilizing neuro imaging, such as stereotactic surgery, transmission computerized tomography (CT) and magnetic resonance imaging (MRI). The atlas is based on anatomical information obtained from a digitized cryosectioned brain. It can be adjusted to fit a wide range of images from individual brains with normal anatomy. The corresponding transformation is chosen so that the modified atlas agrees with a set of CT or NMR images of the patient. The computerized atlas can be used to improve the quantification and evaluation of PET data by: Aiding and improving the selection of regions of interests. Facilitating comparisons of functional image data from different individuals or groups of individuals. Facilitating the comparison of different examinations of the same patient, thus reducing the need of reproducible fixation systems. Providing external a priori anatomical information to be used in the image reconstruction. Improving the attenuation and scatter corrections. Aiding in selecting a suitable patient orientation during the PET study. By applying the inverse atlas transformation to PET data set it is possible to relate the PET information to the anatomy of the reference atlas. Thus reformatted PET data from different patients can be averaged, and averages from different categories of patients can be compared. This procedure will facilitate the identification of statistically significant differences in the PET information from different groups of patients.

Brain↗
PubMed1995

CBA--an atlas-based software tool used to facilitate the interpretation of neuroimaging data.

CBA, a software tool used to improve quantification and evaluation of neuroimaging data has been developed. It uses a detailed 3-dimensional brain atlas that can be adapted to fit the brain of an individual patient represented by a series of displayed images. Anatomical information from the atlas can then be introduced into the images. If the patient has been imaged in different modalities, adaptation of the atlas to the different images will provide the transformation that brings the images into registration. CBA can thus be used as a tool for fusing multimodality information from the same patient. Furthermore, by applying the inverse atlas transformation, images from a patient can be transformed to conform to the anatomy of the atlas brain. This anatomical standardization, where the atlas brain itself serves as the anatomy standard, brings data from different individuals into a compatible form providing possibilities to perform individual-group and group-by-group comparisons between patients and normal controls.

Animals↗
PubMed1988

Anatomical atlas of the baboon's brain in the orbito-meatal plane used in experimental positron emission tomography.

An anatomical atlas has been constructed of the brain of the baboon (Papio papio) in the orbito-meatal plane (OM-plane) which is frequently used in experimental positron emission tomography (PET) investigations. The atlas comprises 12 photographic reproductions of histological brain sections separated by 2.5 mm intervals, and covers telencephalic to pontine brain stem levels. The anatomical atlas was used in analysis of some PET scan images obtained after administration of either a benzodiazepine (BZ) antagonist, (11C)-Ro 15-1788, or a dopamine D2 receptor antagonist, (76Br)-bromospiperone. Since PET camera detects radiation emitted from a slice of tissue of 15 mm thickness, each PET image corresponds to the tissue represented on six levels of the anatomical atlas. In optimal conditions, the PET image shows a pattern of receptor labelling reminiscent of anatomical structures in the atlas. Sometimes, however, the superimposition of different labelled structures yields a PET image which lacks any apparent resemblance with individual anatomical structures. In these cases, the analysis of the PET scan must rely on the anatomical atlas, as well as available data on the distribution of specific binding sites.

Animals↗