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At least 217 records · Page 12Linked to original sources
PubMedDate not supplied

Bony anomalies of the craniocervical junction.

A review of the literature on bony anomalies of the craniovertebral junction was carried out with emphasis on anomalous manifestations associated with the occipital bone, atlas and axis vertebrae. A summary of the evolution and normal development of the above bony structures and the embryological structures contributing to the bony anomalies is presented. In addition the diagnostic measurements used for the diagnosis of the bony anomalies of the craniocervical junction and their clinical presentation were summarised. This review was prepared with the aim of providing reference material for neurosurgeons and radiologists.

Atlanto-Axial Joint↗
PubMed2005

Atlas-based hippocampus segmentation in Alzheimer's disease and mild cognitive impairment.

This study assesses the performance of public-domain automated methodologies for MRI-based segmentation of the hippocampus in elderly subjects with Alzheimer's disease (AD) and mild cognitive impairment (MCI). Structural MR images of 54 age- and gender-matched healthy elderly individuals, subjects with probable AD, and subjects with MCI were collected at the University of Pittsburgh Alzheimer's Disease Research Center. Hippocampi in subject images were automatically segmented by using AIR, SPM, FLIRT, and the fully deformable method of Chen to align the images to the Harvard atlas, MNI atlas, and randomly selected, manually labeled subject images ("cohort atlases"). Mixed-effects statistical models analyzed the effects of side of the brain, disease state, registration method, choice of atlas, and manual tracing protocol on the spatial overlap between automated segmentations and expert manual segmentations. Registration methods that produced higher degrees of geometric deformation produced automated segmentations with higher agreement with manual segmentations. Side of the brain, presence of AD, choice of reference image, and manual tracing protocol were also significant factors contributing to automated segmentation performance. Fully automated techniques can be competitive with human raters on this difficult segmentation task, but a rigorous statistical analysis shows that a variety of methodological factors must be carefully considered to insure that automated methods perform well in practice. The use of fully deformable registration methods, cohort atlases, and user-defined manual tracings are recommended for highest performance in fully automated hippocampus segmentation.

Aged↗
PubMed2000

A Dense Grid of Reference Iodine Lines for Optical Frequency Calibration in the Range 595-655 nm.

A dense grid of reference lines in the hyperfine structure of the B-X transitions of molecular iodine ((127)I(2)) is presented. Frequencies of 481 "t"-hyperfine components in 15 vibrational bands covering the wavelength range 595-655 nm were determined with an absolute accuracy of 1.0 MHz (1varsigma uncertainty). Spectra were obtained by Doppler-free saturation spectroscopy using a cw ring-dye laser of 1-MHz bandwidth. Center-of-gravity frequencies of rovibronic lines, determined by correcting for the calculated hyperfine shift, are included separately in a least-squares parametrization for each band. From the obtained molecular constants a prediction is made for all t-hyperfine components of the 15 bands covering 595-655 nm. Hence a dense grid of reference lines of 1 MHz (1varsigma) absolute accuracy is created, with a line in each interval of 1 cm(-1) in the entire range. This spectral atlas of about 3400 lines may provide a useful calibration tool in many laboratories. Copyright 2000 Academic Press.

Journal Article↗
PubMedDate not supplied

Synthesized image processing in clinical neurosurgery.

In an effort to achieve efficient image management in clinical neurosurgery utilizing a local image filing system (EFPACS, Fuji Electric Co., Ltd), adequate image-processing and display techniques were developed. One is a method whereby the anatomical location of the thalamic and basal ganglion lesions is determined by automatically superimposing these lesions defined by magnetic resonance imaging (MRI) directly onto the Schaltenbrand-Wahren's human brain atlas. Horizontal, coronal and sagittal MR images are initially obtained based on the intercommissural line and a perpendicular erected on the midcommissural point as the basic reference coordinates. Precise superimposition is accomplished by the use of these reference axes. This imaging technique may offer the potential for help in anatomical identification of small intracranial lesions. Another technique described in the current communication is automated synthesis of two cerebral angiograms. By simply indicating two reference points, nasion and inion, with a cursor on the display screen, two films are automatically superimposed and displayed as a single synthesized image, featuring two different vascular phases simultaneously by a positive(vein)-negative(artery) mode. This technique was applied to patients with complete occlusion of the middle cerebral artery with or without sufficient blood flow through collateral circulation and was found useful in evaluating basic hemodynamics on a single angiographic image.

Aged↗
PubMed2006

Osteophytes, juxta-articular radiolucencies and cancellous bone changes in the proximal tibia of patients with knee osteoarthritis.

OBJECTIVE: To determine differences in tibial cancellous bone organisation in knee osteoarthritis (OA) between the central weight-bearing region and juxta-articular radiolucencies adjacent to small, medium or large marginal osteophytes. METHODS: Patients with medial compartment OA (n = 60; F = 39), mean (SD) age 60.0 (9.7) years, and non-OA reference subjects (n = 21; F = 5), mean (SD) age 36.8 (11.5) years, had x4 macroradiographs digitised by laser scanner. Using a modified Osteoarthritis Research Society (OARS) Atlas, right and/or left knees were graded according to marginal osteophyte size into those with small (n = 30), medium (n = 30) or large (n = 27) marginal osteophytes, identified as OPH1, OPH2 and OPH3, respectively. Non-OA knees (n = 30) were anatomically normal. Computerised method of Fractal Signature Analysis (FSA) quantified differences in cancellous bone structure between non-OA and osteophyte subgroups at two regions of interest (ROIs); central weight-bearing and tibial margin. RESULTS: Compared to non-OA, vertical trabecular number increased significantly (P < 0.05) in all osteophyte subgroups (width range 0.12-1.14 mm) within both ROIs. In OPH3, this increase was significantly (P < 0.05) greater compared to OPH2 in the central ROI, and to OPH2 and OPH1 in the marginal ROI at most trabecular widths (0.12-1.14 mm). In the marginal ROI, compared to non-OA, horizontal trabeculae number decreased in all osteophyte subgroups. This decrease was significantly greater in OPH3 compared to OPH2 and OPH1 at small to medium trabecular widths (0.12-0.54 mm). CONCLUSION: Compared to disease associated bone loss at the central ROI of the tibia, the extent of juxta-articular bone loss appears to be associated with the size of the marginal osteophytes.

Adult↗
PubMed1998

[Colliculus atlantis--a rarely observed anatomic structure--in a transoral roentgen image of the thoracic spine].

PURPOSE: To study the time and mode of the development of the colliculus atlantis, the rate of its occurrence, the causes for its absence, and the radiological-clinical importance in the analysis of open-mouth-view radiographs. MATERIAL AND METHODS: Retrospective analysis of standardized radiographs of the cervical spine in more than 20,000 adults and 100 children. Study of 234 human skeletons of different ages and of 38 isolated adult atlases. Cadaveric dissection of 42 adults (age 48-87). Axial radiographs of isolated atlases and analysis of the bony structures of the colliculus atlantis. RESULTS: The colliculus atlantis develops between age 10 and 13 years. It is always present after age 13 years. For the development of the colliculus atlantis a normal function of the craniocervical joints is necessary. In congenital dysmorphias of the craniocervical region with dysfunction of the craniocervical joints and in fractures of the dens axis before age 10 years with instable healing the colliculus atlantis is absent. CONCLUSIONS: The colliculus atlantis is developed at age 13 years apart from some rare exceptions as mentioned. Changes of the site and the structure of the colliculus atlantis allow an early diagnosis of certain traumatically and inflammatory diseases of this region. Furthermore, it serves as an additional parameter in functional analysis of the craniocervical joints.

Adolescent↗
PubMed1990

Tc-99m HMPAO brain perfusion tomography atlas using a high resolution SPECT system.

Excellent SPECT images of brain perfusion with Tc-99m HMPAO were obtained by the use of a three-head rotating gamma camera SPECT system with high resolution (FWHM 7mm) in a normal volunteer. These images should be clinically effective for evaluating various neurologic disorders. Transverse, coronal, and sagittal sectional HMPAO-SPECT images are correlated with corresponding brain MRI images of the same normal volunteer in this atlas.

Adult↗
PubMed1993

Rationale and clinical indications for contrast agents in MR imaging of the brain and spine.

This presentation explores clinical indications, limitations, and the scientific rationale for use of gadolinium contrast agents in MR imaging of the brain and spine. Enhancement of abnormal CNS tissues is related to structure and function of the blood-brain barrier under pathologic conditions, the prototype of which is tumor angiogenesis. Gadolinium administration can improve the diagnostic sensitivity of intracranial MR imaging, facilitating detection of leptomeningeal or ependymal disease spread and metastases. Moreover, use of contrast often provides greater diagnostic specificity by virtue of the presence and, in many cases, the absence of enhancement. This is particularly helpful in distinguishing metastases from other potential causes of high signal intensity on unenhanced spin-echo (SE) images. In addition to improving diagnosis of neoplasia, gadolinium use is often necessary to demonstrate most cranial neuropathies and to differentiate herniated disc from epidural fibrosis in the failed-back surgery syndrome. Advanced techniques that exploit gadolinium's properties (e.g., MR angiography, perfusion MR imaging) or increase its diagnostic effectiveness (e.g., fat suppression in the postoperative spine) are treated.

Brain↗
PubMed2001

Three-dimensional digital mouse atlas using high-resolution MRI.

We present an archetypal digital atlas of the mouse embryo based on microscopic magnetic resonance imaging. The atlas is composed of three modules: (1) images of fixed embryos 6 to 15.5 days postconception (dpc) [Theiler Stages (TS) 8 to 24]; (2) an annotated atlas of the anterior portion of a 13.5 dpc (TS 22) mouse with anatomical structures delineated and linked to explanatory files; and (3) three-dimensional renderings of the entire 13.5 dpc embryo and specific organ systems. The explanatory files include brief descriptions of the structure at each volume element in the image and links to 3D reconstructions, allowing visualization of the shape of the isolated structures. These files can also contain or be linked to other types of information and data including detailed anatomical and physiological information about structures with pointers to online references, relationships between structures, temporal characteristics (cell lineage patterns, size, and shape changes), and gene expression patterns (both spatial and temporal). As an example, we have "painted" in the expression pattern of Dlx5/Dlx6 genes. This digital atlas provides a means to put specific data within the context of normal specimen anatomy, to analyze the information in 3D, and to examine relationships between different types of information.

Animals↗
PubMedDate not supplied

A missed Jefferson fracture in chiropractic practice.

OBJECTIVE: To review the case of a missed cervical spine fracture in a patient with neck pain. CLINICAL FEATURES: A 21-year-old thatcher with neck pain presented to a chiropractic clinic after a fall from a roof 4 m high. The hospital radiographs were read as normal. The chiropractor suspected a Jefferson fracture of the atlas after evaluation of the same radiographs. INTERVENTION AND OUTCOME: The chiropractor retook the anteroposterior open-mouth radiograph to confirm the suspected fracture. The patient was referred for further imaging and underwent neurosurgical treatment, after which he recovered well. CONCLUSION: Normal radiologic reports from a hospital cannot be relied on for contraindications to manipulative treatment in all instances, as shown in this case of a missed fracture. Chiropractors should therefore always evaluate radiographs that are brought to them.

Adult↗
PubMed1999

Incidence of ponticulus posterior of the atlas in migraine and cervicogenic headache.

BACKGROUND: The clinical significance of the ponticulus posticus is far from clear. It has been associated with headaches, Barré-Lieou syndrome, photophobia, and migraine. However, little epidemiologic evidence for this exists. OBJECTIVE: This study investigated the relationship of ponticulus posticus on x-ray studies and headache symptoms in a series of chiropractic patients. METHODS: Eight hundred ninety-five patients who visited a chiropractic clinic for the first time and whose conditions required cervical spine x-ray examinations were studied. Complaints were categorized as migraine with aura, migraine without aura, cervicogenic headache, neck pain only, and other conditions. The presence or absence of the ponticulus posticus (whether partial or complete) was determined by means of a lateral cervical film and noted as a positive or negative finding. The data were analyzed by frequency analysis and Pearson's chi 2 test. RESULTS: Forty-six percent of the sample were men and the predominant complaint was neck pain (33%). Most patients were in the fourth decade of life. The frequencies of the other complaints were migraine with aura (7%), migraine without aura (4%), cervicogenic headache (22%), other conditions (33%). An 18% prevalence of ponticulus posticus was found. This finding was significantly associated with migraine without aura (chi 2 = 4.97; P = .03) and not with any other conditions. CONCLUSION: In a chiropractic patient population that required cervical x-ray examinations, a significant association was found between ponticulus posticus and migraine without aura, with an odds ratio of 2.19:1 in favor of this complaint being present with the osseous anomaly. The mechanism for this remains obscure but may be related to ischemic compression of the vertebral artery or by dural tension at the craniocervical junction.

Adult↗
PubMed2003

Establishing a normative atlas of the human lung: intersubject warping and registration of volumetric CT images.

RATIONALE AND OBJECTIVES: To establish the range of normal values for quantitative CT-based measures of lung structure and function, the authors developed a method for matching pulmonary structures across individuals and creating a normative human lung atlas. MATERIALS AND METHODS: A computerized human lung atlas was synthesized from computed tomographic (CT) images from six subjects by means of three-dimensional image registration. The authors identified a set of reproducible feature points for each CT image and used these points to establish correspondences across subjects, used a landmark- and intensity-based consistent image registration algorithm to register a template image volume from the population to the rest of the pulmonary CT volumes in the population, averaged these transformations, and constructed an atlas by deforming the template with the average transformation. RESULTS: The effectiveness of the authors' method was evaluated and visualized by means of both gray-level and segmented CT images. The method reduced the average landmark registration error from 10.5 mm to 0.4 mm and the average relative volume overlap error from 0.7 to 0.11 for the six data sets studied. CONCLUSION: The method, and the computerized human lung atlas constructed and visualized by the authors with this method, provides a basis for establishing regional ranges of normative values for structural and functional measures of the human lung.

Algorithms↗
PubMedDate not supplied

[Congenital disorders in the stability of the cranio-vertebral region].

A functional radiographic examination of the craniovertebral zone was conducted in 600 normal adults and in 15 children. Normal peculiarities of the interrelationship of the atlantoaxial articulation found in 542 persons were classified. In 58 of them (9.7%) excessive mobility of the atlantoaxial articulations was found, 50 of them having a subluxation of the Cruveilhier joint with a dynamic narrowing of the vertebral canal. The remaining 8 persons had an excessive mobility of C1 along the axis of the dens of C2 overlapping half of the anterior arch of C1 above the apex of C2-dens. Such chronic disorders in the interrelationship of the craniovertebral zone elements caused no neurological disorders. However, in unfavourable cases, like forced movements of the head, a severe acute pathogenetic neurological situation may occur.

Adolescent↗
PubMed1982

[Individual variability of the human caudate nucleus].

When establishing borders microscopically and cytoarchitectonically, the volume of the nucleus caudatus (NC) has been measured in human brains from persons of various sex and age (21 persons and 27 hemispheres). The NC volume varies greatly in some persons and it is connected neither with the brain mass, nor with the sex and age. Difference between the extreme variants is more than twice as great. Great morphological differences are supposed to demonstrate a corresponding individual functional specificity. The extreme variants occur rather seldom, cases with less range of differences prevalence. The NC asymmetry is revealed, with the right-sides (5 cases) or left-sided (1 case) prevalence. Very great individual peculiarities are revealed in relations of the form and the extent of various components of the NC: head, body and tail, as well as in the peculiar ending of the latter. Owing to the data obtained, it is necessary to revise the competency of the view on proportional dependence between the external and internal cerebral structures which make the base for using stereotaxic atlases of the human brain, since the existence of the extreme variants creates a real threat of complications in these cases at various operative interventions relying upon the reference points available.

Adult↗
PubMed1998

The effect of atlas anterior translation and rotation on axis canal size. A computer-assisted anatomic study.

Eighteen adult paired atlas and axis specimens were used in conjunction with computer analysis to determine the average transverse canal area of the axis after different degrees of anterior translation and three types of rotation of the atlas. After each displacement, the remaining transverse canal area of the axis was calculated. The data showed that the mean transverse canal area of the axis was 351.5 +/- 8.8 mm2 for males and 276.9 +/- 8.6 mm2 for females, respectively. After a 3-, 4-, and 5-mm anterior translation of the atlas, the mean transverse canal area of the axis decreased to 300.4 +/- 5.1 mm2 (85.5%) for males and 238.0 +/- 2.1 mm2 (85.9%) for females, 283.9 +/- 5.9 mm2 (80.8%) for males and 228.5 +/- 3.1 mm2 (82.5%) for females, and 260.4 +/- 4.2 mm2 (74.1%) for males and 216.4 +/- 2.8 mm2 (78.2%) for females, respectively. After a 40 degree rotation, 40 degree rotation with 4-mm anterior translation, and 40 degree rotation with 8-mm anterior translation of the atlas, the mean transverse canal area of the axis for both sexes decreased approximately to 58%, 42%, and 23%, respectively. This study confirmed that the size of the transverse canal area of the axis was consistently correlated with the degrees of the anterior translation and rotation of the atlas.

Adult↗
PubMed2003

Influence of high-frequency electromagnetic fields on different modes of cell death and gene expression.

PURPOSE: International thresholds for exposure to non-ionizing radiation leading to non-thermal effects were conservatively set by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). The aim of this study was to examine whether biological effects such as different modes of cell death and gene expression modifications related to tumorgenesis are detectable above the threshold defined. MATERIALS AND METHODS: Human leukaemia cells (HL-60) grown in vitro were exposed to electromagnetic fields (EMF; t 1/2(r) about 1 ns; field strength about 25 times higher than the ICNIRP reference levels for occupational exposure) leading to non-thermal effects using a high-voltage-improved GTEM cell 5302 (EMCO) connected to a pulse generator NP20 (C = 1 nF, U(Load) = 20kV). HL-60 cells were harvested at 0, 24, 48 and 72 h after radiation exposure. Micronuclei, apoptosis and abnormal cells (e.g. necrosis) were determined using morphological criteria. In parallel, the expression of 1176 genes was measured using Atlas Human 1.2. Array. Based on high data reproducibility calculated from two independent experiments (> 99%), array analysis was performed. RESULTS: No significant change in apoptosis, micronucleation, abnormal cells and differential gene expression was found. CONCLUSIONS: Exposure of HL-60 cells to EMFs 25 times higher than the ICNIRP reference levels for occupational exposure failed to induce any changes in apoptosis, micronucleation, abnormal morphologies and gene expression. Further experiments using EMFs above the conservatively defined reference level set by the ICNIRP may be desirable.

Apoptosis↗