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PubMed1992

ATLAS-plus: multimedia instruction in embryology, gross anatomy, and histology.

ATLAS-plus [Advanced Tools for Learning Anatomical Structure] is a multimedia program used to assist in the teaching of anatomy at the University of Michigan Medical School. ATLAS-plus contains three courses: Histology, Embryology, and Gross Anatomy. In addition to the three courses, a glossary containing terms from the three courses is available. All three courses and the glossary are accessible in the ATLAS-plus environment. The ATLAS-plus environment provides a consistent set of tools and options so that the user can navigate easily and intelligently in and between the various courses and modules in the ATLAS-plus world. The program is a collaboration between anatomy and cell biology faculty, medical students, graphic artists, systems analysts, and instructional designers.

Anatomy↗
PubMed2004

Parametric brain MR atlases: standardization for imaging informatics.

This paper is focused on the development of normal MR brain atlases of intrinsic MR parameters. These parameters permit quantitative comparisons across imaging studies (as opposed to raw image intensity values) and are important markers of neurological diseases. The development includes fast sequences to generate three parameters (T1: spin-lattice relaxation, T2: spin-spin relaxation, and Diffusion Tensor) covering the whole brain with isotropic and high-resolution images. The analysis of raw data to generate the parametric images is followed by registration algorithms to bring the image studies acquired on normal subjects aligned to a common frame of reference. The registration method includes both linear and non-linear algorithms. Two atlas schemes are discussed: an average atlas and a probabilistic atlas. Initial results on sequence development and registration are presented. The atlases are envisaged as an integral part of an imaging informatics infrastructure that enables image analysis across imaging studies to perform automated image data mining.

Algorithms↗
PubMed2004

MRI-based individual 3D region-of-interest atlases of the human brain: a new method for analyzing functional data.

OBJECTIVES: Introduction of a new atlas-based method for analyzing functional data which takes into account the variability of individual human brains and the partial volume, effects of functional emission computed tomography, images in complex anatomical 3D regions, as well as, describing the underlying multi-modal image processing, principles. METHODS: 3D atlas extraction is done directly by automated segmentation of individual magnetic resonance images of the patient's head. This is done in two steps: voxel-based classification of T1-weighted images for tissue differentiation (low-level processing) is followed by knowledge-based analysis of the classified images for extraction of 3D anatomical regions (high-level processing). For atlas-based quantification of co-registered functional images, 3D anatomical regions can be convoluted with an idealized point spread function of the emission computed tomography system, after which a partial volume-dependent threshold can be determined. RESULTS: Quantitative evaluation studies, based on 50 realistic software head phantoms and 24 image data sets obtained from healthy subjects and patients, show low misclassification rates and stable results for the neural network-based classification approach (mean +/- SD 3.587 +/- 0.466%, range 2.726-4.927%) as well as for the adjustable parameters of the knowledge-based approach. Computation time is <5 min for classification, <1 min for most of the extraction algorithms. The influence of the partial volume-dependent threshold is shown for an activation study. CONCLUSIONS: This new method allows 3D atlas generation without the need to warp individual image data to an anatomical or statistical brain atlas. Going beyond the purely tissue-oriented approach, partial volume effects of emission computed tomography images can be analyzed in complex anatomical 3D regions.

Algorithms↗
PubMed2006

A human protein atlas based on antibody proteomics.

The Human Protein Atlas is a comprehensive database that provides the protein expression profiles for a large number of human proteins, presented as immunohistological images from most human tissues. This review provides an overview of the contents of the atlas, discusses the project strategy and highlights the importance of open access for data validation and quality. Essential procedures that are implemented during antibody production and image generation, such as the use of protein epitope signature tags (PrEST) antigens, monospecific antibodies, tissue microarrays and thorough quality validation, are also discussed. The Human Protein Atlas is related to four other expression atlas initiatives, including, in particular, an upcoming protein atlas developed by the Sanger Institute.

Animals↗
PubMed1978

A stereotaxic atlas of the brain of the three-day-old domestic chick.

Preparation of a stereotaxic atlas of the brain of the 3-day-old domestic chick was prompted by the widespread use of chicks in behavioral and pharmacological research. The atlas is comprised of 26 frontal plates extending from the frontal pole to the level of the hypoglossal nucleus, and one sagittal plate at lateral 0.4 mm. Marking lesions were used to ascertain coordinates, the brains were embedded in albumin and sections cut at 36 mmu. The brain sections were stained with cresyl violet for nuclei and with hematoxylin for fibers. Unstained brain sections were used as a guide in drawing the plates to correct for shrinkage and distortion. The use of the atlas for research purposes for one year, plus test lesions targeted for specific brain structures, indicates the atlas is accurate to within 0.5 mm.

Animals↗
PubMed1989

Marked canal stenosis at the level of the atlas.

A 38-year-old man with severe canal stenosis at the level of the atlas is reported. The clinical manifestations were muscular weakness and wasting of the upper limbs and spastic paresis of the lower limbs, which all progressed slowly. The atlas was hypoplastic and its retrodental space was narrow. The spinal cord was markedly compressed between the odontoid process and the posterior arch of the atlas. The clinical manifestations improved after a posterior laminectomy of the atlas.

Adult↗
PubMed1983

Fractures of the arches of the atlas: a study of their causation.

The autopsy findings in 32 accidental deaths which showed fracture(s) of the arches of the atlas have been correlated to reconstructions of the course of events in the accidents. Flexion of the head causing fracture(s) of the neural arch or odontoid process of the axis also resulted in fracture(s) of the posterior arch due to downward traction. Extension of the head causing fracture of the odontoid process of the axis gave rise to fractures of the posterior arch due to pressure from below. Tilting of the head caused marginal fractures of the anterior arch due to oblique traction. Tilting of the head also caused fracture(s) of the anterior and/or posterior arch due to transverse extension of the atlas ring and/or superior dislocation of one lateral mass in relation to the other. Oblique flexion or extension of the head resulted in similar fractures. Flexion of the head with some rotation combined with compression of the neck can cause the anterior margin of one upper joint surface of the axis to act as a wedge separating the anterior arch of the atlas from below. Extension of the head with some rotation combined with compression of the neck can lead to a fracture running through one lateral mass due to its tilting-dislocation in posterior direction. It is striking that there was no fracture of the atlas which could be ascribed to a simple and symmetric compression of the neck (classical Jefferson's fracture).

Accidents, Traffic↗
PubMed1994

Spinal canal stenosis at the level of the atlas: case report.

We describe a rare case of cervical canal stenosis at the level of the atlas, presenting with cervical myelopathy as an initial symptom. A 55-year-old man was admitted to our hospital with a 4-month history of gait disturbance and clumsiness in both hands. He had no history of trauma, and showed left-sided hemihyperesthesia and mild quadriplegia with exaggerated deep tendon reflexes. Plain cervical tomography revealed marked spinal canal stenosis, with the diameter of 8.0 mm at the level of the atlas. Magnetic resonance imaging demonstrated severe compression of the spinal cord at the atlas, with an extensive high intensity area indicating edema on T2-weighted images. The patient showed an excellent recovery after laminectomy of the atlas combined with decompression of the lower posterior fossa of the foramen magnum and dural plasty.

Cervical Atlas↗
PubMed2005

Why Atlas, why not Heracles: reflections on the rheumatoid cervical spine.

Rheumatoid involvement of the 24 joints of the cervical spine leads to prominent changes in the occipito-atlanto-axial area. Eight different subtypes of such changes are recognized, depicted, and defined. The frequencies of these 8 subtypes in rheumatoid arthritis and other arthritides are tabulated. A central role in these disorders is played by a small-size, heavy-duty fitting piece or adapter, atlas, between the occiput and C2. The history of the fate of Atlas, who led the fight of godlike titans against the new gods of Olympos, is recapitulated. In particular, for a short moment Atlas was released from his heavy physical ordeal by another strongman, the heavy-weight wrestler of his times, Heracles. The reasons for the current nomenclature and answer to the question "Why Atlas, why not Heracles" are provided.

Arthritis, Rheumatoid↗
PubMed2006

Chiari I malformation accompanied by assimilation of the atlas, Klippel-Feil syndrome, and syringomyelia: case report.

BACKGROUND: Chiari I malformation, accompanied by superposed bony anomaly of the craniovertebral junction, is comparatively rare. We report a case of Chiari I malformation accompanied by assimilation of the atlas, Klippel-Feil syndrome, and syringomyelia. CASE DESCRIPTION: The patient was a 61-year-old woman demonstrating numbness of the extremities, sensory impairment, muscular weakness, and tendon hyper-reflexia. X-ray images and CT scans demonstrated assimilation of the atlas to the occipital bone, C2 and C3 fusion, abnormal passage of the vertebral arteries, and an anomalous bony mass on the right lateral mass of the atlas protruding into the spinal column. The odontoid process was also deviated to the left. Magnetic resonance images demonstrated bilateral descent of the cerebellar tonsils and syringomyelia extending from C6 to T8. Computed tomographic scans with the head rotated to the right demonstrated increased narrowing of the vertebral column caused by the right lateral mass of the atlas, and MR images confirmed exaggerated deformation of the spinal cord at the same region. This deformation manifested no neurologic symptoms, and we therefore performed foramen magnum decompression and duraplasty using Gore-Tex (W.L. Gore & Associates, Inc., Flagstaff, AZ). In the early postoperative period, neurologic symptoms improved. CONCLUSION: We believe it is important that a treatment plan for Chiari I malformation accompanied by bony anomaly of the craniovertebral junction be determined based on morphologic investigation of the region supplemented by dynamic imaging-based evaluation of instability, or a careful inspection for atypical passage of the vertebral arteries, a frequent site of complication.

Arnold-Chiari Malformation↗
PubMed1999

Compression of the internal jugular vein by the transverse process of the atlas as the cause of cerebellar hemorrhage after supratentorial craniotomy.

BACKGROUND: The cerebellar hemorrhage reported in numerous cases after supratentorial craniotomy has uniformly exhibited the characteristics of hemorrhage associated with venous infarction rather than arterial bleeding. The cause has remained obscure, although previous reports suggested that the cause may be obstruction of flow in the internal jugular vein immediately below the base of the skull. METHODS: The microsurgical anatomy of 36 internal jugular veins in the upper cervical region were defined in adult cadaveric specimens using 3-40x magnification with special attention to the relationship of the vein to the atlas. RESULTS: In every specimen, the posterior wall of the internal jugular vein rested against the transverse process of the atlas as the vein descended immediately below the jugular foramen. In 14 of 36 specimens, the transverse process indented the posterior wall of the vein, causing the vein to be slightly or moderately angulated as it descended across the anterior surface of the transverse process. Three veins were severely kinked as they descended across the transverse process of the atlas. CONCLUSIONS: Obstruction of flow in the internal jugular vein at the site where the vein descends across the transverse process of the atlas is a likely cause of the venous hypertension that has resulted in the cerebellar hemorrhage reported in numerous cases after supratentorial craniotomy. An examination of the biomechanics of the region confirms that turning the head to the side opposite a supratentorial craniotomy and extending the neck, common practices with unilateral supratentorial craniotomy, further aggravates the angulation and obstruction of the internal jugular vein at the transverse process of C1 on the side ipsilateral to the craniotomy.

Adult↗
PubMed2002

Vertebral height, disc height, posteroanterior displacement and dens-atlas gap in the cervical spine: precision measurement protocol and normal data.

OBJECTIVE: (1) Precise measurement of vertebral height, disc height, posteroanterior displacement and dens-atlas gap from lateral radiographic views of the cervical spine. (2) Compilation of a normative database for these parameters, specifying dependence on gender and age. DESIGN: Descriptive study, based on measurements from lateral radiographic views of the cervical spine of healthy subjects. BACKGROUND: Normal data of vertebral height, disc height, posteroanterior displacement and size of the dens-atlas gap as well as their biological range of variation and potential dependence on gender and age are not available. METHODS: Based on computer-aided measurements from lateral radiographic views of the cervical spine, a new protocol determines these parameters. RESULTS: are compensated for radiographic magnification, variation in stature and the individually adopted posture of the cervical spine; they are virtually uninfluenced by radiographic distortion and patient alignment errors. A specimen study as well as inter- and intra-observer studies quantify measurement errors.Results. Employing the new protocol, vertebral height C3-C7 and disc height C2/C3-C6/C7 are measured with relative errors of 3.9% and 5.7% respectively. Posteroanterior displacement C1/C2 to C6/C7 is measured with an error of 2.8% of mean vertebral depth and the dens-atlas gap is measured with an error of <1.8% of the depth of C2. A normal database for the dimensions of cervical vertebrae and discs as well as of the sagittal plane alignment of the vertebrae within the cervical spine is compiled from 135 lateral views of healthy adults. CONCLUSIONS: Vertebral height, disc height, posteroanterior displacement and size of the dens-atlas gap are measured with high precision. Normal data are presented for the first time. RELEVANCE: The new protocol in conjunction with the normal database enables future studies detecting or monitoring morphological effects of, for example, trauma, long-term high mechanical loading, disc degeneration, rheumatoid arthritis, fusion or other surgical interventions.

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↗
PubMed2001

Posterolateral tunnels and ponticuli in human atlas vertebrae.

The posterolateral tunnel on the superior surface of the first cervical (atlas) vertebra is of normal occurrence in monkeys and other lower animals, but its presence in the form of a tunnel-like canal, for the passage of the third part of the vertebral artery over the posterior arch of the human atlas vertebra is not reported. The aim of the present study was to detect the presence of such a canal, in addition to other types of ponticuli (little bridges) reported by earlier investigators, in macerated atlas vertebrae and routine cadaveric dissections. The posterolateral tunnel was detected in 1.14%, and the posterior and lateral ponticuli in 6.57 and 2% of vertebrae. Probably the bony roof of the posterolateral tunnel serves the purpose of additional lateral extension for the attachment of the posterior atlanto-occipital membrane in quadrupeds, where the load of the head is supported by the extensor muscles of the neck, ligaments and posterior atlanto-occipital membrane. In man, where the weight of the head is borne by the vertical loading of the superior articular process of the atlas, the roof of the tunnel has disappeared.

Adult↗
PubMed1998

Cervical myelopathy caused by hypoplasia of the atlas: two case reports and review of the literature.

OBJECTIVE AND IMPORTANCE: Congenital anomalies of the posterior arch of the atlas (C1) are uncommon. They range from partial clefts to total agenesis of the posterior arch. Developmental cervical canal stenosis is a congenital anomaly that may cause cervical myelopathy. Myelopathy caused by cervical stenosis at the level of the atlas has been reported in only three cases. We present two cases of nontraumatic cervical myelopathy caused by spinal stenosis at the level of the atlas associated with a hypoplastic but complete posterior arch of C1. CLINICAL PRESENTATION: Two elderly Chinese men developed cervical myelopathy gradually during months to years, without preceding trauma. Imaging revealed a hypoplastic but complete posterior C1 arch associated with changes of spondylosis in both patients, producing severe spinal stenosis and spinal cord compression. Posterior decompression was achieved in both by the removal of the posterior arch of C1 with its surrounding thickened posterior ligaments. Symptoms and clinical findings improved in the two patients during the follow-up period. CONCLUSION: The anomaly presented in our two cases differs from the established classification of congenital abnormalities of the posterior arch of the atlas, suggesting a different embryological defect. The hypoplastic posterior C1 arch created a congenitally narrowed spinal canal in our patients, rendering the spinal cord more susceptible to compression related to degenerative changes of the spine. Surgical removal of the shortened posterior C1 arch and surrounding degenerative ligaments is an effective treatment for symptomatic patients with this condition.

Aged↗
PubMed2002

Isolated fractures of the atlas in adults.

STANDARDS: There is insufficient evidence to support treatment standards. GUIDELINES: There is insufficient evidence to support treatment guidelines. OPTIONS: Treatment options in the management of isolated fractures of the atlas are based on the specific atlas fracture type. It is recommended that isolated fractures of the atlas with an intact transverse atlantal ligament be treated with cervical immobilization alone. It is recommended that isolated fractures of the atlas with disruption of the transverse atlantal ligament be treated with either cervical immobilization alone or surgical fixation and fusion.

Cervical Atlas↗
PubMed1991

Experimental study of atlas injuries. II. Relevance to clinical diagnosis and treatment.

Atlas injuries were produced in vitro and evaluated by radiographic examinations and anatomic studies from a clinical viewpoint. Ten cadaveric human upper cervical spine specimens were subjected to a high-speed axial impact. Injuries to the atlas consisted of six bursting fractures, two ruptures of the transverse ligament, one four-part fracture without a prominent bursting, and one posterior arch fracture. The major soft tissue injury involved the transverse ligament. There were five bony avulsions and three midsubstance tears. In this study, computed tomographic examinations clearly demonstrated the sites of fracture and bony avulsions of the transverse ligament. The best diagnostic tool for function of the transverse ligament was determined to be the atlantodental interval on flexion radiographs. Axial traction force reduced a bursting fracture of the atlas ring. The in vitro atlas injury model gives useful information for clinical diagnosis and treatment.

Biomechanical Phenomena↗
PubMed1998

The quantitative anatomy of the vertebral artery groove of the atlas and its relation to the posterior atlantoaxial approach.

STUDY DESIGN: An evaluation of the vertebral artery groove of the atlas vertebra using dry bony vertebrae. OBJECTIVES: To measure the dimension of the vertebral artery groove of the atlas and to define its relation to the posterior midline. SUMMARY OF BACKGROUND DATA: Anatomic descriptions of the vertebral artery groove of the atlas exist, but very little quantitative data focused on this groove have been reported. METHODS: Fifty dry atlas vertebrae were obtained for this study. Anatomic evaluation focused on the vertebral artery groove and its relation to the midline. A total of eight linear and two angular measurements were made bilaterally. The mean, range, and standard deviation were calculated for all of the specimens and for male and female specimens separately. RESULTS: Differences in dimensions of male and female specimens were found to be statistically significant in one linear and two angular parameters. The average depths of the medial and lateral entrances, lengths of the axis, and thicknesses of the vertebral artery groove for male and female specimens were 9 mm, 6 mm, 14 mm, and 4 mm, respectively. The average angle of the vertebral artery groove axis for both genders was 64 degrees lateral to the sagittal plane. The distances from the midline to the medial-most edge of the vertebral artery groove on the inner and outer cortexes for male and female specimens averaged 10 mm, with a minimum of 8 mm, and 18 mm, with a minimum of 12 mm, respectively. CONCLUSIONS: The results of this study suggest that dissection on the posterior aspect of the posterior ring should remain within 12 mm lateral to the midline, and dissection on the superior aspect of the posterior ring should remain within 8 mm of the midline.

Adult↗