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At least 127 records · Page 7Linked to original sources
PubMed1989

[Reference line for delineation of the intraparotid facial nerve on MRI].

Exact identification of intraparotid facial nerve is important in surgical management of parotid tumors. To delineate the intraparotid facial nerve on MRI, we proposed a new reference line, which was drawn between the inferior margin of the bone marrow of the atlas and superior margin of the bone marrow of the mandible on midsagittal section. This reference line crossed with orbito-meatal line at the mean angle of 37 +/- 3 degrees. By scanning parallel to this line, intraparotid facial nerve was clearly identified in 19 (79%) of 24 normal parotid glands.

Facial Nerve↗
PubMedDate not supplied

A computerized three-dimensional atlas of the human skull and brain.

PURPOSE: To develop an anatomic atlas of the human head based on a volume model derived from MR and CT. METHODS: Every voxel of this model was labeled by a neuroanatomist concerning its membership to a structural and/or functional region. A computer program was written that, instead of displaying precomputed images, allows the user to choose and compose arbitrary views. RESULTS: The user can subtract parts and ask for annotations just by using the mouse. Conversely, one can compose images by choosing objects from the list of anatomical constituents which is displayed on the screen. A set of dissection tools allows a "look and feel" that comes near to a true dissection. Operations that are not possible in a real dissection, such as reassembly or filling cavities, can be performed. CONCLUSION: The authors have developed a computerized model that can be used for anatomy teaching and also as a reference for radiologists or surgeons. To replace classical atlases, the spatial resolution must be improved and speed must approach real time. Functional imaging data (position emission tomography and single photon emission CT) can be added to the system. The system is mobile and can be situated in classrooms, operating rooms, reading rooms, and libraries.

Brain↗
PubMed2006

The creation of a brain atlas for image guided neurosurgery using serial histological data.

Digital and print brain atlases have been used with success to help in the planning of neurosurgical interventions. In this paper, a technique presented for the creation of a brain atlas of the basal ganglia and the thalamus derived from serial histological data. Photographs of coronal histological sections were digitized and anatomical structures were manually segmented. A slice-to-slice nonlinear registration technique was used to correct for spatial distortions introduced into the histological data set at the time of acquisition. Since the histological data were acquired without any anatomical reference (e.g., block-face imaging, post-mortem MRI), this registration technique was optimized to use an error metric which calculates a nonlinear transformation minimizing the mean distance between the segmented contours between adjacent pairs of slices in the data set. A voxel-by-voxel intensity correction field was also estimated for each slice to correct for lighting and staining inhomogeneity. The reconstructed three-dimensional (3D) histological volume can be viewed in transverse and sagittal directions in addition to the original coronal. Nonlinear transformations used to correct for spatial distortions of the histological data were applied to the segmented structure contours. These contours were then tessellated to create three-dimensional geometric objects representing the different anatomic regions in register with the histological volumes. This yields two alternate representations (one histological and one geometric) of the atlas. To register the atlas to a standard reference MR volume created from the average of 27 T1-weighted MR volumes, a pseudo-MRI was created by setting the intensity of each anatomical region defined in the geometric atlas to match the intensity of the corresponding region of the reference MR volume. This allowed the estimation of a 3D nonlinear transformation using a correlation based registration scheme to fit the atlas to the reference MRI. The result of this procedure is a contiguous 3D histological volume, a set of 3D objects defining the basal ganglia and thalamus, both of which are registered to a standard MRI data set, for use for neurosurgical planning.

Algorithms↗
PubMed1993

Functional neurosurgery using 3-D computer stereotactic atlas.

To facilitate a full-scale representation of thalamic nuclei and surrounding subcortical structures in the course of stereotactic procedures, a 3-D computer atlas of this region has been created, which permits visualization of the operative field including the involved structures and the position of the instrument. Necessary adaptation is performed according to the position of the intracranial reference points derived from CT-scan. Working with the atlas permitted more accurate and safer surgery. An IBM PC/AT computer was used.

Adult↗
PubMed1989

Geographical patterns of cancer mortality in Spain.

This report discusses the methodology and main findings of the Atlas of Cancer Mortality in Spain with special reference to some major forms of cancer. The mortality for all cancers and specifically lung cancer, for both sexes, is highest in the peripheral regions of Spain. This agrees basically with the level of urbanization and industrialization which has developed during the past several decades. Madrid is the outstanding exception to these relationships. The mortality pattern for stomach cancer is directly opposite to that of lung cancer, the more rural inland provinces having higher mortalities and most Mediterranean provinces showing lower mortalities. For breast cancer areas of higher mortality are some northern and some Mediterranean provinces. A similar pattern is shown by other uterus cancer with areas of higher mortality in the Mediterranean provinces. Considered individually, the province of Cádiz shows the greatest risk of death from cancer, being ranked first for the following cancers: lung, oral cavity and pharynx, esophagus, larynx, and prostate for males and esophagus, other uterus, and bone for females. All these findings definitely produce more questions than answers. Future research on analytical epidemiology of cancer in Spain is strongly recommended.

Cluster Analysis↗
PubMed1991

Distribution of cortical neural networks involved in word comprehension and word retrieval.

Six normal volunteers were studied with positron emission tomography to identify the cortical neural networks that participate in the processing of single words. Activity-related changes in regional cerebral blood flow were measured consecutively on 6 occasions in each subject, 2 while the subject was at rest and 4 while single word language tasks were being performed. The data from each subject were standardized for brain shape and size, reconstructed parallel to the intercommissural line, normalized for global flow differences, and then averaged for each activation condition across the 6 subjects. Significant areas of change in rCBF (P less than 0.05, with appropriate Bonferroni corrections) between task and rest conditions were displayed with reference to the coordinates of a standard neuroanatomical atlas. We have demonstrated that categorical judgements on heard pairs of real words activate neural networks along both superior temporal gyri, but with an anatomical distribution no different from that seen when the subjects listened to nonwords: the tasks would appear to be very different in cognitive demands but not in terms of the distribution of activation. However, during a verb generation task that involved thinking of verbs appropriate to heard nouns presented at a slow rate, the only temporal region activated was the left posterior superior temporal association cortex (Wernicke's area). Further analysis showed that whereas activation in other superior temporal regions, both left and right, correlated with rates of word presentation during the 4 tasks, there was no such correlation in Wernicke's area; evidence that this site is responsible for more than early acoustic processing. During verb generation there was also activation of left premotor and prefrontal cortex (including Broca's area and the supplementary motor area). The supplementary motor area is thought to be involved in the motor planning of speech. The subjects did not vocalize during the task, and therefore it would appear that the act of retrieving words from semantic memory activates networks concerned with the production of speech sounds. We conclude that single word comprehension and retrieval activate very different distributed regions of cerebral cortex, with Wernicke's area the only region engaged by both processes and with participation during silent word generation of networks involved in vocalization.

Adult↗
PubMed1975

Specialized reference works and their users. A preliminary study.

An examination of the use of three specialized reference works was made to identify users of the reference tools and the benefits from their use. The feasibility of locating and interviewing users was tested, and an attempt was made to determine the situations in which the works are used. Methods of locating users are described. Users were interviewed to determine the value of each work and alternative sources of information. The works were compared with alternative sources to test their comprehensiveness. Conclusions are: (1) identification of users and their needs is complex, and requires the combination of a number of research methods; (2) the availability and accessibility of alternate information sources varies with both the reference work and the type of user.

Alkaloids↗
PubMed1994

A new method for practicing exploration, dissection, and simulation with a complete computerized three-dimensional model of the brain and skull.

In current practice, anatomical atlases are based on a collection of planar images presented in a book or, recently, stored on digital media. We present a new kind of interactive true three-dimensional (3D) anatomical atlases based on a volume model derived from MRI and CT. The model has a two-layer structure. The lower level is a volume model with a set of semantic attributes connected to each voxel. The semantic attributes are assigned by an anatomist using a volume editor. THe upper level represents a set of relations between these attributes. Interactive visualization tools such as multiple surface display, preparation of transparent material and cutting are provided. It is shown that the combination of this model with advanced tools for volume visualization provides the 'look and feel' of real dissection. The system therefore represents a bridge between real dissection of a cadaver and textbooks and classical atlases of anatomy. First tests have shown that the atlas system may be used successfully for teaching anatomy, but also as a reference for radiologists or surgeons. The powerful underlying data structure potentially includes all classical visual teaching aids. As a replacement of classical atlases, however, spatial resolution has still to be improved.

Anatomy↗
PubMed2004

Interpretation of genital findings in microbicide safety trials: review of the 'Photo Atlas for Microbicide Evaluation'.

The Photo Atlas for Microbicide Evaluation was published in May 2002 for distribution among researchers to be used as a training or reference document during microbicide clinical trials. We have reviewed the contents of the Photo Atlas, including the interpretation and documentation of genital findings. The rationale for the categorization of genital lesions into different lesion types is also discussed. Efforts will continue to standardize colposcopy until more accurate and objective methods become available to assess the safety of candidate microbicides.

Anti-Infective Agents↗
PubMed1999

Kinematic magnetic resonance imaging of the upper cervical spine using a novel positioning device.

STUDY DESIGN: The development of a novel positioning device for magnetic resonance imaging of the upper cervical spine and an evaluation of motion patterns of the craniovertebral junction in asymptomatic volunteers as a part of the whole cervical spine motion. OBJECTIVES: To design and construct a positioning device that enables magnetic resonance imaging of the cervical spine in rotation, lateral bending, flexion, and extension in a horizontally open magnetic resonance scanner, and to define reference values for movements of the occiput (C0), the atlas (C1), and the axis (C2) in asymptomatic volunteers. SUMMARY OF BACKGROUND DATA: In previously used devices, the direction of motion is limited usually to flexion-extension, or the position of the head and neck are adjusted without a positioning device using semihard wedges or pillows. METHODS: Magnetic resonance imaging of the upper cervical spine in 20 asymptomatic individuals (10 men and 10 women) was performed in a horizontally open 0.23-T magnetic resonance imager in progressive steps during rotation, lateral bending, and flexion-extension using axial, coronal, and sagittal imaging planes, respectively. The positions of C0, C1, and C2 were measured, and pattern of motions between segments analyzed. Lateral displacement of the atlas during lateral bending and cranial migration distance during flexion-extension were assessed. RESULTS: The nonferromagnetic positioning device was designed and constructed. The motion patterns of the craniovertebral junction during rotation did not differ between the men and women, but in lateral bending there was a small difference between genders at C1-C2. In men, the position of C1 during flexion-extension was consistently more extended in relation to C0 and C2 than in women. CONCLUSIONS: The new positioning device allows magnetic resonance imaging of the upper cervical spine during flexion, extension, rotation, and lateral bending. To assess the relationship between C0-C1 and C1-C2 in flexion and extension, separate reference values for men and women are recommended.

Adolescent↗
PubMed1987

Microcomputer stereotactic atlas.

A stereotactic atlas to determine thalamic target sites has been incorporated into a microcomputer. Variability studies of the thalamus with mean and standard deviations of nuclear borders are depicted graphically for overlay onto operative images. Internal landmarks traditionally used to reference target points for functional stereotaxis may be determined by conventional ventriculography or derived from magnetic resonance scans. Modeling of polyline vertices established from gray scale contour mapping and atlas reconstructions further enhance the spatial understanding of relationships to midline structures. Computer integration of anatomic reference points, graphically depicted images and stereotactic atlas data into head frame coordinates can be accomplished. This method is consistent with established stereotactic techniques and allows the visual conceptualization of imaged and graphic data for functional stereotaxis.

Brain↗
PubMed1999

MR imaging anatomy of the optic pathways.

Imaging in neuro-ophthalmology is a major, developing field. Visual and motor ocular symptoms and signs are of diagnostic and localizing significance, and occur frequently in patients with brain space-occupying lesions. Knowledge of the anatomy of the optic pathways extending from the retina to the calcarine fissure throughout the brain is crucial. Multiplanar high resolution MR imaging permits the physician to depict the visual path with exquisite detail. This article provides a correlative regional anatomic and imaging atlas of the brain following the optic pathways, with reference to the most accurate technical imaging procedures.

Anatomy, Artistic↗
PubMed2005

Sonographic detection of the optic radiation.

OBJECTIVE: To describe a region of hyperechoic white matter adjacent to the atrium of the lateral ventricle of preterms, and to speculate on the relevance of detecting preterm white matter injury. PATIENTS AND METHODS: Cranial ultrasound images of 92 preterms of gestational age (GA) 32 wk or less were reviewed. For each infant, one first week standard coronal image was used for measurement of grey values around the para-atrial region of interest (PAROI) relative to the choroid plexus. For verification of the sonographic anatomy, MR images of an adult brain were used. For reference, neuro-anatomical images were compared in several atlases. In a group of nine preterms of similar GA with cystic periventricular leukomalacia (PVL) or MR-confirmed white matter disease, the disappearance of the PAROI was examined. RESULTS: The hyperechoic para-atrial area, subjectively detected in 84% of the patients, was situated bilaterally between the inner end of the lateral fissure and the upper third of the choroid plexus. In white matter caudal to the atrium, the hyperechoic band could be pursued towards the calcarine area. The average ratio of grey value around the PAROI to the choroid plexus was 0.787 (SD = 0.072, median 0.791). There was no correlation between PAROI grey value and gestational age. At 26 wk gestational age, the average ratio was 0.781 (n = 14), and 0.789 (n = 17) at 31 wk. Location of the PAROI agrees with the angle of the upper loop of the optic radiation. None of the nine infants with white matter damage had PAROIs clearly distinguishable from flaring. CONCLUSION: The symmetrical and unchanged acoustic character between 26 and 31 wk of gestational age argues in favour of the hypothesis that the PAROI is an anatomical structure. The localization of the hyperechoic band supports the hypothesis that it represents part of the optic radiation. Further study is needed to examine the absence of a hyperechoic para-atrial band as a prognostic marker of the extension and severity of white matter injury.

Adult↗
PubMed1993

Estimation of dopamine D2 receptor binding potential in the striatum with iodine-123-IBZM SPECT: technical and interobserver variability.

Factors contributing to the quantification of the striatal dopamine D2 receptor binding potential in vivo using 123I-iodobenzamide (123I-IBZM) and SPECT were analyzed in phantom studies, healthy volunteers and in patients with the parkinsonian syndrome. A cylindrical brain phantom based on a stereotactic brain atlas was constructed with independently fillable compartments representing two striata (ST), cerebellum (CB) and background. Clinical 123I-IBZM SPECT studies were performed on 15 healthy volunteers and on 28 patients with parkinsonian syndrome. Interobserver variability of region of interest (ROI) selection and count ratios were estimated by two independent observers. ROIs for the striatum were either fixed, based on a stereotactic brain atlas, or drawn manually, based on 70% isocontour lines. Reference regions were either the cerebellum (isocontour ROIs) or the occipital cortex (occiptal cortex; fixed ROIs). The brain phantom measurements showed linearity with respect to radioactivity concentration, good reproducibility and good contrast recovery. The interobserver study showed that the striatum-to-occiptal cortex ratio with fixed ROIs for the striatum, as an estimate for striatal D2 receptor binding potential, resulted in a means of separating patients with normal receptor activity from those with decreased striatal dopamine D2 receptor activity.

Adolescent↗
PubMed1994

Distinguishable groups of musculoskeletal low back pain patients and asymptomatic control subjects based on physical measures of the NIOSH Low Back Atlas.

STUDY DESIGN: The authors performed an empirical prospective study of 115 patients referred to physical therapy for low back pain and 112 control subjects of similar age and gender. OBJECTIVES: The authors defined and compared subgroups based on physical tests and described demographic and psychosocial characteristics by group. SUMMARY OF BACKGROUND DATA: Prospective studies of intervention for persons with low back pain are limited by inability to randomize subjects into distinguishable groups. Previous attempts have not been empirical and have not focused on musculoskeletal LBP. METHODS: Ten physical therapists administered 52 tests and 6 questionnaires to subjects in seven different clinics. Data were subjected to reliability and cluster and comparative analyses. RESULTS: Tests were reliable. Groups were distinguished by measures of symmetry, flexibility, strength, and dynamic mobility. CONCLUSION: Distinguishable groups can be determined; decreased trunk mobility characterized all groups of patients and imbalances in muscle length, strength, and symmetry described specific groups of subjects with and without low back pain.

Cluster Analysis↗
PubMed1993

Definition of reference frames on human skeleton.

In our modeling study of the human cardiovascular system, some forms of subject motion or posture, e.g., those experienced or assumed by a fighter pilot, can not be neglected in considering the overall system dynamics. This investigation aims at establishing a set of reference frames on the human skeleton which are based on the observations and measurements taken on four skeleton systems. These frames are coupled together at the articulation positions to form a base of operation of 3-D translation and rotation. The coupling at a specified reference position was verified against the proportional measurements taken from X-ray films, CAT scan films, atlases and two human cadavers. A program was written to perform the forementioned transformations on the frames coupled at the reference position such that any posture can be achieved as long as the necessary angular anthropometric measurements are provided. If a set of angular profiles at all involved joints are given, the human motion can be mathematically animated to a certain degree of accuracy appropriate for specified computer simulation studies. Under this definition, any major segment of our cardiovascular system model can be specified in terms of spatial position and orientation. [table: see text]

Anthropometry↗
PubMed2002

Atlas-based segmentation of pathological knee joints.

Efficiency, comparability and simplicity are key aspects for user acceptance of surgical planning systems in the long term. Automatic segmentation and identification of geometric reference systems of the anatomical structures are essential to fulfill these requirements. A statistical motivated shape atlas of the knee joint, based on 235 normal and abnormal MR and CT volume sets, is constructed for automatic segmentation of CT image data. In the first step of the atlas construction, the bony structures of the knee were segmented semi-automatically and processed into a dense and a sparse triangulated surface mesh to obtain training data sets. To establish an inter-individual correspondence, a skeleton-based registration method is used. The registered sparse surface meshes are retriangulated to estimate a pointwise inter-individual correspondence. The shape atlas is build upon these correspondences and integrated into a segmentation algorithm. An iterative segmentation scheme is proposed, which consists of a combination of the iterative-closest-point algorithm for spatial registration and of a downhill-simplex optimization procedure for deformation of the statistical motivated shape atlas to the image data. We expect the statistical shape model to be a robust and image modality independent method for the segmentation of pathological knee joints in CT image data.

Arthroplasty, Replacement, Knee↗
PubMed2000

Mathematical theory of stereotactic coordinate transformation: elimination of rotational targeting error by addition of a third reference point. Technical note.

All frame-based stereotactic procedures require localization of an anatomical target within the coordinate system of the stereotactic frame. If the target is defined by its coordinates given in a stereotactic atlas (indirect localization), the neurosurgeon faces the mathematical task of transforming atlas coordinates into frame coordinates. In the method usually used, the frame coordinates of two reference points (the anterior and posterior commissures) are obtained from computerized tomography or magnetic resonance images, and serve as the basis for the coordinate transformation. This two-point algorithm relies on the additional assumption that the frame sits on the patient's head without exhibiting roll, that is, rotation about the anteroposterior axis (y axis). Usually this assumption is nearly, but not exactly, correct. An amount of roll as small as 3 degrees can cause a targeting error on the order of 1 mm when a two-point algorithm is used. This potential source of error can be eliminated by using a new method of coordinate transformation, the derivation of which is mathematically reported in this article. The new method requires a third reference point located in the midsagittal plane, in addition to the two commissural reference points.

Algorithms↗