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Results for “computational morphology”

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At least 163 records · Page 9Linked to original sources

PubMed2001

Euler-Poincaré characteristics of classes of disordered media.

We consider a family of statistical measures based on the Euler-Poincaré characteristic of n-dimensional space that are sensitive to the morphology of disordered structures. These measures embody information from every order of the correlation function but can be calculated simply by summing over local contributions. We compute the evolution of the measures with density for a range of disordered microstructural models; particle-based models, amorphous microstructures, and cellular and foamlike structures. Analytic results for the particle-based models are given and the computational algorithm verified. Computational results for the different microstructures exhibit a range of qualitative behavior. A length scale is derived based on two-point autocorrelation functions to allow qualitative comparison between the different structures. We compute the morphological parameters for the experimental microstructure of a sandstone sample and compare them to three common stochastic model systems for porous media. None of the statistical models are able to accurately reproduce the morphology of the sandstone.

Journal Article↗

PubMed1992

Cytologic diagnosis of non-oxyphil follicular neoplasias of the thyroid. Multivariate classification procedure based on quantitative nucleolar features.

The study was done on cytologic material of 58 non-oxyphil follicular neoplasias of the thyroid, 32 of which were adenomas and 26 carcinomas. Three groups of nucleolar features were quantified using a routine microscope with an ocular micrometer: frequency-, size-, and margination-related features. Since value overlap was present between two categories for all the variables, stepwise discriminant analysis was applied. The following three features were selected by the computer for calculation of one canonical discriminant function: percentage of marginated nucleoli, percentage of nuclei with one nucleolus, mean major nucleolar diameter. The percentage of agreement between morphologic and computer classifications was 95%. Two follicular adenomas were allocated to the carcinoma category, whereas one follicular carcinoma was allocated to the adenoma category. Out of 58, 52 were diagnosed by the computer into one of the two diagnostic categories with a very high probability, i.e. P greater than 0.75, the remaining 6 being considered intermediate.

Adenoma↗

PubMed1992

The relation of computer-based measures of sperm morphology and motility to male infertility.

We investigated the relation between various sperm characteristics, including morphometric parameters, and impaired fertility among 596 men who participated in a national study. Semen was collected and processed by using a standardized protocol, and sperm measurements were made using a computer-aided sperm analysis instrument. We defined infertility in two ways: (1) the inability to father a child after trying for a year or longer, and (2) the number of children fathered. We found that all measures of sperm motion were decreased among men with impaired fertility. After adjustment for the other motion parameters and various potential confounders, however, only the percentage of progressive cells was associated with infertility. One morphometric parameter, the mean length/width ratio, was consistently associated with both measures of infertility, even after adjustment for potential covariates. This measure was also strongly associated with infertility among various subgroups defined by poor sperm concentration, motility, and morphology. The sperm length/width ratio appears to be an important correlate of infertility in males.

Adult↗

PubMed1993

The role of early baseline computed tomography in the interpretation of morphological changes after kidney-pancreas transplantation.

In a prospective study, 17 early baseline computed tomography (CT) scans were obtained 2 or 3 days after simultaneous kidney-pancreas transplantation. Morphological changes and their relevance to the early detection of graft rejection and complications were evaluated. The pancreatic grafts were enlarged and showed signs of mild pancreatitis. Serial scans obtained during the first renal graft rejection episode were compared with the baseline CT scans (n = 7). They showed a significant increase in pancreatic graft size in the case of biopsy-proven severe renal graft rejection (P = 0.008). Normally functioning pancreatic allografts showed a 15%-40% decrease in size 1-6 months after transplantation. We conclude that the morphological changes observed early after transplantation are compatible with mild pancreatitis, which may contribute to the development of pancreatic graft thrombosis. There is an increase in the number of morphological changes during severe rejection, yet enlarged pancreatic grafts appear to recover from transplantation-related damage and regain their normal size without signs of atrophy.

Adolescent↗

PubMed2004

Computed tomographic measurements of the hip morphology of 10 healthy German shepherd dogs.

Linear measurements were made by computed tomography of the diameter of the femoral head, the width and depth of the acetabulum and the dorsal and ventral acetabular rim distances in 10 healthy German shepherd dogs, and angular measurements were made of the axial acetabular index, acetabular anteversion, and the dorsal and ventral centre-edge angles. There were no significant differences between the measurements made on the left and right sides. The width of the acetabulum was about twice its depth, and was a little larger than the diameter of the femoral head. The mean values of the axial acetabular index, acetabular anteversion, and ventral and dorsal centre-edge angles were 100.9 degrees, 25.1 degrees, 48.0 degrees and 12.2 degrees, respectively.

Acetabulum↗

PubMed2006

Fully automated system for three-dimensional bronchial morphology analysis using volumetric multidetector computed tomography of the chest.

Recent advancements in computed tomography (CT) have enabled quantitative assessment of severity and progression of large airway damage in chronic pulmonary disease. The advent of fast multidetector computed tomography scanning has allowed the acquisition of rapid, low-dose 3D volumetric pulmonary scans that depict the bronchial tree in great detail. Volumetric CT allows quantitative indices of bronchial airway morphology to be calculated, including airway diameters, wall thicknesses, wall area, airway segment lengths, airway taper indices, and airway branching patterns. However, the complexity and size of the bronchial tree render manual measurement methods impractical and inaccurate. We have developed an integrated software package utilizing a new measurement algorithm termed mirror-image Gaussian fit that enables the user to perform automated bronchial segmentation, measurement, and database archiving of the bronchial morphology in high resolution and volumetric CT scans and also allows 3D localization, visualization, and registration.

Algorithms↗

PubMed1983

[Computer tomographic functional diagnosis of the larynx].

The computer tomographic morphology of the larynx was studied in 19 patients during various phases of respiration, such as during quiet breathing and in expiratory phonation. The diagnostic information which can be obtained by computer tomographic functional studies of laryngeal neoplasms is discussed.

Adult↗

PubMed2006

[Imaging strategy for staging and follow-up of endocrine tumors].

Endocrine tumours constitute a homogeneous network of tumours scattered in the body and characterized by several common features including their capacity to secrete hormones, their association as part of inherited syndrome and their ability to be explored either by functioning imaging than by morphological imaging. However, they have a broad and initially misleading clinical spectrum. Staging of these tumours must be multidisciplinary with the association of primary tumour exploration, staging and follow-up. It also contribute to the screening of complications due to hormonal secretions, the exploration of inherited syndromes and a second cancer diagnosis. First we review the technical characteristics of each imaging modality including morphological imaging (computed tomography, magnetic resonance imaging), metabolic imaging (somatostatin receptors scintigraphy, PET-scan), endoscopy and vascular imaging. Then we review for each endocrine tumour localization and clinical presentation, the imaging strategy as well as the most common morphological and functional features.

Bronchial Neoplasms↗

PubMed1997

[Ossification of the stylohyoid chain in computerized tomography--Eagle syndrome].

The computed tomographic morphology of a typical Eagle syndrome is presented on the basis of a case history. In a 40-year old male patient [correction of female] presenting with bilateral tinnitus, globus hystericus, and increasing hoarseness computed tomography revealed bilateral ossification of the stylohyoid ligament. The incidence of stylalgia is very low in comparison to the occurrence of a elongated styloid process or an ossified stylohyoid ligament. However, in cases of unexplained complaints in the head and neck region it should be considered in the differential diagnosis as it has therapeutic consequences.

Adult↗

PubMed1981

Vascular endothelial morphology as an indicator of the pattern of blood flow.

A quantitative study of the en face size and shape of endothelial cells from aortic intercostal ostia has been carried out in rabbits. Photomicrographs were taken from vascular casts of the rabbit aorta and the endothelial cell outlines were analyzed quantitatively using a digitizer and digital computer. The morphology of the endothelial cells was described using 8 calculated parameters (area, perimeter, length, width, angle of orientation, width: length ratio, axis-intersection ratio and shape index). Marked changes in cell morphology were found in the regions proximal and distal to ostia as well as around flow dividers. Cells on the aorta are aligned with the flow direction, and the endothelial cells within the ostia have an angle of orientation of approximately 45 deg to the axis of the vessel. The results obtained to date suggest that endothelial cell morphology and orientation around a branch vessel may be a natural marker or indicator of the detailed features of blood flow.

Animals↗

PubMed1995

Computer model of human lung morphology to complement SPECT analyses.

Aerosol therapy protocols could be improved if inhaled pharmacologic drugs were selectively deposited within the human lung. The targeted delivery to specific sites, such as receptors and sensitive airway cells, would enhance the efficacies of airborne pharmaceuticals. The high spatial discrimination of deposition patterns of inhaled particles can be determined via Single Photon Emission Computer Tomography (SPECT). However, major problems continue to compromise SPECT protocols. Our work focuses on two issues: how can the spatial discrimination be improved; and how are the images to be interpreted? We present a methodology, described by a mathematical model and supercomputer code, for systematically slicing through the human lung in a prescribed manner that is conducive to implementation into SPECT analyses. The lung is divided into concentric shells, or annuli, and the airway generation-by-generation composition of the respective shells determined. This identification was accomplished by superimposing the new shell structure with the 3-D branching network presented by Martonen et al. [23]. Perhaps the key aspect of the model-code is that the supercomputer is instructed to determine the 3-D spatial coordinates of each of the airways (over 16 million) of the lung with respect to the clinician-selected contours of shells within the lung.

Administration, Inhalation↗

PubMed2000

Affixal homonymy triggers full-form storage, even with inflected words, even in a morphologically rich language.

This paper investigates whether affixal homonymy, the phenomenon that one affix form serves two or more semantic/syntactic functions, affects lexical processing of inflected words in a similar way for a morphologically rich language such as Finnish as for morphologically restricted languages such as Dutch and English. For the latter two languages, there is evidence that affixal homonymy triggers full-form storage for inflected words (Bertram, R., Schreuder, R., and Baayen, R. H. (in press). The balance of storage and computation in morphological processing: the role of word formation type, affixal homonymy, and productivity. Journal of Experimental Psychology: Learning, Memory, and Cognition; Sereno and Jongman (1997). Processing of English inflectional morphology. Memory and Cognition, 25, 425-437). Two visual lexical decision experiments show the same pattern for Finnish. Apparently, the substantially richer morphology in Finnish does not prevent full-form storage for inflected words when the affix is homonymic.

Cognition↗

PubMedDate not supplied

Structural computation and the role of morphological markings in the processing of Japanese.

In an SOV, strictly head-final language with otherwise relatively free word-order such as Japanese, disambiguating information including verb information is not available until the end of a clause. In such a language, a sentence theoretically has numerous possible syntactic structures before the verb information becomes available. The current study investigated (1) whether syntactic computation takes place in an ambiguous sentence fragment in Japanese and (2) if and how information from constituents other than the verb is utilized. Two experiments were conducted using automated, word-by-word visual presentations with a lexical decision task on an extrasentential target. The results suggest that syntactic computation takes place in Japanese before verb information becomes available. A strong preference was observed for a simplex clause when three differently Case-marked arguments belonged to the same clause. The findings also indicate that information from surface Case marking is utilized productively, and when there is ambiguity in marking between arguments and adjuncts, the distinction is made before incorporating the constituents into the existing structure.

Adolescent↗

PubMed1988

Lumbosacral plexus lesions: correlation of clinical signs and computed tomography.

Neurological signs and computed tomographic morphology were compared in 60 patients. The primary neurological deficit was most commonly located in the sacral (n = 31) or lumbar plexus (n = 23) and was most commonly caused by a neoplasm (n = 40). In 78% of the patients it correlated with the lesions detected by computed tomography (CT). CT reliably demonstrates extraspinal mass lesions, but only moderately well predicts functional signs.

Fecal Incontinence↗

PubMed1998

[Examination of the lower respiratory tract of Psittacines and Amazoniae varieties by means of reconstructed computer x ray tomography. 1: Examination of healthy parrots].

The number of psittacines kept as pets is rapidly increasing in Germany. The main cause of disease and death in these and other tropical birds are respiratory tract affections. Yet, a lack of consolidated, systematic research on the anatomy and pathology of these affections in gray parrots and amazons still widely persists. In a first step examinations on the anatomy of the respiratory tract of gray parrots and amazons were performed. By the means of computed tomography, morphological structures as well as volume and density measurements were conducted on this subject for the first time. By this, important, fundamental knowledge on the anatomy of the different parts of the psittacine respiratory tract as well as aspects of volume and density were gained. The computed tomography (CT) proved to be a valuable, informative and due to its non-invasive application, a careful method for examining patients. These aspects recommend it in the examination and research projects of other endangered exotic species as well. Due to its ability to image a longitudinal cross section as a standard cross section--which is not possible in humans or large animals--better information on the expansion of organs/structures in the longitudinal body axis could be obtained. A remarkable reduction of costs and performance time as well as the possibility of a direct comparison with conventional radiographs is also given. In a second step, with the use of the CT, pathological alterations in diseased gray parrots and amazons were then assessed based on anatomical data gained in the previous investigations on healthy birds. These results will be described later in a second part.

Animals↗

PubMed1997

Mechanisms of acute intraocular pressure increases after phacoemulsification lens extraction in dogs.

OBJECTIVE: To investigate the mechanisms by which intraocular pressure (IOP) increases acutely after phacoemulsification (PE) lens extraction in clinically normal dogs. ANIMALS: 24 young adult dogs. PROCEDURE: Intraocular pressure was monitored for up to 24 hours after unilateral intercapsular PE in 17 clinically normal, adult dogs. In 8 of these dogs, use of 2% hydroxypropyl methylcellulose (HPMC) aided capsulorhexis. Mean volume of irrigation, PE time, and power were constant between groups. After surgery, dogs were randomized then euthanatized, and eyes were examined grossly and histologically at 0 (n = 4), 3 (n = 7), and 24 hours (n = 6) after PE. Seven additional dogs underwent anterior chamber decompression alone (n = 4) or served as morphologic controls (n = 3). RESULTS: Intraocular pressure peaked by postoperative hour 3 at 49.9 +/- 5.0 mm of Hg and normalized by 24 hours. Use of HPMC did not affect the peak or duration of IOP increase. Blood refluxed into the collecting channels and corneoscleral trabecular meshwork in operated eyes. Computer-aided morphologic analysis indicated significant (P < 0.001) reduction in ciliary cleft cross-sectional surface area and width immediately after PE, but not after anterior chamber decompression alone. Cleft collapse was significantly (P < 0.02) greater at 24 than at 3 hours, despite return of IOP to control values by 24 hours. Plasmoid aqueous also was found in the meshwork. CONCLUSIONS AND CLINICAL RELEVANCE: Sudden, large increases in IOP with few overt clinical signs may occur immediately after lens extraction in dogs. Such increases risk compromising the corneal incision and may damage the optic nerve, thereby complicating lens extraction. Structural alterations in the trabecular meshwork persist after IOP has normalized in 24 hours and may contribute to genesis of glaucoma in the late postoperative period.

Analysis of Variance↗

PubMed2002

Computer-assisted analysis of sperm morphology with the aid of lectin staining.

Lectins are useful for staining the acrosome, which is a pre-requisite for the assessment of acrosome reaction in vitro. We tested wheat germ agglutinin, peanut agglutinin and pisum sativum agglutinin. The determination of the categories of normal and abnormal spermatozoa as defined by the World Health Organization, including an additional category 'acrosome-less cell', was performed with the aid of a system of computer-assisted semen analysis (CASA) in comparison with visual estimation. The acrosome reaction in vitro was induced by calcium ionophore A23187. Incubation with A23187 decreased the percentage of normal sperm heads and increased the number of acrosome-less sperm heads in comparison with the control samples. This shift was demonstrable with all three lectin staining procedures. No significant differences were observed in the comparison of sperm classes obtained by visual assessment or determination by CASA with two of the lectin staining procedures. After staining with pisum sativum agglutinin the classes of normal and of acrosome-less spermatozoa were significantly different between visual and CASA estimation. Our results indicate that estimation of the acrosomal status in vitro is possible by CASA when lectin staining is used.

Agglutinins↗

PubMed2000

[Clinical examinations on lung cancer].

The incidence of lung cancer is increasing in Japan and it is important to know whether a patient has a history of primary smoking/second-hand smoking because smoking is the main cause of lung cancer. Lung cancer is often found on chest roentgenography. In order to determine the strategy of the treatment, the stage of the disease can be studied by the examinations of morphology(chest computed tomography), pathology(biopsy under bronchoscopy) and biochemistry(tumor markers and genetic analysis). Most lung cancers are detected in the advanced stage with metastasis. Performance status should be useful for the estimation of the prognosis of patients. In the symposium, we reported two of our clinical cases, in which urinary deoxypyridinoline, a bone absorption marker, facilitated the discovery of the bone metastasis of lung cancers with negative bone scans. We were requested to verify the early diagnosis of lung cancers with a collection of data on morphology, pathology and biochemistry.

Amino Acids↗