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Results for “computational morphology”

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At least 109 records · Page 6Linked to original sources
PubMed2000

Three-dimensional computed tomographic evaluation of morphologic airway changes after mandibular setback osteotomy for prognathism.

OBJECTIVE: To observe changes in the pharyngeal airway and the hyoid bone position after mandibular setback osteotomy in 30 patients with mandibular prognathism by means of 3-dimensional computed tomography (3DCT). STUDY DESIGN: Preoperative and postoperative computed tomography (CT) examinations were performed on 17 patients treated by sagittal split ramus osteotomy with rigid osteosynthesis and on 13 patients treated by intraoral vertical ramus osteotomy without osteosynthesis. The amount of mandibular setback was measured by the preoperative to postoperative difference of the mandibular position in axial CT images. The sizes of the preoperative and postoperative pharyngeal airway were evaluated from semitransparent and crosscut 3DCT images. Postoperative displacement of the hyoid bone was evaluated by a technique to superimpose a postoperative hard tissue 3DCT image on the preoperative image. The helical scan technique was used in the CT examination. The volume rendering technique was used to create 3DCT images. RESULTS: The mean mandibular setback was 7.8 +/- 2.1 mm with a range of 5 to 11 mm. Three months after surgery, the lateral and frontal widths of the pharyngeal airway had decreased significantly in comparison with the preoperative width. The mean reduction rates of the lateral and frontal width were 23.6% and 11.4%, respectively. The diminished airway did not recover by either 6 months or 1 year after surgery in most cases. Downward and posterior displacement of the hyoid bone was seen postoperatively. There were positive correlations between the amount of mandibular setback and reduction of the lateral width of the pharyngeal airway (r = 0.54) and the amount of hyoid bone displacement (r = 0.42). There were no significant differences between the two surgical techniques. CONCLUSION: Three-dimensional computed tomography was a practical imaging technique to evaluate the morphologic airway changes. The pharyngeal airway may have irreversible narrowing after mandibular setback surgery.

Adolescent↗
PubMedDate not supplied

A computer model of lung morphology to analyze SPECT images.

Measurement of the spatial distribution of aerosol deposition in human lungs can be performed using single photon emission computed tomography (SPECT). To relate deposition patterns to real lung structures, a computer model of the airway network has been developed. Computer simulations are presented that are compatible with the analysis of SPECT images. Computational techniques that are consistent with clinical procedures are used to analyze airways by type and number within transverse slices of the lung volume. The computer models serve as customized templates, which when analyzed alongside gamma scintigraphy images, can assist in the interpretation of human test data.

Computer Simulation↗
PubMed1986

Conformational studies of (2'-5') polynucleotides: theoretical computations of energy, base morphology, helical structure, and duplex formation.

A detailed theoretical analysis has been carried out to probe the conformational characteristics of (2'-5') polynucleotide chains. Semi-empirical energy calculations are used to estimate the preferred torsional combinations of the monomeric repeating unit. The resulting morphology of adjacent bases and the tendency to form regular single-stranded structures are determined by standard computational procedures. The torsional preferences are in agreement with available nmr measurements on model compounds. The tendencies to adopt base stacked and intercalative geometries are markedly depressed compared to those in (3'-5') chains. Very limited families of regular monomerically repeating single-stranded (2'-5') helices are found. Base stacking, however, can be enhanced (but helix formation is at the same time depressed) in mixed puckered chains. Constrained (2'-5') duplex structures have been constructed from a search of all intervening glycosyl and sugar conformations that form geometrically feasible phosphodiester linkages. Both A- and B-type base stacking are found to generate non-standard backbone torsions and mixed glycosyl/sugar combinations. The 2'- and 5'-residues are locked in totally different arrangements and are thereby prevented from generating long helical structures.

Adenine Nucleotides↗
PubMed1995

[Restorative proctocolectomy. A morphological-functional study by computed tomography with coronal scans].

Restorative proctocolectomy with ileal pouch has become the surgical treatment of choice for patients with ulcerative colitis and familial polyposis of the colon. Defecography is the radiologic technique commonly used to obtain detailed information on function and morphology of the ileal pouch, but it fails to depict the pelvis. Computed Tomography (CT), with coronal images only was used to examine 10 patients with ulcerative colitis, submitted to restorative proctocolectomy. Coronal CT, yielding a panoramic view of the pelvis, represent an effective alternative technique to defecography. In fact, the two techniques provide comparable information relative to the ileal pouch; coronal CT also depicts the possible thickening of pouch walls and of pelvic fat tissue. Coronal CT also depicts the continence of ileo-anal and ileo-ileal anastomoses and the functional changes of the perineal muscles at rest and during squeezing. Coronal CT images allow easy and clear detection of such major postoperative complications as pelvic inflammation and fistulae (less frequently stenosis or dehiscences of the anastomosis).

Adult↗
PubMed1987

Morphological analysis and computer-aided, three dimensional reconstruction of chondrocytic columns in rabbit growth plates.

Proximal tibial growth plates of New Zealand white rabbits were serially sectioned in parasagittal and horizontal planes for three dimensional, light microscopic analysis of the chondrocytic columns. A total of 431 columns was analysed. Of these, 258 columns extended through the full height of the growth plate. The remaining columns were considerably shorter, being located either predominantly in the epiphyseal half of the growth plate (100) or in the metaphyseal half of the growth plate (73). The epiphyseal and metaphyseal columns were found in clusters in the plate. Some columns in all three groups had interruptions along their length, while others had duplications. Computer-aided, three dimensional graphic reconstructions were prepared of a selected group of columns. The reconstructions illustrated the variability in the morphology and the dimensions of the neighbouring chondrocytic columns. The observations suggest that chondrocytic columns in rabbit growth plates are replaced regularly and that the small cell zone may play an important role as the cellular source for column renewal.

Animals↗
PubMed1981

Computer graphics in facial morphology analysis.

Stereophotogrammetry is an attractive technique for mapping changes in facial form and contour following surgery. The need for trained personnel, however, has prevented the technique from gaining wide use. We report the development of a stereophotogrammetric system in combination with an inter-graphics computer system which overcomes this and other limitations. An interactive computer graphics system is used to record, present and manipulate the three-dimensional data obtained from a digitized stereophotogrammetric picture. The system also permits measurement of morphological changes following surgery as well as volume changes and has the potential for use in indicating the order in which multistage procedures should be undertaken and the time delay before such surgeries.

Cephalometry↗
PubMed2003

New approaches in hominoid taxonomy: morphometrics.

We report here on new cranial data relevant to hominoid taxonomic analyses, based on a study of 438 skulls belonging to 13 nonhuman living hominoid taxa. Nineteen landmarks were selected to describe the overall shape of the maxillofacial complex, in order to investigate its discriminative power in taxonomic analyses. We used a geometric morphometrics approach to depict morphological variation from the genus down to the subspecific level, and we evaluated whether our morphologic criteria are relevant to discriminating species and subspecies among living hominoids. Considering previous genetic studies, we discuss whether our results can be extrapolated to the hominin fossil record, providing a reference for species and subspecies morphologic differentiation. Our results indicate that the relative warp method, as applied to facial landmarks, provides a powerful tool to discriminate taxa down to a subspecific level. Results show a noticeable divergence of P. t. verus compared to P. t. troglodytes and P. t. schweinfurthii. According to our data, the distance between eastern and western gorilla populations as well as between Bornean and Sumatran orangutan subspecies is as great as between the two species of Pan. In the same manner, differences between Hylobates and Symphalangus are similar to those between Pan and Gorilla genera. Congruence between the morphological distances computed in this study and previous morphological and genetical studies strongly supports their relevance for morphological species recognition in paleoanthropology. Our data provide an objective standard for assessing taxonomic differences among hominoids, and will enable us to define more precisely the significance of morphological differences in the fossil record.

Animals↗
PubMed2001

Reentry in a morphologically realistic atrial model.

INTRODUCTION: Atrial fibrillation is the most common cardiac arrhythmia. In ablation procedures, identification of the reentrant pathways is vital. This has proven difficult because of the complex morphology of the atria. The purpose of this study was to ascertain the role of specific anatomic structures on reentry induction and maintenance. METHOD AND RESULTS: A computationally efficient, morphologically realistic, computer model of the atria was developed that incorporates its major structural features, including discrete electrical connections between the right and left atria, physiologic fiber orientation in three dimensions, muscle structures representing the crista terminalis (CT) and pectinate muscles, and openings for the veins and AV valves. Reentries were induced near the venous openings in the left and right atria, the mouth of the coronary sinus, and the free wall of the right atrium. The roles of certain muscular structures were ascertained by selectively removing the structures and observing how the propagation of activity was affected. CONCLUSION: (1) The muscular sheath of the coronary sinus acts as a pathway for a reentrant circuit and stabilizes any circuits that utilize the isthmus near the inferior vena cava. (2) Poor trans-CT coupling serves to stabilize flutter circuits. (3) Wall thickness is an important factor in the propagation of electrical activity, especially in the left atrium. (4) The openings of the inferior and superior venae cavae form natural anatomic anchors that make reentry easier to initiate by allowing for smaller ectopic beats to induce reentry.

Atrial Fibrillation↗
PubMed1996

A prospective study on the predictive value of normal sperm morphology as evaluated by computer (IVOS).

OBJECTIVE: To evaluate the IVOS (Hamilton Thorne Research Version 2.1 Dimension Program, Beverly, MA) system's ability to predict fertilization in vitro in a prospective study. DESIGN: Hospital-based academic ART program. PATIENTS: Eighty patients from the IVF-GIFT program were evaluated. The same semen sample was analyzed on a day-to-day basis by both laboratory (manual method) and the computerized system for percentage normal morphology, concentration/mL, motility, and forward progression. Only patients with two or more metaphase II (MII) oocytes available were allowed into the study and excluded where the male partner had antisperm antibodies or qualified for intracytoplasmic sperm injection (<500,000 motile spermatozoa obtained after glass wool separation). STATISTICAL ANALYSIS: Logistic regression analysis was used to study predictors of fertilization in vitro. RESULTS: Three hundred thirty-eight oocytes were obtained from 80 patients of which 239 fertilized. The logistic regression analysis of the manual method (percentage normal morphology) and IVOS indicated that both were predictors of fertilization. Sperm morphology as evaluated by IVOS in patients with <10 x 10(6) motile spermatozoa/mL retrieved after swim-up was a significant predictor of fertilization as was the number of oocytes obtained. Thus, the more oocytes obtained in the lower morphological groups, the better the chance of fertilization. The fertilization rate in the morphology group of 0% to 4% normal forms was 45.6% (37/81) and in the group >14% normal forms was 85.2% (69/81). CONCLUSIONS: It was shown that in patients where </= 10 x 10(6) motile spermatozoa were obtained, the role of morphology (evaluated by IVOS) as well as the number of oocytes were important predictors of fertilization. The computer can assist to identify these patients with a poor prognosis for fertilization.

Computer Simulation↗
PubMed2005

Airway identification within planar gamma camera images using computer models of lung morphology.

PURPOSE: Quantification of inhaled aerosols by planar gamma scintigraphy could be improved if a more comprehensive assessment of aerosol distribution patterns among lung airways were obtained. The analysis of planar scans can be quite subjective because of overlaying of small, peripheral airways with large, conducting airways. Herein, a computer modeling technique of the three-dimensional (3-D) branching structure of human lung airways was applied to assist in the interpretation of planar gamma camera images. METHODS: Airway dimensions were derived from morphometric data, and lung boundaries were formulated from scintigraphy protocols. Central, intermediate, and peripheral regions were superimposed on a planar view of the 3-D simulations, and airways were then tabulated by type, number, surface area, and volume in each respective region. RESULTS: These findings indicate that the central region, for example, consists mostly of alveolated airways. Specifically, it was found that alveolated airways comprise over 99% of the total number of airways, over 95% of the total airway surface area, and approximately 80% of the total airway volume in the central region. CONCLUSIONS: The computer simulations are designed to serve as templates that can assist in the interpretation of aerosol deposition data from scintigraphy images.

Computer Simulation↗
PubMed2002

Computed tomography of the brain morphology of patients with first-episode schizophrenic psychosis.

OBJECTIVE: To report computed tomographic (CT) scan ratings of various aspects of brain morphology of a large representative sample of patients with a first episode of schizophrenic psychosis and to compare these ratings with those from a previously reported sample of patients with chronic schizophrenia. METHODS: A brain CT scan was performed on 114 patients with a diagnosis of first episode of schizophrenia or schizophreniform psychosis. Ratings on sulcal and ventricular enlargement and sylvian fissure were obtained using the Computed Tomographic Rating Scale for Schizophrenia. The influence of age, sex, age of onset, duration of illness and clinical psychopathology on CT ratings was assessed using bivariate correlations and multiple regression analyses. The CT ratings were also compared with those from a sample of patients with chronic schizophrenia. RESULTS: First-episode patients showed a modest enlargement of sulci and ventricles and a reversed asymmetry of the sylvian fissure. Age was the only independent predictor of these regional changes. Clinical symptoms, sex or duration of untreated psychosis showed no relation to CT ratings. A comparison of first-episode patients with chronically ill patients, with the effect of age covaried, revealed the sylvian fissure was significantly larger (right and left sides) in the chronically ill patients. CONCLUSIONS: Patients with a first episode of schizophrenic psychosis showed evidence of morphological changes generally associated with chronic schizophrenia. Such changes are not likely related to sex, clinical symptoms or duration of untreated psychosis, but are influenced by age. Changes in the ventricles and sulcal size are unlikely to be progressive, suggesting a neurodevelopmental origin, whereas changes in the area of the sylvian fissure may be of a more degenerative nature.

Adult↗
PubMed1994

Effects of pulmonary fibrosis on the distribution of edema. Computed tomographic scanning and morphology.

The pulmonary interstitium acts as an important safety factor against alveolar flooding. To test the hypothesis that in advanced fibrosis, edema is redistributed away from a less compliant interstitium to flood alveoli, we induced severe left lung fibrosis in six dogs with radiation and intratracheal bleomycin. Twenty-four months later, edema was induced by infusing 20% body weight lactated Ringer's solution over 30 min, preceded and followed by computed tomography (CT) scanning. Lower lobes were frozen, and samples were taken for extravascular lung water measurements (Qwl/dQl), regional blood volume, and light microscopic grading of interstitial and alveolar edema. The total volumes of the control and fibrotic lungs were 800 +/- 63 and 45 +/- 10 ml (SE), respectively, indicative of severe fibrosis. Before edema, the fibrotic carinal and basal slices had CT densities 3.5 and 2.2 times greater than respective control slices. After edema, the densities of all control lung slices rose 2.5 times and that of fibrotic carinal and basal slices rose 1.5 times. Edema significantly accentuated the small gravity-dependent gradient in CT density of control lungs, but it had minimal effect on this gradient in fibrotic lungs. The Qwl/dQl for control and fibrotic lower lobes were 8.7 +/- 0.8 and 6.8 +/- 0.7 g H2O/g dry lung, respectively, but the amounts of water per lung volume were similar, and there was no gravity-dependent gradient in Qwl/dQl or in regional blood contents. By light microscopy, we found significantly less interstitial and more alveolar edema in the fibrotic lobes. We conclude that in severe pulmonary fibrosis, similar amounts of water accumulate per lung volume as in controls, and that there is predominant alveolar flooding over interstitial edema. We also conclude that the gravity-dependent gradients in CT densities postedema in the control lungs are not accounted for by edema fluid or congestion, but probably by atelectasis.

Animals↗
PubMed1997

Morphology according to cranial computed tomography of first-episode cycloid psychosis and its long-term-course: differences compared to schizophrenia.

Cranial computed tomography (CCT) findings for 37 patients with cycloid psychosis and 19 patients with DSM-III-R schizophrenia were compared with findings for age- and sex-matched controls. Schizophrenic patients showed enlarged ventricles compared both to controls and to patients suffering from cycloid psychosis. In patients with cycloid psychosis, neither at the first episode nor after many years (mean 16.6 years) of disease were significant differences found compared to control subjects. Over the course of the illness, patients with cycloid psychosis showed ventricular enlargement which was correlated with age but not with the duration of illness. The morphological differences provide further evidence for the proposed nosological distinction between cycloid psychosis and schizophrenia.

Adult↗
PubMedDate not supplied

The use of computed microtomography to monitor morphological changes in small animals.

RATIONALE AND OBJECTIVES: We investigate the methodological aspects of computerised microtomography (Cm 1) for monitoring the development of osteoporosis in male Sprague-Dawley rats. METHODS: 120 Rats were gastrectomized or sham operated. Femurs were prepared and tomograms with spatial resolutions of 5-500 mm were made. Bone diameters, bone areas and moments of inertia were determined from the tomograms. Optimal slice position and the need for spatial resolution for future in vivo applications were investigated. In order to minimise the absorbed dose to the specimen, a theoretical model for determination of optimal irradiation conditions is developed. RESULTS: Gastrectomy caused dramatic changes in the bone architecture. The main features were vaccuolisation of the bone and reduced amounts of compact bone. While the outer diameters of tubular bones were largely unaffected, their inner diameters were greatly increased following gastrectomy. Relative bone area and moment of inertia were greatly reduced. Optimal photon energy was 12 keV. CONCLUSIONS: It is possible to monitor gastrectomy-evoked changes in bone morphology at various sites in rats with computerised microtomography. The changes are suggestive of osteoporosis.

Animals↗
PubMed1993

[Biometric data using follow-up x-ray computed tomography of the morphological and structural changes of mandibular bone reconstructions using hydroxyapatite-collagen-GAG].

The use of biomaterials for bone reconstruction raises the problem of their architectural and structural outcome. CT makes an accurate biometric follow-up possible. The association of HA, collagen and GAG appears to be a reliable substitute for bone, owing to the permanence of the dimensional results and to the structural evolution that seems to finally provide total structural restoration.

Animals↗
PubMed1999

Repeatability and variance analysis on multiple computer-assisted (IVOS) sperm morphology readings.

The repeatability of the Hamilton Thorne Research IVOS (version 10) semen analyser (dimension specific software, version 3) in the evaluation of sperm morphology according to strict criteria was investigated in this study. The repeat measures investigated were cell-cell (300 cells, 3 x each), intraslide (20 slides, 3 x each) and interslide (30 samples, 3 slides each), and their normal sperm morphology outcomes were recorded. Semen samples with varying normal sperm morphology percentages were obtained and sperm morphology slides prepared. The slides were stained with Diff-Quik stain. Agreements between evaluations were determined using the kappa statistic and average coefficients of variation. The predictive probability for an abnormal cell given a prior abnormal cell outcome was 91%, and 89% for a similar prediction of a normal cell. The predictive probabilities for an abnormal or a normal cell given two prior abnormal or two prior normal cell outcomes were 95% and 94%, respectively. No significant bias was obtained between the repeat probabilities for normal and abnormal sperm cells. The average coefficients of variation for the intraslide trial were 9.73% and 8.30% when 100 and 200 sperm cells were evaluated, respectively. The average coefficient of variation for the interslide trial was 15.39%. The technical importance of good sample and slide preparation technique has once again been highlighted by this study. A uniform (spatial homogeneity), high concentration (5-10 cells per computer screen) smear must be made and the cells stained with optimal intensity (maximum contrast). In a trial in which 2000 cells were evaluated, 19 objects (0.95%) were identified as spermatozoa, but were debris. The automated semen analysing system (IVOS) used in this study was shown to maintain a level of repeatability, precision and accuracy acceptable for the application of the system in a routine semen analysis situation.

Analysis of Variance↗