(1/8132) Structural origins of fibrin clot rheology.
The origins of clot rheological behavior associated with network morphology and factor XIIIa-induced cross-linking were studied in fibrin clots. Network morphology was manipulated by varying the concentrations of fibrinogen, thrombin, and calcium ion, and cross-linking was controlled by a synthetic, active-center inhibitor of FXIIIa. Quantitative measurements of network features (fiber lengths, fiber diameters, and fiber and branching densities) were made by analyzing computerized three-dimensional models constructed from stereo pairs of scanning electron micrographs. Large fiber diameters and lengths were established only when branching was minimal, and increases in fiber length were generally associated with increases in fiber diameter. Junctions at which three fibers joined were the dominant branchpoint type. Viscoelastic properties of the clots were measured with a rheometer and were correlated with structural features of the networks. At constant fibrinogen but varying thrombin and calcium concentrations, maximal rigidities were established in samples (both cross-linked and noncross-linked) which displayed a balance between large fiber sizes and great branching. Clot rigidity was also enhanced by increasing fiber and branchpoint densities at greater fibrinogen concentrations. Network morphology is only minimally altered by the FXIIIa-catalyzed cross-linking reaction, which seems to augment clot rigidity most likely by the stiffening of existing fibers. (+info)
(2/8132) Three-dimensional facial growth studied by optical surface scanning.
The objective of the investigation was to study the three-dimensional growth of the face, and to examine the hypothesis that there are three-dimensional differences between the faces of boys and girls. The subjects comprised 132 British Caucasians aged 5-10 years measured by optical surface scanning in this cross-sectional study. Average scans for each age and sex subgroup were superimposed to assess the differences with age and sex. Males were generally larger than females. The greatest difference was between the facial heights and the least in the mid-facial dimensions. The face height of both sexes increased by an average of 3-4 mm annually. Mid-face prominence and width altered little. Mandibular width increased by 1-3 mm a year, rising to 3-5 mm in some years at the inferior areas of the mandibular region. Mandibular prominence also increased. Nose height and prominence and alar base width increased by 2 mm per year on average. Dorsum width changed little. Boys were generally larger than girls. Growth in facial height was greatest. Mid-face prominence and width changed little with age, whilst the prominence and width of the lower face increased more. Nasal prominence and alar base width increased at most ages. Dimensions changed more than reported by cephalometric studies, possibly as this study included the soft tissues. Refereed Scientific Paper (+info)
(3/8132) Detection of viable myocardium by dobutamine stress tagging magnetic resonance imaging with three-dimensional analysis by automatic trace method.
The present study attempted to detect the viability of myocardium by quantitative automatic 3-dimensional analysis of the improvement of regional wall motion using an magnetic resonance imaging (MRI) tagging method. Twenty-two subjects with ischemic heart disease who had abnormal wall motion on echocardiography at rest were enrolled. All patients underwent dobutamine stress echocardiography (DSE), coronary arteriography and left ventriculography. The results were compared with those of 7 normal volunteers. MRI studies were done with myocardial tagging using the spatial modulation of magnetization technique. Automatic tracing with an original program was performed, and wall motion was compared before and during dobutamine infusion. The evaluation of myocardial viability with MRI and echocardiography had similar results in 19 (86.4%) of the 22 patients; 20 were studied by positron emission tomography or thallium-201 single photon emission computed tomography for myocardial viability, or studied for improvement of wall motion following coronary intervention. The sensitivity of dobutamine stress MRI (DSMRI) with tagging was 75.9% whereas that of DSE was 65.5%. The specificity of DSMRI was 85.7% (6/7) and that of DSE was 100% (7/7). The accuracy of DSMRI was 77.8% (28/36) and that of DSE 72.2% (26/36). DSMRI was shown to be superior to DSE in terms of evaluation of myocardial viability. (+info)
(4/8132) Left cervical aortic arch with aortic coarctation and saccular aneurysm.
Cervical aortic arch is a very rare malformation and is occasionally accompanied by other cardiovascular anomalies. A 48-year-old male patient had a left cervical aortic arch with aortic coarctation and saccular aneurysm distal to the coarcted segment. The major clinical manifestations were upper body hypertension with a 50-mmHg discrepancy between the upper and lower limbs and a loud continuous murmur in the upper chest and back. Magnetic resonance angiography successfully depicted the anomalous aorta, and the aortic coarctation and aneurysm were surgically resected and the thoracic aorta was reconstructed. The discrepancy in blood pressure diminished after the operation, but antihypertensive medication was continued to satisfactorily control the hypertension. (+info)
(5/8132) Three-dimensional ultrasonographic imaging of the neonatal brain in high-risk neonates: preliminary study.
The aim of this investigation was to compare the utility of three-dimensional ultrasonography versus two-dimensional ultrasonography in imaging the neonatal brain. Thirty patients in the neonatal intensive care unit underwent two-dimensional and three-dimensional ultrasonography. The resultant two- and three-dimensional images recorded on film and three-dimensional volumes (reviewed on a workstation) were evaluated independently. Comparable numbers of normal and abnormal studies were diagnosed by each modality. Axial images were considered useful in approximately 50% of three-dimensional cases. Image quality, overall and in the far-field, was rated higher on two-dimensional images. Three-dimensional sonographic acquisition time in the neonatal intensive care unit (1.7 min+/-0.7 standard deviation) was significantly shorter than that for two-dimensional sonography (9.0+/-4.5 min). The total time for evaluation on the three-dimensional workstation (4.4+/-1.1 min) was significantly less than that for two-dimensional images on film (10.6+/-4.7 min). In conclusion, three-dimensional ultrasonography is a promising, diagnostically accurate, and efficient imaging tool for evaluation of the neonatal brain; however, visualization must improve before it can replace two-dimensional ultrasonography. (+info)
(6/8132) Usefulness of three-dimensional visualization of coronary arteries using electron-beam computed tomography data with volume rendering.
Three-dimensional images of the coronary arteries using electron-beam computed tomography (EBCT) data with shaded surface rendering makes it possible to achieve images easily with a short reconstruction time. However, a lower threshold is required to estimate vessel diameters and there is a quantitative problem compared with conventional coronary arteriography. In combination with volume rendering, EBCT may be useful to detect the normal coronary artery wall, the major components of the atherosclerotic plaque (lipid, fibrous connective tissue and calcium). EBCT scans offer a new, non-invasive alternative to conventional coronary arteriography for diagnosis of coronary artery disease. (+info)
(7/8132) Unilateral semicircular canal aplasia in Goldenhar's syndrome.
A patient with Goldenhar's syndrome (oculoauriculovertebral dysplasia) and unilateral aplasia of all semicircular canals is presented. This is the first report of such a finding and may support the hypothesis that Goldenhar's syndrome and the CHARGE association have a common pathogenetic mechanism. (+info)
(8/8132) Clinical application of three-dimensional ultrasound in fetal brain assessment.
AIM: To clarify the usefulness of three-dimensional (3D) ultrasound in the assessment of the fetal head and brain, according to 3D ultrasound surface reconstruction, multiplanar image analysis, three-dimensional angiography, and volume calculation. METHODS: We examined 326 normal fetuses between 10 and 40 weeks of gestation using 3D ultrasound (Voluson, 530D, Medison, Seoul, Korea), mainly with transvaginal 3D transducer. Fetal head structures, such as the skull, brain structure, and brain circulation, were presented by surface mode, multiplanar imaging mode, and three-dimensional Doppler mode. After automatic volume acquisition of the fetal head, image analyses were performed off-line, and 3D View software was used for volume imaging of the lateral ventricle and choroid plexus in randomly selected 30 normal fetuses. Seven fetuses with intracranial abnormalities were evaluated by 3D ultrasound functions. RESULTS: Surface mode of 3D ultrasound objectively depicted in vivo development of the cranial bones and formation of the cranial sutures and fontanelles in normal fetuses. Multiplanar image analysis of the brain structure presented a fetal brain in more cutting sections than conventional 2D ultrasound. Transvaginal 3D angiography was successful in 13% of normal fetuses and rotation of 3D circulatory image allowed the analysis of the intracranial vessels. Volume imaging showed the intracranial structures, such as the lateral ventricle and choroid plexus. Intracranial abnormalities were longitudinally evaluated by 3D ultrasound and objective images helped in reaching prenatal diagnoses. CONCLUSION: Advanced 3D ultrasonography and software for volume analysis can provide additional objective information about the fetal skull formation, brain structure, and brain circulation. (+info)