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PubMed1992

Separation of ventricular tachycardia from sinus rhythm using a practical, real-time template matching computer system.

Template matching morphology analysis of the intraventricular electrogram (IVEG) has been proposed for inclusion in implantable cardioverter defibrillators (ICDs) to reduce the number of false ventricular tachyarrhythmia detections caused by rate overlap between ventricular tachycardia (VT) and sinus tachycardia and/or supraventricular tachycardia. Template matching techniques have been developed that reduce the computational complexity while preserving the perceived important aspects of electrogram amplitude and baseline independence found in such computationally unsolved methods as correlation waveform analysis (CWA). These methods have been shown to work as well as CWA for separation of VT, however, they have not been proven in real-time on a system that incorporates many of the constraints of present day ICDs. The present study was undertaken with two purposes: (1) to determine if real-time IVEG template matching analysis on an ICD sensing emulator was accurate in separating VT from sinus rhythm (SR) electrograms; and (2) to compare amplitude normalized area of difference (NAD) with signature analysis (SIG), a new, computationally less expensive technique that normalizes for amplitude variation within the expected physiological level of variability. In this study, IVEGs, obtained from 16 patients who underwent electrophysiological study (EPS) for evaluation of sustained ventricular arrhythmia, were digitized to 250 Hz with 6-bit quantization after filtering (16-44 Hz) and differentiation. After an SR template was selected and periodically updated, it was compared to subsequent IVEGs using NAD and SIG. In general, SIG calculates the fraction of samples occurring outside template window boundaries. Eleven-beat running medians from beat-by-beat NAD and SIG results were determined.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed2000

Three-dimensional morphological analysis of the proximal femoral canal, using computer-aided design system, in Japanese patients with osteoarthrosis of the hip.

An accurate three-dimensional morphological analysis of the femur is required to produce well fitting uncemented femoral implants. A computer-aided design system made it possible to produce three-dimensional femoral models and to accurately measure certain parameters with planes standardized for all subjects. The study subjects were Japanese; there were 89 patients (113 hips) with osteoarthrosis (OA) and 18 volunteers (36 hips) free of hip joint complaints and with no abnormal radiological findings (normal; N). The femoral canal was classified into three types, A-I, A-II, and B-II, based on the shape in the frontal and sagittal planes. Either triangular (type T) or circular (type C) shapes were identified at the proximal cross section. Type A-II, which is considered the standard type, accounted for 89% of the N hips, and 42% of the OA hips. Type A-I, with a posterior canal plane strongly inclined toward the anterior, accounted for 26% of the OA hips and 6% of the N hips; 96% of type A-I hips were triangular. Type B-II, which had a steep medial canal plane, accounted for 29% of the OA hips and 6% of the N hips; 63% of type B-II hips were circular.

Adult↗
PubMed2000

Rapid and sensitive neurotoxicity test based on the morphological changes of PC12 cells with simple computer-assisted image analysis.

In order to develop a rapid and sensitive bioassay for the screening of chemicals with possible neurotoxicity, a computer-assisted simple image-analysis system was developed to quantify small changes in the specific morphology of the cultured pheochromocytoma cell line, PC12. This cell forms a neuron-like microfibril network (neurites) in response to a nerve growth factor (NGF) stimulation in vitro. Dichrolvos (DDVP) and methylmercury chloride (MMC) were employed as model neurotoxicants. In DDVP treatment, there was no large difference in the ED50s (effective dose that reduces the morphological index by 50%) among the toxicities determined from various morphological indices, but they were significantly lower than those observed by whole-cell-area-based toxicity assay using the hepatoblastoma cell line, Hep G2. In contrast, in MMC treatment, neurite-length-based toxicity was observed as early as 2 h, and at 48 h this was lower by over three orders of magnitude compared with whole-cell-area-based one (2.06 x 10(-7) mM vs. 6.42 x 10(-4) mM). These results demonstrate that the developed bioassay using image analysis of nerve-tissue-derived cell morphology allows us to screen possible neurotoxic chemicals very rapidly with highly enhanced sensitivity, particularly for some chemicals that preferentially act on nerve fibers.

Journal Article↗
PubMedDate not supplied

[Radiation diagnosis of bronchioloalveolar cancer].

The paper analyzes the results of examination of 260 patients with bronchioloalveolar cancer (BAC) who were followed up at the Russian Research Center of Radiology and Roentgenology for 30 years. It provides its clinical, X-ray, and morphological manifestations and classification and the methodological aspects of differential diagnosis. An optimum radiation diagnosis programme has been drawn up, which involves currently available procedures, including computed tomography. The morphological forms of BAC are given in detail.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed1983

[Computerized tomography and lung function scintigraphy in central bronchial cancer. Comparison between morphologic and functional changes].

Functional scintigraphic and computer tomographic findings in 20 patients with central bronchial carcinomas were compared in order to determine to what extent functional changes correlate with morphological appearances. Computer tomography shows alterations in the bronchial system more clearly than changes in large or small pulmonary vessels. Pre-operative and subsequent scintigraphy is essential for exact determination of regional lung function. It was shown that short-lived radio-active gases, such as krypton 81, may indicate a total lack of ventilation where there is only a severe bronchial stenosis; the use of longer half-life nucleids, such as krypton 85 or xenon 133, provides good correlation with computer tomographic findings of a bronchial stenosis.

Bronchi↗
PubMed2001

Optimized 3-D CT scan protocol for longitudinal morphological estimation in craniofacial surgery.

Frequent three-dimensional computed tomography scanning may cause deterioration of the lenses of the eye, which are susceptible to x-rays. The authors performed an experimental study using a phantom head to establish an optimized three-dimensional computed tomography scan protocol for longitudinal morphological estimation in craniofacial surgery. Volume computed tomography scans were performed using a Hi-Speed Advantage SG CT scanner (GE Medical Systems, Milwaukee, WI) in the axial plane with a combination of scan parameters of varied values. The radiation doses induced by each scanning were measured using thermoluminescent dosimeter chips attached to the position of the lenses in the phantom. Two-dimensional images in the coronal plane and three-dimensional images of the osseous surface were generated from each accumulated data set. For each scan parameter, the images generated from data accumulated using different values were compared. The study showed that lens radiation dose increased with tube potential and was almost directly proportional to tube current and 1/pitch. The slice thickness did not affect lens radiation doses significantly. Images with good contrast resolution and low artifact level sufficient for estimating morphological changes were obtained using a low tube potential of 100 kVp and a tube current of 100 mA. In regard to z-axis spatial resolution, a slice thickness of less than 3 mm was required for precisely pointing out bony edges in the two-dimensional reformation images. These results led us to conclude that volume computed tomography for longitudinal examination in craniofacial surgery should be kept to a minimum frequency and performed using a low-dose technique, small slice thickness, and large pitch.

Artifacts↗
PubMed1987

Effectiveness of a salt transport cascade in the renal medulla: computer simulations.

Based on morphological observations, it has been concluded that the upper parts of the long descending limbs of Henle's loops should be able to secrete salts into the tubular fluid (Kriz, W. Federation Proc. 42:2379-2385, 1983). In the same article, a hypothesis is given depicting how this active transport in concert with certain characteristics of the medullary architecture might produce a transport cascade toward the papillary tip, thus supporting the accumulation of salts in this region. The effectiveness of the proposed mechanism can be judged by a mathematical model only. The computer simulations of the present study demonstrate that this mechanism indeed leads to an increase of the concentrating capability of the renal countercurrent system.

Biological Transport, Active↗
PubMed1992

High resolution computed tomography in sarcoidosis and extrinsic allergic alveolitis: imaging insights.

Chest radiography gives a useful but imprecise indication of the extent of diffuse lung disease. The limitations in sensitivity and specificity of chest radiography in this context are well known and have been reinforced with the advent of computed tomography and its application to this difficult diagnostic area. High resolution computed tomography shows morphological detail invisible on chest radiography and both sensitivity and specificity in diffuse lung disease are greatly improved with this technique. Features of sarcoidosis and extrinsic allergic alveolitis revealed by high resolution computed tomography are examined in this review.

Alveolitis, Extrinsic Allergic↗
PubMed1999

End-stage primary sclerosing cholangitis: CT findings of hepatic morphology in 36 patients.

PURPOSE: To determine if there is a significant difference in the hepatic morphology depicted on computed tomographic (CT) scans in patients with end-stage cirrhosis caused by primary sclerosing cholangitis versus that in patients with end-stage cirrhosis caused by other factors. MATERIALS AND METHODS: The frequency of five morphologic findings of the liver parenchyma and two intrahepatic biliary findings identified on CT scans in 36 patients with end-stage cirrhosis caused by primary sclerosing cholangitis were compared with the frequency of the same findings in 472 patients with end-stage cirrhosis caused by other factors. The morphologic findings were lobulation of the liver contour, atrophy of the lateral or posterior hepatic segments, hypertrophy of the caudate lobe, and pseudotumor of the caudate lobe. Lobulation, atrophy, and hypertrophy were subclassified as mild-moderate or severe. The biliary findings were ductal dilatation and calculi. RESULTS: Each of the 11 findings occurred more frequently (P < .05) in patients with primary sclerosing cholangitis than in the other 472 patients. Six findings occurred more frequently (P < .05) in patients with primary sclerosing cholangitis than in patients with cirrhosis caused by any other single agent. CONCLUSION: There is a significant difference in the hepatic morphology observed in patients with primary sclerosing cholangitis-induced end-stage cirrhosis versus that in patients with end-stage cirrhosis of other causes.

Adolescent↗
PubMed2001

Computer generation and quantitative morphometric analysis of virtual neurons.

An important goal in computational neuroanatomy is the complete and accurate simulation of neuronal morphology. We are developing computational tools to model three-dimensional dendritic structures based on sets of stochastic rules. This paper reports an extensive, quantitative anatomical characterization of simulated motoneurons and Purkinje cells. We used several local and global algorithms implemented in the L-Neuron and ArborVitae programs to generate sets of virtual neurons. Parameters statistics for all algorithms were measured from experimental data, thus providing a compact and consistent description of these morphological classes. We compared the emergent anatomical features of each group of virtual neurons with those of the experimental database in order to gain insights on the plausibility of the model assumptions, potential improvements to the algorithms, and non-trivial relations among morphological parameters. Algorithms mainly based on local constraints (e.g., branch diameter) were successful in reproducing many morphological properties of both motoneurons and Purkinje cells (e.g. total length, asymmetry, number of bifurcations). The addition of global constraints (e.g., trophic factors) improved the angle-dependent emergent characteristics (average Euclidean distance from the soma to the dendritic terminations, dendritic spread). Virtual neurons systematically displayed greater anatomical variability than real cells, suggesting the need for additional constraints in the models. For several emergent anatomical properties, a specific algorithm reproduced the experimental statistics better than the others did. However, relative performances were often reversed for different anatomical properties and/or morphological classes. Thus, combining the strengths of alternative generative models could lead to comprehensive algorithms for the complete and accurate simulation of dendritic morphology.

Algorithms↗
PubMedDate not supplied

Hemodynamic and morphologic changes after portal vein embolization: differential effects in central and peripheral zones in the liver on multiphasic computed tomography.

OBJECTIVE: To evaluate hemodynamic and morphologic effects in the liver after portal vein embolization (PVE). METHODS: Hepatic computed tomography scans of 7 patients who had undergone preoperative PVE were retrospectively reviewed. Pre- and post-PVE computed tomography densities were evaluated for the unenhanced, late arterial, and portal venous phases in peripheral and central hepatic regions and in the 3 main hepatic veins. Relative changes in areas in these regions were assessed in 5 evaluable patients with serial post-PVE scans. RESULTS: During the late arterial phase, enhancement was significantly higher after PVE than it was before PVE in the peripheral hepatic regions, and it was higher in the peripheral regions than in the central regions. Enhancement was also significantly higher in the right main hepatic vein than in the middle and left hepatic veins during the late arterial phase. The ratio of areas of the peripheral/central regions decreased significantly after PVE. CONCLUSIONS: Zonal enhancement in the late arterial phase changed after PVE and seemed to be associated with differential parenchymal atrophy. We speculate that the hepatic arterial supply increases peripherally and that peribiliary/periportal plexuses maintain the portal supply centrally.

Absorptiometry, Photon↗
PubMed1979

Functional anatomy of the cerebral cortex by computed tomography.

The authors describe the morphological characteristics that allow recognition of the individual computed tomography slice and determine its sequence in the series. In addition, each slices is "assembled" by defining the different cortical gyri, sulci, and cortical functional areas (based on Brodmann's maps). This work lays the foundation for correlative studies of location of lesions and the clinical picture.

Brain↗
PubMedDate not supplied

Avoiding an overdiagnosis of pancreatic pseudocysts.

BACKGROUND/AIMS: Thirty-six cases of pancreatic pseudocysts were retrospectively analyzed, to evaluate the clinical features of the pseudocysts which could not be differentiated from the neoplastic cysts until laparotomy. METHODOLOGY: Thirty-one out of 36 cases were diagnosed correctly to be a pseudocyst, in which 10 cases (32.3%) were treated by surgery. Five out of 36 cases were diagnosed to be neoplastic pancreatic cysts (mucinous cystadenoma or cystadenocarcinoma in 4 cases, serous cystadenoma in 1) in which all cases were treated by surgery (100%). To determine the clinical factors contributing to a correct or false diagnosis of pseudocysts, 14 clinical objects were categorized into several factors and analyzed using a contingency table. RESULTS: The clinical factors, including a "history of pancreatitis" (P = 0.070), "upper abdominal pain" (P = 0.083), an "age of less than 42 years" (P = 0.070), and an "elevated serum amylase level on admission" (> or = 200 IU/L, P = 0.067) were all thought to be helpful in establishing a correct diagnosis of pancreatic pseudocyst. In the morphological studies of computed tomography and ultrasonography, "multicystic lesions" (P = 0.045) and "nodular or irregular thickening of the cyst wall" (P = 0.006) significantly mislead us into making a diagnosis of a neoplastic cyst. CONCLUSIONS: In conclusion, the morphological features of a multicystic pattern, with either nodular or irregular thickening of the cyst wall, also belong to the common features of the pancreatic pseudocysts. Since these features tended to be diagnosed as neoplastic, other clinical factors should thus be referred to, in a comprehensive manner, to establish a correct diagnosis of pancreatic pseudocyst.

Adult↗
PubMed1991

[Computed tomographic and anatomical studies on the morphology of the minor pulmonary fissure].

The morphology of the minor fissure, i.e., the shape of the upper surface of the middle lobe, was studied in 10 specimens and in 60 thoracic CT's. In 8 specimens and 54 CT's there was the arrangement typical for the right lung consisting of 3 distinct lobes. The upper surface of the middle lobe had a convex upward shape against the base of the upper lobe in all anatomical preparations and in 52 of the CT's. The position and shape of the convexity was, however, quite variable. In 2 cases the upper surface of the middle lobe was flat. In 78% the minor fissure was incomplete and in 2 cases it was absent.

Adult↗
PubMed2002

Computer-based evaluation of gender identification and morphologic classification of tooth face and arch forms.

STATEMENT OF PROBLEM: In prosthodontics, sex-related differences in tooth forms are assumed, and optimal esthetics is further assumed to be achieved only if the face, arch, and tooth forms are in harmony. However, there is no universally accepted rule or mathematical method to define these morphologic features. PURPOSE: The purpose of this study was to evaluate whether anterior tooth from reflected gender and to question the hypothesis that there was a correlation among face, arch, and tooth forms on the basis of dentists' perceptions. MATERIALS AND METHODS: Photographic records including full face, dental arch, and anterior tooth images of 60 dental students were made by use of digital photography. A database was arranged as a questionnaire for evaluation by prosthodontists who were asked to define the sex and morphologic features of the subjects by examining stored images of the subjects. Thirteen prosthodontists, all with at least 10 years of experience, served as experts and performed these evaluations twice at 2-week intervals. Kappa statistic was used to measure intraobserver and interobserver agreement. RESULTS: The average correctly identified values in females and males were 53% and 58%, respectively. However, the proportions of females and males who were identified correctly and completely the same in both the first and second evaluations were 36% for females and 41% for males. According to the observations of the experts, face-to-arch form (54%) and face-to-tooth form (51%) correlations were higher than the tooth-to-arch form correlation. The overall correlation among face, arch, and tooth forms was 31%. The experts were in fair agreement in defining tooth forms. CONCLUSIONS: The results of gender identification of the subjects showed that the experts were unsuccessful in distinguishing the actual sex by the visual assessment of anterior tooth segment alone, with a fair agreement between 2 evaluation sessions. There were also significant interobserver and intraobserver differences in classifying face, arch, and especially tooth forms. Furthermore, the correlation among these forms was not highly defined.

Cephalometry↗
PubMed2003

Cardiac near-field morphology during conduction around a microscopic obstacle--a computer simulation study.

In a recent paper, we described the behavior of the cardiac electric near-field, E, parallel to the tissue surface during continuous conduction. We found that the tip of E describes a vector-loop during depolarization with the peak field, E, pointing opposite to the direction of propagation, phiI(m). Experimentally recorded loop morphologies of E, however, frequently showed significant deviations from the theoretically predicted behavior. We hypothesized that this variety of morphologies might be caused by conduction obstacles at a microscopic size scale. This study examines the influence of obstacles on the morphology of vector loops of E and whether the peak of distorted loops remains a reliable indicator for the direction of propagation. We used a computer model of a sheet of cardiac tissue with a central conduction obstacle immersed in an unbounded volume conductor. We studied the loop morphologies of E and the differences between the intracellularly determined direction of propagation, phiI(m), and the direction of E, phiE. Distortions of the vector loop were morphologically similar to those observed experimentally. Differences between phiI(m) and phiE were less than 18 degrees at all observation sites. The obstacle led to deformations of the loop morphology, particularly during the initial and terminal phases, and to a lesser degree near the instant of E. We concluded that E is a reliable indicator of phiI(m).

Animals↗
PubMed2001

Changes in root canal geometry after preparation assessed by high-resolution computed tomography.

Root canal morphology changes during canal preparation, and these changes may vary depending on the technique used. Such changes have been studied in vitro by measuring cross-sections of canals before and after preparation. This current study used nondestructive high-resolution scanning tomography to assess changes in the canals' paths after preparation. A microcomputed tomography scanner (cubic resolution 34 microm) was used to analyze 18 canals in 6 extracted maxillary molars. Canals were scanned before and after preparation using either K-Files, Lightspeed, or ProFile .04 rotary instruments. A special mounting device enabled precise repositioning and scanning of the specimens after preparation. Differences in surface area (deltaA in mm2) and volume (deltaV in mm3) of each canal before and after preparation were calculated using custom-made software. deltaV ranged from 0.64 to 2.86, with a mean of 1.61 +/- 0.7, whereas deltaA varied from 0.72 to 9.66, with a mean of 4.16 +/- 2.63. Mean deltaV and deltaA for the K-File, ProFile, and Lightspeed groups were 1.28 +/- 0.57 and 2.58 +/- 1.83; 1.79 +/- 0.66 and 4.86 +/- 2.53; and 1.81 +/- 0.57 and 5.31 +/- 2.98, respectively. Canal anatomy and the effects of preparation were further analyzed using the Structure Model Index and the Transportation of Centers of Mass. Under the conditions of this study variations in canal geometry before preparation had more influence on the changes during preparation than the techniques themselves. Consequently studies comparing the effects of root canal instruments on canal anatomy should also consider details of the preoperative canal geometry.

Computer Simulation↗