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Biomedical subjects

C I Chang

Publications and source records attributed to C I Chang.

46 records · Page 3Linked to original sources
PubMed1987

Surgical anatomy of left ventricular outflow tract obstruction in complete atrioventricular septal defect. A concept for operative repair.

An integral part of the heart with an atrioventricular septal defect and a Rastelli type A valve configuration is left ventricular outflow tract obstruction. Current surgical techniques do not cater to this particular anatomic facet, and left ventricular outflow tract obstruction has been reported as a postoperative problem. The present study has focused on the surgical anatomy of the mode of attachment of the left superior atrioventricular valve and its relationship to the left ventricular outflow tract. It appeared that the anchoring of the superior leaflet was a major factor in limiting the excursions of the superior leaflet, contributing also to the tightness of the subaortic left ventricular outflow channel. On that basis a surgical repair is proposed in which the greater part of the tightly bound superior leaflet is detached from the septal crest, so that the left ventricular outflow tract is widened.

Chordae Tendineae↗
PubMedDate not supplied

Orthogonal subspace projection-based approaches to classification of MR image sequences.

Orthogonal subspace projection (OSP) approach has shown success in hyperspectral image classification. Recently, the feasibility of applying OSP to multispectral image classification was also demonstrated via SPOT (Satellite Pour 1'Observation de la Terra) and Landsat (Land Satellite) images. Since an MR (magnetic resonance) image sequence is also acquired by multiple spectral channels (bands), this paper presents a new application of OSP in MR image classification. The idea is to model an MR image pixel in the sequence as a linear mixture of substances (such as white matter, gray matter, cerebral spinal fluid) of interest from which each of these substances can be classified by a specific subspace projection operator followed by a desired matched filter. The experimental results show that OSP provides a promising alternative to existing MR image classification techniques.

Brain↗
PubMedDate not supplied

A hierarchical model for PACS.

In this paper, a hierarchical model for Picture Archiving and Communication Systems (HPACS) is presented and implemented at Taichung Veterans General Hospital (TCVGH) in Taiwan. Despite the fact that the HPACS is built on the architecture of the second generation PACS, it offers many improved features and has advantages over the second generation PACS, such as the user security control, fast resource dispatch and efficient resource management. This HPACS can be used as a reference model for a hospital with any scale-size. The real implementation of HPACS is currently undertaken in the Taichung Veterans General Hospital (TCVGH), Taiwan, Republic of China and consists of four phases with the first two phases already completed. It is the first pilot system ever to be implemented successfully in a large-scale hospital in Taiwan. The experiences have illustrated the great promise of the HPACS in the future.

Computer Communication Networks↗
PubMedDate not supplied

Clinical implications of short-axis aortopulmonary rotation on juxtacommissural origin of the coronary artery in transposition of the great arteries and surgical strategy.

BACKGROUND: The relationship of short-axis aortopulmonary rotation (APR) with juxtacommissural origin of the coronary arteries (JOCA) in transposition of the great arteries (TGA) has never been elucidated. The surgical outcome of arterial switch operation (ASO) is influenced by the presence of JOCA. METHODS: Fifteen patients with TGA who presented to our institution between 1988 and 1995, and 23 cases from the literature, all with documented JOCA and APR, were analyzed. Each coronary arterial type was assigned to one of five patterns, according to similarities of epicardial configuration. All our patients underwent an ASO with various techniques to deal with JOCA. RESULTS: JOCA near the facing commissure (FC, 35 cases), were more frequent with anterior TGA (29/31, 94%) except types 5cj and 9j that were seen with posterior and right lateral TGA (4/4, 100%); whereas JOCA near the right-hand nonfacing commissure (RNC, 3 cases) were related with posterior TGA. Eta-square analysis showed significant correlation between various JOCA and short axis APR. Thirteen of our cases had JOCA near FC, two near RNC. Five of the former in whom the coronary artery was excised as a single button had a superior trapdoor; using a two-button technique three of the former had a lateral funnel and one of the latter had a medial trapdoor for the JOCA; all survived although on late noncoronary death was noted. In the remaining six cases without augmentation, only one survived (8/1 vs 1/5, p < 0.02). CONCLUSION: JOCA in TGA was related to short axis APR, generally near FC in anterior TGA (except types 5cj and 9j), and near the RNC in posterior TGA. A superior (lateral) or medial flap, to augment the coronary button for JOCA near FC or RNC is helpful for a successful ASO.

Aorta↗
PubMedDate not supplied

A feasibility study of multispectral image analysis of skin tumors.

To develop a noninvasive, early-detection method for skin cancers, a feasibility study of multispectral image analysis was investigated. The three most frequently occurring skin cancer types, ten basal-cell carcinomas (BCCs), ten squamous-cell carcinomas (SCCs) and five malignant melanomas (MMs) were studied, along with ten normal moles. Images were acquired by a charge-coupled device camera using eight narrow-band filters ranging from 450 nm to 800 nm, at 50-nm intervals. To extract main features of these tumors, principal components analysis (PCA) was performed, because it projects the multidimensional (here, eight-dimensional) data in the direction of maximum data variance. Then, the primary PCA components for red, green, and blue subset images were analyzed in terms of hue-saturation-intensity (HSI). By hue distributions, the BCCs and SCCs were differentiated from the MMs and normal moles. Texture information was used to further classify tumor types after the HSI analysis. The texture analysis, performed using a spatial gray-level co-occurrence matrix (SGCM), could separate MMs from normal moles. The BCCs and SCCs were further studied by Fisher's linear discriminant analysis. Distribution was described as a Gaussian mixture model. By this classification procedure, seven BCCs, eight SCCs, five MMs, and ten NMs were correctly classified. Three BCCs and two SCCs were unseparable. Thus, multispectral skin cancer image analysis has potential to diagnose skin cancers.

Algorithms↗
PubMedDate not supplied

Double-orifice mitral valve: report of two cases.

Two cases of double-orifice mitral valve are reported. The first case was associated with coarctation of the aorta and a large perimembranous ventricular septal defect, and the second case had an associated large patent ductus arteriosus. A bridge-type defect created two equal-sized openings in the mitral valve in case 1. In case 2, a small accessary opening was located in the posteromedial leaflet of the mitral valve. Double-orifice mitral valve is a rare anomaly associated with coarctation of the aorta, ventricular septal defect, and patent ductus arteriosus. The morphology of a double-orifice mitral valve can be clearly delineated by 2-D echocardiography.

Aortic Coarctation↗
PubMedDate not supplied

Flow characteristics in infants with hypoplastic left heart syndrome: an echocardiographic study.

From July 1992 to January 1993, a total of 5 cases of hypoplastic left heart syndrome were diagnosed by echocardiograms and confirmed by available angiographic, surgical or autopsy results. The flow dynamics disclosed by spectrum display in the aortic root and patent ductus arteriosus (PDA), in systole, were: (1) antegrade in the ascending aorta and descending aorta (below PDA), and retrograde in the transverse aorta, and (2) right-to-left shunt in the PDA. While in diastole, there were (1) antegrade in the transverse aorta, and retrograde in the ascending aorta and descending aorta (below PDA), and (2) left-to-right shunt in the PDA. No ventriculocoronary fistulas were identified. With both the characteristic flow pattern and the extremely narrow diameters of the ascending aorta in hypoplastic left heart syndrome, we can differentiate it from those heart diseases associated with secondary hypoplastic left heart due to total anomalous pulmonary venous connection or congenital pulmonary venous stenosis. Both help us understand better the hemodynamics and pathophysiology of hypoplastic left heart syndrome in these patients.

Aorta↗
PubMedDate not supplied

Scimitar syndrome complicated with right pneumonectomy syndrome: report of one case.

A 2-month-old infant, suffering from respiratory distress, was suspected to have scimitar syndrome from a chest roentgenogram and was diagnosed by cardiac catheterization. Ligation of the aberrant feeding arteries and right lung resection was performed at three and four months of age, respectively. However, the postoperative course was complicated with right pneumonectomy syndrome requiring continuous artificial ventilation. With supportive management, the patient improved gradually and was eventually weaned off the ventilator at three years of age.

Female↗