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Biomedical subjects

B K Han

Publications and source records attributed to B K Han.

80 records · Page 5Linked to original sources
PubMedDate not supplied

MR imaging in the morphologic diagnosis of congenital heart disease.

The ability of magnetic resonance (MR) imaging to depict cardiovascular structures is especially useful in patients with congenital heart disease (CHD). While MR imaging techniques that focus on cardiac function or blood flow have not been used frequently in the evaluation of CHD, MR imaging has been useful in morphologic diagnosis of CHD. Spin-echo MR imaging can depict relevant morphologic features of most types of CHD. MR imaging provides important diagnostic information in evaluation of right ventricular outflow tract obstruction (eg, pulmonary atresia), postoperative status, pulmonary venous anomalies, and complex ventricular anomalies. MR imaging can replace angiography in some situations, including evaluation of simple defects, right ventricular outflow tract obstruction, and postoperative status. MR imaging is the modality of choice in evaluation of aortic coarctation, interrupted aortic arch, and hemitruncus. MR images in three orthogonal planes are useful in analyzing the morphology and arrangement of cardiac segments in univentricular heart, criss-cross heart, and abnormal visceroatrial situs.

Adolescent↗
PubMedDate not supplied

Functional MR imaging of working memory in the human brain.

OBJECTIVE: In order to investigate the functional brain anatomy associated with verbal and visual working memory, functional magnetic resonance imaging was performed. MATERIALS AND METHODS: In ten normal right handed subjects, functional MR images were obtained using a 1.5-T MR scanner and the EPI BOLD technique. An item recognition task was used for stimulation, and during the activation period of the verbal working memory task, consonant letters were used. During the activation period of the visual working memory task, symbols or diagrams were employed instead of letters. For the post-processing of images, the SPM program was used, with the threshold of significance set at p <.001. We assessed activated brain areas during the two stimulation tasks and compared the activated regions between the two tasks. RESULTS: The prefrontal cortex and secondary visual cortex were activated bilaterally by both verbal and visual working memory tasks, and the patterns of activated signals were similar in both tasks. The superior parietal cortex was also activated by both tasks, with lateralization to the left in the verbal task, and bilaterally without lateralization in the visual task. The inferior frontal cortex, inferior parietal cortex and temporal gyrus were activated exclusively by the verbal working memory task, predominantly in the left hemisphere. CONCLUSION: The prefrontal cortex is activated by two stimulation tasks, and this is related to the function of the central executive. The language areas activated by the verbal working memory task may be a function of the phonological loop. Bilateral prefrontal and superior parietal cortices activated by the visual working memory task may be related to the visual maintenance of objects, representing visual working memory.

Adult↗
PubMedDate not supplied

Airway reactivity to bronchoconstrictor and bronchodilator: assessment using thin-section and volumetric three-dimensional CT.

OBJECTIVE: To determine the extent to which thin-section and volumetric threedimensional CT can depict airway reactivity to bronchostimulator, and to assess the effect of different airway sizes on the degree of reactivity. MATERIALS AND METHODS: In eight dogs, thin-section CT scans were obtained before and after the administration of methacholine and ventolin. Cross-sectional areas of bronchi at multiple levels, as shown by axial CT, proximal airway volume as revealed by three-dimensional imaging, and peak airway pressure were measured. The significance of airway change induced by methacholine and ventolin, expressed by percentage changes in cross-sectional area, proximal airway volume, and peak airway pressure was statistically evaluated, as was correlation between the degree of airway reactivity and the area of airways. RESULTS: Cross-sectional areas of the bronchi decreased significantly after the administration of methacholine, and scans obtained after a delay of 5 minutes showed that normalization was insufficient. Ventolin induced a significant increase in cross-sectional areas and an increase in proximal airway volume, while the effect of methacholine on the latter was the opposite. Peak airway pressure increased after the administration of methacholine, and after a 5-minute delay its level was near that of the control state. Ventolin, however, induced no significant decrease. The degree of airway reactivity did not correlate with airway size. CONCLUSION: Thin-section and volumetric spiral CT with three-dimensional reconstruction can demonstrate airway reactivity to bronchostimulator. The degree of reactivity did not correlate with airway size.

Albuterol↗
PubMedDate not supplied

Foreign body granulomas of the breast presenting as bilateral spiculated masses.

In Asia, mammography following the injection of foreign materials into the breasts for cosmetic augmentation is frequently seen and diagnosis based on the typical radiologic findings is straightforward. We report the unusual radiologic findings in two patients with foreign body granulomas caused by injected foreign materials and discovered incidentally during screening work up. The mammographic findings were bilateral, hyperdense, spiculated masses, with occasional microcalcification, and at sonography, markedly hypoechoic, spiculated solid masses, located near the pectoralis muscle and partly extending into it, were observed. These radiologic findings mimicked malignancy.

Breast Neoplasms↗
PubMedDate not supplied

Reversal sign on CT: effect of anoxic/ischemic cerebral injury in children.

A retrospective study was performed to determine the clinical and pathologic features, etiology, and outcome of children with the reversal sign. The reversal sign, a striking CT finding, probably represents a diffuse, anoxic/ischemic cerebral injury. CT features of the reversal sign are diffusely decreased density of cerebral cortical gray and white matter with a decreased or lost gray/white matter interface, or reversal of the gray/white matter densities and relatively increased density of the thalami, brainstem, and cerebellum. Twenty children with the reversal sign were retrospectively analyzed. We divided the patients into three groups: (1) acute reversal, (2) intermediate group, and (3) chronic reversal. There were nine cases of trauma (seven of child abuse); nine hypoxia/anoxia incidents (birth asphyxia, drowning, status epilepticus); one bacterial meningitis; and one degenerative encephalitis. All acute- and intermediate-group patients had respiratory problems requiring ventilator support and intensive care. In five of seven patients who died, autopsy findings were consistent with anoxic/ischemic encephalopathy. Surviving patients have profound neurologic deficits with severe developmental delay. The CT reversal sign carries a poor prognosis and indicates irreversible brain damage.

Brain↗
PubMedDate not supplied

Intracranial hemorrhage in premature infants: sonographic-pathologic correlation.

Spontaneous intracranial hemorrhage is the most common central nervous system abnormality in premature infants. In this report the cranial sonographic and pathologic findings of 25 autopsied premature infants are correlated. The presence and size of subependymal, intraventricular, and intraparenchymal hemorrhage were well documented by sonography. Cerebellar, choroid plexus, and cortical hemorrhage, though less frequent, were also recognized. There was good correlation as to the presence and degree of hydrocephalus. Prominent subarachnoid spaces on sonography correlated poorly with subarachnoid hemorrhage at autopsy and may be a normal variant in the premature infant. Anoxic brain damage was not diagnosed early by sonography unless associated with hemorrhage, but diffuse brain atrophy with hydrocephalus exvacuo was detected by sonography.

Autopsy↗