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Biomedical subjects

J G Im

Publications and source records attributed to J G Im.

At least 55 records · Page 3Linked to original sources
PubMed1996

Spiral CT angiography of the thoracic aorta.

Computed tomographic (CT) angiography is a new minimally invasive vascular imaging modality. FOr its clinical use to increase, the advantages and potential applications of this modality must be understood. The clinical applications of CT angiography in the thoracic aorta and its branches include evaluation of congenital aortic anomalies, aortic aneurysm, aortic dissection, Takayasu arteritis, penetrating aortic atherosclerotic ulcer, traumatic aortic injury, the postoperative aorta, arch vessels, and pulmonary sequestration. The advantages of CT angiography over conventional angiography are as follows: (a) high-quality, thin axial sections that demonstrate mural changes, extraluminal pathologic conditions, and spatial relationships with adjacent organs; (b) high contrast resolution and high sensitivity for detecting calcified lesions; (c) angiographic or three-dimensional display of vascular structures and adjacent organs in any projection with a single spiral acquisition; and (d) demonstration of extrinsic causes of vascular compromise. CT angiography has the potential to replace conventional catheter angiography in the diagnosis of many pathologic conditions of the thoracic aorta.

Aortic Dissection↗
PubMed1996

Mediastinal tuberculous lymphadenitis: MR imaging appearance with clinicopathologic correlation.

OBJECTIVE: The purpose of our study was to determine the MR imaging appearance of mediastinal tuberculous lymphadenitis and to compare these findings with clinical and pathologic findings. MATERIALS AND METHODS: MR images of 23 consecutive patients with mediastinal tuberculous lymphadenitis were retrospectively analyzed with regard to homogeneity, signal intensity, and enhancement of diseased nodes after injection of contrast material (n = 19), and the imaging findings were grouped by patterns and correlated with clinical signs or symptoms and with pathologic (n = 9) findings. RESULTS: Three imaging patterns of mediastinal tuberculous lymphadenitis (113 nodes) were seen of MR images. In six patients, nodes (type 1, n = 25) were relatively homogeneous and hyperintense to muscle on both T1- and T2-weighted images and enhanced homogeneously after injection of contrast material. The patients had mild (n = 2) or no (n = 4) constitutional symptoms. The nodes corresponded pathologically to tuberculous granulomas without or with minimal necrosis. In 14 patients, nodes (type 2, n = 71) were inhomogeneous with a strong peripheral enhancement after injection of contrast material. Enhancing areas were of intermediate intensity on T1-weighted images and hypointense on T2-weighted images, and corresponded pathologically to peripheral granulation tissue within the nodes. Unenhanced areas were relatively hypointense on T1-weighted images and markedly hyperintense on T2-weighted images, and corresponded pathologically to central caseation or liquefaction necrosis within the nodes. All but one patient with type 2 nodes had moderate to severe clinical signs and symptoms. In the remaining three patients, nodes (type 3, n = 17) were homogeneously hypointense on both T1- and T2-weighted images and did not enhance after injection of contrast material. No patient with type 3 nodes had clinical signs or symptoms. The nodes corresponded pathologically to fibrocalcified nodes. CONCLUSION: The most common MR imaging appearance of mediastinal tuberculous lymphadenitis was as inhomogeneous nodes with marked hyperintensity on T2-weighted images and peripheral enhancement after injection of contrast material. This typical MR imaging appearance was mostly seen in severely symptomatic patients and was due to caseation necrosis of the tuberculous nodes.

Adolescent↗
PubMed1996

Laryngeal tuberculosis: CT findings.

OBJECTIVE: The purpose of this study was to evaluate the CT findings of laryngeal tuberculosis (TB). SUBJECTS AND METHODS: CT scans, laryngoscopic examinations, and chest radiographs of 12 patients (21-63 years old) with histologically (n = 8) or bacteriologically (n = 4) confirmed laryngeal TB were retrospectively reviewed. RESULTS: Bilateral diffuse thickening of the vocal cords and diffuse thickening and increased density of the aryepiglottic folds and paralaryngeal tissues were present in all patients. Diffuse thickening of the epiglottis was observed in seven patients. In four patients, a focal mass was noted in the anterior portions of the vocal cords (n = 3) or tip of the epiglottis (n =1). Destruction or sclerosis of cartilage was not found. Subglottic extension of the lesion was suspected in only one patient. Enlarged cervical lymph nodes were found in five patients. On laryngoscopic examinations, swelling of the vocal cords (n = 12) or epiglottis (n = 6) was present in all patients and was bilateral in nine patients. Vocal cord mobility was impaired in only one patient. Radiographic findings consistent with active pulmonary TB were present in all patients. CONCLUSION: Although the CT appearances of laryngeal TB are not specific, the possibility of laryngeal TB should be raised when bilateral and diffuse laryngeal lesions are encountered without destruction of the laryngeal architecture in patients with pulmonary TB.

Adult↗
PubMed1996

Thin-section CT findings of the lungs: experimentally induced bronchial and pulmonary artery obstruction in pigs.

OBJECTIVE: The purpose of this study was to investigate whether a mosaic pattern of lung attenuation, or lobular low attenuation, is revealed on CT imaging after induction of bronchial and pulmonary artery obstruction in pigs. MATERIALS AND METHODS: Eight anesthetized and ventilated pigs, four for bronchial obstruction and four for pulmonary artery obstruction, were examined with thin-section CT. Bronchial obstruction was induced at the subsegmental level using 2- to 3-mm radiopaque silicon spheres at 14 sites. Pulmonary artery obstruction was induced at 11 sites by dislodging 2- to 3-mm silicon spheres at the level of the superior vena cava. CT scans were obtained at end expiration immediately after the obstruction in all pigs (n = 8) and after 1 day (n = 3), 3 days (n = 5), 7 days (n = 4), 14 days (n = 4), and 28 days (n = 3). RESULTS: Of the 14 sites of bronchial obstruction, six sites (43%) on the immediate scans showed a lobular distribution of low attenuation distal to the spheres, which changed to atelectasis, consolidation, or normal on follow-up CT. Of the four sites that did not show changes in lung attenuation on immediate CT scans, two sites showed lobular low attenuation after 1 day. The mean attenuation value +/- SD for the lobular low attenuation was -737 H +/- 122 and that of the adjacent lung was -522 H +/- 53 (p = .0077). None of the pulmonary artery obstruction sites showed visible change in lung attenuation, and mean attenuation values for obstructed sites and unobstructed sites did not show significant differences when scanned as many as 28 days after the immediate scans. CONCLUSION: Lobular low attenuation on thin-section CT was induced by bronchial obstruction, but we found no change in lung attenuation due to obstruction of the pulmonary arteries as many as 28 days after the immediate scans.

Animals↗
PubMed1995

Sonography of the costal cartilage: normal anatomy and preliminary clinical application.

Costal cartilages of 10 controls and 12 patients with Tietze's syndrome (n = 6), deformed (exaggerated bowing) cartilage (n = 4), focal enlargement (n = 1), and cancer-invaded cartilage (n = 1) were examined with ultrasonography. In controls, ultrasonography detected 237 of 240 costal cartilages (98.8%) and 58 of 105 intercartilage connections (55%) with three variations. Correlation with CT was available in 7 patients (1 Tietze's syndrome, 4 deformities, 1 cartilage enlargement, and 1 cancer) among 8 patients whose CT results were known to the sonographer. Sonography showed normal (n = 4) or marginally blurred (n = 2) cartilages in 6 Tietze's syndromes. Ultrasonography is a promising technique in the examination of costal cartilages.

Adolescent↗
PubMed1995

CT of pulmonary tuberculosis.

CT scans in patients with primary tuberculosis commonly show lymphohematogenous spread of the disease, whereas those of postprimary (reactivation) tuberculosis commonly show bronchogenic spread. High-resolution CT (HCRT) is extremely helpful in understanding pathomorphological changes, mode of spread of the disease, and sequential morphological change after antituberculous chemotherapy, and possibly in diagnosing activity of the disease. Centrilobular 2- to 4-mm nodules or branching linear lesions representing intrabronchiolar and peribronchiolar caseation necrosis are the most common findings of early bronchogenic spread of tuberculosis. The 2- to 4-mm centrilobular nodules may coalesce to form 5- to 8-mm nodules or lobular consolidation. Cavitation usually begins at the central portion of a lobule around the bronchioles. Resolution of the tuberculous lesions occurs with antituberculous chemotherapy, resulting in varying degrees of fibrosis, bronchovascular distortion, emphysema, and bronchiectasis. HRCT may show both paracicatricial irregular emphysema and lobular emphysema. CT findings of early miliary dissemination commonly include ground-glass opacification with barely discernible nodules that show discrete miliary nodules thereafter. CT also is useful in the evaluation of long-standing destructive pulmonary lesions and tracheobronchial tuberculosis.

Humans↗
PubMed1995

Thoracic manifestations of Behçet syndrome: radiographic and CT findings in nine patients.

PURPOSE: To evaluate the radiographic and computed tomographic (CT) findings of patients with thoracic Behçet syndrome. MATERIALS AND METHODS: Chest radiographs and CT scans of nine patients with thoracic Behçet syndrome were retrospectively reviewed. Findings were compared. RESULTS: Radiographs of the nine patients showed mediastinal widening in five (56%), air-space consolidation in five (56%), and lung mass in three (33%). CT scans of the nine patients showed that mediastinal widening was due to thrombosis in four (44%) or narrowing of the superior vena cava in one [11%], which caused mediastinal edema; that air-space consolidation (seen on both radiographs and CT scans) was due to pulmonary hemorrhage or infarction in five (56%); and that lung mass was due to aneurysm of the right or left pulmonary artery in three (33%). In addition, CT scans showed hyperinflation in one patient. CONCLUSION: Chest radiographic findings of thoracic Behçet syndrome are variable and nonspecific. CT can be helpful in the assessment of the syndrome by showing thrombosis of the superior vena cava and characteristic aneurysms of the pulmonary arteries.

Adolescent↗
PubMed1995

Takayasu arteritis: evaluation of mural changes in the aorta and pulmonary artery with CT angiography.

PURPOSE: To evaluate mural changes in the aorta and pulmonary artery in Takayasu arteritis by using computed tomographic (CT) angiography. MATERIALS AND METHODS: CT angiography was prospectively performed in 12 women with Takayasu arteritis and in 10 healthy adults. Scanning included three distinct phases: precontrast (before administration of contrast material), arterial, and delayed. RESULTS: Precontrast transverse images revealed a high-attenuation aortic wall (10 patients) and mural calcifications in the aorta (nine patients). Arterial-phase images revealed circumferential wall thickening of 1-4 mm in all patients and enhancement in five patients with active disease. Delayed-phase CT revealed circumferential enhancement in eight patients. A concentric, low-attenuation ring was also identified inside the aorta on the arterial-phase (two patients) and delayed-phase (three patients) images. In the pulmonary artery, wall thickening was revealed with early and delayed enhancement in two patients. CONCLUSION: CT angiography may demonstrate changes in the vascular wall in patients with Takayasu arteritis.

Adult↗
PubMed1995

CT in adults with tuberculosis of the chest: characteristic findings and role in management.

The frequency of tuberculosis decreased continuously until 1985, when the trend reversed, mainly because of the large number of cases in patients with AIDS [1-3]. Pulmonary tuberculosis remains a common disease in North America, particularly in groups such as the socioeconomically disadvantaged, the elderly, chronically debilitated patients, immigrants, refugees, and prisoners [1-3]. The prevalence and incidence of the disease are still high in endemic areas [4].

Humans↗
PubMed1995

Lipid peroxidation and 8-hydroxydeoxyguanosine formation in rats fed fish oil with different levels of vitamin E.

This study was conducted to investigate the protective role of vitamin E against the formations of lipid peroxides in plasma and tissues and of 8-hydroxydeoxyguanosine (8-OHdG) in livers of rats fed fish oil. Six-week-old male Sprague-Dawley rats were divided into four groups and fed experimental diets for 8 weeks. Three fish oil (F) groups were fed a menhaden fish oil and soybean oil (9:1) mixture as 10% (wt/wt) of their diet. These three groups (F0, FI, and FII) were provided with < or = 3, 45, and 209 IU of vitamin E/kg diet, respectively. The SI group was fed soybean oil with < or = 45 IU of vitamin E/kg diet. The F0 group had the highest levels of thiobarbituric acid-reactive substances (TBARS) in plasma (per milligram lipid), and liver, lung, heart, and kidney. The FI group had higher levels of TBARS than the SI group in plasma and tissues except the lung. In liver, the TBARS levels of the FII group were also higher than those of SI group, but in other tissues, similar levels were observed in the FII and SI groups. Plasma level of vitamin E was lowest in F0 group and vitamin E levels were generally lower in F groups than in SI group. These levels were expressed as vitamin E per milliliter of plasma. However, plasma E levels were similar when expressed per milligram plasma lipid. The liver 8-OHdG concentration tended to decrease as dietary vitamin E increased in the F groups, but there was no difference in the level of 8-OHdG between the FI and SI groups. These results suggest that vitamin E should be supplemented in fish oil feeding to prevent the enhanced lipid peroxidation and the formation of 8-OHdG in the body.

Administration, Oral↗
PubMed1995

CT-pathology correlation of pulmonary tuberculosis.

Pulmonary tuberculosis is a chronic granulomatous disease characterized radiologically by nodules, air-space consolidation, propensity for cavitation, and calcification, and pathologically by caseating granulomas or pneumonia, and a great propensity for fibrosis and dystrophic calcification. Primary tuberculosis typically appears as air-space consolidation with hilar or mediastinal lymphadenitis. Postprimary tuberculosis appears most commonly as nodular and linear opacities at the lung apex. CT findings of early bronchogenic spread of postprimary tuberculosis are centrilobular 2- to 4-mm nodules or branching linear structure, 5- to 8-mm poorly defined nodules, lobular consolidation, cavities, and thickening of interlobular septa. Centrilobular nodules or branching linear lesions and poorly defined nodules on CT scan correspond to caseation materials filling the bronchioles, and centrilobular air-space consolidation with caseation necrosis. Poorly defined nodule or lobular consolidation usually consists of central caseation necrosis and peripheral nonspecific inflammation. Cavitation usually occurs at the centrilobular area and may progress to a larger coalescent cavity. With antituberculous therapy, resolution typically occurs from the peripheral portion of the poorly defined nodule or lobular consolidation and results in varying degrees of fibrous bands, bronchovascular distortion, emphysema, and bronchiectasis. Miliary tuberculosis appears as well-defined randomly distributed nodules on CT scan that correspond with nodules consisting of central caseation necrosis and peripheral epitheloid and fibrous tissue. Analysis of CT images on the basis of pathologic correlation is helpful in understanding the morphology of pulmonary tuberculosis.

Adult↗
PubMed1994

Castleman's disease of the mediastinum: MR imaging features.

We present the MR imaging features in two cases of mediastinal Castleman's disease of the hyaline-vascular type. T1-weighted MR images showed rounded hilar masses of intermediate or high signal intensity with areas of low signal due to vessels and calcification. On T2-weighted images, the masses were of high signal intensity. Mediastinal masses with the above signal characteristics and vascular signal voids may suggest a diagnosis of Castleman's disease.

Adult↗
PubMed1994

Improved visualization of stimulated nodules by adaptive enhancement of digital chest radiography.

RATIONALE AND OBJECTIVES: Although digital radiography of the chest has a wide dynamic range, difficulties still remain in visualizing the acquired images faithfully on gray-scale displays (cathode-ray tube [CRT] displays), which have a much lower level of luminance than film view boxes. We propose an adaptive-enhancement algorithm for digital chest radiography that provides faithful visualization of the chest on the CRT. METHODS: We investigated the contrast sensitivity of a CRT monitor and developed an image processing algorithm that compresses the dynamic range and enhances image contrast selectively in the mediastinal area and that transforms the gray scale to visualize the image by use of the full effective dynamic range of the CRT. We performed a receiver-operating characteristic (ROC) study by using simulated nodules to evaluate the clinical value of the proposed algorithm. RESULTS: The processed images provided improved visualization of both mediastinal and lung regions. The area under the ROC curve for retrocardiac or subdiaphragmatic nodule detection increased significantly (from 0.69 to 0.79; P < 0.05). The area under the ROC curve for lung nodule detection also increased (from 0.64 to 0.75; P < 0.1), although not to the level of statistical significance. CONCLUSION: The proposed algorithm allows improved visualization of nodules on digital chest radiographs with the CRT display.

Algorithms↗
PubMed1994

Hydrostatic versus oleic acid-induced pulmonary edema: high-resolution computed tomography findings in the pig lung.

RATIONALE AND OBJECTIVES: We evaluated the differences between combined hydrostatic and hypervolemic edema and oleic acid-induced edema on high-resolution computed tomography (HRCT) scans. METHODS: Twelve anesthetized and ventilated pigs were studied. Hydrostatic edema was induced by ligation of the abdominal aorta and infusion of normal saline (n = 4); permeability edema was induced by intravenous injection of oleic acid (n = 4). Four pigs were studied as normal controls. Serial scans were obtained before and after induction of edema at a constant position in the caudal lobe of the lung. The distribution of edema was assessed visually. Cross-sectional areas (CSAs) of the pulmonary artery and vein were measured both at the lobar and segmental levels. RESULTS: Gravity-dependent opacity, peribronchovascular fluid collection, prominent centrilobular core, thickening of the interlobular septa, and air-space consolidation at the dependent site were the sequential HRCT findings of hydrostatic edema. Randomly distributed, diffuse patchy high attenuation areas with a tendency for predilection in the subpleural and peripheral areas of the secondary lobule were the findings of oleic acid-induced edema. Hydrostatic edema increased the mean CSAs of the lobular vein by 137.8% +/- 78.7, but oleic acid edema decreased the mean CSAs by 33.2% +/- 22.7. Changes in the mean CSAs of the pulmonary arteries were not significant. The mean vein-to-artery ratio increased significantly in hydrostatic edema but decreased in oleic acid edema. CONCLUSION: HRCT findings for hydrostatic and oleic acid-induced pulmonary edema differed both in distribution of edema and in pulmonary vascular response.

Animals↗