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Biomedical subjects

W R Webb

Publications and source records attributed to W R Webb.

At least 19 recordsLinked to original sources
PubMed1992

Comparative effects of endothelin (ET-1) and U46619 on human saphenous vein and gastroepiploic artery, sources of human autologous grafts.

The effects of endothelin (ET-1) on smooth muscle contractile activity were investigated and compared in human saphenous vein and gastroepiploic artery, vessels frequently used in revascularization procedures. ET-1 contracted saphenous vein and gastroepiploic artery in a concentration-dependent manner. The peptide produced a greater maximal effect in the vein than in the artery and, in both preparations, ET-1 was less efficacious than U46619, an agent which mimics the actions of thromboxane A2 at the thromboxane A2/prostaglandin H2 receptor. The contractile response to ET-1 declined spontaneously at a more rapid rate in the artery than in the vein. The present data indicate that ET-1 has significant contractile activity in both vessels which are used for coronary arterial bypass surgery and suggest that although, a weaker vasoconstrictor than U46619, the peptide could induce vasospasm in both graft vessels.

Arteries↗
PubMed1992

Cystic lung disease associated with eosinophilic granuloma and tuberous sclerosis: air trapping at dynamic ultrafast high-resolution CT.

Thin-walled lung cysts can occur in association with advanced pulmonary eosinophilic granuloma and lymphangioleimyomatosis (LAM). In LAM, cysts occur as an isolated abnormality or in association with tuberous sclerosis. The cause of these cysts is unclear, but some investigators have postulated that they result from air trapping. To determine if lung cysts in these two diseases are associated with air trapping, the authors performed dynamic ultrafast high-resolution computed tomography (DUHRCT) during forced expiration in two patients (one with eosinophilic granuloma and one with tuberous sclerosis) with lung cysts and correlated the results with results of pulmonary function tests. DUHRCT demonstrated focal and diffuse air trapping; in some lung regions, a less than normal increase in lung attenuation during forced exhalation was evident. These studies do not allow a conclusion regarding the mechanism of cyst formation in eosinophilic granuloma and LAM-tuberous sclerosis, but they confirm the association between lung cysts and morphologic findings of air trapping.

Adult↗
PubMed1992

High-resolution CT diagnosis of emphysema in symptomatic patients with normal chest radiographs and isolated low diffusing capacity.

To determine the prevalence of "nonobstructive" (impairment of gas transfer) emphysema in a select population of smokers with dyspnea, a retrospective study of patients with emphysema evident at high-resolution computed tomography (HRCT) was undertaken. Four hundred seventy HRCT studies were reviewed. In 47 cases, centrilobular emphysema was the dominant or sole parenchymal abnormality. Concomitant chest radiographs were available in 41 of these cases; 16 of the 41 lacked radiographic findings of emphysema. Among these 16 patients, pulmonary function testing revealed 10 to have normal flow rates (ratio of forced expiratory volume in 1 second to forced vital capacity and forced expiratory volume in 1 second greater than 80% predicted) and impaired gas transfer (single-breath carbon monoxide diffusing capacity [DLCOSB] less than 80% predicted). With the exclusion of one patient with congestive heart failure from the group of 10, the severity of emphysema at HRCT correlated inversely with DLCOSB (r = -.643). These results indicate that HRCT allows detection of emphysema in symptomatic patients when chest radiographs and pulmonary function tests are nondiagnostic.

Female↗
PubMed1992

Computed radiography.

Explore the source record for details and available documents.

Radiographic Image Interpretation, Computer-Assist↗
PubMed1992

High-resolution computed tomography of the mammalian lung.

High-resolution computed tomography (HRCT) was performed in 21 isolated animal lungs, from 4 mammalian species (pigs, rabbits, dogs, sheep). Gross and subgross central and peripheral lung morphology was determined by HRCT. Three distinct types of lungs can be identified, principally based on the extent of interlobular septal development; the relationship of major vessels to airways; and the thickness of the visceral pleura. Type-I lung is found in pigs, sheep, and cattle; type-II lung is found in rabbits, dogs, cats, and monkeys; and type-III lung is found in human beings and horses. These mammalian lungs were compared with human lungs. The potential use of HRCT to investigate specific human lung diseases in the aforementioned species also was considered.

Animals↗
PubMed1992

Iodized talc pleurodesis for the treatment of pleural effusions.

This prospective study was designed to determine the efficacy of iodized talc pleurodesis in patients with pleural effusions. Thirty-four patients underwent this treatment (three bilaterally) between October 1, 1989, and March 31, 1991. All patients had to have complete or nearly complete lung reexpansion after tube thoracostomy with fluid drainage less than 100 ml in 24 hours. A slurry containing 5 gm of talc and 3 gm of thymol iodide was instilled into the pleural space through the chest tube. Chest tubes were removed after complete reexpansion and clearing of the effusions, usually in 3 to 5 days. The patients' ages ranged from 26 to 88 years (average 50 years). Eighteen patients had lung carcinoma, two had mesothelioma, and one each had carcinoma of the ovary, breast, or anorectum, multiple myeloma, schwannoma, or Hodgkin's lymphoma. Two patients had an unknown adenocarcinoma primary and five other patients had acquired immunodeficiency syndrome. One patient had congestive heart failure. Nineteen patients had left, 12 had right, and three had bilateral pleural effusions. The effusion was serosanguineous in 26 and serofibrinous in eight patients. Serial chest radiography showed complete response in all patients. The period of follow-up ranged from 1 to 21 (average 4.9) months, with no recurrences. Twenty-three patients have died during the follow-up period, and there was no sign that reaccumulated pleural effusion existed in any, despite clinical evidence of systemic tumor progression. These observations indicate that intrapleural instillation of a slurry of iodized talc is a safe, adequate, and effective treatment for control of neoplastic or benign pleural effusions.

Acquired Immunodeficiency Syndrome↗
PubMed1991

The radiologic staging of lung cancer.

The radiographic evaluation and staging of bronchogenic carcinoma remains one of the greatest challenges to the thoracic radiologist and one of his or her most important responsibilities. With lung cancer now the most common malignant tumor in both men and women, there will be a continued need for radiologists to guide clinicians to the appropriate diagnostic and staging procedures, to help plan curative surgery, and to assess the response to therapy or progression of disease. The article reviews the radiographic approach to lung cancer diagnosis and staging with an emphasis on the use of computed tomography and magnetic resonance imaging for the evaluation of the primary tumor and mediastinal and hilar lymph node metastases.

Carcinoma, Bronchogenic↗
PubMed1991

Inferior hilar window.

The authors undertook a study to determine the ability to detect mass or adenopathy in the "inferior hilar window," a normally avascular region inferior to the shadow of the right pulmonary artery and vein and anterior to the descending left pulmonary artery on lateral chest radiographs. Fifty patients with normal results of thoracic computed tomography (CT) and 25 with unilateral or bilateral hilar masses or adenopathy (defined as opacity greater than 10 mm in diameter) were selected retrospectively. Patients with concomitant pulmonary masses or consolidation at CT that might be confused with or obscure an inferior hilar mass or adenopathy were excluded from study. The 75 corresponding lateral chest radiographs were then evaluated blindly. Forty-seven of the 50 normal cases were correctly interpreted (specificity = 94%). The anterior walls of the right and left lower lobe bronchi were seen in 36% and 84% of normal cases, respectively; the average thickness was 2 mm. Of the 25 patients with inferior hilar masses, 22 were recognized as having abnormalities (sensitivity = 88%); two of the three patients with false-negative results had right hilar masses. Overall accuracy was 92%. For only eight (32%) of the 25 patients was the laterality of abnormality correctly diagnosed. Evaluation of the inferior hilar window on lateral chest radiographs is accurate in assessing the presence or absence of inferior hilar mass or adenopathy.

False Negative Reactions↗
PubMed1991

CT and MR imaging in staging non-small cell bronchogenic carcinoma: report of the Radiologic Diagnostic Oncology Group.

The accuracies of magnetic resonance (MR) imaging and computed tomography (CT) in determining tumor classification and assessing mediastinal node metastases were compared in a prospective cooperative study of 170 patients with non-small cell bronchogenic carcinoma. The sensitivity of CT in distinguishing T3-T4 tumors from T0-T2 tumors was 63%; specificity was 84%. These values for MR imaging were not significantly different (56% and 80%). With receiver operating characteristic (ROC) analysis, no difference existed between the accuracies of CT and MR imaging in diagnosis of bronchial involvement or chest wall invasion, but MR imaging was significantly more accurate than CT (P = .047) in diagnosis of mediastinal invasion. Lymph node sampling was performed in 155 patients (642 node stations). Cancerous nodes were found in 14% of stations in 21% of patients. There was no significant difference between the accuracies of CT and MR imaging in detecting mediastinal node metastases (N2 or N3); the sensitivities were 52% and 48%, respectively, and specificities were 69% and 64%. ROC analysis also showed no difference between CT and MR imaging.

Carcinoma, Non-Small-Cell Lung↗
PubMed1991

Apical opacity associated with pulmonary tuberculosis: high-resolution CT findings.

To elucidate the nature of the apical opacity that is commonly seen in patients with tuberculosis--usually referred to as an "apical cap" or "apical pleural thickening"--18 patients with upper lobe tuberculosis were studied with high-resolution computed tomography (HRCT). All had a homogeneous apical opacity at least 1 cm thick on chest radiographs. Fifteen of the 18 had a history of pulmonary tuberculosis of more than 5 years duration, and nine showed evidence of ipsilateral pleurisy. HRCT scans at the apex of the thorax in all nine patients scanned at this level showed that extrapleural fat with interspersed vessels accounted for most of the plain radiographic opacity. Scans obtained at a level slightly above visible aerated lung showed extrapleural fat 3-25 mm thick peripherally and atelectatic lung centrally. At more caudal levels, at which both aerated lung and "thickened pleura" were visible on plain radiographs, HRCT showed extrapleural fat (3-20 mm thick), thickened pleura (1-3 mm thick), and atelectatic lung peripherally and areas of emphysematous bullae, bronchiectasis, and atelectatic lung centrally.

Diagnosis, Differential↗
PubMed1991

Pathogenesis of pulmonary edema during interleukin-2 therapy: correlation of chest radiographic and clinical findings in 54 patients.

The pathogenesis of pulmonary edema that occurs during interleukin-2 therapy has often been attributed to an increase in pulmonary capillary permeability. However, renal insufficiency, fluid overload, and hypotension also develop in many patients. These manifestations of systemic toxicity may contribute to the development of pulmonary edema during therapy. Understanding the cause of pulmonary edema during interleukin-2 therapy could directly affect patients' care. Therefore, we reviewed the chest radiographs and clinical course of 54 patients who received high-dose interleukin-2 therapy and lymphokine-activated killer cells for advanced carcinoma. The type, frequency, and course over time of pulmonary abnormalities were recorded and correlated with clinical measures of renal function, fluid status, and blood pressure. Focal or diffuse parenchymal lung opacities were found on radiographs in 43 (80%) of 54 patients. Findings of interstitial pulmonary edema were most common, occurring in 76% of patients. Weight gain, hypotension, and elevation of the serum creatinine level were not associated statistically with interstitial edema. Diffuse air-space disease developed in 20% of patients. Focal consolidation, which was associated with positive central venous catheter cultures (p less than .03), developed in 28% of patients. Pleural effusion occurred in 48% of patients and was associated with all types of parenchymal disease. These data suggest that the frequent development of pulmonary edema during interleukin-2 therapy is not due to renal insufficiency, fluid overload, or hypotension, but is more likely the result of an interleukin-2-related increase in pulmonary capillary permeability.

Adult↗
PubMed1991

Adenocarcinoma of the gallbladder associated with congenital choledochal cyst and anomalous pancreaticobiliary ductal junction. Case report.

In a 61-year-old woman, villous adenocarcinoma of the gallbladder was associated with a congenital choledochal cyst and anomalous pancreaticobiliary ductal junction. The patient had a history of congenital choledochal cyst treated by cystoduodenostomy 27 years previously. The condition was demonstrated by intraoperative cholangiography and histologically confirmed. Extended cholecystectomy, regional lymph node dissection, excision of the cyst and hepaticojejunostomy were performed successfully.

Adenocarcinoma↗
PubMed1991

High resolution lung computed tomography. Normal anatomic and pathologic findings.

The use of high resolution computed tomography (HRCT) for evaluating the lung parenchyma requires an understanding of normal lung anatomy and the pathologic alterations in anatomy that occur in the presence of disease. Most important is an understanding of the secondary pulmonary lobule; HRCT can show many features of the secondary lobule in both normal and abnormal lungs, and many lung diseases, particularly interstitial diseases, produce characteristic alterations in lobular anatomy. HRCT is capable of diagnosing interstitial abnormalities, air-space consolidation airway diseases, and emphysema.

Air↗
PubMed1991

Imaging strategies in the staging of lung cancer.

Plain radiographs and computed tomography are the imaging techniques of most value in staging patients with lung cancer. Although each can provide significant anatomic information regarding the extent of intrathoracic tumor, it must be realized that these techniques have limited accuracy for diagnosing the presence of chest wall or mediastinal invasion by tumor and the presence of mediastinal node metastases; however, the appropriate use of imaging studies, including magnetic resonance imaging, is valuable in determining whether invasive diagnostic procedures are necessary for staging, which invasive procedure should be performed, and how these procedures are guided and eventual surgery should be planned.

Carcinoma, Bronchogenic↗