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W Richard Webb

Publications and source records attributed to W Richard Webb.

9 recordsLinked to original sources
PubMed2002

Clinical and radiographic predictors of the etiology of computed tomography-diagnosed intrathoracic lymphadenopathy in HIV-infected patients.

In HIV-infected patients with intrathoracic lymphadenopathy, it is not known whether clinical and radiographic findings are useful in predicting a specific diagnosis. We determined the etiology and predictors of the etiology of computed tomography (CT)-diagnosed intrathoracic lymphadenopathy in HIV-infected patients evaluated from June 1993 through April 1999. Multivariate analyses were performed to determine clinical and radiographic predictors of the three most common diagnoses. Of 318 patients, 110 (35%) had lymphadenopathy on chest CT. Among these 110 patients, tuberculosis/nontuberculous mycobacterial disease ( = 31), bacterial pneumonia ( = 26), and lymphoma ( = 21) were the most common diagnoses. Multivariate analysis identified cough and necrosis of lymph nodes on chest CT as independent predictors of tuberculosis/nontuberculous mycobacterial disease. African-American race, symptoms for 1 to 7 days, dyspnea, and presence of airways disease on chest CT were independent predictors of bacterial pneumonia; symptoms for >7 days, absence of cough, and absence of pulmonary nodules on CT independently predicted lymphoma. Intrathoracic lymphadenopathy is a frequent chest CT finding in HIV-infected patients. Opportunistic infections and lymphoma are the most common causes, and specific clinical and radiographic features can suggest these particular diagnoses.

AIDS-Related Opportunistic Infections↗
PubMed2002

Thoracic complications of illicit drug use: an organ system approach.

Illicit drug use constitutes a major health problem and may be associated with various thoracic complications. These complications vary depending on the specific drug used and the route of administration. Commonly abused drugs that may play a role in causing thoracic disease include cocaine, opiates, and methamphetamine derivatives. Intravenously abused oral medications may contain filler agents that may be responsible for disease. Thoracic complications may be categorized as pulmonary, pleural, mediastinal, cardiovascular, and chest wall complications. Pulmonary complications of drug abuse include pneumonia, cardiogenic edema, acute lung injury, pulmonary hemorrhage, and aspiration pneumonia. Filler agents such as talc may result in panacinar emphysema or high-attenuation upper-lobe conglomerate masses. The primary pleural complication of illicit drug use is pneumothorax. Mediastinal and cardiovascular complications of illicit drug use include pneumomediastinum, cardiomyopathy, myocardial infarction, aortic dissection, and injection-related pseudoaneurysms. Chest wall complications include diskitis and vertebral osteomyelitis, epidural abscess, necrotizing fasciitis, costochondritis, and septic arthritis. Categorization of thoracic complications of illicit drug use may facilitate understanding of these disorders and allow accurate diagnosis.

Aortic Dissection↗
PubMed2002

Tracheal compression by the stomach following gastric pull-up: diagnosis with CT and treatment with expandable metallic stent placement.

Surgical treatment of recurrent achalasia includes esophagectomy with gastric pull-up. A MEDLINE search yielded no articles describing an adverse effect of this surgery on pulmonary function. We report the first case of acute ventilatory failure caused by gastric pull-up. An evaluation by flexible bronchoscopy, spirometry with flow-volume loops, and dynamic CT scanning revealed extrinsic compression of the trachea by the stomach causing obstruction. Endotracheal placement of a self- expanding stent resulted in the rapid extubation of the patient with normalization of the flow-volume loop and dramatic improvement in the FVC, FEV(1), and peak expiratory flow.

Constriction, Pathologic↗
PubMed2002

Air trapping on CT of patients with pulmonary embolism.

OBJECTIVE: We evaluated the relationship of air trapping to mosaic perfusion in patients with pulmonary embolism. SUBJECTS AND METHODS: Forty-one consecutive patients with suspected pulmonary embolism underwent expiratory CT followed by helical CT angiography. After excluding 12 patients who had airway disease or were smokers, we divided the patients into two groups: those with (n = 15) and without (n = 14) pulmonary embolism. For each patient, six expiratory images were evaluated for the presence of air trapping, and the corresponding six images from CT angiography were evaluated for the presence of mosaic perfusion. Clot locations were assessed on CT angiography and were correlated with the presence of air trapping and mosaic perfusion. RESULTS: In patients with pulmonary embolism, mosaic perfusion was identified in 32 areas (seven patients, 46.7%), and air trapping was identified 68 areas (nine patients, 60%). Of the 32 areas of mosaic perfusion, 23 areas (71.9%) showed air trapping on expiratory CT scans. Of the 68 areas with air trapping on expiratory scans, 23 areas (33.8%) showed mosaic perfusion on inspiratory scans, and 44 areas (64.7%) had clots in the arteries leading to them. Clots were more frequently identified in areas of lower attenuation on inspiratory CT scans and air trapping (21/23) than in those of normal attenuation on inspiratory CT scans and air trapping (23/45) (p < 0.005). Only one patient without pulmonary embolism had air trapping (p < 0.005). CONCLUSION: Air trapping is common in pulmonary embolism and may be the cause of mosaic perfusion. Air trapping can be seen distal to vessels not showing pulmonary embolism.

Adolescent↗
PubMed2002

Helical CT with sagittal and coronal reconstructions: accuracy for detection of diaphragmatic injury.

OBJECTIVE: The objectives of our study were to determine the accuracy of single-detector helical CT (including coronal and sagittal reconstructions) for the diagnosis of traumatic diaphragmatic injury, establish measurements for the thickness of the normal diaphragmatic crus, and describe an additional sign of diaphragmatic injury: active arterial extravasation of contrast material at the level of the diaphragm. MATERIALS AND METHODS: The CT scans of 25 patients with surgically proven diaphragmatic injury and 22 patients with surgically confirmed uninjured diaphragms were blindly reviewed by five thoracic radiologists. Sagittal and coronal reconstructions were performed for 20 of the 25 patients with a proven diaphragmatic injury and for all the patients without a diaphragmatic injury. Scans were evaluated for findings suggestive of diaphragmatic injury and for associated injuries. Reviewers scored the usefulness of the reconstructed images for establishing the final diagnosis. Measurements of the right and left crura were performed to establish a threshold measurement that would enable radiologists to discriminate between a normal diaphragm and an injured diaphragm. RESULTS: The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of helical CT were 84%, 77%, 81%, 81%, and 83%, respectively. Scans showing active arterial extravasation of contrast material enabled reviewers to correctly identify diaphragmatic injury in two patients. Reconstructed images confirmed the correct diagnosis in three patients but supported an incorrect diagnosis in two. The mean thickness of the diaphragmatic crura (right and left) was not significantly greater in patients with an injured diaphragm than in those with an uninjured diaphragm. CONCLUSION: Helical CT shows good sensitivity, specificity, and accuracy for the diagnosis of diaphragmatic injury. Coronal and sagittal reconstructions are of limited use in establishing or refuting this diagnosis. Active arterial extravasation of contrast material near the diaphragm should raise suspicion for injury. Crus measurements cannot be used to reliably distinguish between injured and uninjured diaphragms.

Adolescent↗
PubMedDate not supplied

The radiologic spectrum of pulmonary Aspergillus infections.

Aspergillus infections may be categorized by specific radiographic patterns, the patient's immunologic status, and the presence or absence of preexisting structural lung disease. General patterns include invasive aspergillosis (both vascular and airway invasive varieties and acute tracheobronchitis), semiinvasive aspergillosis (including allergic bronchopulmonary aspergillosis and hypersensitivity pneumonitis), mycetoma, allergic aspergillosis, and obstructing bronchial aspergillosis. Knowledge of these various radiographic patterns as well as the immune derangements that accompany these infections may allow proper diagnosis.

Aspergillosis, Allergic Bronchopulmonary↗
PubMedDate not supplied

Benign tracheobronchial stenoses: changes in short-term and long-term pulmonary function testing after expandable metallic stent placement.

PURPOSE: To determine the short- and long-term improvement in airflow dynamics in patients undergoing tracheobronchial stent placement for benign airway stenoses. METHODS: Twenty-two patients underwent 34 tracheal and/or bronchial stent placement procedures for benign airway stenoses and had the results of pulmonary function tests available. Stent placement indications included bronchomalacia after lung transplantation (n = 11), postintubation stenoses (n = 6), relapsing polychondritis (n = 2), and 1 each of tracheomalacia, tracheal compression, and histoplasmosis. Six patients underwent more than one stent placement procedure (range: 2-7 procedures). The mean forced expiratory volume in one second (FEV(1) ), forced expiratory flow rate in the midportion of the forced vital capacity curve (FEF(25-75) ), forced vital capacity, and peak flow (PF) rate obtained before stent placement were compared with those immediately after stent placement and with those measurements most remote from stent placement using the paired two-tailed test. RESULTS: All patients reported improved respiratory function immediately after stent placement. The mean FEV(1), FEF(25-75), and PF rate improved significantly (p < 0.001, p = 0.002, and p = 0.009, respectively) after stent placement. On long-term follow-up averaging 15 months after stent placement, these parameters declined despite patients' subjective sense of improvement. Segregating the population into transplant and nontransplant airway stenosis etiologies, however, FEF(25-75) and PF rate remained significantly improved (p = 0.045, p = 0.027, respectively), over the long term for the latter. FEV increased after subsequent stent placements for patients receiving multiple stents. CONCLUSION: Stent placement for benign tracheobronchial stenoses provides significant immediate improvement in airflow dynamics. Long-term improvement in airflow obstruction may be expected, and additional stent placements may further improve pulmonary function.

Adult↗
PubMedDate not supplied

Dependent lung opacity at thin-section CT: evaluation by spirometrically-gated CT of the influence of lung volume.

OBJECTIVE: To evaluate the influence of lung volume on dependent lung opacity seen at thin-section CT. MATERIALS AND METHODS: In thirteen healthy volunteers, thin-section CT scans were performed at three levels (upper, mid, and lower portion of the lung) and at different lung volumes (10, 30, 50, and 100% vital capacity), using spirometric gated CT. Using a three-point scale, two radiologists determined whether dependent opacity was present, and estimated its degree. Regional lung attenuation at a level 2 cm above the diaphragm was determined using semiautomatic segmentation, and the diameter of a branch of the right lower posterior basal segmental artery was measured at each different vital capacity. RESULTS: At all three anatomic levels, dependent opacity occurred significantly more often at lower vital capacities (10, 30%) than at 100% vital capacity (p = 0.001). Visually estimated dependent opacity was significantly related to regional lung attenuation (p < 0.0001), which in dependent areas progressively increased as vital capacity decreased (p < 0.0001). The presence of dependent opacity and regional lung attenuation of a dependent area correlated significantly with increased diameter of a segmental arterial branch (r = 0.493 and p = 0.0002; r = 0.486 and p = 0.0003, respectively). CONCLUSION: Visual estimation and CT measurements of dependent opacity obtained by semiautomatic segmentation are significantly influenced by lung volume and are related to vascular diameter.

Adult↗