Biomedical subjects

A U Wells

Publications and source records attributed to A U Wells.

At least 73 records · Page 4Linked to original sources

PubMed1999

Visual quantitation and observer variation of signs of small airways disease at inspiratory and expiratory CT.

Areas of decreased pulmonary attenuation representing small airways disease can be identified on computed tomography (CT). The objective was to quantify differences between inspiratory and expiratory CT for the detection of signs of small airways disease by four observers. Observer variation and the superiority of a fine versus a coarse grading system were also evaluated. Inspiratory and expiratory CT scans of 106 patients with conditions characterized by small airways disease and 19 healthy individuals were assessed by four observers. The extent of decreased attenuation was scored on a fine scale to the nearest 5% and also semiquantitatively on a coarser 5-point scale. Decreased attenuation was more extensive on expiratory CT (median. 6.7%; 0-76.7%) than on inspiratory CT (median, 3.8%; 0-81.7%). The fine scoring system had unacceptable interobserver variation (coefficient of variation, 80% for inspiratory CT, 70% for expiratory CT). The semiquantitative system had acceptable interobserver agreement (inspiratory CT k(w) = 0.64; expiratory CT, k(w) = 0.69) and good intra-observer agreement (inspiratory CT, k(w) = 0.80; expiratory CT, k(w) = 0.64). The major CT sign of small airways disease is more confidently quantified on expiratory CT. A fine scoring system is associated with unacceptable observer variation, and a coarse semiquantitative system is more suitable for quantitative studies of small airways disease.

Adolescent↗

PubMed1999

Acute respiratory distress syndrome: CT abnormalities at long-term follow-up.

PURPOSE: To document abnormalities at computed tomography (CT) in adult survivors of acute respiratory distress syndrome (ARDS), to determine the relationships between CT patients during the acute phase and at follow-up, and to assess the effects of mechanical ventilation on the development of CT abnormalities. MATERIALS AND METHODS: Thin-section CT scans were obtained during the acute illness and at follow-up in 27 patients with ARDS. The extent and distribution of individual CT patterns were independently analyzed. RESULTS: At follow-up CT, a reticular pattern was the most prevalent (23 patients [85%]) and extensive CT abnormality, with a striking anterior distribution (more anterior distribution than posterior distribution, P < .001). A reticular pattern at follow-up was inversely correlated with the extent of intense parenchymal opacification on scans obtained during the acute illness (Spearman r = -0.26; P < .001). The extent of a reticular pattern at follow-up CT was independently related to the total duration of mechanical ventilation (P = .02) but was most strongly related to the duration of pressure-controlled inverse-ratio ventilation (P < .001). CONCLUSION: A reticular pattern, with a striking anterior distribution, is a frequent finding of follow-up CT in ARDS survivors and is most strongly related to the duration of pressure-controlled inverse-ratio ventilation.

Acute Disease↗

PubMed1999

Follicular bronchiolitis: thin-section CT and histologic findings.

PURPOSE: To evaluate the thin-section computed tomographic (CT) findings of follicular bronchiolitis and compare them with the histologic findings. MATERIALS AND METHODS: Thin-section CT scans obtained in 12 patients (age range, 24-77 years; mean age, 47 years) with follicular bronchiolitis proved at open lung biopsy were reviewed by two observers. Underlying conditions included rheumatoid arthritis (n = 8), mixed collagen vascular disorders (n = 2), autoimmune disorder (n = 1), and acquired immunodeficiency syndrome (n = 1). All patients had thin-section CT scans (1.0-1.5-mm collimation, 11 patients; 3.0-mm collimation, one patient; high-spatial-frequency reconstruction algorithm) obtained at 10-mm intervals through the chest. RESULTS: The main CT findings included bilateral centrilobular (n = 12) and peribronchial (n = 5) nodules. All 12 patients had nodules smaller than 3 mm in diameter; six patients also had nodules 3-12 mm in diameter. Areas of ground-glass opacity were present in nine (75%) patients. Histologically, all patients had lymphoid hyperplasia along the bronchioles; eight had peribronchiolar lymphocytic infiltration. CONCLUSION: The cardinal CT feature of follicular bronchiolitis consists of small centrilobular nodules variably associated with peribronchial nodules and areas of ground-glass opacity.

Acquired Immunodeficiency Syndrome↗

PubMed1999

Mechanism of mosaic attenuation of the lungs on computed tomography in induced bronchospasm.

The purpose of this study was to investigate whether hypoxic pulmonary vasoconstriction is the major determinant of the computed tomography (CT) pattern of mosaic attenuation in asthmatic patients with induced bronchoconstriction. Thin-section CT was performed at suspended full inspiration immediately and 30 min after methacholine bronchoprovocation in 22 asthmatic subjects, who were randomly assigned to breathe room air (group A, n = 8), oxygen via nasal prongs at 5 l/min (group B, n = 8), and oxygen via face mask at 12 l/min (group C, n = 6). CT changes were quantified in terms of global lung density and density in hypodense and hyperdense areas. Lung parenchymal density increases were greatest in group C and greater in group B than in group A, globally (P = 0.03) and in hypodense regions (P = 0.01). On bivariate analysis, the only change in cross-sectional area was related to change in global density. In hypodense regions, density change was related both to reduction in cross-sectional area (P < 0.0005) and to oxygen administration (P = 0.01). After correction for changes in global lung density, only oxygen was independently related to density increase in hypodense areas (P = 0.02). In induced bronchoconstriction, the CT appearance of mosaic attenuation can be largely ascribed to hypoxic vasoconstriction rather than to changes in lung inflation.

Adult↗

PubMed1999

Pericardial thickening or effusion in patients with pulmonary artery hypertension: a CT study.

OBJECTIVE: The aim of the study was to determine the prevalence of pericardial thickening or effusion revealed by CT in patients with pulmonary artery hypertension. MATERIALS AND METHODS: Forty-five patients underwent pulmonary artery catheterization and CT of the thorax. On CT, we measured the maximum pericardial thickness, total pericardial score (the sum of four measures of pericardial thickness), and thickness of the anterior pericardial recess. Patients were grouped according to mean pulmonary artery pressure: group 1, less than 21 mm Hg (n = 15); group 2, 21-35 mm Hg (n = 15); and group 3, greater than 35 mm Hg (n = 15). RESULTS: The prevalence of an increased pericardial score and increased maximum pericardial thickening was higher in group 3 than in group 1 or group 2 (p = .02 and < .001, respectively). Anterior pericardial recess thickening was markedly increased in group 3 (p < .0001). For all patients, significant correlations (Spearman's rank correlation coefficient = .44-.56, p < .005-.0001) were found between mean pulmonary artery pressure and all pericardial measures. CONCLUSION: On CT, pericardial thickening or effusion is a frequent finding in patients with severe pulmonary hypertension.

Adult↗

PubMed1998

Computed tomographic imaging of bronchiolar disorders.

The bronchiolitides can be categorized broadly as constrictive or proliferative, each with characteristic CT features. The cardinal CT signs of constrictive bronchiolitis are mosaic perfusion, enhanced on expiratory CT scan and variably associated with bronchiectasis and, less frequently, centrilobular branching structures. These features are common to postinfective bronchiolitis, bronchiolitis associated with collagen vascular disease, obliterative bronchiolitis following lung transplantation, and bronchiolitis following inhalation of toxic fumes and consumption of Sauropus androgynus. Proliferative bronchiolitis manifests on CT scan as patchy bilateral consolidation, variably associated with nodular abnormalities. The CT appearances of other rare bronchiolitides are discussed here including diffuse panbronchiolitis, follicular bronchiolitis, and respiratory bronchiolitis-associated interstitial lung disease.

Bronchiolitis Obliterans↗

PubMed1998

Bronchiectasis following colectomy for Crohn's disease.

Bronchiectasis developing following colectomy for ulcerative colitis has been reported in a few cases. This may be the first report of bronchiectasis developing after colectomy for Crohn's disease. The close temporal relationship to colectomy, lack of bacterial pathogens in the sputum, and an impressive response to oral steroids suggest a difference in pathogenesis from idiopathic bronchiectasis.

Adult↗

PubMed1998

Pulmonary sarcoidosis: morphologic associations of airflow obstruction at thin-section CT.

PURPOSE: To identify relationships between the obstructive defects of pulmonary sarcoidosis and the computed tomographic (CT) patterns of disease. MATERIAL AND METHODS: CT scans obtained in 45 patients were scored semiquantitatively for extent of five CT patterns, and the functional importance of each pattern was evaluated. RESULTS: The most prevalent CT patterns were decreased attenuation (n = 40), a reticular pattern (n = 37), and a nodular pattern (n = 36). At univariate and multivariate analyses, a reticular pattern was the main determinant of functional impairment, particularly airflow obstruction. The extent of a reticular pattern was independently associated with airflow obstruction, as shown by the inverse relationships with the forced expiratory volume in 1 second (FEV1) (P < .001), FEV1-forced vital capacity ratio (P < .01), maximum expiratory flow at 25% above residual volume (P < .001), and maximum expiratory flow at 50% above residual volume (P < .001) and the positive relationship with the residual volume-total lung capacity ratio (P < .001). CONCLUSION: In sarcoidosis, CT features compatible with small airways disease are common but contribute little to airflow obstruction, particularly in more advanced disease, which is characterized by an extensive reticular pattern. A reticular pattern at CT is the major morphologic association of airflow obstruction.

Adult↗

PubMed1998

Bronchoalveolar lavage cellularity: lone cryptogenic fibrosing alveolitis compared with the fibrosing alveolitis of systemic sclerosis.

Lone cryptogenic fibrosing alveolitis (CFA) is histologically identical to fibrosing alveolitis associated with systemic sclerosis (FASSc), but it has a much worse prognosis after matching for disease severity at presentation. The aims of this study were to gain insights into possible pathogenetic mechanisms contributing to this prognostic difference, by comparing bronchoalveolar lavage (BAL) cellularity in the two diseases, and to evaluate the relationships between BAL findings and the regional and global extent of disease, quantified by thin-section computed tomography (CT) and lung function indices. Patients with CFA were distinguished by more extensive fibrosing alveolitis on CT (p < 0.02) and by higher counts of neutrophils (total per ml, p < 0.02; percentage p < 0.03) and eosinophils (total per ml, p < 0.002; percentages, p < 0.02) in BAL fluid. After adjustment for functional and morphologic measures of disease extent, eosinophil percentages and total counts were increased in CFA (p < 0.05 in all 12 multivariate models), but they were not independently related to regional or global disease severity. Neutrophil percentages and total counts were virtually identical in CFA and FASSc in disease of comparable severity, and they increased with increasingly extensive lobar disease and global disease, as judged by CT, p < 0.0005 in all analyses. Neutrophil levels were more closely linked to the extent of disease on CT than to the severity of functional impairment, on univariate and multivariate analysis. The higher BAL eosinophil levels seen in CFA, compared with those seen in FASSc, after adjustment for disease extent, indicate that an eosinophilic influx may be linked to the pathogenesis of fibrosing alveolitis. By contrast, BAL neutrophil levels increase with increasingly extensive disease on CT, but they do not differ independently between CFA and FASSc, suggesting that neutrophil degradation products are unlikely to account for the excess mortality in CFA, compared with that in FASSc.

Bronchoalveolar Lavage Fluid↗

PubMed1997

Fibrosing alveolitis in systemic sclerosis: indices of lung function in relation to extent of disease on computed tomography.

OBJECTIVE: Thin-section computed tomography (CT) provides a sensitive and reproducible method of quantifying the morphologic extent of disease in the clinical management of fibrosing alveolitis associated with systemic sclerosis (FASSc). The aim of this study was to determine which indices of lung function best reflect the extent of disease on CT in FASSc, and to determine the independent influences of smoking history, extent of fibrosing alveolitis, demographic features, and concurrent treatment upon functional impairment in FASSc. METHODS: Sixty-four patients with FASSc were studied using CT and static and exercise lung function testing. Statistical relationships were determined by multiple regression analyses. RESULTS: Five patients with overt pulmonary hypertension were characterized by severe impairment in 3 indices of lung function: diffusing capacity for carbon monoxide (DLCO), DLCO adjusted for alveolar volume (KCO), and arterial partial pressure of oxygen. On multiple regression analysis, the major determinant of functional impairment was the extent of fibrosing alveolitis on CT. A history of smoking was independently associated with preservation of total lung capacity and depression of KCO, but did not otherwise influence functional-morphologic correlations. The percent predicted DLCO correlated better with extent of disease on CT (r = -0.70) than did oxygen desaturation on exercise (r = 0.55), the physiologic component of the clinical-radiographic-physiologic score (CRP index) (r = 0.52), or other indices of lung function. Lung volume measures correlated poorly with disease extent on CT. CONCLUSION: The percent predicted DLCO best reflects the extent of fibrosing alveolitis in FASSc, and therefore should be measured in routine evaluations. Exercise testing may also have a useful role in staging the severity of pulmonary fibrosis, but the CRP index offers no additional advantage over the DLCO and exercise testing.

Carbon Monoxide↗

PubMed1997

Comparison of Doppler echocardiography and right heart catheterization to assess pulmonary hypertension in systemic sclerosis.

Pulmonary hypertension (PHT) is an important complication of systemic sclerosis (SSc). Echocardiography can be used to detect PHT and, with Doppler echocardiography, the pulmonary arterial systolic pressure (PASP) can often be estimated. We have undertaken a study to compare echocardiographic assessment with right heart catheterization (RHC) in 33 SSc patients in whom clinical assessment [including ECG, chest X-ray, lung function tests and high-resolution computed tomography (HRCT) had raised strong suspicion of PHT. The mean (S.D.) interval between echocardiography and RHC was 1.8 (2.3) months. Twenty-one patients (64%) had PHT (PASP > or = 30 mmHg) on RHC, and echocardiography correctly identified 19 of these (sensitivity 90%). Of the 12 patients without PHT on RHC, nine were correctly identified by echocardiography (specificity 75%). The five incorrectly classified patients all had PASP in the borderline normal/abnormal range. The presence of tricuspid regurgitation allowed Doppler measurement of PASP in 20 patients (61%) and this correlated significantly with RHC values (r = 0.83, P < 0.001). We conclude that echocardiography is a reliable method for detecting PHT and it may be particularly useful for the early detection and monitoring of this potentially fatal complication in SSc.

Adult↗

PubMed1997

Effects of airway infection by Pseudomonas aeruginosa: a computed tomographic study.

BACKGROUND: Pseudomonas aeruginosa commonly infects the airways of patients with bronchiectasis. A study was undertaken to examine the relationship between infection of the airways with this pathogen, the morphological pattern of bronchiectasis on thin section computed tomographic (CT) scanning, symptom duration, smoking habits of the patients, and the presence of airflow obstruction. METHODS: Thin section CT scans of 22 adult patients with bronchiectasis and concurrent sputum infected by P aeruginosa (Pa +ve) and those of 45 randomly selected patients not infected by P aeruginosa (Pa -ve) were analysed independently by two thoracic radiologists. Patients with cystic fibrosis were excluded. Each scan was scored at a lobar level for extent of bronchiectasis, severity of bronchial wall thickening and dilatation, predominant pattern of bronchiectasis, presence of mucus plugging, and degree of decreased attenuation of the lung parenchyma. RESULTS: The Pa +ve group had more extensive bronchiectasis and a greater degree of bronchial wall thickening and dilatation on the CT scan than the Pa -ve group; more extensive decreased attenuation was seen in the Pa +ve group. These findings were robust on multivariate analysis; decreased attenuation was also independently related to the duration of sputum production. CONCLUSION: Patients with bronchiectasis infected by P aeruginosa have more extensive and severe bronchiectasis on thin section CT scanning than those without P aeruginosa infection. The bronchi and small airways are both involved, reflecting the end result of complex interactions between host airways and the numerous virulence factors produced by P aeruginosa.

Adult↗

PubMed1997

Cryptogenic fibrosing alveolitis and the fibrosing alveolitis of systemic sclerosis: morphological differences on computed tomographic scans.

BACKGROUND: The purpose of this study was to identify morphological differences on the computed tomographic (CT) scan between cryptogenic fibrosing alveolitis (CFA) and the fibrosing alveolitis associated with systemic sclerosis (FASSc), and to examine their biological relevance. METHODS: One hundred and seven patients with CFA (n = 55) or FASSc (n = 52) who had undergone thin section CT scanning were included. Multivariate analysis was used to identify morphological differences on the CT scans between lone CFA and FASSc, and to determine whether the pattern and distribution of disease on the CT scans were functionally significant (as judged by the lung transfer factor (TLCO), forced vital capacity (FVC), and arterial oxygen tension (PaO2)) or predictive of survival (independent of the type and extent of fibrosing alveolitis, age, sex, and smoking history). RESULTS: Increasingly extensive disease on CT scans was associated with a coarser reticular pattern (increase in reticular score per percentage increase in disease extent = 0.06, 95% confidence interval (CI) 0.03 to 0.09, p < 0.0005) and increasing upper zone involvement (increase in ratio of upper zone to total disease per percentage increase in disease extent = 0.002, 95% CI 0.000 to 0.003, p < 0.04). Patients with CFA were characterised by a higher upper zone ratio (difference = 0.08, 95% CI 0.02 to 0.13, p < 0.004) and a weak trend towards a coarser reticular pattern (p = 0.09), independent of disease extent. Smokers with CFA had more upper zone involvement (difference = 0.11, 95% CI 0.05 to 0.16, p < 0.0005) and a coarser reticular pattern (difference in reticular score = 1.92, 95% CI 0.27 to 3.55, p < 0.02) than smokers with FASSc. The extent of disease on the CT scan was predictive of lung function impairment and survival but the pattern and distribution of disease were not. CONCLUSIONS: Patients with CFA have relatively more upper zone involvement than those with FASSc independent of the extent of disease on the CT scan. This finding may result from smoking related damage but is not functionally significant.

Diagnosis, Differential↗

PubMed1997

Obliterative bronchiolitis: individual CT signs of small airways disease and functional correlation.

PURPOSE: Individual features of small airways disease depicted at computed tomography (CT) were correlated with functional indexes in patients with obliterative bronchiolitis. MATERIALS AND METHODS: Fifteen patients (all women) who fulfilled the strict criteria for diagnosis of obliterative bronchiolitis underwent thin-section CT at full inspiration and at end expiration. The CT scans were scored by two observers for extent of decreased attenuation of the lung parenchyma; end-expiration CT signs of air trapping; and bronchial dilation, wall thickening, and mucous plugging. The functional importance of each CT sign was evaluated. RESULTS: Areas of decreased attenuation were present in all patients (median score at end expiration, 61%; range, 21%-83%). Bronchial wall thickening was identified in 13 of the 15 patients. Correlations of the extent of decreased attenuation and measures of air-flow obstruction were strongest between decreased attenuation at end expiration and air flow at low lung volumes (r(s) = -.70, P < .005). This relationship remained intact after correction for the severity of bronchial wall thickening. CONCLUSION: In patients with obliterative bronchiolitis, the extent of decreased attenuation at CT was most strongly related to depression of pulmonary function tests of the small airways. Decreased attenuation is the cardinal sign for further quantitative studies of obliterative bronchiolitis.

Adult↗

PubMed1997

Lone cryptogenic fibrosing alveolitis: a functional-morphologic correlation based on extent of disease on thin-section computed tomography.

In most clinical series of patients with cryptogenic fibrosing alveolitis (CFA), disease severity is staged using lung function indices. However, many physiologic indices are measured in routine clinical practice; the choice of variable to evaluate functional severity is contentious. Computed tomography (CT) provides a reproducible means of quantifying the morphologic extent of disease. The aim of this study was to evaluate the functional consequences of smoking-related lung damage in CFA and to identify functional measures best reflecting the extent of fibrosing alveolitis on CT. Sixty-eight patients with CFA were studied. Fourteen patients with emphysema on CT were characterized by relative preservation of FVC and TLC (p < 0.005) and relative depression of DLCO (p < 0.05) and KCO (p < 0.00005). On multivariate analysis, the extent of fibrosing alveolitis and the presence of emphysema were independent determinants of functional impairment; there was no independent relationship between smoking history and functional abnormalities. In patients without emphysema on CT, percent predicted DLCO (r = -0.68), oxygen desaturation on exercise (r = 0.64), and the physiologic component of the clinical-radiographic-physiologic (CRP) score (r = 0.62) correlated much better with the extent of disease on CT than spirometric and plethysmographic volumes. A composite functional index was generated against the extent of disease on CT, using multivariate analysis; comparison with the CRP score suggested that the relationship between morphologic disease extent and the CRP score would be improved by the inclusion of DLCO and by the use of negative weighting for depression of FEV1. These findings indicate that in CFA, the presence of concurrent emphysema on CT has a more profound influence upon functional measures than the smoking history, and underline the importance of both the measurements of DLCO and exercise testing in the assessment of the severity of CFA.

Case-Control Studies↗

PubMed1997

Functional impairment in lone cryptogenic fibrosing alveolitis and fibrosing alveolitis associated with systemic sclerosis: a comparison.

Lone cryptogenic fibrosing alveolitis (CFA) is histologically identical to fibrosing alveolitis associated with systemic sclerosis (FASSc), but it has a much worse prognosis after matching for disease severity at presentation. Thin-section CT scanning (CT) provides a reproducible method of quantifying the morphologic extent of fibrosing alveolitis. The aim of this study was to gain insights into contrasting pathophysiologic mechanisms in the two diseases by comparing patterns of functional impairment after matching for extent of disease on CT, demographic factors, smoking history, and concurrent treatment. Patients with emphysema on CT (n = 16) and patients with FASSc with overt pulmonary hypertension (n = 5) were excluded; 111 patients were studied (CFA, n = 54; FASSc, n = 57). Patients with CFA were distinguished by more severe functional impairment and more extensive disease on CT (40.1 versus 22.1%, p < 0.00005). On multivariate analysis, patients with CFA had greater reduction in arterial P(O2) (p < 0.0005), wider AaP(O2) (p < 0.0005), greater oxygen desaturation on maximal exercise (p < 0.03), and higher dyspnea scores (p < 0.02) than did patients with FASSc after controlling for extent of disease on CT and other covariates. Measures of lung volume and gas transfer did not differ independently between CFA and FASSc. These findings persisted in subanalyses of patients with limited disease, extensive disease, histologic confirmation of fibrosing alveolitis, and with the reinclusion of patients with emphysema and pulmonary hypertension. The patterns of functional impairment were indicative of more severe ventilation-perfusion mismatch or anatomic shunting in CFA after adjustment for disease extent; we speculate that perfusion of poorly ventilated lung parenchyma in CFA occurs through new vessels formed in areas of intense inflammation. This mechanism may contribute to the greater mortality of patients with CFA than of patients with FASSc because of the deleterious effects of hypoxia on concurrent cardiac disease.

Female↗

PubMed1997

Functional impairment in fibrosing alveolitis: relationship to reversible disease on thin section computed tomography.

Thin-section computed tomography (CT) provides a reproducible method of quantifying global disease extent and can also discriminate between fibrotic disease, with predominance of reticular abnormalities, and reversible inflammatory cell infiltration, shown as ground-glass attenuation. The aim of this study was to determine whether functional impairment varied according to the presence of ground-glass attenuation on CT, independently of extent of disease on CT, demographic factors, smoking history, therapeutic status, and the type of fibrosing alveolitis (lone cryptogenic fibrosing alveolitis (CFA) versus fibrosing alveolitis associated with systemic sclerosis (FASSc)). Patients with concurrent emphysema on CT (n = 16) and FASSc patients with end-stage pulmonary hypertension (n = 5) were excluded. One hundred and eleven patients were studied (CFA, n = 54; FASSc, n = 57). The severity of functional impairment did not vary independently with the presence of predominant ground-glass attenuation, mixed appearance and predominant reticulation on CT. In 34 treated patients undergoing serial CT scanning, the severity of functional impairment did not differ independently between patients with and without regression of ground-glass attenuation at follow-up. We conclude that the severity of functional impairment does not discriminate between inflammatory and fibrotic disease in fibrosing alveolitis, as judged by initial and serial computed tomographic scanning, after adjustment for the morphological extent of disease on computed tomography.

Female↗

PubMed1996

Changes in cross-sectional area of the lungs on end expiratory computed tomography in normal individuals.

With the increasing use of expiratory computed tomography (CT) for the detection of air-trapping, and specifically the diagnosis of small airways disease, information about the range of excursion of the chest wall in normal individuals is needed. CT was performed, in full inspiration and end expiration, in 78 individuals (age range 17-70 years) with no demonstrable lung disease. The area of the lungs was measured at the level of the carina, in inspiration and end expiration, and the percentage change in area was calculated. In normal subjects there is, on average, a 55% (SD 8.7%) change in cross-sectional area of the lungs at the level of the carina. Awareness of the normal change in area is of value in assessing the severity of air-trapping in patients undergoing CT for suspected obstructive lung disease.

Adolescent↗