PubMed Health⌕ Search

Biomedical subjects

A N Leung

Publications and source records attributed to A N Leung.

At least 19 recordsLinked to original sources
PubMed2003

Invasive aspergillosis in the setting of cardiac transplantation.

Among patients undergoing heart transplantation, Aspergillus is the opportunistic pathogen with the highest attributable mortality. The median time of onset from transplantation for invasive pulmonary aspergillosis (IPA) was 46 days, but the median time to first positive culture result was 104 days among patients with Aspergillus colonization but no invasive disease. Most patients with IPA presented with fever and cough within the first 90 days of transplantation and with single or multiple pulmonary nodules. None of the heart transplant recipients with either IPA or invasive extrapulmonary aspergillosis (IEPA) had associated neutropenia. Human leukocyte antigen A1 locus was found significantly more frequently among patients colonized with Aspergillus than among patients with IPA (P<.006) or IEPA (P<.001). Even in the absence of neutropenia, IPA should be suspected for heart transplant recipients who have fever and respiratory symptoms within the first 3 months of transplantation, have a positive result of culture of respiratory secretions, and have abnormal radiological findings (particularly nodules).

Adult↗
PubMed2001

CT of noninfectious granulomatous lung disease.

Noninfectious granulomatous diseases of the lung consist of a diverse group of disorders that logically can be subdivided into those with and without associated vasculitis. This article reviews the epidemiologic, clinical, pathologic, and radiologic features of sarcoidosis, hypersensitivity pneumonitis, berylliosis, and the five entities traditionally classified as pulmonary angiitis and granulomatosis.

Diagnosis, Differential↗
PubMed2001

Spirometer-triggered high-resolution computed tomography and pulmonary function measurements during an acute exacerbation in patients with cystic fibrosis.

OBJECTIVE: To evaluate a high-resolution computed tomography (HRCT) scoring system, clinical parameters, and pulmonary function measurements in patients with cystic fibrosis (CF) before and after therapy for a pulmonary exacerbation. STUDY DESIGN: Patients (n = 17) were evaluated by spirometer-triggered HRCT imaging, clinical parameters, and pulmonary function tests (PFTs) before and after treatment. HRCT scans were reviewed by 3 radiologists using a modified Bhalla scoring system. RESULTS: Bronchiectasis, bronchial wall thickening, and air trapping were identified in all subjects on initial evaluation. The initial total HRCT score correlated significantly with the Brasfield score (r = -.91, P <.001) and several PFT measures. After treatment, there were improvements in the acute change clinical score (ACCS) (P <.001), most pulmonary function measurements, and total HRCT score (P <.05). Bronchiectasis, bronchial wall thickening, and air trapping did not significantly change. Mucus plugging subcomponent HRCT score, slow vital capacity (SVC), forced expiratory volume in 1 second (FEV(1)), and forced vital capacity (FVC) (percent predicted) and reversible and total HRCT scores were most sensitive to change by effect size analysis. CONCLUSIONS: Improvements occurred with treatment in total and reversible HRCT scores, PFTs, and ACCS. Total and reversible HRCT scores and percent predicted SVC, FEV1, and FVC were the most sensitive to change. The greatest change was seen in the mucus plugging subcomponent HRCT score.

Adolescent↗
PubMed2001

Digital storage phosphor chest radiography: an ROC study of the effect of 2K versus 4K matrix size on observer performance.

PURPOSE: To compare observer performance in the detection of abnormalities on 1,760 x 2,140 matrix (2K) and 3,520 x 4,280 matrix (4K) digital storage phosphor chest radiographs. MATERIALS AND METHODS: One hundred sixty patients who underwent dedicated computed tomography (CT) of the thorax were prospectively recruited into the study. Posteroanterior and lateral computed radiographs of the chest were acquired in each patient and printed in 2K and 4K formats. Six radiologists independently analyzed the hard-copy images and scored the presence of parenchymal (opacities </=2 cm, opacities >2 cm, and subtle interstitial), mediastinal, and pleural abnormalities on a five-point confidence scale. With CT as the reference standard, observer performance tests were carried out by using receiver operating characteristic (ROC) analysis. RESULTS: Analysis of averaged observer performance showed 2K and 4K images were equally effective in detection of all three groups of abnormalities. In the detection of the three subtypes of parenchymal abnormalities, there were no significant differences in averaged performance between the 2K and 4K formats (area below ROC curve [A(z)] values: opacities </=2 cm, 0.62 +/- 0.056 [standard error] and 0.59 +/- 0.045; opacities >2 cm, 0.86 +/-.025 and 0.85 +/- 0.030; subtle interstitial abnormalities, 0.73 +/- 0.041 and 0.72 +/- 0.041). Averaged performance in detection of mediastinal and pleural abnormalities was equivalent (A(z) values: mediastinal, 0.70 +/- 0.046 and 0.73 +/- 0.033; pleural, 0.85 +/- 0.032 and 0.86 +/- 0.033). CONCLUSION: Observer performance in detection of parenchymal, mediastinal, and pleural abnormalities was not significantly different on 2K and 4K storage phosphor chest radiographs.

Female↗
PubMed2000

A model for faculty mentoring in academic radiology.

RATIONALE AND OBJECTIVES: The purpose of this report is to describe the development and implementation of a faculty mentoring program in radiology designed to promote the career development of junior faculty and enhance communication in the department. MATERIALS AND METHODS: The mentoring program was implemented in five stages: organizational readiness, participant recruitment, mentor matching and orientation, implementation, and evaluation. Evaluations were based on Likert scale ratings and qualitative feedback. A retrospective analysis was also conducted of the annual performance reviews of junior faculty in the areas of research, teaching, patient care, and overall performance. RESULTS: An average of 83% (19 of 23) of the junior faculty participated in the pilot phase of the mentoring program. During five rounds of testing, the median rating (1 indicates not important; 10, extremely important) from responding junior faculty was 10 for overall value of individual mentoring meetings; the median rating for the mentors responding was 8.75. Research and academic development were identified as the areas of greatest importance to the faculty. Research and patient care were most improved as assessed by faculty peers during performance reviews. The schedule of semiannual formal mentoring meetings was reported to be optimal. CONCLUSION: The program was implemented to the satisfaction of junior faculty and mentors, and longitudinal performance suggests positive effects. Issues to be contended with include confidentiality and the time needed for mentoring beyond already saturated schedules. Overall, the authors propose that mentoring programs can be an asset to academic radiology departments and a key factor in maintaining their vitality.

Academic Medical Centers↗
PubMed2000

Bronchocentric granulomatosis: computed tomographic findings in five patients.

AIM: The aim of this study was to assess the CT manifestations of bronchocentric granulomatosis. SUBJECTS AND METHODS: The CT results of five patients with bronchocentric granulomatosis were retrospectively analysed. The patients ranged from 20 to 72 years of age and included three men and two women. The diagnosis of bronchocentric granulomatosis was made at lobectomy (n = 2), open lung biopsy (n = 2), and transbronchial biopsy (n = 1). Only one of the five patients had asthma. RESULTS: The main findings consisted of a spiculated mass lesion (n = 3) or lobar consolidation with associated mild volume loss (n = 2). One of the two patients with consolidation had extensive mucoid impaction. The abnormalities involved predominantly an upper lobe in four patients and a lower lobe in one patient. In the four resected specimens, the macroscopic pathological appearance was consolidation (n = 2) and mass lesion (n = 2). Microscopically, the typical histology of airway-centred necrotizing granulomata was present in all cases. Aspergillus hyphae were identified in two cases. Nocardia sp. was cultured from the biopsy specimen in one case. CONCLUSION: The CT manifestations of bronchocentric granulomatosis consist of a focal mass or lobar consolidation with atelectasis. These reflect the presence of granuloma formation with or without associated bronchial obstruction.

Adult↗
PubMed2000

Primary bronchogenic carcinoma after heart or lung transplantation: radiologic and clinical findings.

Chronic immunosuppression in organ transplant recipients predisposes to the development of malignant disease. The authors describe their 29-year institutional experience of bronchogenic carcinoma developing after heart and lung transplantation. Seven cases of bronchogenic carcinoma were diagnosed in 1,119 heart and lung transplant recipients. Computed tomography scans and radiographs at time of diagnosis, as well as prior radiographs available in six patients were retrospectively analyzed by two radiologists in consensus. The seven cases involved six heart and one lung transplant recipients. Six patients were smokers with a mean smoking history of 66 pack-years. Mean time interval from transplantation to cancer detection was 25 months. Radiologic findings consisted of a solitary pulmonary nodule (n = 3), mass with satellite nodules (n = 1), and obstructive pneumonitis (n = 1). In the sixth patient, the cancer was not radiographically visible because of obscuration by adjacent fibrosis. On review, radiographic abnormalities were present a mean of 12 months prior to diagnosis in 66% of patients. In the heart or lung transplant population, bronchogenic carcinoma develops in recipients with extensive smoking histories. It presents radiographically as a nodule, mass, or obstructive pneumonitis, and is usually visible on radiographs before the time of diagnosis.

Adult↗
PubMed2000

Aorta and iliac arteries: single versus multiple detector-row helical CT angiography.

PURPOSE: To compare single- versus four-channel helical computed tomographic (CT) aortography. MATERIALS AND METHODS: Forty-eight patients with aortic aneurysm or dissection underwent four- and one-channel CT angiography. Scan pairs covered the thoracic inlet to the diaphragm (n = 10) and supraceliac abdominal aorta (n = 19) or thoracic inlet (n = 19) to the femoral arterial bifurcations. For four-channel CT, nominal section thickness and pitch were 2.5 mm and 6.0, respectively, and for one-channel CT, 3.0 mm and 2.0 to the infrarenal aorta and 5.0 mm and 2.0 to the femoral arteries. Effective section thickness, scanning duration, scanning coverage, dose of iodinated contrast material, and mean aortoiliac attenuation were compared. Data were summarized as speed (coverage/duration), scanning efficiency (speed/section thickness), and contrast efficiency (mean aortic attenuation/dose of contrast material). RESULTS: At four- versus one-channel CT, CT angiography was 2.6 times faster, scanning efficiency was 4.1 times greater, contrast efficiency was 2.5 times greater, dose of contrast material was reduced (mean, 57%; 97 vs 232 mL) without a significant change in aortic enhancement, and sections were thinner (mean, 40%; 3.2 vs 5.3 mm) despite a 59% shorter scanning duration (22 vs 56 seconds). CONCLUSION: Substantially reduced doses of contrast medium, shorter scanning durations, and narrower effective sections result with four- versus one-channel CT aortography. No advantages of one-channel CT aortography were demonstrated.

Aortic Dissection↗
PubMed1999

Radiology of pneumonia.

Chest radiography is the imaging technique of choice in evaluating patients with suspected pneumonia because of its low radiation dose, low cost, and wide accessibility. In daily practice, radiographs are used to confirm the clinical diagnosis of pneumonia, characterize the extent and severity of disease, search for complications such as empyema, monitor the response to therapy, and examine for possible alternative or additional diagnoses. Although CT scan has no defined role in the routine assessment of patients with either community-acquired or nosocomial pneumonias, its advantages of superior contrast resolution and cross-sectional display can often be helpful in the analysis of complex cases, particularly when radiographic evidence of associated central obstruction, cavitation, lymphadenopathy, or empyema is equivocal. In the immunocompromised patient population, high-resolution CT has been shown to be more sensitive than plain film radiography in the early detection of pulmonary infections.

Adult↗
PubMed1999

Lung transplantation for lymphangioleiomyomatosis: role of imaging in the assessment of complications related to the underlying disease.

PURPOSE: To identify the complications and imaging findings related to lymphangioleiomyomatosis (LAM) after lung transplantation. MATERIALS AND METHODS: The authors retrospectively reviewed the clinical histories and imaging studies of 13 patients from five major medical centers who underwent unilateral (n = 8) or bilateral (n = 5) lung transplantation for LAM between 1991 and 1997. Complications related to LAM, both before and after transplantation, were recorded. RESULTS: The following LAM-related complications were found during and after transplantation: excessive pleural adhesions (n = 4), native lung pneumothorax (n = 3), chylous effusion (n = 1), chylous ascites (n = 3), complications from renal angiomyolipomas (n = 4), and recurrent LAM (n = 1). Diagnosis could be made or suggested with computed tomography (CT) in all cases. Four patients (31%) died; one patient died of complications of LAM. CONCLUSIONS: Patients who have undergone lung transplantation for LAM have increased morbidity and mortality due to complications related to their underlying disease. These LAM-related complications can be diagnosed or suggested with CT.

Adult↗
PubMed1999

Pulmonary infections after bone marrow transplantation: clinical and radiographic findings.

PURPOSE: To assess the clinical and radiographic findings of pulmonary infections diagnosed by using invasive means. MATERIALS AND METHODS: Fifty-nine episodes of pulmonary infection were diagnosed in 52 (7.2%) of a consecutive series of 725 adult bone marrow transplant recipients. Causative organisms, time of diagnoses, radiographic patterns, and mortality rates were reviewed. RESULTS: Cytomegalovirus and Aspergillus species were the two most common pathogens, accounting for 22 and 17 episodes, respectively. During the first 30 days after bone marrow transplantation, fungi caused the majority (nine [82%] of 11 episodes) of pulmonary infections; from days 31 to 100, viruses predominated (21 [62%] of 34 episodes). Recipients of allogeneic transplants had a higher probability of developing Cytomegalovirus pneumonitis than did the recipients of autologous and syngeneic transplants (P < .001). Radiographic findings of Cytomegalovirus pneumonia consisted of parenchymal opacification (90%) and innumerable nodules smaller than 5 mm (29%); in two patients, radiographs were normal. Nodules, masses, or nodules and masses, present in nine (69%) of the 13 patients with Aspergillus infection, were the most common radiographic findings in invasive aspergillosis. Bone marrow transplant recipients with a documented pulmonary infection were found to have a lower event-free survival than recipients without infection (P < .001). CONCLUSION: Opportunistic pathogens account for the majority of pulmonary infections requiring invasive diagnosis and tend to manifest at predictable times in the course of events following recovery from bone marrow transplantation. Cytomegalovirus, the most common pathogen, causes a spectrum of radiographic findings that includes normal findings. Occurrence of a pulmonary infection is associated with an increased mortality rate.

Adolescent↗
PubMed1999

Accuracy of CT in the diagnosis of allergic bronchopulmonary aspergillosis in asthmatic patients.

OBJECTIVE: The purpose of this study was to assess the accuracy of high-resolution CT in the diagnosis of allergic bronchopulmonary aspergillosis in asthmatic patients. MATERIALS AND METHODS: The high-resolution CT scans of 44 asthmatic patients with allergic bronchopulmonary aspergillosis and 38 asthmatic patients without allergic bronchopulmonary aspergillosis were analyzed retrospectively and randomly by two independent observers for these features: bronchial wall thickening, bronchiectasis, centrilobular nodules, mucoid impaction, mosaic perfusion, atelectasis, and consolidation. Each observer made a final diagnosis with a stated degree of confidence. The results are expressed as the average number of observations by the two observers. RESULTS: Findings seen more commonly in patients with allergic bronchopulmonary aspergillosis than in patients with asthma alone included bronchiectasis, centrilobular nodules, and mucoid impaction (p < .01, chi-square test). Bronchiectasis was present in 42 (95%) of 44 patients with allergic bronchopulmonary aspergillosis, centrilobular nodules in 41 (93%), and mucoid impaction in 29.5 (67%) (average of two observers). In the asthmatic control group, bronchiectasis was detected in 11 (29%) of 38 patients, centrilobular nodules in 10.5 (28%), and mucoid impaction in 4%. Bronchiectasis was seen in 184 (70%) of 264 lobes of patients with allergic bronchopulmonary aspergillosis compared with 19.5 (9%) of 228 lobes in asthmatic controls (p < .001, chi-square test). CONCLUSION: In asthmatic patients, bronchiectasis affecting three or more lobes, centrilobular nodules, and mucoid impaction are findings on high-resolution CT that are highly suggestive of allergic bronchopulmonary aspergillosis.

Adult↗