Reference standard and statistical model for intersite and temporal comparisons of CT attenuation in a multicenter quantitative lung study.

PURPOSE: The purpose of this study was to detect and analyze anomalies between a large number of computed tomography (CT) scanners, tracked over time, utilized to collect human pulmonary CT data for a national multicenter study: chronic obstructive pulmonary disease genetic epidemiology study (COPDGene). METHODS: A custom designed CT reference standard "Test Object" has been developed to evaluate the relevant differences in CT attenuation between CT scanners in COPDGene. The materials used in the Test Object to assess CT scanner accuracy and precision included lung equivalent foam (-856 HU), internal air (-1000 HU), water (0 HU), and acrylic (120 HU). Nineteen examples of the Test Object were manufactured. Initially, all Test Objects were scanned on the same CT scanner before the Test Objects were sent to the 20 specific sites and 42 individual CT scanners that were used in the study. The Test Objects were scanned over 17 months while the COPDGene study continued to recruit subjects. A mixed linear effect statistical analysis of the CT scans on the 19 Test Objects was performed. The statistical model reflected influence of reconstruction kernels, tube current, individual Test Objects, CT scanner models, and temporal consistency on CT attenuation. RESULTS: Depending on the Test Object material, there were significant differences between reconstruction kernels, tube current, individual Test Objects, CT scanner models, and temporal consistency. The two Test Object materials of most interest were lung equivalent foam and internal air. With lung equivalent foam, there were significant (p < 0.05) differences between the Siemens B31 (-856.6, ±0.82; mean ± SE) and the GE Standard (-856.6 ± 0.83) reconstruction kernel relative to the Siemens B35 reference standard (-852.5 ± 1.4). Comparing lung equivalent foam attenuation there were also significant differences between CT scanner models (p < 0.01), tube current (p < 0.005), and in temporal consistency (p < 0.005) at individual sites. However, there were no significant effects measurable using different examples of the Test Objects at the various sites compared to the reference scans of the 19 Test Objects. For internal air, significant (p < 0.005) differences were found between all reconstruction kernels (Siemens B31, GE Standard, and Phillips B) compared to the reference standard. There were significant differences between CT models (p < 0.005), and tube current (p < 0.005). There were no significant effects measurable using different examples of the Test Objects at the various sites compared to the reference scans of the 19 Test Objects. Differences, across scanners, between external air and internal air measures in this simple (relative to the in vivo lung) test object varied by as much as 15 HU. CONCLUSIONS: The authors conclude that the Test Object designed for this study was able to detect significant effects regarding individual CT scanners that altered the CT attenuation measurements relevant to the study that are used to determine lung density. Through an understanding of individual scanners, the Test Object analysis can be used to detect anomalies in an individual CT scanner and to statistically model out scanner differences and individual scanner changes over time in a large multicenter trial.

A computer-aided diagnosis system for quantitative scoring of extent of lung fibrosis in scleroderma patients.

OBJECTIVES: To evaluate an improved quantitative lung fibrosis score based on a computer-aided diagnosis (CAD) system that classifies CT pixels with the visual semi-quantitative pulmonary fibrosis score in patients with scleroderma-related interstitial lung disease (SSc-ILD). METHODS: High-resolution, thin-section CT images were obtained and analysed on 129 subjects with SSc-ILD (36 men, 93 women; mean age 48.8±12.1 years) who underwent baseline CT in the prone position at full inspiration. The CAD system segmented each lung of each patient into 3 zones. A quantitative lung fibrosis (QLF) score was established via 5 steps: 1) images were denoised; 2) images were grid sampled; 3) the characteristics of grid intensities were converted into texture features; 4) texture features classified pixels as fibrotic or non-fibrotic, with fibrosis defined by a reticular pattern with architectural distortion; and 5) fibrotic pixels were reported as percentages. Quantitative scores were obtained from 709 zones with complete data and then compared with ordinal scores from two independent expert radiologists. ROC curve analyses were used to measure performance. RESULTS: When the two radiologists agreed that fibrosis affected more than 1% or 25% of a zone or zones, the areas under the ROC curves for QLF score were 0.86 and 0.96, respectively. CONCLUSIONS: Our technique exhibited good accuracy for detecting fibrosis at a threshold of both 1% (i.e. presence or absence of pulmonary fibrosis) and a clinically meaningful threshold of 25% extent of fibrosis in patients with SSc-ILD.

Small airway segmentation in thoracic computed tomography scans: a machine learning approach.

Small airway obstruction is a main cause for chronic obstructive pulmonary disease (COPD). We propose a novel method based on machine learning to extract the airway system from a thoracic computed tomography (CT) scan. The emphasis of the proposed method is on including the smallest airways that are still visible on CT. We used an optimized sampling procedure to extract airway and non-airway voxel samples from a large set of scans for which a semi-automatically constructed reference standard was available. We created a set of features which represent tubular and texture properties that are characteristic for small airway voxels. A random forest classifier was used to determine for each voxel if it belongs to the airway class. Our method was validated on a set of 20 clinical thoracic CT scans from the COPDGene study. Experiments show that our method is effective in extracting the full airway system and in detecting a large number of small airways that were missed by the semi-automatically constructed reference standard.

Quantitative computed tomography detects air trapping due to asthma.

OBJECTIVE: The purpose of this study was to prospectively see if quantitative computed tomography (QCT) could separate asthmatic patients from normal control subjects. The QCT results were also correlated with the pulmonary function tests (PFT) that were done on both the asthmatic patients and control subjects. SUBJECTS AND METHODS: Eighteen adult nonsmoking asthmatics and 22 adult control subjects were entered into the study. Quantitative CT was performed at the level of the transverse aorta and just above the diaphragm at both end inspiration and end expiration in all patients and control subjects: 10-mm and 1.5-mm collimation using a high spatial frequency algorithm was used to obtain the QCT examinations. The percent of pixels below -900 Hounsfeld units, pixel index, in each of the QCT axial images of the lungs was calculated for each asthmatic and control subject in the study. Pulmonary function testing was performed on both the asthmatics and control subjects and included determination of FEV1, FVC, FRC, RV, and TLC. Unpaired Student's t test analysis of the QCT data was done to statistically compare the asthmatics with the control subjects. Linear regression analysis was done to compare the QCT results with PFT data on the asthmatics and control subjects. RESULTS: When scans were performed at end expiration, at a level immediately superior to the diaphragm, the mean pixel index was significantly higher in asthmatic subjects compared with normal individuals on both CT (mean for normal subjects 0.16 vs 4.45 for asthmatics, p < 0.004) and high-resolution CT (HRCT) images (mean for normal subjects 1.04 vs 10.03 in asthmatics, p < 0.0001) indicating more areas of low attenuation in asthmatics. The CT and HRCT images from the lower lung zones that were performed at end expiration provided the best separation between the groups. The pixel index on expiration correlated with the degree of air trapping and airflow limitation in the asthmatic group based on FEV1, FRC, RV, and to a lesser extent, FVC. CONCLUSION: Expiratory QCT is a useful method to assess air trapping in asthmatic patients. The percent of abnormal lung in asthmatics as determined by QCT has a significant correlation with the PFTs that reflect air trapping in asthmatic patients. Quantitative CT may be helpful in assessing degrees of air trapping present in other diseases affecting the airways.

Gaucher's disease. An unusual cause of intrathoracic extramedullary hematopoiesis.

A thoracic paravertebral mass in an asymptomatic woman with type 1 Gaucher's disease proved to be due to extramedullary hematopoiesis. This is, to our knowledge, the first case of intrathoracic extramedullary hematopoiesis reported with Gaucher's disease.

Radiologic findings of adult primary immunodeficiency disorders. Contribution of CT.

STUDY OBJECTIVE: We wished to review the chest radiographic and computed tomographic (CT) findings in adults with primary immunodeficiency disorders, and to evaluate the influence of CT on the treatment of these patients. DESIGN: Retrospective blinded review of radiographs, CT scans, and clinical data. SETTING: National referral center for immunodeficiency disorders. PATIENTS: Forty-six chest radiographs and 22 CT examinations of subjects with primary immunodeficiency disorders were independently scored. Nineteen of the subjects who had CT scans had B-cell deficiency, while 3 had T-cell deficiency. RESULTS: CT-detected bronchiectasis in 15 of 19 subjects with B-cell deficiency, compared with 7 cases detected on chest radiograph. Unsuspected upper lobe bronchiectasis was found on CT in 15 cases. Other CT findings in this group included small nodules in seven subjects, interstitial lines in four, air trapping in seven, ground glass or parenchymal consolidation in nine, evidence of small airways disease in nine, and mucus plugs in four. Two of the three subjects with T-cell disorders showed cavitation and two had unsuspected reactive mediastinal adenopathy. Clinical management appeared to be altered in five subjects with B-cell deficiency by CT findings of severe focal or diffuse bronchiectasis or small airways disease. Additionally, CT localized the bleeding site in three subjects with hemoptysis. CONCLUSIONS: CT is valuable for detection of bronchiectasis in subjects with B-cell immunodeficiency and may alter treatment of these patients.

Hypoxemia explained 36 years later.

A 37-year-old man who had an atrial septal defect (ASD) corrected as an infant was found to be hypoxemic with a 22% shunt. An MRI scan revealed that the patient's inferior vena cava drained into his left rather than his right atrium, a previously undetected complication of his ASD repair 36 years before.

Quantitative CT predicts the severity of physiologic dysfunction in patients with lymphangioleiomyomatosis.

PURPOSE: To assess quantitative high-resolution CT (quantitative CT) as a diagnostic and prognostic tool in pulmonary lymphangioleiomyomatosis. METHODS: Spirometry, lung volumes, diffusing capacity, exercise physiology, and expiratory high-resolution CT (HRCT) examinations were performed on a cohort of ten patients with the diagnosis of lymphangioleiomyomatosis (LAM) referred to a tertiary care center. HRCT examinations were also done on ten normal control subjects. A thresholding technique was used to quantitatively assess the amount of abnormal cystic parenchyma present on each of the two images obtained for each subject with LAM and for each normal control subject. This numeric index of cystic parenchyma, the quantitative CT index, was then examined (1) as a diagnostic measure to distinguish the subjects with LAM from the normal control subjects and (2) as a prognostic measure to assess disease severity in the subjects with LAM. Linear regression of the quantitative CT index against physiologic indexes of pulmonary function and exercise performance was analyzed to determine the relationship between this radiologic assessment of disease severity and functional impairment. RESULTS: The quantitative CT index was significantly greater for the LAM patients, 37.2 +/- 6.9 (SEM), compared with the control group, 0.8 +/- 0.2 (p = 0.0001). Linear regression analysis demonstrated significant linear correlation between the quantitative CT index and measures of airflow (FEV1, r = -0.90, p = 0.0005), air trapping (residual volume, r = 0.70, p = 0.02), diffusing capacity (diffusing capacity for carbon monoxide, r = -0.76, p = 0.01), gas exchange (alveolar to arterial oxygen gradient) at rest, r = 0.69, p = 0.007, and at maximum exercise, r = 0.79, p = 0.007) and exercise performance (maximum workload, r = -0.84, p = 0.002), and oxygen utilization (oxygen utilization at maximum exercise, r = -0.76, p = 0.01). CONCLUSION: Quantitative CT techniques can distinguish subjects with LAM from normal controls. Further, the quantitative CT index correlates well with physiologic measurements of airflow, lung volumes, diffusing capacity, and exercise performance and, thus, may provide a useful measure of disease severity.

Mycoplasma pneumoniae-associated bronchiolitis causing severe restrictive lung disease in adults: report of three cases and literature review.

STUDY OBJECTIVES: To characterize adult Mycoplasma pneumoniae-induced bronchiolitis requiring hospitalization. DESIGN: We encountered an adult patient with severe bronchiolitis in the absence of pneumonia due to M. pneumoniae. To determine the relative frequency of such a condition, we retrospectively reviewed the medical records of adults over a 4-year period with a hospital discharge diagnosis of "bronchiolitis" from a university hospital. SETTING: University Hospital of the University of Colorado Health Sciences Center, Denver, CO. STUDY SUBJECTS: From 1994 to 1998, 10 adult inpatients were identified with a diagnosis of bronchiolitis. There were two with respiratory bronchiolitis, one with panbronchiolitis, one patient with bronchiolitis obliterans organizing pneumonia (BOOP), and six with acute inflammatory bronchiolitis. Including the initial patient, three had a definitive clinical diagnosis of Mycoplasma-associated bronchiolitis. RESULTS: The three adult patients with bronchiolitis due to M. pneumoniae are unusual because they occurred in the absence of radiographic features of a lobar or patchy alveolar pneumonia. Hospital admission was occasioned by the severity of symptoms and gas exchange abnormalities. One patient had bronchiolitis as well as organizing pneumonia (BOOP) that responded favorably to corticosteroid treatment. The other two had high-resolution CT findings diagnostic of an acute inflammatory bronchiolitis. One of the patients with inflammatory bronchiolitis had an unusual pattern of marked ventilation and perfusion defects localized predominantly to the left lung. All three had restrictive ventilatory impairment on physiologic testing. CONCLUSIONS: In adults, Mycoplasma-associated bronchiolitis without pneumonia is rarely reported, but in hospitalized patients, it may be more common than expected and may be associated with severe physiologic disturbances.

Interferon-gamma for delayed pulmonary toxicity syndrome resistant to steroids.

Delayed pulmonary toxicity syndrome, characterized by interstitial pneumonia and pulmonary fibrosis, is common following high-dose bischloroethylnitrosourea (BCNU) (carmustine, [1,3-bis (2-chloroethyl)-1-nitrosourea]) containing chemotherapeutic regimens. Depending upon the treatment protocol, it may develop in over 70% of patients. Early and aggressive corticosteroid treatment leads to improvement in the majority of patients. However, up to 8% of affected patients may fail to respond to corticosteroids and develop progressive respiratory failure leading to death. No alternatives to corticosteroids have thus far been shown useful. We report the symptomatic and physiological improvement of a patient with severe steroid-resistant delayed pulmonary toxicity syndrome, following treatment with interferon-gamma.

Cell proliferation in the post-surgical stomach, dietary salt, and the effect of H pylori eradication.

AIMS: To study the epithelial kinetics of the post-surgical stomach with reference to dietary salt intake and H pylori. METHODS: Endoscopic biopsies of the antrum/anastomosis and corpus were taken for histology and MIB-1 immunostaining. The labelling index (LI%) was determined in the three zones of the gastric glands (zone 1 = surface + gastric pit; zone 2 = isthmus; zone 3 = gland base) in patients with vagotomy and pyloroplasty (n = 12), gastroenterostomy + vagotomy (n = 4), partial gastrectomy (n = 3), and Billroth I operation (n = 3). Dietary salt was determined by urinary sodium/creatinine ratio. Twelve patients were H pylori positive (10 vagotomy and pyloroplasty; 2 partial gastrectomy) and had a repeat biopsy three months after antihelicobacter treatment (10 were H pylori negative after treatment). RESULTS: There was no correlation between salt intake and antrum/anastomosis (r = -0.34; p = 0.2) or corpus (r = -0.16; p = 0.2) labelling indices. Gastric mucosal proliferation is increased in the antrum/ anastomosis compared to the corpus in H pylori positive (p = 0.014) but not H pylori negative subjects (p = 0.084). This may reflect the different types of post-surgical stomach in each group. Gastric mucosal proliferation is reduced in antrum/anastomosis (p = 0.002) and corpus (p = 0.016) following H pylori eradication. CONCLUSIONS: Dietary salt does not influence gastric mucosal proliferation in the post-surgical stomach but H pylori may have a role in gastric stump carcinogenesis.

Cell proliferation in type C gastritis affecting the intact stomach.

AIMS: Type C gastritis caused by bile reflux has a characteristic appearance, similar to that seen in other forms of chemical gastritis, such as those associated with NSAIDs or alcohol. An increase in mucosal cell proliferation increases the likelihood of a neoplastic clone of epithelial cells emerging, particularly where there is chronic epithelial injury associated with bile reflux. It has been shown previously that type C gastritis is associated with increased cell proliferation in the postsurgical stomach. The aim of this study was to determine cell proliferation in type C gastritis caused by bile reflux affecting the intact stomach. METHODS: Specimens from 15 patients with a histological diagnosis of type C gastritis on antral biopsy were obtained from the pathology archives between 1994 and 1997. A control group of nine normal antral biopsies was also selected and all underwent MIB-1 immunostaining. The gastric glands were divided into three zones (zone 1, gastric pit; zone 2, isthmus; and zone 3, gland base) and the numbers of positively staining nuclei for 500 epithelial cell nuclei were counted in each zone to determine the percentage labelling index (LI%). RESULTS: Cell proliferation was significantly higher in all three zones of the gastric glands with type C gastritis compared with controls as follows: zone 1, median LI% in type C gastritis 64.7 (range, 7.8-99.2), controls 4.7 (range, 2.0-11.3); zone 2, median LI% in type C gastritis 94.7 (range, 28.8-98.7), controls 40.2 (range, 23.1-70.3); and zone 3, median LI% in type C gastritis 20.0 (range, 1.3-96.0), controls 2.6 (range, 0.9-8.7). CONCLUSIONS: Bile reflux is thought to act as a promoter of gastric carcinogenesis in the postsurgical stomach. The same may be true in the intact stomach.

Comparison of labelling by bromodeoxyuridine, MIB-1, and proliferating cell nuclear antigen in gastric mucosal biopsy specimens.

AIMS: To compare proliferating cell nuclear antigen (PCNA) and MIB-1 with bromodeoxyuridine (BrdU) pulse labelling, a specific marker of cell proliferation, in endoscopic gastric biopsy specimens. METHODS: Twenty four biopsy specimens were obtained from 12 patients: 10 antral and eight body specimens were suitable. Each specimen was routinely processed and stained with haematoxylin and eosin. A modified Giemsa stain was used to detect the presence of Helicobacter pylori. Sections of the specimens were labelled with BrdU, MIB-1, and PC10. Gastric mucosa specimens were divided into three zones. The numbers of positively staining nuclei for 500 epithelial cell nuclei were counted in each zone and expressed as a percentage. RESULTS: The proportion of PCNA positive cells (range 0-90%) was much greater in all specimens (10 antrum, eight body). BrdU positive cells were virtually all confined to zone 2 (0-17% cells in this zone were positive) (zone 1 = surface and gastric pit, zone 2 = isthmus, zone 3 = gland base), while PCNA positive cells were present in all three zones (1 = 23-90%, 2 = 43-90%, 3 = 0-74%). Spearman's rank coefficient correlation of 0.57 confirmed that the percentage of positively staining cells varied in the same direction for both PCNA and BrdU (p < 0.001). PCNA, however, was overexpressed in all zones of the gastric epithelium compared with BrdU. In 38 biopsy specimens from 19 patients, of which 14 antrum and 11 body were suitable, the proportion of MIB-1 positive cells (0-59%) was greater than BrdU in most. As with BrdU labelling, the MIB-1 positive cells were confined to zone 2 (zone 1 = 1-11%); zone 2 = 21-59%; zone 3 = 0-13%) and the coefficient correlation for MIB-1 and BrdU was 0.63 (p < 0.001). CONCLUSIONS: MIB-1 accurately reflects the S-phase fraction in gastric mucosa, determined by BrdU labelling in conventionally processed gastric biopsy material. Caution is needed in the interpretation of PCNA labelling detected by PC10, which should not be accepted uncritically as a marker of cell proliferation in paraffin wax embedded material.

Small intestine in lymphocytic and collagenous colitis: mucosal morphology, permeability, and secretory immunity to gliadin.

There is a recognised association between the "microscopic" forms of colitis and coeliac disease. There are a variety of subtle small intestinal changes in patients with "latent" gluten sensitivity, namely high intraepithelial lymphocyte (IEL) counts, abnormal mucosal permeability, and high levels of secretory IgA and IgM antibody to gliadin. These changes have hitherto not been investigated in microscopic colitis. Nine patients (four collagenous, five lymphocytic colitis) with normal villous architecture were studied. Small intestinal biopsies were obtained by Crosby capsule; small intestinal fluid was aspirated via the capsule. IEL counts were expressed per 100 epithelial cells, and intestinal IgA and IgM antigliadin antibody levels were measured by ELISA. Small intestinal permeability was measured by the lactulose:mannitol differential sugar permeability test. IEL counts were normal in all cases, median 17, range 7-30. Intestinal antigliadin antibodies were measured in six cases and were significantly elevated in two patients (both IgA and IgM). Intestinal permeability was measured in eight cases and was abnormal in two and borderline in one. These abnormalities did not overlap: four of nine patients had evidence of abnormal small intestinal function. Subclinical small intestinal disease is common in the two main forms of microscopic colitis.

Lymphocytic gastritis and associated small bowel disease: a diffuse lymphocytic gastroenteropathy?

AIM: To investigate the natural history of lymphocytic gastritis (LG) and its relation to Helicobacter pylori infection and to coeliac disease using serology, duodenal biopsy and a small intestinal permeability test. METHOD: Twenty two patients diagnosed as having LG between 1984 and 1994 were investigated by upper gastrointestinal endoscopy at which gastric and duodenal biopsy specimens were taken for histological assessment and immunohistology. Serum was collected for measurement of anti-H pylori, anti-gliadin and anti-endomysial antibodies. A lactulose/mannitol absorption test was performed within one week of endoscopy. Control groups were studied by histology, serology and permeability tests. RESULTS: Three patients had been recently diagnosed as having LG while 15 still had the condition after a mean of 13.9 (range two to 38) months. LG involved the antrum alone in three patients, antrum and body in seven, body alone in six, and gastric remnant in two. Gastroduodenal intraepithelial lymphocytes (IELs) were T cells and predominantly of T suppressor (CD8) type. Duodenal IELs were increased compared to age/sex matched controls with chronic gastritis. Four patients had duodenal villous atrophy. Four patients no longer had LG after a mean of 29.3 (10-70) months but had increased gastroduodenal IELs. H pylori was present in four (22%) of 18 patients with LG but H pylori serology was positive in 11 (61%) of 18. There was no difference in seropositivity when compared with age/sex matched controls with dyspepsia. Eleven of 20 patients with LG tested had abnormal lactulose/mannitol absorption (v none of 22 controls with chronic gastritis). Four patients with LG, all with villous atrophy, were seropositive for IgA endomysial antibody. CONCLUSIONS: The persistence of LG with time, the association with increased duodenal IELs and abnormal small intestinal permeability suggests LG may be a manifestation of a diffuse lymphocytic gastroenteropathy related to sensitivity to gluten or some other agent.

Identification of Helicobacter pylori DNA in the mouths and stomachs of patients with gastritis using PCR.

AIMS: To determine the prevalence of Helicobacter pylori colonisation in the mouths of patients with H pylori gastritis. METHODS: A nested polymerase chain reaction test for the 16S ribosomal RNA gene of H pylori was used on saliva, dental plaque, gastric juice and gastric biopsy specimens from patients attending a dyspepsia clinic. RESULTS: Thirteen patients had histologically confirmed Helicobacter associated gastritis. Twelve of these had positive gastric aspirates by PCR. Five had at least one positive oral specimen. Eight patients with normal gastric biopsy specimens had no PCR positive oral specimens or gastric aspirates. All, however, had PCR positive gastric biopsy specimens. In an attempt to determine the origin of these positive results in normal patients, it was shown that biopsy forceps could contaminate specimens with DNA from previous patients. CONCLUSION: The demonstration of the organism in the mouths of a substantial proportion of dyspeptic patients has major implications for the spread of H pylori and identifies a potential source for reinfection following eradication of the organism from the stomach.

Correlation between epithelial cell proliferation and histological grading in gastric mucosa.

AIM: To determine if there is a correlation between the histological findings in the gastric mucosa and the degree of cell proliferation in gastric antral biopsies. METHODS: Cell proliferation in gastric antral biopsies was determined by in vitro bromodeoxyuridine labelling. Histological sections were assessed using the Sydney System. RESULTS: There was a positive correlation between antral mucosal cell proliferation and the acute inflammatory cell infiltrate (r = 0.29; p = 0.03). There was a stronger correlation with the chronic inflammatory cell infiltrate (r = 0.53; p < 0.0001) and the density of H pylori colonisation (r = 0.54; p < 0.0001). There was no correlation between gastric epithelial proliferation and the degree of atrophy. Stepwise multiple regression indicates that the only independent predictor of epithelial cell proliferation is the density of H pylori colonisation (p < 0.0001). CONCLUSIONS: H pylori increases gastric epithelial cell proliferation through the mucosal inflammatory response and probably by other means. The strong correlation between epithelial proliferation, the chronic inflammatory cell infiltrate, and the density of H pylori colonization may have implications for gastric carcinogenesis.

Male adolescents and physician sex preference.

OBJECTIVE: To investigate the physician sex preference of male adolescents and to explore the factors that may moderate this preference. DESIGN: Anonymous survey. SETTING: An adolescent clinic associated with a large pediatric hospital centrally located within a metropolitan Midwestern city. PARTICIPANTS: The 67 male adolescent patients in the convenience sample ranged in age from 10 to 18 years, and 43.3% were African American, 40.3% were white, and 16.4% were classified as "other." More than half of the subjects reported being raised by a single mother with just enough money to meet their basic needs. INTERVENTION: None. MAIN OUTCOME MEASURES: Among the variables investigated were expressed physician sex preference and participant connectedness to a male and/or female parent or role model. RESULTS: More subjects reported a preference for a female physician (50.8%) than for a male physician (39.4%) when the examination was a physical or medical checkup. The preference for a female physician during a genital examination was also higher (49.2%) than preference for a male physician (39.1%). Analysis of variance revealed significant ethnic group differences in physician sex preference (F2,64 = 12.02, P<.001). African American males had a significantly higher preference for a female physician than did whites or those who identified themselves as other. Neither socioeconomic status nor age demonstrated a statistically significant effect. CONCLUSIONS: This preliminary investigation has provided evidence that ethnicity of the adolescent and the sex of the examining physician may contribute significantly to the success of the health care interaction.

Imaging of asthma and allergic bronchopulmonary mycosis.

The chest radiograph of the patient with asthma is characterized by bronchial wall thickening and hyperinflation. On CT scanning of patients with asthma one may see airway wall thickening, thickened centrilobular structures, and focal or diffuse hyperlucency. Apparent bronchial dilation may be seen, but the diagnosis of bronchiectasis should be made with caution. Quantification of changes in the airway wall and lung parenchyma may be valuable in understanding the mechanisms of asthma and in evaluating the effects of treatment. Central bronchiectasis occurs in most, but not all, cases of ABPA. Patchy airspace opacity may be the sole radiologic manifestation of ABPA in some cases. Other fungi can rarely cause a similar syndrome. The challenge for the radiologist evaluating the images of a patient with asthma is to find complications, such as ABPA, or alternative diagnoses.

High-resolution CT of idiopathic interstitial pneumonias.

Important recent changes have occurred in our understanding of the IIPs. IPF (characterized histologically as UIP) is recognized as a progressive disease with a relatively poor prognosis, and with a characteristic CT appearance. The radiologist must be able to distinguish between UIP and the other IIPs. Complications of IPF include accelerated progression, lung cancer, and secondary infection. NSIP has a better prognosis than IPF, and has ground-glass attenuation as its salient CT feature. COP (formerly known as BOOP) is included as an IIP because its clinical, physiologic, and imaging features overlap with those of the other IIPs. It is characterized on CT by consolidation and ground-glass attenuation. AIP is the idiopathic form of ARDS. LIP and DIP are less common IIPs, both characterized by ground-glass attenuation.