The correlation of emphysema or airway obstruction with the risk of lung cancer: a matched case-controlled study.

A matched case-controlled study was conducted to determine if airway obstruction or emphysema were associated with an increased risk of lung cancer. Lung cancer cases (n=24) were identified through a low-dose spiral computed tomography (CT) screening trial from 1,520 participants. Four controls without lung cancer were selected for each case from the participants and matched by sex, age and smoking history. Emphysema was assessed by quantitative CT analysis. Conditional logistic regression was employed to assess results of spirometry and CT quantitative analysis as potential risk factors for lung cancer. The likelihood of lung cancer was found to be significantly increased for those with forced expiratory volume in one second (FEV1) < or = 40% of predicted. The results suggested that a lower percentage of predicted FEV1 was indicative of lung cancer. No compelling evidence was found to suggest that the percentage of emphysema was associated with lung cancer. These results suggest an increased risk of lung cancer associated with airway obstruction. However, percentage of emphysema as determined by computed tomography was not associated with an increased risk of lung cancer.

JavaScript and interactive web pages in radiology.

Web publishing is becoming a more common method of disseminating information. JavaScript is an object-orientated language embedded into modern browsers and has a wide variety of uses. The use of JavaScript in radiology is illustrated by calculating the indices of sensitivity, specificity, and predictive values from a table of true positives, true negatives, false positives, and false negatives. In addition, a single line of JavaScript code can be used to annotate images, which has a wide variety of uses.

Wisconsin cystic fibrosis chest radiograph scoring system: validation and standardization for application to longitudinal studies.

This study was designed to achieve a final modeling, validation, and standardization plan for the Wisconsin cystic fibrosis (CF) chest radiographic scoring system. Sixty chest radiographs were selected to reflect a range of severity of lung pathology in children with CF. Seven experienced volunteer raters (three radiologists and four pediatric pulmonologists) from five institutions were recruited to evaluate and score the films. Analysis of scores revealed that the subcomponents of the Wisconsin system showed considerable variation from rater to rater, but reliability assessment indicated satisfactory Cronbach's alpha coefficients (0.83-0.90) among the seven raters. It was found that an additive method of total score computation is significantly more reliable (P < 0.05) than either the original multiplicative model or the traditional Brasfield scoring system. Comparison of radiologists and pulmonologists revealed a marked, systematic difference in scoring with the former group being more conservative in interpretation of abnormalities than the pulmonologists, and some of the raters showing very limited sensitivity. Quantitative chest radiology applied to children with cystic fibrosis studied long-term in longitudinal research projects requires the careful use of sensitive scoring methods and careful selection and training of multiple raters. This is particularly important since pulmonologists and radiologists can differ systematically in interpreting/scoring abnormalities.

Spontaneous reduction in size of bullae (autobullectomy).

The authors describe three patients with apical bullous disease that showed partial to near complete spontaneous regression over time. This phenomenon, termed autobullectomy, is a heretofore little known or recognized manifestation of a common pulmonary disease.

Ventilator-associated pneumonia in patients with adult respiratory distress syndrome: CT evaluation.

PURPOSE: To determine the diagnostic accuracy of computed tomography (CT) for pneumonia in patients with adult respiratory distress syndrome (ARDS). MATERIALS AND METHODS: CT scans were obtained within 1 week of bronchoscopic sampling in 31 patients receiving mechanical ventilation for ARDS for more than 48 hours. Of 11 patients with pneumonia, five developed symptoms less than 11 days after the onset of ARDS (early ARDS). CT scans were rated for pneumonia independently by four radiologists who were unaware of the clinical diagnosis. Diagnostic accuracy was defined by means of the area under the receiver operating characteristic curve, or A2. RESULTS: Diagnostic accuracy for pneumonia was fair (A2 = 0.69 +/- 0.04 [standard error]) owing to 70% true-negative ratings (vs 59% true-positive ratings). The generalizability coefficient was good (0.79). No single CT finding was significantly different for the presence of pneumonia. Nondependent opacities predominated in 10 (91%) of 11 patients with pneumonia and 12 (60%) of 20 without pneumonia. Nondependent opacities predominated in nine (56%) of 16 patients with early ARDS and 13 (87%) of 15 with late ARDS. CONCLUSION: CT has fair diagnostic accuracy for ventilator-associated pneumonia in patients with ARDS owing primarily to identification of patients without pneumonia. No single CT sign was significantly different for pneumonia, but dependent atelectasis was more common in patients with early ARDS without pneumonia.

Pathophysiology of obstructive airways disease.

Chronic obstructive pulmonary disease is a group of disorders that have in common abnormal airway structure that results in obstruction to airflow. In emphysema, obstruction is thought to be due to the loss of normal elastic tension in the lung parenchyma. Cigarette smoke is the most important cause of emphysema. Injurious agents, either in the gas or particulate phase, incite a proteolytic reaction in the lung. The type of emphysema and its topographic distribution in the lung stem from normal physiologic processes that concentrate the cigarette puff both within the lung and within the secondary pulmonary lobule.

Distribution of disease in cystic fibrosis: correlation with pulmonary function.

STUDY OBJECTIVE: We hypothesized that the radiographic distribution of disease is important in determining pulmonary function, with the lower lung zones of more importance than the upper lung zones. To test this hypothesis, we retrospectively studied patients with cystic fibrosis, a disease with a known proclivity for the upper lung zones. SUBJECTS AND METHODS: Two hundred seventy-six chest radiographs obtained at 2- to 3-year intervals from 51 patients were scored by two radiologists using a 100-point visual severity scale. The distribution of disease was assessed by dividing the lungs into four equal horizontal zones and scoring each zone for the severity of disease. There were 146 concurrent chest radiographs and pulmonary function tests from which multiple linear regression was used to correlate these zonal scores with FEV1/FVC percent predicted. RESULTS: There was excellent interobserver agreement, intraclass correlation coefficients >0.7. The distribution of disease became predominant in the upper lung zones as the patients aged. Although the median score in the upper lung zones was nearly twice that of the lower lung zones, the lower lung zones were nearly three times (partial F ratio; 6.9 lower zone score vs 2.4 upper lung zone score) as important in determining pulmonary function. CONCLUSION: The regional distribution of disease is important in determining pulmonary function. Sparing of the lower lung zones is important in preserving pulmonary function.

Pulmonary histoplasmosis.

Histoplasmosis is a common infection in the central United States and is acquired through inhalation of airborne spores. The majority of infected persons have an asymptomatic, self-limiting illness. Clinical pneumonia occurs in those with exposure to a large number of infecting spores. Resolution of the pneumonia often leaves calcified pulmonary nodules, calcified mediastinal lymph nodes, or splenic calcifications. Chronic disease, which mimics tuberculosis, may develop in those with underlying emphysema. In patients with deficient cell-mediated immunity, Histoplasma capsulatum may disseminate throughout the body; this often is fatal. Delayed manifestations arise months or years after the primary infection. Broncholithiasis occurs when peribronchial calcific nodes produce bronchial obstruction. Mediastinal granuloma is the continued proliferation of fibrous tissue in draining mediastinal lymph nodes. These granulomas may obstruct adjacent veins, arteries, or airways and lead to various clinical symptoms.

Missed lung cancer at CT: imaging findings in nine patients.

PURPOSE: To assess the imaging findings and course of lung cancers missed on computed tomographic (CT) scans. MATERIALS AND METHODS: A retrospective review of CT scans was performed on nine patients who underwent CT examination for various clinical indications and in whom a lung cancer had been missed. Subspecialty chest radiologists determined whether retrospectively identified lesions were missed due to observer error or technical failure. RESULTS: Five missed tumors were peripheral and four were central in location. All peripheral tumors were less than 3 mm in diameter. The interval from initial examination to detection of peripheral tumors ranged from 8 to 95 months. This interval for central tumors was shorter (3-14 months). Estimated doubling times ranged from 24 to 285 days. CONCLUSION: Small lung cancers that are near the threshold for detectability may be missed at CT. Such failure of detection is attributable primarily to the poor conspicuity of lesions. Retrospective identification at CT raises medicolegal issues.

Atypical manifestations of pulmonary atelectasis.

Recognizing atelectasis has always been a challenge. Atypical patterns further our knowledge of this subject. The lung has two mechanisms to help keep the lobes inflated: collateral ventilation and trapped nitrogen both tend to inflate the lungs when the airways are obstructed. Peripheral upper-lobe atelectasis resembles apical pleural fluid. Instead of collapsing superomedially, the upper lobe collapses posterolaterally, marginated by either the middle lobe or the superior segment of the lower lobe. This pattern may also be produced by segmental atelectasis of the apical-posterior segments of the upper lobe. Combined right-upper- and middle-lobe atelectasis usually stems from malignancy and violates Felson's double lesion sign. Upper-lobe atelectasis may produce a localized pneumothorax (pneumothorax ex vacuo), analogous to the vacuum joint phenomenon. Conversely, a large pneumothorax may cause torsion of an upper-lobe bronchus, leading to atelectasis. It is important to distinguish between these two conditions in order to choose the appropriate treatment-bronchoscopy in the former and chest tube drainage in the latter. Round atelectasis is a form of peripheral atelectasis that is variable in size and is thought to occur either when the lung collapses around a cleft in the presence of a pleural effusion or when shrinkage of a pleural scar pinches the adjacent lung. Round atelectasis has many features of plate atelectasis and may represent a special form of this condition.

Pulmonary complications after bone marrow transplantation.

Many of the pulmonary complications that we have described have a nonspecific radiographic appearance. The most crucial information for proper interpretation of the chest radiographs is the chronologic onset of radiographic abnormalities after transplantation. Before and immediately after engraftment, local peripheral opacities accompanied by a surrounding rim of edema are regarded as fungal infections, and therapy with granulocyte transfusions and amphotericin B is initiated. Diffuse interstitial thickening is likely to represent edema, pulmonary hemorrhage, bacterial infection, or ARDS rather than CMV or P. carinii pneumonia in the neutropenic host. After engraftment, diffuse interstitial processes become the predominant lung abnormalities. In allogeneic transplant patients who are serologically positive for CMV or who receive serologically positive donor marrow for CMV, pneumonitis caused by this virus is perhaps the most common treatable lung infection. Idiopathic interstitial pneumonias present in a similar fashion to CMV pneumonia; however, the response to corticosteroid therapy is only occasionally gratifying. The onset of nodular opacities in this period may be due to a number of disorders, such as opportunistic infection, BOOP, PTLPD or recurrent tumor. Open lung biopsy usually is required for definitive diagnosis.

Solitary pulmonary nodules: determining the likelihood of malignancy with neural network analysis.

PURPOSE: To test a neural network in differentiation of benign from malignant solitary pulmonary nodules. MATERIALS AND METHODS: Neural networks were trained and tested on the characteristics of 318 nodules. Predictive accuracy of the network was judged for calibration and discrimination. Network results were compared with those with a simpler Bayesian method. RESULTS: The Brier score was 0.142 (calibration, 0.003; discrimination, 0.139) for the neural network and 0.133 for the Bayesian analysis (calibration, 0.012; discrimination, 0.121). Analysis of the calibration curve revealed no significant difference (P < .05) between the slope (b = 1.09) and the line of identity (b = 1) for the neural network or the Bayesian analysis. The area under the receiver operating characteristic curve was 0.871 for the neural network and 0.894 for the Bayesian analysis (P < .05). There were 23 and 21 false-positive predictions and 18 and six false-negative predictions for the neural network and Bayesian analysis, respectively. CONCLUSION: The Bayesian method was better than the neural network in prediction of probability of malignancy in solitary pulmonary nodules.

The pathophysiology of airways disease.

More than 10 million airway branches exist in the normal human lung. Radiographic visualization is < 1% of this total. Many diseases affect the airways, each pathologic insult ultimately resulting in obstruction to airflow. Normally there is little resistance to airflow in the small airways (< 2 mm diameter); thus extensive disease may be present before it becomes clinically evident. Centrilobular emphysema is characterized by dilation and destruction of small airways, whereas bronchiolitis obliterans is characterized by concentric fibrous obliteration of small airways. High-resolution computed tomography, particularly comparison of images at full inspiration and full expiration, is the most sensitive radiographic method with which to image small airways disease.