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OBJECTIVE: To determine whether a clinical prediction model developed to identify malignant lung nodules based on clinical data and radiologic lung nodule characteristics could predict a malignant lung nodule diagnosis with higher accuracy than physicians. MATERIAL AND METHODS: One hundred cases were obtained by using a stratified random sample from a retrospective cohort of 629 patients with newly discovered 4- to 30-mm radiologically indeterminate solitary pulmonary nodules (SPNs) on chest radiography. A chest radiologist, pulmonologist, thoracic surgeon, and general internist made predictions of a malignant lesion and recommendations for management (thoracotomy, transthoracic needle aspiration biopsy, or observation) on the basis of radiologic and clinical data used to develop the clinical prediction rule. The predictions of a malignant lung nodule were compared with the probability of malignant involvement from a previously validated clinical prediction model to identify malignant nodules on the basis of three clinical characteristics (age, smoking status, and history of cancer greater than or equal to 5 years previously) and three radiologic characteristics (nodule diameter, spiculation, and upper lobe location). RESULTS: Receiver operating characteristic analysis showed no significant difference between the logistic model and the physicians' predictions. Calibration curves revealed that physicians overestimated the probability of a malignant lesion in patients with low risk of malignant disease by the prediction rule; this finding suggests a potential for the decision rule to improve the management of patients with SPNs that are likely to be benign. CONCLUSION: The prediction model was not better than physicians' predictions of malignant SPNs. The prediction rule may have potential to improve the management of patients with SPNs that are likely to be benign.

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OBJECTIVE: To test the hypothesis that the advanced multiple beam equalization radiography (AMBER) imaging system is superior to conventional chest radiography in the demonstration of diffuse infiltrative lung disease, emphysema, pulmonary nodules, calcification within nodules, and mediastinal or hilar masses and lymphadenopathy. MATERIAL AND METHODS: The study involved 115 patients, each of whom underwent chest computed tomography (CT), AMBER, posteroanterior chest radiography, and conventional posteroanterior stereoscopic chest radiography (two films). All radiographs were obtained with the InSight Thoracic Imaging System. Four chest radiologists independently analyzed the 115 AMBER studies, 115 unpaired single conventional radiographs (a single film from a stereoscopic pair), and 115 stereoscopic conventional radiographs (2 films) for the presence of diffuse infiltrative lung disease, emphysema, pulmonary nodules, calcification within nodules, and mediastinal or hilar masses and lymphadenopathy. For each abnormality detected, the radiologists described their level of confidence based on a scale of 1 to 5. The 115 CT examinations were interpreted by consensus among 3 of the chest radiologists. The CT results were considered the standard. Receiver operating characteristic (ROC) techniques were used for statistical analysis. RESULTS: No statistically significant differences were found with ROC techniques between the AMBER system and single or stereoscopic conventional screen-film radiography for the abnormalities studied. CONCLUSION: We noted no clinically significant difference between AMBER and either single or stereoscopic conventional screen-film radiography in this prospective study of 115 patients in which CT (performed within 1 week of both radiographic examinations) was the standard.

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PURPOSE: To determine if there is a subset of patients undergoing surgical biopsy for diffuse lung disease in whom accurate diagnosis can be made with computed tomography (CT) only. MATERIALS AND METHODS: Two chest radiologists retrospectively reviewed the CT scans of 85 patients in whom surgical biopsy for diffuse lung disease was performed. Thin-section CT images were available in 58 (68%) of the 85 cases. By consensus, the radiologists listed the three most likely diagnoses in order of probability and rated their level of confidence in the first choice. RESULTS: Each of 85 patients with diffuse lung disease had one of 16 diseases. In 79 (93%) cases, the correct diagnosis was one of the three choices. In 54 (64%) cases, the correct diagnosis was the radiologists' first choice. A high level of confidence in the first choice was reached in 20 (24%) cases; all 20 cases were forms of chronic lung disease. In 18 (90%) of these 20 cases, the first choice was correct. CONCLUSION: In a subset of patients with diffuse lung disease who undergo surgical biopsy, accurate diagnosis can be made with CT findings only.

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OBJECTIVE: To attempt to determine whether a relationship exists between carcinoid tumors and sarcoidosis. MATERIAL AND METHODS: We present a series of seven case reports and discuss hypotheses about possible disease associations. RESULTS: Certain malignant lesions have tended to occur in patients with sarcoidosis. Seven patients who were encountered at Mayo Clinic Rochester between 1950 and 1994 had both sarcoidosis and carcinoid tumors. These patients ranged in age from 31 to 66 years, and three of the patients had a history of benign thyroid disorders. Malignant tumors have been thought to be related to sarcoidosis in one of two ways: (1) immunologic abnormalities in sarcoidosis may promote the development of neoplasms or (2) malignant disease may promote the onset of sarcoidosis either by causing local sarcoid reactions that progress or by directly initiating the manifestations of systemic sarcoidosis. Because the chronology of events differed in our seven cases, various mechanisms of action may have a role in the manifestations of these two disease entities. Our cases emphasize the importance of avoiding the diagnosis of disseminated malignant disease in patients with cancer and associated hilar and mediastinal lymphadenopathy without biopsy confirmation of metastatic disease. CONCLUSION: Application of the knowledge gained about the mechanisms of disease in sarcoidosis will perhaps facilitate identification of the pathogenesis of carcinoid tumors and other neuroendocrine tumors.

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OBJECTIVE: We have observed a significant CT artifact in the evaluation of lung nodules that occurred with the use of high-spatial-frequency reconstruction algorithms. We have seen this lead to a false-positive diagnosis of calcification in a small uncalcified lung nodule. Because of the seriousness of misinterpretation of benign calcification in an uncalcified nodule, we reviewed the various effects of several reconstruction algorithms on different scanners. MATERIALS AND METHODS: Using high-spatial-frequency, smoothing, and intermediate reconstruction algorithms, we studied standardized cylinders in a CT reference phantom and lung nodules in eight patients. Algorithms on four CT scanners were analyzed. RESULTS: We found peripheral edge enhancement artifact on some CT images of phantom cylinders and uncalcified lung nodules. The images with edge enhancement artifact were obtained from two scanners with the use of high-spatial-frequency algorithms (Picker 1200 SX and GE HiSpeed Advantage). CONCLUSION: Use of high-spatial-frequency reconstruction algorithms for the analysis of lung nodules with thin-section CT may lead to an erroneous diagnosis of calcification.

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Over a period of 10 years, employees in a manufacturing plant experienced sporadic flu-like episodes after work in a basement containing a recirculated washwater mist. We report a cross-sectional study to define the flu-like illness and bioaerosol exposures. High concentrations of gram-negative bacteria (GNB) (> 10(7) cfu/ml) and endotoxin (range 34-46 micrograms/ml) were found in the water. Mist contained > 10(3) cfu/m3 of GNB, and endotoxin up to 13,900 to 27,800 ng/m3. Few fungi and thermotolerant Bacillus species and no Actinomycetes, Legionella species, or amoeba were found in washwater. Airborne levels of fungi were of the same species and magnitudes as outdoor samples. Subjects volunteered (n = 28) because of a history of flu-like symptoms or were randomly selected (n = 102) from workers with and without current exposure to the basement. No acute cases were examined. Cases did not fulfill criteria for hypersensitivity pneumonitis (HP) and high levels of IgG antibodies to water-borne antigens were not observed. However, among 20 subjects indicating a history of severe flu-like episodes (severe basement flu, SBF), diffusion capacity (DLCO) was significantly lower (p = 0.015) than among other workers. The prevalence of SBF was independent of smoking. Cases occurred in clusters, and SBF was more common among workers with intermittent exposure to the basement (19 cases) than with daily exposure (1 case). These findings suggest that SBF and associated chronically depressed DLCO resulted from toxic injury following high-level endotoxin exposure. Asthma was prevalent in the study population, particularly among employees with daily, rather than intermittent, exposure to endotoxin-containing mist (odds ratio 6.7, p = 0.02). Thus, endotoxin exposure in this study was associated with two distinct sequelae depending on the temporal pattern of exposure.

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Primary mediastinal neoplasms encompass a long list of histologically diverse lesions that can arise from a wide variety of mediastinal structures. Recent advances in diagnostic techniques have considerably enhanced the evaluation of the mediastinum with use of noninvasive or minimally invasive procedures. In adults, most primary mediastinal neoplasms can be classified in one of four categories: thymus-derived neoplasms, neurogenic tumors, lymphomas, or germ cell neoplasms. In children, neurogenic tumors (especially neuroblastomas) and lymphomas are most frequently encountered. Because of the presence of many vital structures in the confined thoracic cavity, even benign mediastinal neoplasms can cause severe symptoms from the mass effect and therefore warrant a carefully planned management strategy. With modern therapeutic and surgical interventions, associated morbidity and mortality can often be substantially decreased.

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OBJECTIVE: A new asymmetric screen-film combination for conventional chest radiography was evaluated by four thoracic radiologists. MATERIALS AND METHODS: Fifty chest radiographs obtained with a new asymmetric screen-film combination were compared with radiographs obtained in the same patients during the same breath-hold with a conventional system. Patients referred from the oncology service were studied because of the increased prevalence of abnormal findings on chest radiographs in this population. The differences in the quality of the images were assessed by four chest radiologists who used a direct-comparison technique. Eleven anatomic shadows that are normal on chest radiographs were assessed. Fifty abnormal findings also were compared. RESULTS: The image quality of the new asymmetric screen-film combination was judged to be superior to that of the conventional system for normal anatomy and abnormal findings (p < or = .003). CONCLUSION: The new asymmetric film consistently showed more clinically useful detail in the mediastinum and in the lung projected over the diaphragm and heart. The radiation dose was about 30% less with the new screen-film system.

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High-resolution CT (HRCT) is a technique that optimizes the spatial resolution of conventional scanners. HRCT shows exquisite detail of both normal and diseased lung. The findings seen with HRCT of the lung correlate well with the microscopic and gross pathologic findings. In this review, we describe the technical features of HRCT and discuss the HRCT findings in various lung diseases.

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CT and MR imaging allow earlier diagnosis and more specific characterization of anterior mediastinal masses than is possible with plain film radiographs. This review describes state-of-the-art CT and MR imaging of the anterior mediastinum. After a discussion of CT and MR imaging and indications for their use, normal and abnormal CT and MR findings in the anterior mediastinum are reviewed. Abnormalities include benign and malignant neoplasms, cysts, and mediastinal thyroid. Several masses such as thymolipomas, goiters, cysts, and lymphangiomas often do not require removal and now can be diagnosed with reasonable accuracy when imaging results are combined with clinical history. Detection, diagnosis, staging, and follow-up of malignant anterior mediastinal masses are important and have been improved with CT and MR imaging.

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High-resolution computed tomography (HRCT) and thin-section CT are techniques that are particularly suited for evaluation of the pulmonary parenchyma. These techniques have been found useful in the assessment of bronchiectasis and solitary pulmonary nodules. HRCT offers promise in evaluation of diffuse and focal pulmonary parenchymal disease. The principles and applications of HRCT of the lung are reviewed.

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The computed tomography (CT) findings of five benign, mature teratomas of the anterior mediastinum collected during a ten-year period are described, and their case histories are reviewed. Three of the five were primarily cystic, with only small soft tissue components. One of the five contained equal cystic and solid elements. All cysts had a higher attenuation than water. Three tumors contained small foci of dense calcification or ossification. Only two contained fat. Computed tomography accurately predicted the presence of adherence to adjacent structures in all five. Four of five patients were less than 22 years of age, and benign teratoma of the mediastinum was not a common neoplasm at any age. The origin and pathology of germ cell tumors of the mediastinum are briefly reviewed.

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Classic neurofibromatosis, tuberous sclerosis, and ataxia-telangiectasia can affect the chest and respiratory system. These diseases are reviewed with particular emphasis on their thoracic and radiographic manifestations.

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A study was undertaken of five patients with Cushing syndrome due to adrenocorticotropin (ACTH) production by thymic carcinoid tumor (primary mediastinal APUDomas), including two recent patients examined by computed tomography (CT) of the chest. Plain roentgenography of the chest initially failed to detect tumor in four of the five patients, while CT of the chest yielded definitive diagnostic information in both patients in whom it was employed. For one of these patients, a mediastinal tumor could be seen retrospectively on plain roentgenograms of the chest, although it had been missed on the first examination. One of the tumors appeared to be partially calcified on CT scan, a finding not previously reported. Blastic osseous metastasis, which is common when malignant carcinoid tumors spread to bone, was seen in one patient. Our data suggest that in patients with suspected ectopic ACTH production, CT scanning of the mediastinum should be performed early in order to avoid delay in diagnosis of an ACTH-secreting carcinoid tumor of the mediastinum.

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