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Rationale: Indeterminate pulmonary nodules are a common radiographic finding and require further evaluation because of the concern for lung cancer., Objectives: We developed an algorithm to assign patients to a low- or high-risk category for lung cancer, based on a combination of serum biomarker levels and nodule size., Methods: For the serum biomarker assay, we determined levels of carcinoembryonic antigen, α1-antitrypsin, and squamous cell carcinoma antigen. Serum data and nodule size from a training set of 509 patients with (n = 298) and without (n = 211) lung cancer were subjected to classification and regression tree and logistic regression analyses. Multiple models were developed and tested in an independent, masked validation set for their ability to categorize patients with (n = 203) or without (n = 196) lung cancer as being low- or high-risk for lung cancer., Measurements and Main Results: In all models, a large percentage of individuals in the validation study with small nodules (<1 cm) were assigned to the low-risk group, and a large percentage of individuals with large nodules (≥3 cm) were assigned to the high-risk group. In the validation study, the classification and regression tree algorithm had overall sensitivity, specificity, and positive and negative predictive values for determining lung cancer of 88%, 82%, 84%, and 87%, respectively. The logistic regression model had overall sensitivity, specificity, and positive and negative predictive values of 80%, 89%, 89%, and 81%, respectively., Conclusion: Integration of biomarkers with lung nodule size has the potential to help guide the management of patients with indeterminate pulmonary nodules.

Breast cancer, a common malignancy in women, is a major cause of cancer-related deaths. Metastases to the thorax are common in patients with breast cancer. Metastases can manifest radiographically as pulmonary nodules, lymphangitis carcinomatosa, endobronchial masses, intrathoracic adenopathy, pericardial or myocardial masses and pleural effusions. Additionally, pulmonary abnormalities occur after radiotherapy, chemotherapy and autologous bone marrow transplantation. Knowledge of the various intrathoracic manifestations of metastases and complications of therapy is important in staging and evaluating patients with breast cancer and deciding on the most appropriate treatment.

The D-glucose analogue 2-(fluorine-18) fluoro-2-deoxy-D-glucose (FDG) is the most commonly used radionuclide in positron emission tomography (PET) of the thorax. Increased glucose metabolism by malignant cells allows physiologic differentiation between benign and malignant abnormalities. FDG PET is consequently useful in characterizing indeterminate pulmonary nodules and in staging and assessing the response to treatment of lung cancer. FDG PET is accurate in classification of indeterminate pulmonary nodules as benign. Nodules with low FDG uptake are followed up radiographically; nodules with increased FDG uptake should be evaluated with biopsy or resected. In the staging of lung cancer, FDG PET is useful in evaluating local disease and pleural and chest wall involvement. The accuracy of FDG PET in demonstrating intrathoracic metastatic nodal disease is greater than that of computed tomography or magnetic resonance imaging. Whole-body PET is useful in detection of extrathoracic metastases. Conventional imaging often does not allow differentiation of tumor from posttreatment scarring. Increased FDG uptake at the sites of residual radiographic abnormalities is indicative of persistent or recurrent tumor.

Positron emission tomography (PET) is just beginning to emerge as a clinically useful tool in the thorax. Imaging with FDG is used primarily to differentiate benign from malignant abnormalities, including solitary pulmonary nodules, staging bronchogenic carcinoma, and differentiating recurrent tumor from fibrosis following treatment. This article discusses the fundamental properties of PET images, techniques, and current clinical indications in the thorax.

CT is the most sensitive radiologic method for the detection of differences in radiographic density in chest lesions. Areas of high attenuation (visually as opaque as bony structures) in an abnormality on CT scans can be an important clue to the correct diagnosis. The high attenuation is most often caused by calcification, but may also be due to iodine, barium, or radiopaque foreign bodies. This essay illustrates the patterns of high attenuation associated with chest diseases on unenhanced CT scans.

Physiologic changes during pregnancy affect nearly every organ system. In the thorax, the diaphragm elevates as much as 4 cm because of displacement of the abdominal organs by the gravid uterus, resulting in lower lung volumes. Maternal blood volume and cardiac output increase approximately 45% by mid-pregnancy. Cardiac output can increase as much as 80% during vaginal delivery and up to 50% with cesarean section. These changes result in pulmonary vascular engorgement, progressive left ventricular dilatation, and mild hypertrophy (Fig. 1). Pregnant patients are also prone to a number of pulmonary insults, including infection, aspiration, and neoplastic disease. These abnormalities have several radiographic patterns: cardiogenic and noncardiogenic pulmonary edema, focal pulmonary abnormalities, and extraalveolar air. Radiologists must recognize not only the normal chest radiographic appearance in these patients but also the thoracic complications associated with pregnancy.

The authors assessed the role of positron emission tomography (PET) with fluorine-18 fluorodeoxyglucose (FDG) in differentiation of benign from malignant focal pulmonary abnormalities seen on chest radiographs. Fifty-one patients underwent FDG PET scanning. Focal abnormalities at radiography included solitary pulmonary nodules (n = 38), pulmonary masses (n = 5), and poorly marginated infiltrates or opacities (n = 8). Proof of diagnosis was obtained by means of transbronchial biopsy (n = 21), open lung biopsy (n = 14), percutaneous needle biopsy (n = 14), or cytologic evaluation of sputum (n = 1). A nodule in one patient had been radiographically stable for at least 8 years. Quantitative analysis was performed by calculation of a standardized uptake ratio (SUR). Thirty-three malignant lesions had a mean SUR (+/- 1 standard deviation) of 6.5 +/- 2.9. Eighteen benign lesions had a mean SUR of 1.7 +/- 1.2. For a benign lesion with SUR of 2.5 or less, specificity of FDG PET was 100%, while sensitivity was 89%. These results suggest that FDG PET is accurate in differentiation of benign from malignant focal pulmonary abnormalities.