Multidimensional imaging of the thorax: practical applications.

Over the past decade, faster CT scan times, thinner collimation, and the development of multirow detectors, coupled with the increasing capability of computers to process large amounts of data in short periods of time, have lead to an expansion in the ability to create diagnostically useful two-dimensional (2D) and three-dimensional (3D) images within the thorax. Applications within the thorax include, but are not limited to, evaluation of pulmonary and systemic vasculature, evaluation of the tracheobronchial tree, and delineation of diffuse lung disease. Pulmonary nodule volume and growth can be more accurately predicted, and represents an improvement in the evaluation of the solitary pulmonary nodule. Multiplanar images increase our understanding of thoracic anatomy and can help to guide bronchoscopic procedures. Because there are strengths and weaknesses to all the reconstruction algorithms, the utility of any given technique is dependent on the clinical question to be answered. For instance, although maximum intensity projection imaging (MIP) is helpful in the evaluation of micronodular lung disease, it is of little value in the diagnosis of aortic dissection. As the ability to generate faster and more precise multidimensional images grow, the demand for such imaging is likely to increase. In this review, the authors discuss the various reconstruction techniques available, followed by a discussion of the clinical applications.

Radiation exposure and image quality in chest CT examinations.

OBJECTIVE: The purpose of this study was to determine how changes in radiographic tube current affect patient dose and image quality in unenhanced chest CT examinations. SUBJECTS AND METHODS: Ten sets of CT images were obtained from patients undergoing CT-guided chest biopsies. For each patient, six images of the same region were obtained at settings between 40 and 280 mAs. CT data were used to reconstruct tomographic sections with a field of view limited to the normal contralateral lung. Images were printed using lung and mediastinal image display settings. Image quality was determined by asking radiologists to assess the perceived level of mottle in CT images. Five chest radiologists ranked the relative image quality of six images. Patient effective doses were computed for chest CT examinations performed at each milliampere-second setting. Radiologists indicated whether any perceived improvement of image quality at the higher radiation exposures was worth the additional radiation dose. RESULTS: The differences in quality of chest CT images generated at greater than or equal to 160 mAs were negligible. Reducing the radiographic technique factor below 160 mAs resulted in a perceptible reduction in image quality. Differences in CT image quality for radiographic techniques between 120 and 280 mAs were deemed to be insufficient to justify any additional patient exposure. However, the use of 40 mAs results in an inferior image quality that would justify increased patient exposure. CONCLUSION: Radiographic techniques for unenhanced chest CT examinations can be reduced from 280 to 120 mAs without compromising image quality.

Chest radiographic features of engraftment syndrome.

About the time of hematopoietic engraftment, patients undergoing autologous hematopoietic stem cell transplantation in the form of peripheral blood stem cell transplantation (PSCT) may develop an "engraftment syndrome" that includes fever, skin rash, and capillary leak. This condition is usually self-limited, as opposed to other early complications of bone marrow transplantation such as infection and drug reactions. This article describes the chest radiographic manifestations of engraftment syndrome. The medical records and chest radiographs of 50 consecutive breast cancer patients who underwent PSCT were retrospectively reviewed. Engraftment syndrome was diagnosed if the expected clinical findings occurred at the time of engraftment of neutrophils and no other cause was identified. The chest radiographs were correlated with the clinical course. Sixteen patients were found to have engraftment syndrome (32%). Of these, eight had abnormal radiographs. Radiographic findings consisted of pleural effusions and interstitial pulmonary edema. No patient progressed to adult respiratory distress syndrome. Interstitial pulmonary edema and pleural effusions were observed in association with engraftment syndrome from PSCT. Correlation of these findings with clinical history and neutrophil count is important so that engraftment syndrome can be distinguished from other causes of fever.

Lemierre syndrome: forgotten but not extinct--report of four cases.

Four cases of Lemierre syndrome are reported in which metastatic abscesses resulted from septic thrombosis of the internal jugular vein secondary to bacterial pharyngitis. While chest radiographic findings were nonspecific, results of computed tomography (CT) of the thorax in each case were highly suggestive of septic pulmonary emboli. Internal jugular venous thrombosis was demonstrated at ultrasonography and contrast material-enhanced CT.