The authors examined 10 healthy male subjects with dynamic computed tomography to determine normal dynamic and expiratory findings. In both the supine and prone positions, the average increase in lung attenuation during exhalation was found to be significantly greater in dependent lung regions than in nondependent lung regions. In each of the lung zones studied, there was a significant correlation between the decrease in cross-sectional lung area during exhalation and the increase in lung attenuation. At the lung bases, a greater increase in lung attenuation was noted during exhalation for a given change in cross-sectional lung area than in the upper lungs. All 10 subjects showed a distinct lobar attenuation gradient in the supine position. In general, lung attenuation increased homogeneously during exhalation, but four of the 10 subjects showed regions of inhomogeneity in lung attenuation during rapid exhalation indicative of air trapping, despite normal results on pulmonary function tests.

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A predominant left-sided pleural effusion and a pericardial fat stripe are chest radiographic signs that are suggestive, but not diagnostic, of pericardial effusion. Because these signs cannot reliably confirm or exclude the presence of pericardial effusion, we conclude that chest radiography is poorly diagnostic of this condition.

Residual thymic tissue in adults on MDCT is both more prevalent and more prominent than that reported in earlier studies and can be visible into the seventh decade. We recommend that radiologists and clinicians familiarize themselves with the normal range appearances of the thymus on MDCT, in order to prevent misinterpretation of normal thymic tissue as pathology, which may result in unnecessary procedures.

Contrast media have been used for the study of disease of the thorax. Most experience has consisted of the use of MR contrast media for improving the delineation of acute myocardial infarction, for demarcating the area of acute myocardial ischemia, and for demonstrating the area of potentially jeopardized myocardium after acute coronary occlusion. Contrast agents demonstrate the ischemic or jeopardized area as a zone of decreased signal intensity to normal myocardium. On the other hand, the magnetic susceptibility agents demonstrate the ischemic or jeopardized area as a zone of increased signal intensity to normal myocardium. Little experience exists concerning the use of MR contrast media for enhancing mediastinal and lung masses. The few reports to date demonstrate that contrast media can improve the conspicuity of thoracic masses. A new nonionic contrast medium, gadodiamide injection, has been shown to considerably increase S/N and C/N of thoracic masses. Further studies are necessary to define the role of MR contrast media in the evaluation of myocardial ischemia and thoracic masses in clinical practice.

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Multidetector computed tomography (MDCT) cystography is rapidly becoming the most recommended study for evaluation of the bladder for suspected trauma. This article reviews the bladder trauma with emphasis on the application of MDCT cystography to traumatic bladder injuries using a pictorial essay based on images collected in our level I trauma center.

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