Caroline Chiles

Radiographic recognition of pneumothorax in the intensive care unit.

Recognizing pneumothorax and hydropneumothorax on chest x-rays of supine ICU patients requires attention to areas other than the lung apex. Pleural air in a supine patient collects in the anterior costophrenic sulcus, producing hyperlucency over the upper abdominal quadrants, and the deep costophrenic sulcus sign. Hydropneumothorax may be recognized when a sharp pleural line is bordered by increased opacity within the pleural space. The presence of pneumothorax and hydropneumothorax can be confirmed by decubitus or upright chest x-rays.

Image optimization in a computed-radiography/photostimulable-phosphor system

Photostimulable phosphor imaging is an exciting new technology that has several advantages over film/screen radiography, the most important of which is the linearity of the photostimulable phosphor system over a wide exposure latitude. The photostimulable phosphor image is digital, and as such, provides options of how the image is viewed by radiologists. This report discusses the various image-processing parameters available for a photostimulable phosphor system and describes a rational approach for selecting these parameters in portable chest radiography. As photostimulable phosphor imaging becomes more widely implemented, an understanding of the processing parameters will facilitate the production of images that take full advantage of the benefits of these systems.

Digital synthesis of lung nodules.

Studies evaluating observer accuracy and visual perception of pulmonary nodules usually are based upon test films obtained from clinical practice in patients with proven pulmonary nodules. Unfortunately, such nodules do not always occur in the optimal size and location to facilitate testing. Such studies would be enhanced by the ability to place nodules of desired size and location on chest radiographs. This report describes a method of placing a computer-generated (synthesized) nodule on a digitized chest radiograph. To demonstrate the similarity of these synthesized nodules to real nodules, each digitized radiograph with a computer-generated nodule was paired with a digitized chest radiograph of a patient with a clinically proven pulmonary nodule. A total of 22 pairs of chest radiographs were then shown to 13 radiologists, who were asked to distinguish the synthesized nodule from the real nodule. With this two alternative forced-choice test, the radiologists were only able to distinguish the synthesized nodule in 51% of the cases, strongly suggesting that computer generated nodules may be used to simulate real pulmonary nodules in future tests of nodule detection.

Physical principles governing the interrelationships of pressure, flow and volume in collapsible tubes.

Basic principles of fluid mechanics may be used to analyze the relationships of flow, pressure and cross-sectional area of any collapsible tube, including pulmonary blood vessels. The cross-sectional area of a collapsible tube is a direct function of transmural pressure. Alterations in pressure inside the tube may result from changes in fluid velocity, downstream constriction in the tube, or direct increase in internal pressure, as with a manometer. This paper reviews the basic equations applicable to flow in collapsible tubes and illustrates the principles of such flow with a physical model. Depending upon the circumstances, changes in size of the tube may or may not reflect changes in flow or changes in fluid velocity.

One Hundred Years of Imaging: New Benefits, New Challenges

Computed tomography and ultrasound, including Doppler vascular imaging, are now commonplace. Magnetic resonance imaging (MRI) is rapidly becoming a routine imaging option, while MRI spectroscopy is undergoing experimental evaluation. Positron emission tomography (PET) has undergone many years of research and is being used increasingly for functional imaging ofmetabolism of the brain and heart. With the added sophistication of these imaging modalities, interventional radiology has seen its options broadened. In addition to the improvements in radiologic imaging technology, computers are becoming a more integral part of the radiology department. Advances in digital imaging techniques have created exciting future possibiities for displaying conventional radiographs. Currently, digitized images can be transmitted within a hospital or even to another hospital for viewing on a display monitor. Technological innovations with diagnostic capabilities will continue to enhance the efficacy of the radiology department and challenge its departmental staff.