AJR. American journal of roentgenology
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AJR Am J Roentgenol · Nov 1993
Metaphyseal abnormalities in children: pathophysiology and radiologic appearance.
The most active site of formation of bone in children is the metaphysis. Systemic and local diseases are reflected by alterations in the morphology of this region. In this pictorial essay, we examine several patterns of metaphyseal abnormalities seen on radiologic images and review the associated pathophysiology. Differential diagnosis may be aided by considering the pathologic mechanisms responsible for the various metaphyseal alterations.
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AJR Am J Roentgenol · Oct 1993
Cause of regional ventilation-perfusion mismatching in patients with idiopathic pulmonary fibrosis: a combined CT and scintigraphic study.
Regional ventilation and perfusion were studied in patients with idiopathic pulmonary fibrosis (cryptogenic fibrosing alveolitis) to seek an explanation for the mismatched ventilation/perfusion (V/Q) seen on scintigrams, which may suggest pulmonary embolic disease. ⋯ The cystic air spaces that are often seen on CT scans of patients with idiopathic pulmonary fibrosis are unperfused (probably due to vascular obliteration) but are usually normally ventilated. This V/Q mismatch on scintigrams explains the large physiologic dead space seen at rest and on exercise and could suggest pulmonary embolism unless a CT scan is obtained. Conversely, the larger cystic spaces might be mistaken for emphysema unless V/Q scintigraphy is done.
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AJR Am J Roentgenol · Oct 1993
Differences in CT density between dependent and nondependent portions of the lung: influence of lung volume.
Lung tissue, blood, and air determine the physical density of the lung and hence the attenuation measured on CT scans. These components are not homogeneously distributed throughout the lungs, and their relative proportion changes continuously during respiration. The objective of this study was to measure densities in various areas of the normal lung with CT and to examine the influences of gravity and of the degree of lung inflation on these densities. ⋯ Changes in lung volume have different effects on changes in lung density in dependent and nondependent parts of the lung. The largest changes in lung density occur in the dependent regions. The difference in density between dependent and nondependent lung regions is smallest for lung volumes near total lung capacity. These findings may be useful as a baseline for interpreting CT measurements of regional lung density in suspected cases of lung disease, which would alter the physical density of lung tissue. Our results also suggest that measurements near total lung capacity should be included.
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AJR Am J Roentgenol · Sep 1993
Calcaneus as a site for assessment of bone mineral density: evaluation in cadavers and healthy volunteers.
The value of calcaneal dual-energy X-ray absorptiometry for monitoring changes in bone mineral density has not yet been established. Accordingly, the focus of this study was to determine the usefulness of the calcaneus as the site for bone mineral density measurement with dual-energy X-ray absorptiometry. ⋯ Taken together, these results suggest that the calcaneus can be used as an additional site for determining bone mineral density to assess osteopenia in patients when deformities of the spine make quantitative CT or other methods of density measurement impossible.
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AJR Am J Roentgenol · Sep 1993
Malignant pleural mesothelioma caused by environmental exposure to asbestos or erionite in rural Turkey: CT findings in 84 patients.
Malignant pleural mesothelioma in rural Turkey frequently results from environmental exposure to tremolite asbestos or fibrous zeolite (erionite). The aim of this study was to determine the CT features of malignant pleural mesothelioma in patients exposed to asbestos or erionite. ⋯ The most common CT findings in cases of malignant pleural mesothelioma were unilateral pleural thickening or pleural nodules/masses with or without effusion. CT provided valuable information on the extent of the disease, which was important for staging. Although the CT features are not pathognomonic, they provide valuable clues to the diagnosis in patients who have been exposed to mineral fibers.