Radiographics : a review publication of the Radiological Society of North America, Inc
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Frontal and lateral radiography has traditionally been used to evaluate the chest, although computed tomography (CT) and high-resolution CT are increasingly being used as an adjunct to conventional radiography for the evaluation of parenchymal and mediastinal disease. Nevertheless, radiography remains a very important modality in this context, and use of chest radiography alone can provide a vast amount of useful information. ⋯ Radiologists must be familiar with the anatomic basis of these mediastinal lines and stripes and be able to recognize their normal and abnormal appearances. In this way, they can develop an appropriate differential diagnosis prior to obtaining additional information with chest CT.
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The role of dynamic contrast material-enhanced magnetic resonance (MR) imaging of the breast as an adjunct to the conventional techniques of mammography and ultrasonography has been established in numerous research studies. MR imaging improves the detection and characterization of primary and recurrent breast cancers and allows evaluation of the response to therapy. ⋯ New breast MR imaging techniques that are based on the use of molecular markers of malignancy may help improve lesion characterization. The margin characteristics of a lesion and the intensity of its enhancement at MR imaging 2 minutes or less after contrast material injection are currently considered the most important features for breast lesion diagnosis.
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Magnetic resonance (MR) imaging with cholangiopancreatographic sequences plays a critical role in evaluating alterations in the biliary tract after surgical procedures such as cholecystectomy, liver transplantation, hepatic resection, and the creation of a biliary-enteric anastomosis. MR cholangiopancreatography, a rapid, noninvasive, and accurate imaging technique for the assessment of early and late complications of hepatobiliary surgery, usually enables the identification of normal and abnormal postoperative changes. In cases of complete obstruction of the bile duct, MR cholangiopancreatography allows analysis of the biliary tract above and below the level of the obstruction, a capability essential for treatment planning and one that is not provided by either endoscopic retrograde cholangiopancreatography or percutaneous transhepatic cholangiography. ⋯ It is useful for detecting bile leaks, although it generally does not directly depict the extravasation of bile. In addition to MR cholangiopancreatography, T1- and T2-weighted MR imaging may be performed to depict extrabiliary soft-tissue structures and abnormalities such as an abscess, tumor recurrence or metastasis, hematoma, or hemobilia. Mangafodipir trisodium-enhanced MR cholangiopancreatography, a recently developed technique that provides a combination of anatomic and functional information, is particularly helpful for documenting bile leaks because it allows a functional evaluation of biliary excretion and may directly depict bile leakage from injured ducts.
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Stroke is a leading cause of mortality and morbidity in the developed world. The goals of an imaging evaluation for acute stroke are to establish a diagnosis as early as possible and to obtain accurate information about the intracranial vasculature and brain perfusion for guidance in selecting the appropriate therapy. A comprehensive evaluation may be performed with a combination of computed tomography (CT) or magnetic resonance (MR) imaging techniques. ⋯ Gradient-echo MR sequences can be helpful for detecting a hemorrhage. The status of neck and intracranial vessels can be evaluated with MR angiography, and a mismatch between findings on diffusion and perfusion MR images may be used to predict the presence of a penumbra. The information obtained by combining various imaging techniques may help differentiate patients who do not need intravenous or intraarterial therapy from those who do, and may alter clinical outcomes.
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The median, radial, and ulnar nerves of the upper limbs may be affected by various peripheral neuropathies, each of which may be categorized according to its cause, as either an entrapment or a nonentrapment neuropathy. Entrapment neuropathies, also referred to as nerve compression syndromes, include the supracondylar process syndrome, pronator syndrome, anterior interosseous nerve syndrome, carpal tunnel syndrome, posterior interosseous nerve syndrome, cubital tunnel syndrome, and Guyon canal syndrome. ⋯ In patients with a diagnosis of peripheral neuropathy, MR imaging may help establish the cause of the condition and provide information crucial for conservative management or surgical planning. In addition, knowledge of the normal anatomy and of the possible causes, typical clinical findings, and MR imaging features of peripheral neuropathies that affect the median, radial, and ulnar nerves allows greater confidence in the diagnosis.