Radiographics : a review publication of the Radiological Society of North America, Inc
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Magnetic resonance (MR) imaging is useful in evaluating the wide spectrum of diseases that cause nasal masses. MR imaging is most helpful in (a) defining tumor margins and possible intracranial extension and (b) differentiating tumor (which has intermediate, heterogeneous signal intensity on T2-weighted images) from concurrent postobstructive sinusitis and other infectious or inflammatory masses (which have high, homogeneous signal intensity on T2-weighted images if the secretions are well hydrated). The analysis becomes more complicated in cases with desiccated and mixed composition secretions. ⋯ Low signal intensity on T1-weighted images and marked low signal intensity on T2-weighted images are characteristic of fungal sinusitis, and fat within a nasal mass indicates a dermoid or epidermoid cyst. Idiopathic midline granuloma, Wegener granulomatosis, and "cocaine nose" manifest as predominantly destructive midline masses. Despite the advantages of MR imaging, computed tomography remains the preferred imaging modality for evaluating nasal masses that contain calcification or originate from bone or cartilage.
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Transcranial Doppler sonography can be used to evaluate a spectrum of intracranial and extracranial vascular abnormalities. It is of proved value in the detection and follow-up of vasoconstriction caused by subarachnoid hemorrhage and can be used to demonstrate significant stenosis or occlusion of basal intracranial arteries and coexisting routes of collateral circulation. ⋯ Use of transcranial Doppler sonography enables a rapid, noninvasive diagnosis of the subclavian steal syndrome, and it is a valuable adjunct to duplex carotid sonography for determining the effect of atherosclerotic lesions of the internal carotid artery on cerebral hemodynamics. In the operating room or angiographic suite, transcranial Doppler sonography can be used to monitor patients undergoing surgical, interventional, or diagnostic procedures for the development of cerebrovascular complications.
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Upper airway obstruction in infants and children is a common and distressing problem because of the relatively narrow diameter of the airway in early life. Although ultrasound, computed tomography, and magnetic resonance imaging have become increasingly popular modalities for use in many pediatric diseases, plain radiography and fluoroscopy, with attention to technique, collimation, and patient position, continue to be the mainstays for the evaluation of stridor in children. ⋯ Plain radiographic and fluoroscopic findings from over 100 cases of infants and children with this condition were reviewed to determine how frequently the specific diagnosis was confirmed with these studies. In the vast majority of cases, plain radiography and fluoroscopy suffice.
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Langerhans cell histiocytosis (LCH), previously called histiocytosis X, refers to a spectrum of disease characterized by idiopathic proliferation of histiocytes producing focal or systemic manifestations. Causes and pathogenesis remain unclear. However, recent studies suggest abnormal immune regulation as an important factor. ⋯ Radiographic appearance of osseous LCH depends on site of involvement and phase of the disease. Early lesions appear aggressive with poorly defined margins and lamellated periosteal reaction. Late lesions appear well defined and may show sclerotic margins and expanded remodeled appearance.
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Orbital abnormalities encountered in the pediatric population differ substantially from those found in adult patients. Retinoblastoma, the most serious intraocular tumor, is often difficult to diagnose, but use of computed tomography (CT) (which reveals the characteristic focal calcification) and magnetic resonance (MR) imaging allows this tumor to be differentiated from pseudogliomas, such as Coats disease, and retrolental fibroplasia. ⋯ Both modalities allow the differentiation of rhabdomyosarcoma from dermoid, cavernous hemangioma, and lymphangioma and provide helpful information for the diagnosis of many other tumors. Since CT and MR imaging have widely expanded the capabilities of orbital imaging, it is more important than ever before for radiologists to understand pediatric orbital disease.