Radiographics : a review publication of the Radiological Society of North America, Inc
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Diffusion-weighted imaging has been widely accepted as a powerful imaging technique in neuroradiology. Until recently, the inclusion of diffusion-weighted sequences in body imaging protocols has been hindered by technical limitations. However, with advances in magnetic resonance (MR) imaging technology and technique, these limitations are being overcome. ⋯ Because it does not require injection of a gadolinium-based contrast agent, diffusion-weighted imaging can be used in patients with renal insufficiency or contrast material allergy. Most of the body diffusion-weighted imaging studies reported in the literature to date have been conducted with 1.5-T magnets. However, the feasibility of body diffusion-weighted imaging at 3.0 T is currently under investigation in an effort to determine the efficacy of the routine inclusion of diffusion-weighted imaging sequences in 3.0-T body MR imaging protocols.
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As radiologic imaging technology improves and more intricate details of the anatomy can be evaluated, images provide more precise diagnostic information and allow better localization of abnormalities. For example, standard T2-weighted magnetic resonance (MR) imaging sequences adequately depicted only the larger cranial nerves, whereas current steady-state free precession (SSFP) sequences are capable of depicting the cisternal segments of all 12 cranial nerves. ⋯ Usually referred to by their trade names or acronyms (eg, constructive interference steady state, or CISS, and fast imaging employing steady-state acquisition, or FIESTA), SSFP sequences allow precise differentiation between branches of the facial and vestibulocochlear nerves, accurate detection of small masses in the cerebellopontine angles and internal auditory canals, and detailed evaluation of endolymph and perilymph within the inner ear. To take full advantage of these imaging sequences, radiologists must be familiar with the appearances of similar anatomic details of all 12 cranial nerves on SSFP MR images.
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Patients with chronic liver disease exhibit various cardiovascular and pulmonary complications. Hepatopulmonary syndrome results in dyspnea due to intrapulmonary arteriovenous shunting and ventilation-perfusion mismatch. Portopulmonary hypertension occurs in patients with portal hypertension. ⋯ Hepatocellular carcinoma may produce hematogenous lung metastases, intrathoracic lymph node metastases, direct intracardiac extension, and pulmonary embolism. Interferon therapy for treatment of chronic active hepatitis C may disturb cellular immune activation in some patients and contribute to the onset and progression of sarcoidosis. Awareness of the various thoracic manifestations in chronic liver disease can be helpful for making a differential diagnosis and planning proper management.
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Review
Schatzker classification of tibial plateau fractures: use of CT and MR imaging improves assessment.
The Schatzker classification system for tibial plateau fractures is widely used by orthopedic surgeons to assess the initial injury, plan management, and predict prognosis. Many investigators have found that surgical plans based on plain radiographic findings were modified after preoperative computed tomography (CT) or magnetic resonance (MR) imaging. The Schatzker classification divides tibial plateau fractures into six types: lateral plateau fracture without depression (type I), lateral plateau fracture with depression (type II), compression fracture of the lateral (type IIIA) or central (type IIIB) plateau, medial plateau fracture (type IV), bicondylar plateau fracture (type V), and plateau fracture with diaphyseal discontinuity (type VI). ⋯ The fracture-dislocation mechanism of type IV fractures increases the likelihood of injury to the peroneal nerve or popliteal vessels. In type V and VI fractures, the location of soft-tissue injury dictates the surgical approach and the degree of soft-tissue swelling dictates the timing of definitive surgery and the need for provisional stabilization with an external fixator. CT and MR imaging are more accurate than plain radiography for Schatzker classification of tibial plateau fractures, and use of cross-sectional imaging can improve surgical planning.
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Small bowel obstruction (SBO) is a common clinical syndrome for which effective treatment depends on a rapid and accurate diagnosis. Despite advances in imaging and a better understanding of small bowel pathophysiology, SBO is often diagnosed late or misdiagnosed, resulting in significant morbidity and mortality. A comprehensive approach that includes clinical findings, patient history, and triage examinations such as plain abdominal radiography will help the clinician develop an individualized treatment plan. ⋯ If a complete or high-grade obstruction is suspected, cross-sectional studies such as ultrasonography or multidetector CT are used to exclude strangulation. An algorithmic approach to imaging is proposed for the management of SBO to achieve accurate diagnosis of the obstruction; determine its severity, site, and cause; and assess the presence of strangulation. Radiologists have a pivotal role in clinical decision making in cases of SBO by providing answers to specific questions that significantly affect management.