Radiographics : a review publication of the Radiological Society of North America, Inc
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Whole-body imaging, in particular molecular imaging with fluorine 18 ((18)F)-fluorodeoxyglucose (FDG) positron emission tomography (PET), is essential to management of lymphoma. The assessment of disease extent provided by use of whole-body imaging is mandatory for planning appropriate treatment and determining patient prognosis. Assessment of treatment response allows clinicians to tailor the treatment strategy during therapy if necessary and to document complete remission at the end of treatment. ⋯ Because of their high cellularity and high nucleus-to-cytoplasm ratio, lymphomatous lesions have low ADC values and appear hypointense on ADC maps. As a result, whole-body DW MR imaging with ADC mapping has become a promising tool for lymphoma staging and treatment response assessment. The authors review their 4 years of experience with 1.5-T and 3-T whole-body DW MR imaging used with (18)F-FDG PET/computed tomography at baseline, interim, and end of treatment in patients with Hodgkin lymphoma and diffuse large B-cell lymphoma and discuss the spectrum of imaging findings and potential pitfalls, limitations, and challenges associated with whole-body DW MR imaging in these patients.
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The frequency and importance of the evaluation of the posterior fossa have increased significantly over the past 20 years owing to advances in neuroimaging. Nowadays, conventional and advanced neuroimaging techniques allow detailed evaluation of the complex anatomic structures within the posterior fossa. ⋯ Familiarity with the spectrum of congenital posterior fossa anomalies and their well-defined diagnostic criteria is crucial for optimal therapy, an accurate prognosis, and correct genetic counseling. The authors discuss the spectrum of posterior fossa malformations and disruptions, with emphasis on neuroimaging findings (including diagnostic criteria), neurologic presentation, systemic involvement, prognosis, and risk of recurrence.
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A number of new developments in cervical spine imaging have transpired since the introduction of 64-section computed tomographic (CT) scanners in 2004. An increasing body of evidence favors the use of multidetector CT as a stand-alone screening test for excluding cervical injuries in polytrauma patients with obtundation. A new grading scale that is based on CT and magnetic resonance (MR) imaging findings, the cervical spine Subaxial Injury Classification and Scoring (SLIC) system, is gaining acceptance among spine surgeons. ⋯ Although most patients with blunt trauma are now treated nonsurgically, evolution in the understanding of spinal stability, as well as the development of new surgical techniques and hardware, has driven management strategies that are increasingly favorable toward surgical intervention. It is therefore essential that radiologists recognize findings that distinguish injuries with ligamentous instability or a high likelihood of nonfusion that require surgical stabilization from those that are classically stable and can be treated with a collar or halo vest alone. The purpose of this article is to review the spectrum of cervical spine injuries, from the craniocervical junction through the subaxial spine, and present the most widely used grading systems for each injury type.
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Radiation exposure from computed tomography (CT) has received much attention lately in the medical literature and the media, given the relatively high radiation dose that characterizes a CT examination. Although there are a variety of possible strategies for reducing radiation exposure from CT in an individual patient, optimal CT image acquisition requires that the radiologist understand new scanner technology and how to implement the most effective means of dose reduction while maintaining image quality. ⋯ These variables are discussed in terms of their relative importance to image quality and the implications of parametric changes for image quality and diagnostic content, and practical recommendations are made for their immediate implementation in the clinical setting. Taken together, the principles of physics and key parameters involved in reducing radiation dose while maintaining image quality can serve as a "survival guide" for a diagnostic radiology practice.
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A solitary pulmonary nodule (SPN) is defined as a round opacity that is smaller than 3 cm. It may be solid or subsolid in attenuation. Semisolid nodules may have purely ground-glass attenuation or be partly solid (mixed solid and ground-glass attenuation). ⋯ CT enhancement studies are not applicable for subsolid nodules, and PET is of limited utility because of the low metabolic activity of these lesions. Because of the likelihood that persistent subsolid nodules represent adenocarcinoma with indolent growth, serial imaging reassessment for a minimum of 3 years and/or obtaining tissue samples for histologic analysis are recommended. In the follow-up of subsolid SPNs, imaging features that indicate an increased risk for malignancy include an increase in size, an increase in attenuation, and development of a solid component.