Radiographics : a review publication of the Radiological Society of North America, Inc
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Body magnetic resonance (MR) imaging is challenging because of the complex interaction of multiple factors, including motion arising from respiration and bowel peristalsis, susceptibility effects secondary to bowel gas, and the need to cover a large field of view. The combination of these factors makes body MR imaging more prone to artifacts, compared with imaging of other anatomic regions. Understanding the basic MR physics underlying artifacts is crucial to recognizing the trade-offs involved in mitigating artifacts and improving image quality. ⋯ Motion artifacts can be overcome through respiratory synchronization, alternative k-space sampling schemes, and parallel imaging. Aliasing and truncation artifacts derive from limitations in digital sampling of the MR signal and can be rectified by adjusting the sampling parameters. Understanding the causes of artifacts and their possible solutions will enable practitioners of body MR imaging to meet the challenges of novel pulse sequence design, parallel imaging, and increasing field strength.
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Amyloidosis is a rare diverse condition caused by the pathologic extracellular deposition of abnormal insoluble proteins throughout the body. It may exist as a primary disease or, more commonly, may be secondary to a wide variety of pathologic processes ranging from chronic infection or inflammation to malignancy. Hereditary forms also exist. ⋯ At cardiac magnetic resonance (MR) imaging, the left ventricular wall is typically thickened, with associated diastolic dysfunction. Delayed contrast material-enhanced cardiac MR imaging typically shows global transmural or subendocardial enhancement. The pathophysiology, classification, treatment, and prognosis of amyloidosis are reviewed, followed by case examples of the appearance of thoracic and cardiac amyloidosis on chest radiographs, computed tomographic (CT) images, and cardiac MR images.
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Retroperitoneal fasciitis is a rare but potentially lethal complication of infection. Early diagnosis is crucial and is usually made when there is a high degree of clinical suspicion combined with characteristic imaging findings leading to early surgical intervention. Computed tomography (CT) can play a central role in demonstrating early findings, assessing the extent of disease to help determine the best surgical approach, identifying the primary source of infection, and evaluating the treatment response. ⋯ Findings of indirect tracking and transgression of fascial planes may indicate more severe infection associated with the necrotizing form of retroperitoneal fasciitis. Despite aggressive antibiotic treatment, early and repeated surgical débridement may be required to remove nonviable tissue in patients with the necrotizing form of retroperitoneal fasciitis. Awareness of the anatomy of the retroperitoneum, potential routes of spread of infection, and the spectrum of CT findings in retroperitoneal fasciitis is needed to achieve prompt diagnosis and guide treatment.
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Radiologists play an important role in evaluation of geriatric trauma patients. Geriatric patients have injury patterns that differ markedly from those seen in younger adults and are susceptible to serious injury from minor trauma. The spectrum of trauma in geriatric patients includes head and spine injury, chest and rib trauma, blunt abdominal injury, pelvic fractures, and extremity fractures. ⋯ Radiologists should use age-appropriate algorithms for radiography, computed tomography (CT), and magnetic resonance imaging of geriatric trauma patients and follow guidelines for intravenous contrast agent administration in elderly patients with impaired renal function. Because there is less concern about risk for cancer with use of ionizing radiation in this age group, CT is the primary imaging modality used in the setting of geriatric trauma. Clinical examples are provided from the authors' experience at a trauma center where geriatric patients who have sustained major and minor injuries are treated daily.
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Cardiac sarcoidosis is a rare but potentially fatal disorder with a nonspecific spectrum of clinical manifestations, including conduction disorders, congestive heart failure, ventricular arrhythmias, and sudden cardiac death. Although early treatment to improve morbidity and mortality is desirable, sensitive and accurate detection of cardiac sarcoidosis remains a challenge. Except for the histopathologic finding of noncaseating granulomas in an endomyocardial biopsy specimen, most diagnostic tests are limited and nonspecific at best. ⋯ Advanced imaging modalities, such as cardiac magnetic resonance imaging and positron emission tomography with fluorodeoxyglucose, have become increasingly useful in facilitating diagnosis and therapeutic monitoring, although limited prospective studies exist. This article describes the clinical parameters and pathologic findings of cardiac sarcoidosis and the advanced imaging features and differential diagnostic challenges that must be considered for a successful diagnostic approach. In addition, to improve the understanding of abnormalities detected with different imaging modalities, we suggest a unified terminology in describing radiologic findings related to cardiac sarcoidosis.