The Surgical clinics of North America
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Surg. Clin. North Am. · Feb 2011
Computed tomography, magnetic resonance, and ultrasound imaging: basic principles, glossary of terms, and patient safety.
The basic principles underlying computed tomography, magnetic resonance, and ultrasound are reviewed to promote better understanding of the properties and appropriate applications of these 3 common imaging modalities. A glossary of frequently used terms for each technique is appended for convenience. Risks to patient safety including contrast-induced nephropathy, radiation-induced malignancy, and nephrogenic systemic fibrosis are discussed.
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Originally thought to be a rare occurrence, blunt cerebrovascular injuries (BCVIs) are now diagnosed in approximately 1% of blunt trauma patients. Early imaging of patients has resulted in the diagnosis of BCVIs during the asymptomatic phase, thus allowing prompt treatment. Although the ideal regimen of antithrombotic therapy has yet to be determined, treatment with either antiplatelet agents or anticoagulation has been shown to markedly reduce BCVI-related stroke rate. BCVIs are rare, potentially devastating injuries; appropriate imaging in high-risk patients should be performed and prompt treatment initiated to prevent ischemic neurologic events.
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Cervical spine injury can be excluded by clinical examination, without the need for radiographic study, in many patients. For those who require study, computed tomography of the cervical spine with sagittal and coronal reconstruction is the best modality for both screening and diagnosing cervical spine injury. Optimal evaluation of the obtunded patient remains controversial.
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Acute appendicitis is a common surgical emergency and the diagnosis can often be made clinically; however, many patients present with atypical findings. For these patients, there are multiple imaging modalities available to aid in the diagnosis of suspected appendicitis in an effort to avoid a negative appendectomy. ⋯ Magnetic resonance imaging is recommended when ultrasonography is inconclusive. Appropriate use of these imaging studies avoids delays in treatment, prolonged hospitalization, and unnecessary surgery.