Radiographics : a review publication of the Radiological Society of North America, Inc
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The interpretation of images obtained in the abdomen and pelvis can be challenging, and the coregistration of positron emission tomographic (PET) and computed tomographic (CT) scans may be especially valuable in the evaluation of these anatomic areas. PET-CT represents a major technologic advance, consisting of generally complementary modalities whose combined strength tends to overcome their respective weaknesses. ⋯ The results of recent PET-CT studies have been very encouraging, but larger prospective studies will be needed to establish optimal hybrid scanning protocols. Applying sound imaging principles, paying attention to detail, and staying abreast of advances in this exciting new modality are necessary for harnessing the full diagnostic power of abdominopelvic PET-CT.
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Current strategies for the triage of patients who have chest pain but normal initial cardiac enzyme levels and nondiagnostic electrocardiograms do not permit efficient risk stratification. The potentially fatal consequences and high malpractice costs of missed acute coronary syndromes lead every year to the unnecessary hospital admission of about 2.8 million patients who present with acute chest pain in emergency departments in the United States. Most of these patients are at very low risk for an acute coronary syndrome. ⋯ Preliminary data indicate that multidetector CT also can help quantify and characterize coronary atherosclerotic plaque and that the CT findings are in good agreement with those at intravascular ultrasonography. Although multidetector CT provides accurate information about the presence of coronary artery disease, large blinded observational studies are warranted to identify CT characteristics with high accuracy for diagnosis of acute coronary syndromes. Such information would enable the conduct of randomized controlled trials to determine whether the detection of coronary stenosis and plaque with multidetector CT improves triage and reduces the costs or increases the cost-effectiveness of management of acute chest pain.
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Bowel and mesenteric injuries are detected in 5% of blunt abdominal trauma patients at laparotomy. Computed tomography (CT) has been shown to be accurate for the diagnosis of bowel and mesenteric injuries and is the diagnostic test of choice in the evaluation of blunt abdominal trauma in hemodynamically stable patients. Specific CT findings of bowel and mesenteric injuries include bowel wall defect, intraperitoneal and mesenteric air, intraperitoneal extraluminal contrast material, extravasation of contrast material from mesenteric vessels, and evidence of bowel infarct. ⋯ Less specific signs of bowel and mesenteric injuries include focal bowel wall thickening, mesenteric fat stranding with focal fluid and hematoma, and intraperitoneal or retroperitoneal fluid. When only nonspecific signs of bowel and mesenteric injuries are seen on CT images, correlation of CT features with clinical findings is necessary. A repeat CT examination after 6-8 hours if the patient's condition is stable may help determine the significance of these nonspecific findings.
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Review Comparative Study
CT dose reduction and dose management tools: overview of available options.
In the past decade, the tremendous advances in computed tomography (CT) technology and applications have increased the clinical utilization of CT, creating concerns about individual and population doses of ionizing radiation. Scanner manufacturers have subsequently implemented several options to appropriately manage or reduce the radiation dose from CT. Modulation of the x-ray tube current during scanning is one effective method of managing the dose. ⋯ The dose modulation may occur angularly around the patient, along the long axis of the patient, or both. Finally, the system may allow use of one of several algorithms to automatically adjust the current to achieve the desired image quality. Modulation both angularly around the patient and along the z-axis is optimal, but the tube current must be appropriately adapted to patient size for diagnostic image quality to be achieved.
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The interpretation of magnetic resonance (MR) images of the pediatric brain may require consultation of an atlas to determine if a perceived finding represents an abnormality. However, most hard-copy atlases show only a few levels of the brain at selected points of time in myelination, and therefore a simultaneous comparison of different age groups is difficult with a hard-copy approach. The authors believe that a digital atlas of the normal pediatric brain may be a more efficient way to present this information and that correct interpretation of potential abnormalities may be facilitated by the online atlas they have created (available for free download from http://radiology.seattlechildrens.org/teaching/pediatricbrainatlas). ⋯ The software program used for viewing the atlas, written in C#, incorporates many features of a picture archiving and communication system viewer, such as linked scrolling and resizing. Simultaneous comparison of cases also is possible. The digital atlas facilitates learning about normal changes in the MR appearance of the pediatric brain, and it may be used during online interpretation of cases on a picture archiving and communication system.