Alzheimer Disease: Quantitative Structural Neuroimaging for Detection and Prediction of Clinical and Structural Changes in Mild Cognitive Impairment
Average differences in thickness (mm) for subjects with Alzheimer disease (AD) and mild cognitive impairment (MCI) relative to controls (NC).
Top: Controls versus subjects with AD. Middle: Controls versus subjects with MCI who had AD imaging phenotype. Bottom: Controls versus subjects with MCI who had control imaging phenotype. Right: Lateral views. Left: Mesial views. Blue areas indicate regions of thinning with disease. Scale reflects thickness in millimeters, ranging from -0.3-mm thickness (bright blue or cyan) to +0.3-mm thickness (yellow). (Radiology 2009;251:195-205)
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Semi-automated quantitative structural MR methods can identify a pattern of atrophy characteristic of mild Alzheimer disease (AD) and predict decline in patients with mild cognitive impairment (MCI), researchers have found.
Linda K. McEvoy, Ph.D., of the Department of Radiology at the University of California, San Diego, and colleagues studied 84 patients with mild AD, 175 with MCI and 139 control volunteers. They found that atrophy in the mesial and lateral temporal areas, isthmus cingulate and orbitofrontal areas distinguished patients with AD from controls with 83 percent sensitivity and 93 percent specificity. Patients with MCI with phenotypic AD atrophy showed significantly greater clinical decline.
"Such an improvement in predictive prognostic information could be valuable for individual patient treatment, particularly when aggressive new treatments that may prevent or delay AD become available," the researchers write. "Currently such information could provide an important enrichment strategy for the design of large-scale clinical trials, enabling them to identify a more homogenous cohort of individuals with MCI who are at high risk of imminent decline, allowing for smaller sample sizes and shorter trial durations."
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Nondestructive Insights into Composition of the Sculpture of Egyptian Queen Nefertiti with CT
New examination with 64-slice CT of the bust of Nefertiti on exhibit in Berlin's Altes Museum reveals new details about the sculpture's composition and a more realistic inner face under the stucco mask.
3-D volume-rendered reformations of (a) visible outer layer and (b) hidden inner layer.
Threshold value for surface depiction was set to level higher than 900 HU to subtract outer stucco layer. (a) More pronounced shaping of eyelid corners (*) in comparison with inner layer can be seen. (b) Creases in corners of mouth (arrows) were detected. (Radiology 2009;251:233-240)
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The bust, excavated in 1912 from the workshop of the royal sculptor Thutmose, is composed primarily of stucco layers over a limestone core. An earlier CT study confirmed the bust's antiquity and used a slice thickness of 5 mm. The new study by Alexander Huppertz, M.D., of the Imaging Science Institute Charité in Berlin, and colleagues used a slice thickness of 0.6 mm.
Different attenuation values indicated a multistep process in the sculpture's creation, the researchers note. Differences in the inner and outer faces suggested Thutmose made customized aesthetic changes and the limestone core was not merely a mold. "Nefertiti's inner face was not anonymous, but rather delicately sculpted," Dr. Huppertz and colleagues write.
"While high-resolution CT provided new information regarding the creation and unmasked for the first time the hidden inner face of Nefertiti's bust, it just as importantly documented the conservation status and provided precious information on how to avoid future damage to the art treasure," the researchers conclude.
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Recurrent CT, Cumulative Radiation Exposure, and Associated Radiation-induced Cancer Risks from CT of Adults
Researchers have identified a subgroup of patients who undergo high numbers of recurrent CT imaging procedures with potentially high radiation-induced cancer risks.
"While most patients accrue low radiation-induced cancer risks from cumulative CT exposures, incremental risks above baseline are estimated to exceed 1 percent in 7 percent of scanned patients," writes Aaron Sodickson, M.D., Ph.D., of Brigham and Women's Hospital in Boston.
Distribution of anatomic locations for the 190,712 CT examinations captured over the 22-year study period in the cohort of 31,463 patients.(Radiology 2009;251:175-184) |
Dr. Sodickson and colleagues performed individualized cumulative dose and risk estimates in a cohort of 31,462 patients who underwent CT in 2007 and had a total of 190,712 CT exams in the prior 22 years. Thirty-three percent of patients had five or more lifetime CT exams and 5 percent had between 22 and 132 exams.
Cumulative CT radiation exposure added incrementally to baseline cancer risk and, though the risk for most patients was low, the subgroup undergoing repeated imaging was at higher risk.
The researchers suggest that patient-specific cumulative radiation risk estimates can inform decisions that balance the individual's clinical presentation against anticipated benefits of recurrent imaging. "Identification of patients with the highest rates of recurrent imaging may help to focus radiation protection efforts where they are most needed," the researchers write.
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Media Coverage of Radiology
In February, media outlets carried 195 news stories generated by articles appearing in the print and online editions of Radiology. These stories reached an estimated 93 million people.
News releases promoted findings from a study on a technique using CT guidance and microcoils to locate and remove small lung nodules (Radiology 2009;250:576-585), a study comparing the benefits of exercise and endovascular revascularization in the treatment of intermittent claudication (Radiology 2009;250:586-595), chronic airflow changes in the lungs of patients with asthma (Radiology 2009;250:567-575), extension of the stroke therapy window (Radiology 2009;10.1148/radiol.2503080811) and an atrophy pattern in the brain possibly predictive of Alzheimer disease (Radiology 2009;10.1148/radiol.2511080924).
Coverage included CNN, FOX News Channel, United Press International, Asian News International, Medical News Today, Medscape, Health & Medicine Week, Obesity, Fitness & Wellness Week, HealthImaging.com, Ivanhoe.com, ModernMedicine.com and docguide.com.
Imaging Safety the Focus of April Outreach Activities
In April, RSNA will distribute the "60-Second Checkup" audio program to nearly 100 radio stations across the U.S. Segments will focus on dose reduction in CT scanning and the "Image Gently" campaign to reduce pediatric radiation dose.
