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Vol. LXV, No. 4
February 15, 2013

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Next-Generation CT Scanner Provides Better Images with Minimal Radiation

An example of a computed tomography scanner
An example of a computed tomography scanner

A new computed tomography (CT) scanner substantially reduces potentially harmful radiation while still improving overall image quality. NIH researchers, along with engineers at Toshiba Medical Systems, worked on the scanner. An analysis of data on 107 patients undergoing heart scans found that radiation exposure was reduced by as much as 95 percent compared to the range of current machines, while the resulting images showed less blurriness, reduced graininess and greater visibility of fine details.

The machine recently received approval by the Food and Drug Administration, but more studies will be needed before it can be adopted for wide clinical use.

“CT scans are a great diagnostic tool for heart disease because we can obtain high-resolution 3-D images of the heart quickly and non-invasively,” said coauthor Dr. Andrew Arai, chief of the Cardiovascular and Pulmonary Branch at the National Heart, Lung, and Blood Institute. “However, the benefits of CT have been tempered by concerns over the radiation required to achieve these images. With this next-generation device, we are close to achieving the best of both worlds.”

The study, published Jan. 22 online in the journal Radiology, was funded by NHLBI. The CT machine was provided by Toshiba Medical Systems through a cooperative research agreement.

NIH Study Advances Understanding of Movement Control

Voluntary movements involve the coordinated activation of two brain pathways that connect parts of deep brain structures called the basal ganglia, according to a study in mice by researchers at the National Institute on Alcohol Abuse and Alcoholism. The findings, which challenge the classical view of basal ganglia function, were published online in Nature on Jan. 23.

“By improving our understanding of how the basal ganglia control movements, these findings could aid in the development of treatments for disorders in which these circuits are disrupted, such as Parkinson’s disease, Huntington’s disease and addiction,” says NIAAA acting director Dr. Kenneth Warren.

The predominant model of basal ganglia function proposes that direct and indirect pathways originating in a brain region called the striatum have opposing effects on movement. Activity of neurons in the direct pathway is thought to promote movement, while activity in the indirect pathway is thought to inhibit movement. Newer models, however, suggest that co-activation of these pathways is necessary to synchronize basal ganglia circuits during movement.

Scientists devised a new approach for measuring the activity of neurons deep within the brain during complex behaviors. Their technique uses fiber optic probes implanted in the mouse brain striatum to measure light emissions from neurons engineered to glow when activated.

Using this new approach, the researchers detected neural activity in both the direct and indirect pathways when mice performed a bar-pressing task. No such activity was detected when the mice were inactive.

Candidate Dengue Vaccine Shows Promise in Early Stage Trial

A candidate dengue vaccine developed by scientists at NIH has been found to be safe and to stimulate a strong immune response in most vaccine recipients, according to results from an early stage clinical trial sponsored by the National Institute of Allergy and Infectious Diseases. The trial results appeared in the Jan. 17 issue of the Journal of Infectious Diseases.

Dengue fever, prevalent in many tropical and subtropical regions of the world, is caused by any of four related viruses—DENV-1, DENV-2, DENV-3 and DENV-4—that are transmitted to humans by Aedes mosquitoes. The World Health Organization estimates that every year, 50 million to 100 million cases of dengue occur worldwide, resulting in 500,000 hospitalizations of patients with severe disease, many of them in children.

Infection with one dengue virus results in immunity to that specific virus but not to the other three. Research shows that the likelihood of severe disease increases when a person is subsequently infected with a different dengue virus. This observation suggests that the ideal dengue vaccine would be tetravalent—that is, protective against all four dengue viruses.

“The global burden of dengue is enormous—and it is growing,” said NIAID director Dr. Anthony Fauci. “We are cautiously optimistic about these recent clinical trial results with this candidate tetravalent vaccine developed at NIAID; however, much more work still needs to be done.”

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