BACKGROUND: Researchers have developed a new brain imaging technique for infants called high-density diffuse optical tomography which helps them to study the developing infant brain. This should help treat infant brain injuries by being able to monitor them in their incubators, and help scientists learn important basics about developing brains. The new scanner is quieter, and portable because it is much smaller ý about the size of a small refrigerator ý than typical MRI or CT scan machines. The developers are working to make the unit even smaller, about the size of a microwave.
THE PROBLEM: Scientists have been able to study brain scans of infants while they are asleep or sedated using functional MRI (magnetic resonance imaging). Ideally researchers would like to scan their brains while sitting on a parentýs lap or interacting with their environment. fMRI requires the patient to be inserted into a tightly confined passage through a large, noisy magnet; most infants find it upsetting and difficult to sit still in that environment. In the same way CT scans involve large, loud equipment, and also expose patients to levels of x-rays considered unsafe for infants.
HOW IT WORKS: The high-density diffuse optical tomography (DOT) uses harmless light from the near-infrared light spectrum. Unlike X-rays or ultrasound, near-infrared light passes through bone easily, so scientists can use the diffusing light to determine blood flow and oxygenation in the blood vessels of the brain. When these characteristics increase, it indicates that the area of the brain they are scanning is contributing to a mental task. To scan a patient, scientists attach a flexible cap that covers the exterior of the head above the region of interest. Inside the cap are fiber optic cables. Some of those cables shine light on the head and by determining the way the light is scattered, researchers can learn more about brain activity. Light passes out of one fiber optic cable, goes through the tissue, and is received by another cable. Based on its interpretation of the diffusion data, the machine creates a 3D image based on whether the red blood cells have lots of oxygen or less oxygen to determine brain activity.
WHAT IS fMRI: Magnetic resonance imaging uses radio waves and a strong magnetic field to take clear and detailed pictures of internal organs and tissues. fMRI uses this technology to identify regions of the brain where blood vessels are expanding, chemical changes are taking place, or extra oxygen is being delivered. These are indications that a particular part of the brain is processing information and giving commands to the body. As a patient performs a particular task, the metabolism will increase in the brain area responsible for that task, changing the signal in the MRI image. So by performing specific tasks that correspond to different functions, scientists can locate the part of the brain that governs that function.
The American Association of Physicists in Medicine and The Optical Society of America contributed to the information contained in the TV portion of this report.