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Magnetic resonance imaging, or MRI, is a radiation-free imaging technique that has grown in popularity over the past 15 years due to the high quality, detailed cross sections (“slices”) it can provide of the brain, spine, and other internal organs. Such organs are easy to image because they don’t move.
Recently, however, NIH researchers have developed ways to use MRI to image moving body structures, such as a beating heart. These techniques are called “gated MRI.” Dr. Alex Kane, a fellow with the Clinical Center’s Diagnostic Radiology Department, is using gated MRI to image the soft palate, the upper part of the mouth which acts as a valve, opening and closing to enable us to form intelligible speech.
“This valving capability is nonexistent in children with an unrepaired cleft palate because the hard and soft palate are split down the middle,” said Dr. Kane, a plastic surgeon with an interest in craniofacial surgery and medical imaging. “Even after we repair the palate, in about 20 percent to 30 percent of patients the muscles that form the soft palate still don't function properly. These children may need further surgery.”
But first these patients must undergo further diagnostic tests so the surgeon can see exactly what needs to be done and where. The standard tests are either invasive and uncomfortable,\ involve relatively high doses of radiation, or provide only a limited view of\ the palate, according to Dr. Kane.
Seeking an imaging method without these limitations, Dr. Kane devised a way to simulate a “beating palate,” analogous to a beating heart. He asked normal volunteers to repeat a syllable, such as “paa,” over and over, each time they see a light blink. An MRI picture of the palate was made at the same point in each repetition.
A high-powered computer then assembled and averaged the hundreds of images. The result is a 3 -dimensional “block” that shows the palate\ opening and closing in a continuous\ cycle. The image can be rotated or flipped to be viewed from any angle.
“By wearing special glasses, we are also able to produce stereographic images of the palate moving on screen with simulated depth,” Dr. Kane said. “We anticipate that these imaging techniques will be useful not only in the domain of cleft lip and palate speech problems, but as a general-purpose tool for the study of speech.”
To view a slide presentation on Dr. Kane’s project, go to the Diagnostic Radiology web site at http://www.cc.nih.gov/drd/research.html, and click on the link “Toward an Improved Method for the Study of Speech Using Gated MRI.”
Dr. Kane hopes to add a video to the presentation soon.
Drs. John Butman, Peter Choyke,and Hani Marcos, and Marlene Skopec, M.S. Eng., collaborated on this research. The cardiac gated MRI studies that form the basis for this work are being done by Drs. Robert Balaban and Andrew Arai, of NHLBI’s Laboratory of Cardiac Energetics.