4 D Ultrasounds, Anyone See the Implications?

[Annie]

http://news.nationalgeographic.com/news/2005/02/0225_050225_tv_ultrasound.html

4-D Ultrasound Gives Video View of Fetuses in the Womb

Brian Handwerk
for the National Geographic Channel
and National Geographic News
February 25, 2005
On TV: Catch In the Womb on the National Geographic Channel in the U.S. on March 6 at 8 p.m. ET/9 p.m. PT.

The new generation of three- and four-dimensional ultrasound imagery provides striking views of fetuses inside the womb. Parents-to-be appreciate the lifelike pictures, and doctors gain an improved understanding of fetal development and behavior.

"It's almost a new science, in a way. It's taught us so much about how the fetus develops at an early stage," said Professor Stuart Campbell of the Create Health Clinic in London. Campbell, one of the world's leading experts in obstetrics, has been working with ultrasound technology since its earliest days and with so-called four-dimensional images since their debut about four years ago.

Four-dimensional imagery shows objects in 3-D moving in something close to real time. Doctors have long known that fetuses move, but the physical behavior revealed by 4-D scans is expanding that knowledge exponentially.

"We see the earliest movements at 8 weeks," Campbell said. "By 12 weeks or so they are seen yawning and performing individual finger movements that are often more complex than you'll see in a newborn," he said. "It may be due to the effects of gravity after birth."

The images reveal facial expressions, like smiling, at 20 weeks. Beyond 24 weeks fetuses may suck their thumbs, stick their tongues out (perhaps using newly developed taste buds to sample amniotic fluid imbued with the flavors of the mother's food), and make apparently emotional faces.

Many of the reflexes seem designed to help the fetus with tasks it will need after birth, such as opening its eyes and sucking.

Campbell believes that ever improving imagery—particularly the 4-D scans, which are inching ever closer to displaying real-time movement—represents the tip of the iceberg for fetal-behavior study.

"I think we ought to study the behavior of the fetus prenatally," he said. "For example, we don't understand why cerebral palsy occurs in 90 percent of the cases it does, but we believe it occurs in the uterus. I think the future lies in first-trimester diagnosis. I can see diagnosing abnormalities in the first 12 weeks."

Computer Advances Drive Improving Imagery

Ultrasound images are made by sending high-frequency sound waves into the mother's body, where they penetrate fluids but bounce back off solids. The rebounding waves are collected to produce an image, traditionally seen as a two-dimensional "slice."

"As computers have gotten faster it's possible for them to process many 2-D slices over a very short period of time and then stitch them together. That's how we got from 2-D to 3-D," said Carol Benson, a radiologist specializing in ultrasound at Brigham and Women's Hospital in Boston, Massachusetts.

"With the 4-D, processing is fast enough that you can watch [movement] as it happens. When it gets faster it will eventually appear to be in real time."

But 2-D images aren't going anywhere in the near future. In fact, they usually offer better diagnostic information than their 3-D and 4-D counterparts.

"2-D lets you see inside of structures, because you can take slices within [the fetus's body]," Benson explained. "With 3-D you can do a surface rendering, but you can't see inside the baby any better than I can see inside you."

But because the new kinds of scans are created from many stitched-together 2-D images, the 3-D and 4-D imagery represent a valuable diagnostic resource.

The new processes collect data for the entire volume of the fetus and womb. From this imagery, a more conventional, 2-D image can be separated out and can depict any and all desirable angles.

"When we're looking at the fetus or at the uterus, the position of these structures may not be in the ideal plane to get the information that we want," said Barry B. Goldberg, director of the Jefferson Ultrasound Research and Education Institute in Philadelphia, Pennsylvania.

"With these [new processes] it's possible to reconstruct [2-D cross sections] in different planes," he continued. "We can collect a volume of information, decide what plane we want, and manipulate the image plane to get [the visual] that will give us the most information."

Because the data can be stored on a computer, new slices can be created and examined long after the patient has returned home—though computer capabilities are currently too slow to allow this process to become standard procedure.

Third Dimension Offers Doctors a New View

A three-dimensional view can, in some cases, provide its own diagnostic advantages.

"For the first time it is now possible to visualize fetal organs as more than flat images but rather as three-dimensional objects that can be rotated and examined from different angles," said Wesley Lee, of the Division of Fetal Imaging at William Beaumont Hospital in Royal Oak, Michigan.

Lee stresses that 3-D images are a complement to, rather than a replacement for, 2-D ultrasound.

"[This] technology allows doctors to visualize ultrasound images in different ways that may strengthen or refute an initial diagnostic impression using more conventional tests," he said.

Such images are useful at identifying cleft lip, spina bifida, and some genetic syndromes.

As computers become more powerful and processing speed increases, the technology will only improve.

"We're really at the beginning, 3-D and 4-D image quality appears to be improving every month," the Jefferson Institute's Goldberg noted.

Future advances may allow the digital transfer of complete fetus and uterus volume scans. Such transfers of imagery could enable remote consultation and diagnosis for patients in areas lacking advanced health care.

Everyone agrees that the new scans already provide dramatically better visualization for parents, which can result in an even stronger parent-child bond. High-risk obstetrician and gynecologist Jude Crino is the director of the Perinatal Ultrasound Unit at the Johns Hopkins University School of Medicine in Baltimore, Maryland.

"We can see better, but it's also important that the patient can see better," he explained. "When I give a patient a 2-D image, it's not uncommon for them to ask two or three times, 'What is this? Could you point this out?' If you give them a 3-D image, they are immediately able to recognize it, because it looks like a baby."

Campbell notes that in his clinic the effects of the moving, 4-D images are even greater.

"You just see the whoops of joy when the fetus does something like blink," he said. "That's a very powerful impact."