Advanced imaging technology is giving physicians and parents a high-definition view of babies before birth. Three-dimensional (3-D) ultrasound and magnetic resonance imaging (MRI) produce detailed pictures that enable physicians to visualize the growing fetus and diagnose facial conditions, such as cleft lip and palate.
“Cleft lip, with or without cleft palate, is the most common facial malformation,” says Judy Estroff, MD, co-director of fetal imaging at Children’s Hospital Boston and associate professor of radiology at Harvard Medical School. “Although ultrasound is routinely used to evaluate fetal structure at 18 to 20 weeks of pregnancy, cleft lip and palate often go undetected.”
To enhance detection, radiologists in the Advanced Fetal Care Center (AFCC) at Children’s Hospital Boston now examine the fetal face with both 3-D ultrasound and MRI. AFCC is among just a handful of hospitals nationwide to offer comprehensive services ranging from prenatal diagnosis to care for the baby after birth.
The detection of fetal anomalies often better prepares parents for the birth of their child. But because early diagnosis of an abnormality also sparks questions, worries, and fears, counseling of the prospective parents is an essential part of care.
Imaging in All Dimensions
Ultrasound imaging, also called sonography, is a safe, painless diagnostic test that uses sound waves that penetrate deep within tissue and are reflected back to form an image. A routine part of prenatal care, ultrasound can show the presence of twins or other multiples and detect many fetal abnormalities.
More recently, researchers have developed 3-D and 4-D (full-motion 3-D) ultrasound using powerful computer-based image processing methods. Interestingly, much of the current volume-rendering technology employed in medical imaging originated from computer scientists at Pixar Animation Studios, famous for 3-D computer-animated movies.
Unlike standard ultrasound, which displays flat, thin sections of the body, 3-D ultrasound produces images with greater detail. “Conventional ultrasound,” says Estroff, “is like a flashlight beam cutting through the body. It can show only one thin slice at a time. In contrast, 3-D ultrasound acquires a thicker slice and shows a volume of tissue, which can be viewed in any plane. This 3-D technology allows us to render a realistic image of the soft tissues of the face and see the fetus yawn, smile, or grimace.”
“It was amazing,” says Kira Adams of Peabody, who had one of the first 3-D sonograms at Children’s in 2005. “I could see a lot more than in a regular ultrasound, including features like the nose.”
While commercial enterprises like “Womb with a View” take keepsake 3-D ultrasound images and videos for baby scrapbooks, Estroff urges pregnant women not to substitute these for a comprehensive fetal sonogram performed by a trained medical specialist.
High quality 3-D ultrasound often improves detection of cleft lip by scanning the surface of the face. However, it cannot easily penetrate bony structures, so determining whether a fetus has a cleft of the soft palate is difficult.
“To detect cleft secondary or soft palate on ultrasound, we must use indirect signs, such as the tip of the nose is pointed away from the cleft, the tongue is in an unusually high position, and the eyes are more widely separated than usual,” says Estroff. She notes that gaps in the horseshoe-shaped tooth- bearing alveolar ridge are another indication that the cleft involves more than the lip.
A More Definitive Answer
To diagnose fetal cleft lip and palate more precisely, Estroff and other specialized pediatric radiologists began using a combination of fetal ultrasound and MRI in 2002.
Ellen Caille, who was 7 ⁄2 months pregnant at the time, volunteered for the MRI study after a cleft lip was seen on a routine ultrasound. MRI revealed a high probability of cleft palate as well, and indeed, her daughter, Catherine Souza, was born with both.
A noninvasive test, MRI combines the forces of a powerful magnetic field, radio waves, and computers to create detailed images of internal body structures, including deep, soft tissues of the mouth. MRI offers a view of the entire fetus and can also focus on tiny structures like a 2-millimeter gap in the tooth-bearing alveolus. At Children’s Hospital Boston, fetal MRI is performed anytime after 16 weeks of gestation.
“With fetal MRI, bony structures are no obstacle,” says Estroff. “MRI is a great way to look at the soft palate, which is located deep in the head and is surrounded by bone.”
Improved visualization of bone and soft-tissue facial structures by the combination of ultrasound and MRI has led to more accurate detection of anomalies. AFCC now detects nearly all cases (about 97%) of fetal cleft palate associated with cleft lip.
Being Prepared
When a craniofacial anomaly is suspected, a pregnant woman, her obstetric caregivers, or her previous ultrasonologist can seek a second opinion from AFCC. In a one-day appointment, the mother can have fetal ultrasound and MRI, and see specialist doctors, nurses, and other health care professionals, such as genetic counselors, as needed.
After imaging, radiologists often explain what was seen to the mother and her family. The craniofacial specialist also reviews the images, discusses the diagnosis, and explains the surgical implications to the family. “The strength of our program is the team of specialists who work together to care for as well as counsel the mother-to-be, discussing the range of outcomes for the baby and for the family,” says Estroff.
Radiologists in AFCC, working with Dr. John Mulliken, chief of the Craniofacial Centre at Children’s Hospital Boston, also act as a resource for people outside of the Boston area, who may send fetal sonograms for an interpretation free of charge.
“If the parents know what to expect, and how expertly Dr. Mulliken and other craniofacial surgeons repair clefts, they feel more confident,” says Estroff. “The parents are better prepared for their child’s birth and later corrective operations.”