Thanks to ultra-fast magnetic resonance imaging techniques, MRI now can be used
to provide more information when fetal abnormalities are suspected during a
prenatal ultrasound exam, according to research described in Chicago on
December 1 at the annual meeting of the Radiological Society of North America.
In at least two cases, the MRI-based diagnosis led to treatments that saved the
“Ultrasound is a wonderful tool, but sometimes it is limited in what it
reveals,” said Fergus Coakley, M.B.B.Ch., associate clinical professor of
radiology at the University of California, San Francisco (UCSF), and lead
author of a study using MRI to assess potential fetal abnormalities. “If a
radiologist says to an expectant couple, ‘I don’t like the way your fetus’s
brain is forming,’ they’re terrified. MRI gives them a very powerful tool to
gain more information. When the possibility is that the fetus ranges from near
normal to being in devastatingly poor health, that information means a lot.”
“In some cases, MRI can tell parents not to worry, that everything is normal,
even when an abnormality was suspected on ultrasound,” said Mary C. Frates,
M.D., assistant professor of radiology, Harvard Medical School, radiologist at
Brigham & Women’s Hospital and co-author of a related study using MRI to assess
central nervous system and genitourinary abnormalities.
Both groups used recently developed ultra-fast MRI techniques to obtain
high-quality diagnostic images of the fetus, without sedation or anesthesia.
This was not possible previously, because fetal motion degraded the images
obtained with slower MRI techniques. Now, Coakley said, the radiologist can
ask the mother to hold her breath and take a set of pictures during each
breath-hold. A full exam, taking pictures in several planes, takes half an hour
to an hour.
The MRI exams are used in selected cases in which fetal abnormalities are
suspected. Prior to MRI, parents given questionable or bad news after an
ultrasound had no other imaging options to further investigate the situation.
MRI obtains images based on magnetic fields within the body. Like ultrasound,
it is safe for fetuses because it uses no radiation or contrast media.
Coakley reported to the RSNA meeting on a series of 45 pregnant patients who
received ultrasound and were referred for MR imaging of the fetus. MRI changed
the management of the pregnancy in six of those cases, and provided added
information to ultrasound in nearly half of the cases overall.
MRI findings agreed with ultrasound in 36 cases (80 percent) but added
additional information in 12 of those instances (27 percent). MRI provided
information that was unclear on ultrasound in two cases (4 percent) and
correctly clarified results when there was a discrepancy in the reading of the
ultrasound in four cases (9 percent). In three cases, MRI and ultrasound
readings did not agree: with followup, MRI proved to be correct in two of those
Since the study, 19 women delivered without further interventions (four of the
babies died after birth); intrauterine surgery was successfully performed on
six fetuses; six pregnancies were terminated; and the outcome was unknown in 14
In two of the cases where MR imaging led to a change in case management, the
treatment saved the children’s lives. One fetus’ MRI led to in-utero surgery at
UCSF to repair a defect that was blocking the trachea—a condition that
normally would be fatal before birth. This child now is a healthy two-year-old
learning sign language - his only loss is a lack of vocal cords. A second fetus
was diagnosed with congenital hemochromatosis, a condition that usually is
fatal unless the child receives a liver transplant soon after birth. After an
early delivery and prompt treatment by UCSF neonatologists and pediatric
hepatologists, the baby’s liver recovered and continues to function normally.
UCSF’s fetal diagnosis group analyzes potential birth defects in several
hundred fetuses every year, including ultrasound images sent by referring
physicians from around the world. Such diagnoses can help parents and their
doctors prepare for surgery or other treatments soon after—or sometimes
before—the baby is born. The information can help some couples determine
whether to continue the pregnancy and if so, to prepare for life with a child
with a severe birth defect. And in some cases it can bring relief that a
suspected problem is not serious or doesn’t exist.
“MRI is proving to be an excellent tool to add information and help resolve
questions in some of our most difficult cases,” said Roy Filly, MD, professor
of radiology at UCSF and chief of the university’s fetal ultrasound service, a
co-author of the study.
“MRI can play an invaluable role when couples are faced with an ultrasound
diagnosis of a possibly life-threatening birth defect,” Coakley said. “That is
especially true when treatment may be an option, either in-utero or immediately
after birth. The extra clarification available with an MRI can help parents
and their doctors decide on a plan of action.”
Coakley’s co-authors for the study included Filly and professor of surgery
Michael Harrison, MD, who are co-founders of UCSF’s Fetal Treatment Center;
Anthony J. Barkovich, MD, UCSF professor of radiology and chief of pediatric
neuroradiology; and Hedvig Hricak, MD, PhD, professor of radiology at UCSF.
NOTE TO REPORTERS: INTERVIEW AVAILABILITY
The UCSF and Harvard researchers will discuss their research at a press
conference in Chicago at 11:30 AM Wednesday, Dec. 1, 1999 at the annual meeting
of the Radiological Society of North America. Stories are embargoed until that
time. For details contact the RSNA press liaison at 312-558-1770. From 11/27 to
12/2, contact the RSNA annual meeting press office at 312) 791-6667.
Reporters preparing stories to meet the embargo may contact the UCSF
researchers in advance via UCSF news service at 415-476-2557. Because of
holiday and travel schedules they will be unavailable from November 24-28.
Interviews may be arranged with parents whose children’s treatment was changed
as a result of MRI information added to ultrasound.