MRI Adds to Ultrasound for Fetal Diagnosis

December 01, 1999
News Office: Janet Basu (415) 502-6397

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 researchers at UCSF Medical Center. In at least two cases, the MRI-based diagnosis led to treatments that saved the children's lives.

"Ultrasound is a wonderful tool, but sometimes it is limited in what it reveals," said Fergus Coakley, associate clinical professor of radiology at 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."

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.

In the UCSF study, a series of 45 pregnant patients 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 follow-up, MRI proved to be correct in two of those instances.

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 cases.

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 study co-author Dr. Roy Filly, a radiologist at UCSF Medical Center and chief of the fetal ultrasound service.

"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 of the UCSF Medical Center study included Filly and pediatric surgeon Dr. Michael Harrison, who are co-founders of UCSF's Fetal Treatment Center; Dr. Anthony J. Barkovich, chief of pediatric neuroradiology; and Dr. Hedvig Hricak, a radiologist.