"With echocardiography, the heart looks like a shadow. It looks more like a heart with real-time MRI, with excellent soft tissue contrast", stated paediatric cardiologist Mark A. Fogel, M.D., director of Cardiac MRI at the Children's Hospital of Philadelphia. A research team led by Dr. Fogel reported preliminary findings based on studies on two foetuses in the September/October 2005 issue of Fetal Diagnosis and Therapy. It was the first example of functional MRI used for cardiac imaging in foetuses.
MRI produces three-dimensional images, whereas echocardiography typically relies on geometric assumptions to measure how big the heart is in the foetus, added Dr. Fogel. One consequence of this capability is that MRI can directly measure the volume of the heart's ventricles.
Echocardiography, which uses reflected ultrasound waves to produce images, may allow physicians to estimate such volumes, but only if the heart has a normal shape. "Many heart diseases involve abnormal shapes, and accurately measuring ventricular volume in such cases is important in assessing how well the heart is working, and in guiding doctors to the most appropriate treatment", stated Dr. Fogel.
"For example, if the foetus has poor heart function, a physician might prescribe a drug that improves pumping, or might recommend an earlier delivery", he added. "Better knowledge of specifics of a heart's structure and function could help the physician and parents better prepare for surgery on the infant after birth. This technology may also be useful in determining how the heart becomes malformed in the mother's womb."
Although further studies will be necessary to build on his team's preliminary results, Dr. Fogel suggests that foetal cardiac MRI may be used to complement echocardiography in cases where the latter technology cannot adequately visualize heart structures.
Furthermore, he added, advances in MRI technology may enhance its medical capabilities for foetal medicine. Previously, foetal movement blurred MRI imaging, but as shown in the current study, real-time functional MRI provides usable images in an unsedated, moving fetus. "We expect future MRI technology to provide better resolution and sharper images, produced in shorter times", he stated. "Our study is a first step in that direction."
In addition to Dr. Fogel, co-authors of the study from the Children's Hospital of Philadelphia were Jack Rychik, M.D., and Zhi-Yun Tian, M.D., of the Cardiac Center; R. Douglas Wilson, M.D., Alan Flake, M.D., and Mark Johnson, M.D., of the Center for Foetal Diagnosis and Treatment; and David Cohen, M.D., of the Department of Anaesthesiology and Critical Care Medicine. The Children's Hospital physicians also are faculty members of the University of Pennsylvania School of Medicine. Gary McNeal of Siemens Medical Systems, Malvern, Pennsylvania, also was a co-author.
The Foetal Heart Programme of the Children's Hospital of Philadelphia is part of the hospital's Cardiac Center, named the best paediatric cardiology programme in the United States by Child magazine. The Foetal Heart Programme provides state-of-the-art prenatal diagnosis, monitoring and follow-up care to pregnant women and their unborn children, prior to and following birth. The team includes cardiologists, cardiothoracic surgeons, obstetricians, nurses, technologists, social workers, child life specialists and lactation consultants.
The Children's Hospital of Philadelphia was founded in 1855 as the nation's first paediatric hospital. Through its long-standing commitment to providing exceptional patient care, training new generations of paediatric health care professionals and pioneering major research initiatives, Children's Hospital has fostered many discoveries that have benefited children worldwide. Its paediatric research programme is among the largest in the country, ranking second in National Institutes of Health funding. In addition, its unique family-centred care and public service programmes have brought the 430-bed hospital recognition as a leading advocate for children and adolescents.