Visiting Professor Charles Dumoulin, Scientific Director of the Imaging Research Centre at Cincinnati Children’s Hospital, USA, gives two guest lectures during September. Details of the second lecture are also online.
To overcome the challenges of imaging premature babies, a team of scientists and engineers at Cincinnati Children’s Hospital Medical Center (CCHMC) has created a new type of MR scanner that is small enough to be placed directly in the NICU. These 1.5 Tesla MR scanners employ the same strong magnetic field used in most Radiology departments, but have a footprint of only a few square feet.
The small size of the new NICU scanner offers advantages over large-bore systems. For example, the new NICU systems employ a gradient subsystem that is twice as fast and twice as strong as that found in a conventional adult-sized MR system. This increase in gradient performance is key to pushing the NICU systems’ imaging capability. Because the gradient coils are smaller, however, they also provide a substantial reduction in acoustic noise.
The NICU MRI scanner at CCHMC has been successfully tested in a pilot study of 15 babies. The scanner met all expectations, and provided MR images that matched or exceeded that possible with a conventional large-bore system.
On average, the imaging protocols were found to be 11 dBA quieter than a conventional system, and with hearing protection, all babies were exposed to less than 64 dBA acoustic noise during scanning (i.e. equivalent to a normal conversation). More significant was the reduction in time needed to move the baby from its crib, to the scanner, and back.
Because the NICU scanner is co-located with the babies, and because the scanner is customized for infants, the average transport time (bed to scanner and back) was less than 30 minutes. This is a dramatic improvement over the current practice of moving babies between departments, which is often a multi-hour ordeal.
With the success of the pilot study, the neonatologists and radiologists at CCHMC have begun to use the new system for clinical MR scanning. While most scanning is expected to be performed on the brain, research programs focusing on lung and abdominal imaging are ramping up.
For the first time, researchers and clinicians can envision bringing the full power of diagnostic MRI to bear on problems of prematurity, including: respiratory distress syndrome, vascular malformations, and necrotizing enterocolitis (NEC). Although ultrasound and X-ray imaging systems are available in many NICUs today, MRI has so much more to offer. Ultrasound imaging is limited by the restriction of bone anatomy on acoustic windows, and X-ray has safety concerns arising from ionizing radiation and non-benign contrast agents. Neither of these traditional modalities is well-suited for visualizing soft tissue.
These barriers will continue to be intractable, while the limitations of MRI are now strictly technical in nature. Thus, the research efforts enabled by this new generation of MR scanner provide the strongest and most promising approach to improving diagnostic imaging of premature infants.
The NICU MRI scanner developed at CCHMC provides an opportunity to revisit almost everything that is known about MRI. MR’s new-found accessibility to neonates will open up new clinical horizons, and the capabilities of the new scanner will take MRI into realms that are not possible with large-bore MR systems. No longer will the premature baby’s small size put him/her at a disadvantage when it comes to MR, but instead it will enable MR imaging beyond that possible in an adult scanner.