In the setting of a traumatic brain injury, imaging can be key to diagnosis. Computed tomography (CT) has been the go-to imaging modality for its accuracy and feasibility. Yet we are also aware of the radiation risks of CT scans in young children, making it essential that we not over-scan and when we do scan, we need to ensure that the radiation exposure to a child is minimized. An alternative to this strategy has been the development of “fast magnetic resonance imaging (MRI).” With this strategy, children can be scanned quickly without sedation. This decreases the risk of motion artifact and the risk of sedation. How accurate is fast MRI? Lindberg et al. (10.1542/peds.2019-0419) share with us one of the most informative studies to date comparing CT to fast MRI in children under 6 years of age, 225 of whom had a CT scan and 223 successfully also had a fast MRI. The authors found that using CT as the criterion standard, the sensitivity of fast MRI was 92.8% with six patients missed but with relatively minor findings not requiring change in treatment. They also identified 5 injuries not identified by CT also minor from a TBI standpoint. It took a median time of 59 seconds for CT imaging and 365 seconds for fast MRI.
Should fast MRI become the new standard for imaging children with traumatic brain injuries instead of CT? Not so fast says an accompanying commentary on this study by Drs. Brett Burstein and Christine Saint-Martin (10.1542/peds.2019-2387) from Montreal Children’s Hospital. The authors note that while there may be benefit to fast MRI, there are some substantive limitations to this study that do not yet make it the recommended standard. For example, the total time involved from leaving the ED to returning from the fast MRI is far longer than for CT, and if a patient were not stable, problems could occur in a delay to operate while going through the MRI process. The patients who did receive fast MRI after CT were relatively stable and the findings may not be generalizable for patients less stable where time is of the essence. Appropriate staffing to perform a fast MRI and read it may also be an issue, especially at night. Yet fast MRI may be well worth doing for some children with suspected traumatic brain injury where immediate rapid imaging is less critical. Read this study and commentary, and hopefully the exposure to both will help you better decide just who needs a CT and who might be spared radiation through a fast MRI.
