Quick Brain Magnetic Resonance Imaging With Diffusion- Weighted Imaging as a First Imaging Modality in Pediatric Stroke

Pediatric arterial ischemic stroke (PAIS) is a rare occurrence but it is among the common causes of pediatric mortality. There is much that is yet to be learned about acute management of pediatric stroke but we do face some obstacles including time to diagnosis. Children often get CT scans as the initial mode of imaging at presentation but it has low sensitivity for PAIS, ranging from 17% to 53%, based on previous studies in children. MRI brain often cannot be done quickly either due to need for sedation or lack of availability of the scanner. The time to diagnosis in previous studies has ranged from 12 to 24 hours approximately, which could delay work up for etiology and further management.

This single center, retrospective chart review evaluated the time to diagnosis and sensitivity of quick brain MRI (T2-weighted fast spin-echo images) with diffusion weighted imaging (QB + DWI) vs CT head or full brain MRI as the initial study for suspected PAIS. Twenty-five patients age 1 month to 18 years met the inclusion criteria. The children who got QB + DWI first were younger than the population who got a CT head.  The authors found no statistically significant difference in median time from presentation to diagnostic study between the 3 groups. However, whereas the sensitivity of QB + DWI imaging for PAIS was 100%, that of head CT was only 27.3%.

The median duration of the QB + DWI imaging was 5 minutes. The authors proposed an algorithm which incorporated QB + DWI imaging in the initial diagnostic testing for suspected PAIS in children. A complete MRI brain and MRA was still recommended for children with confirmed PAIS.

The study has a few limitations one of which is the small sample size. There is also variability in the patient data including location at presentation and etiology of stroke which can potentially affect the time to performance of diagnostic study. Another obstacle to consider is the availability of MRI scanner which can often be a limited commodity in some institutions. However, the very short duration of the QB + DWI imaging is advantageous and may make this a viable option. The authors also point out that the sensitivity of the QB + DWI for hemorrhages is still not fully established and CT scan should be considered if there is high suspicion for a hemorrhage.

Despite the limitations, this study paves the way to much needed future studies that can analyze the advantages of QB + DWI imaging. QB + DWI imaging is a good alternative to a CT scan in suspected PAIS, and would avoid exposure to radiation. In cases with negative results it would also prove to be cost effective by avoiding performance of more expensive studies like a complete MRI brain and MRA head/neck, and could also avoid having to sedate a younger child.

Commentary- Sireesha Chinthaparthi, MD (Assistant Professor, University of Texas – Austin)

Abstract

BACKGROUND: Diagnostic delay hinders management of pediatric arterial ischemic stroke. Quick brain MRI with diffusion-weighted imaging sequences may provide a rapid diagnosis without the ionizing radiation of a computed tomography (CT) scan.

METHODS: This was a single center retrospective chart review of children one month to 18 years old with acute arterial ischemic stroke hospitalized between January 2010 and January 2017. We evaluated sensitivity and the time to diagnostic study based on the first imaging study (CT or quick brain MRI with diffusion- weighted imaging).

RESULTS: Twenty-five patients were included. Eleven patients (44%) were initially assessed with CT, 10 (40%) with quick brain MRI with diffusion-weighted imaging, and four (16%) with a full MRI. Compared with children undergoing CT, children with quick brain MRI with diffusion-weighted imaging as first study were younger (5.8 versus 14.1 years, P < 0.001) and were more likely to be hospitalized at stroke onset (70% versus 18.2%, P = 0.03). Quick brain MRI with diffusion-weighted imaging was more sensitive for ischemia than CT (100% versus 27.3%). The median time from presentation to diagnostic imaging was 4.3 hours, with no differences between CT and quick brain MRI with diffusion-weighted imaging groups, although the quick brain MRI with diffusion-weighted imaging group had a shorter median time from first imaging to diagnostic imaging (P = 0.002). There were no significant missed findings on quick brain MRI with diffusion-weighted imaging.

CONCLUSIONS: Quick brain MRI with diffusion- weighted imaging was more sensitive than CT for detecting ischemia and may be considered as the first study for some children presenting with suspected arterial ischemic stroke.

Pediatric Neurology 2018: 78, 55-60

https://doi.org/10.1016/j.pediatrneurol.2017.09.020