By Lucy Piper, medwireNews Reporter
medwireNews: Research suggests that magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) conducted within 2 weeks of a cardiac arrest may help determine longer-term outcomes in children.
The results showed that higher MRI injury score, as well as increased lactate and decreased N-acetylaspartate (NAA) in the basal ganglia, thalamus, parietal white matter and parietooccipital grey matter on MRS were all associated with an unfavourable outcome, defined as a death or survival with a Vineland Adaptive Behavior Scales score below 70, at 1 year.
As reported in JAMA Network Open, outcome data were assessed between January 2022 and February 2023 for 98 children aged between 48 hours and 17 years from the POCCA prospective cohort study. They had been resuscitated from in-hospital or out-of-hospital cardiac arrest and had a clinical brain MRI or MRS performed within 14 days of the arrest.
Of these children, 66 underwent brain MRI. They were aged a median 1 year, 42.4% were girls and the majority (69.7%) were White. The MRI was performed routinely a median 5 days after cardiac arrest and was scored and analysed by two paediatric neurologists.
In all, 23 (34.8%) children had an unfavourable outcome. These children had significantly higher MRI injury scores, a sum of T2-weighted and diffusion-weighted imaging (DWI) for all brain regions, at a median 22 (ranging from 7–32) compared with 1 (0–8) among those with a favourable outcome.
Ericka Fink (University of Pittsburgh Medical Center Children’s Hospital of Pittsburgh, Pennsylvania, USA) and colleagues report that children with unfavourable outcomes were more likely than the other children to have lesions of any severity on T-2 weighted imaging in the thalamus (65.2 vs 11.6%), basal ganglia lenticular nucleus (56.5 vs 11.6%) and basal ganglia caudate nucleus (47.8 vs 7.0%).
On DWI, lesions in all regions, except for the posterior limb of the internal capsule, were more frequent among those with unfavourable versus favourable outcomes, with rates ranging from 21.7% versus 4.7% in the cerebellum to a respective 69.6% versus 18.6% in the parietal lobe.
According to the severity of the lesions, the regions most affected among those with an unfavourable outcome were temporal lobe grey matter, parietal lobe white matter, and the basal ganglia, thalamus and centrum semiovale.
MRI injury score was significantly associated with the likelihood of a poor 1-year outcome (odds ratio [OR]=1.12) after accounting for patient age and sex. In combination with witnessed event status, it predicted an unfavourable outcome with an “excellent” accuracy of 88.6%, say the researchers, which was higher than the 75.5% accuracy achieved using clinical variables alone.
Both deep grey matter injury scores with T-2 weighted imaging and DWI were significantly associated with poor 1-year outcomes, with ORs of 1.70 and 2.01, respectively, and accuracies for predicting unfavourable outcome of 88.8% and 90.0%.
“We were able to show an association of MRI injury score with outcomes, which can be used to support shared decision-making”, comment Fink and team.
Noting that MRS metabolites may “offer better stability over time”, compared with MRI lesions, they obtained MRS data from the basal ganglia, thalamus, parietal-occipital white matter and parietal-occipital grey matter in 32 children aged a median 1 year (40.6% girls, 65.6% White), 37.5% of whom had an unfavourable outcome.
Lactate was significantly increased in all four regions of interest in children with an unfavourable compared with a favourable outcome, with differences ranging from 1.0 versus 0.4 IU in the basal ganglia and 2.8 versus 0.3 IU in the parietal-occipital grey matter.
Significant decreases in NAA were also seen in association with unfavourable versus favourable outcome, with differences ranging from 4.8 IU versus 2.9 IU in the basal ganglia and 5.2 IU versus 2.6 IU in the parietal-occipital white matter.
This meant that the ratio of lactate to NAA was also significantly higher in those children with an unfavourable outcome.
On univariate analysis, increased lactate and decreased NAA in all four regions were significantly associated with the risk for unfavourable outcome, with respective accuracies of between 77.6% and 89.8%, and 75.0% and 83.0%.
Multivariable analysis was not conducted for MRS measures due to the small sample size, which resulted in large confidence intervals, the researchers note.
They say the study “suggests that MRS may provide additional key information” and provides support for “the potential utility for MRS as an objective prognostic biomarker in pediatric cardiac arrest.”
However, the investigators add: “Still, more work is needed to demonstrate that MRS improves the diagnostic accuracy of clinical variables and conventional MRI.”
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JAMA Netw Open 2023; 6: e2320713