Brain MR imaging and spectroscopy for outcome prognostication after pediatric cardiac arrest

Abstract

Aim: Children surviving cardiac arrest are at high risk of neurological morbidity and mortality; however, there is a lack of validated prognostic biomarkers. We aimed to evaluate brain magnetic resonance imaging (MRI) and spectroscopy (MRS) as predictors of death and disability. Secondly, we evaluated whether MRI/S by randomized group.

Methods: This single center study analyzed clinically indicated brain MRI/S data from children enrolled in a randomized controlled trial of 24 vs. 72 h of hypothermia following cardiac arrest. Two pediatric radiologists scored conventional MRIs. Lactate and N-acetyl-aspartate (NAA) concentrations (mmol/kg) were determined from spectra acquired from the basal ganglia, thalamus, parietal white matter and parietooccipital gray matter. Mortality and neurological outcomes (favorable = Pediatric Cerebral Performance Category [PCPC] 1, 2, 3 or increase < 2) were assessed at hospital discharge. Non-parametric tests were used to test for associations between MRI/S biomarkers and outcome and randomized group.

Results: 23 children with (median [interquartile range]) age of 1.5 (0.3-4.0) years. Ten (44%) had favorable outcome. There were more T2 brain lesions in the lentiform nuclei in children with unfavorable 12 (92%) vs. favorable 3 (33%) outcome, p = 0.007. Increased lactate and decreased NAA concentrations in the parietooccipital gray matter and decreased NAA in the parietal white matter were associated with unfavorable outcome (p's < 0.05). There were no differences for any biomarker by randomized group.

Conclusion: Regional cerebral and metabolic MRI/S biomarkers are predictive of neurological outcomes at hospital discharge in pediatric cardiac arrest and should undergo validation testing in a large sample.

Trial registration: ClinicalTrials.gov NCT00797680.

Keywords: Cardiac arrest; Magnetic resonance imaging; Magnetic resonance spectroscopy; Outcome; Pediatric; Prognostication.

Figure 1.

Magnetic resonance spectroscopy regions of interest. A) Basal ganglia: caudate (C) and putamen (P); B) Parietooccipital gray matter; C) Parietal white matter; and D) Thalamus (T). CC, corpus callosum.

Figure 2.

CONSORT diagram of patients who received imaging after enrollment into the parent randomized, controlled trial.

Figure 3.

A previously well 3-year old child with severe asthma, respiratory failure, and asphyxia cardiac arrest peri-intubation in the intensive care unit. A) Axial T2-weighted and B) Diffusion-weighted MRI 9 days post-arrest showing injury to the basal ganglia (solid arrow), occipital lobe (dashed arrow), and cerebellum (dotted arrow). Spectra from the C) basal ganglia, D) thalamus, E) occipitoparietal gray and F) parietal white matter regions of interest show possibly mildly decreased N-acetyl-aspartate (NAA, arrows) and a small lactate (Lac) signal. Signals from creatine (Cr) and choline (Cho) are also labeled. Shown are the unprocessed data (thin black lines) with the superimposed fit (thick gray lines) used for quantitation. The patient had mild neurologic disability at hospital discharge and no noticeable disability at 6 months follow-up.

Figure 4.

A previously well 4-month old child with asphyxial cardiac arrest at home. A) Axial T2-weighted and B) Diffusion-weighted brain MRI 3 days post-arrest showing injury to the basal ganglia (solid arrow), thalamus (dashed arrow), occipital lobe (dotted arrow), and cerebellum (dotted arrow). Spectroscopy studies performed in the C) basal ganglia, D) thalamus, E) occipital/parietal gray matter and F) parietal white matter regions of interest show decreased NAA in all regions being particularly pronounced in gray matter. In addition, lactate (and underlying lipids) is increased in gray matter consistent with acute and significant hypoxic ischemic brain injury in this region. The patient died following withdrawal of support due to severe neurologic injury.