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Association Between Quantitative Diffusion-Weighted Magnetic Resonance Neuroimaging and Outcome After Pediatric
Matthew P Kirschen1, Jeffrey I Berman2, Hongyan Liu2
1From the Departments of Anesthesiology and Critical Care Medicine (M.P.K., C.L., M.W., J.H., R.A.B., A.T.), and Radiology (J.I.B., M.O., H.H., A.V.); Data Science and Biostatistics Unit (H.L., A.M., H.G.), Department of Biomedical and Health Informatics, and Department of Neurosurgery (S.-S.L.), Children's Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia. kirschenm@chop.edu.
Insights
Diffusion MRI can predict outcomes after pediatric cardiac arrest. Age-dependent apparent diffusion coefficient (ADC) thresholds show improved accuracy in identifying unfavorable neurologic outcomes in children.
Area of Science:
- Neurology
- Radiology
- Pediatrics
Background:
- Diffusion MRI quantifies hypoxic-ischemic brain injury.
- Adult ADC thresholds may not apply to pediatric cardiac arrest outcomes.
Purpose of the Study:
- Determine if adult ADC thresholds predict outcomes in pediatric cardiac arrest.
- Investigate novel age-dependent ADC thresholds for improved prediction.
- Assess age-normalized whole-brain mean ADC association with outcomes.
Main Methods:
- Retrospective study of pediatric patients (≤18 years) post-cardiac arrest with MRI within 7 days.
- Assessed unfavorable neurologic status via Pediatric Cerebral Performance Category score.
- Calculated apparent diffusion coefficient (ADC) thresholds and whole-brain mean ADC.
Main Results:
- An age-independent ADC threshold (>10% voxels <650 × 10-6 mm2/s) showed 15x higher odds of unfavorable outcome.
- Age-dependent ADC thresholds (<300 × 10-6 mm2/s below predicted mean) improved sensitivity and specificity.
- Lower age-normalized whole-brain mean ADC also correlated with unfavorable outcomes.
Conclusions:
- Quantitative diffusion MRI thresholds within 7 days post-cardiac arrest predict outcomes in children.
- Age-dependent ADC thresholds enhance prognostic accuracy compared to age-independent ones.
- Further research with larger cohorts is recommended for age-dependent ADC thresholds.
Background And Objectives:
Diffusion MRI can quantify the extent of hypoxic-ischemic brain injury after cardiac arrest. Our objective was to determine the association between the adult-derived threshold of apparent diffusion coefficient (ADC) <650 × 10-6 mm2/s in >10% of brain tissue and an unfavorable outcome after pediatric cardiac arrest. Since ADC decreases exponentially as a function of increasing age, we determined the association between (1) having >10% of brain tissue below a novel age-dependent ADC threshold, and (2) age-normalized whole-brain mean ADC and unfavorable outcome.
Methods:
This was a retrospective study of patients aged ≤18 years who had cardiac arrest and a clinically obtained brain MRI within 7 days. The primary outcome was unfavorable neurologic status at hospital discharge based on the Pediatric Cerebral Performance Category score. ADC images were extracted from 3-direction diffusion imaging. We determined whether each patient had >10% of voxels with an ADC below prespecified thresholds. We computed the whole-brain mean ADC for each patient.
Results:
One hundred thirty-four patients were analyzed. Patients with ADC <650 × 10-6 mm2/s in >10% of voxels had 15 times higher odds (95% CI 5-65) of an unfavorable outcome compared with patients with ADC <650 × 10-6 mm2/s (area under the receiver operating characteristic curve [AUROC] 0.72 [95% CI 0.63-0.80]). These ADC criteria had a sensitivity and specificity of 0.49 and 0.94, respectively, and positive and negative predictive values of 0.93 and 0.52, respectively, for an unfavorable outcome. The age-dependent ADC threshold that yielded optimal sensitivity and specificity for unfavorable outcomes was <300 × 10-6 mm2/s below each patient's predicted whole-brain mean ADC. The sensitivity, specificity, and positive and negative predictive values for this ADC threshold were 0.53, 0.96, 0.96, and 0.54, respectively (odds ratio [OR] 26.4 [95% CI 7.5-168.3]; AUROC 0.74 [95% CI 0.66-0.83]). Lower age-normalized whole-brain mean ADC was also associated with an unfavorable outcome (OR 0.42 [0.24-0.64], AUROC 0.76 [95% CI 0.66-0.82]).
Discussion:
Quantitative diffusion thresholds on MRI within 7 days after cardiac arrest were associated with an unfavorable outcome in children. The age-independent ADC threshold was highly specific for predicting an unfavorable outcome. However, the specificity and sensitivity increased when using age-dependent ADC thresholds. Age-dependent ADC thresholds may improve prognostic accuracy and require further investigation in larger cohorts.
Classification Of Evidence:
This study provides Class III evidence that quantitative diffusion-weighted imaging within 7 days postarrest can predict an unfavorable clinical outcome in children.
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