Association Between Quantitative Diffusion-Weighted Magnetic Resonance Neuroimaging and Outcome After Pediatric Cardiac Arrest
Matthew P. Kirschen, Jeffrey Berman, Hongyan Liu, Minhui Ouyang, Antara Mondal, Heather Griffis, Cindee Levow, Madeline Winters, Shih‐Shan Lang, Jimmy W. Huh, Hao Huang, Robert A. Berg, Arastoo Vossough, Alexis Topjian
Abstract
<h3>Background and Objectives</h3> 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<sup>−6</sup> mm<sup>2</sup>/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. <h3>Methods</h3> 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. <h3>Results</h3> One hundred thirty-four patients were analyzed. Patients with ADC <650 × 10<sup>−6</sup> mm<sup>2</sup>/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<sup>−6</sup> mm<sup>2</sup>/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<sup>−6</sup> mm<sup>2</sup>/s below each patient9s 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]). <h3>Discussion</h3> 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. <h3>Classification of Evidence</h3> This study provides Class III evidence that quantitative diffusion-weighted imaging within 7 days postarrest can predict an unfavorable clinical outcome in children.