Abstract 103: Quantitative Analysis of Apparent Diffusion Coefficients to Predict Neurological Prognosis in Cardiac Arrest Survivors: An Observational Derivation and Internal-External Validation Study

Abstract

Aim: Our study aimed to develop apparent diffusion coefficient (ADC) values and thresholds to predict poor outcomes in out-of-hospital cardiac arrest (OHCA) survivors by quantitatively analyzing ADC values in brain MRI. Methods: This observational study utilized prospectively collected data two tertiary academic hospitals. The derivation cohort comprised 70% of patients randomly selected from one hospital, whereas the internal validation cohort comprised the remaining 30%. The external validation cohort used data from the other hospital. MRI data were restricted to scans conducted at 3T within 72-96 h after OHCA. We analyzed the % voxels of ADC thresholds (percentage of voxels below ADC thresholds per total voxel [PV]) at 50-step intervals ranging from 200 to 1200 х 10 -6 mm/s. Poor neurological outcomes were defined as cerebral performance categories 3-5 at 6 months after OHCA. Results: In total, 448 brain MRI scans were evaluated, including a derivation cohort (n=224) and internal/external validation cohorts (n=96 and 128, respectively). The PV values of 500, 550, 600, 650 and 700 х 10 -6 mm/s were determined using the area under the curve (AUC) and demonstrated better performance than higher values in predicting poor neurological outcomes across the derivation (AUC 0.90-0.91), internal validation (AUC 0.87-0.91), and external validation cohorts (AUC 0.91-0.92), showing similar performance levels. A PV of 600х10 -6 mm/s predicted a poor outcome with 100% specificity at a threshold of >13.2% in the derivation cohort, with a sensitivity of 74% (95% CI 66-81) at 100% specificity. In both the internal and external validation cohorts, when using the same threshold, a specificity of 100% corresponded to sensitivities of 75% (95% CI 63-85) and 78% (95% CI 66-87), respectively (Figure). Conclusions: Quantitative analysis of ADC values in brain MRI is a promising tool for predicting poor neurological outcomes in OHCA survivors, with high sensitivity at a specificity of 100%.