Elsevier

Resuscitation

Volume 187, June 2023, 109761
Resuscitation

Clinical paper
Association between the extent of diffusion restriction on brain diffusion-weighted imaging and neurological outcomes after an out-of-hospital cardiac arrest

https://doi.org/10.1016/j.resuscitation.2023.109761Get rights and content

Abstract

Background

This study evaluated the association between the extent of diffusion restriction on brain diffusion-weighted imaging (DWI) and neurological outcomes in patients who underwent targeted temperature management (TTM) after an out-of-hospital cardiac arrest (OHCA).

Methods

Patients who underwent brain magnetic resonance imaging within 10 days of OHCA between 2012 and 2021 were analysed. The extent of diffusion restriction was described according to the modified DWI Alberta Stroke Program Early Computed Tomography Score (DWI-ASPECTS). The 35 predefined brain regions were assigned a score if diffuse signal changes were concordantly present in DWI scans and apparent diffusion coefficient maps. The primary outcome was an unfavourable neurological outcome at 6 months. The sensitivity, specificity, and receiver operating characteristic (ROC) curves for the measured parameters were analysed. Cut-off values were determined to predict the primary outcome. The predictive cut-off DWI-ASPECTS was internally validated using five-fold cross-validation.

Results

Of the 301 patients, 108 (35.9%) had 6-month favourable neurological outcomes. Patients with unfavourable outcomes had higher whole-brain DWI-ASPECTS (median, 31 [26–33] vs. 0 [0–1], P < 0.001) than those with favourable outcomes. The area under the ROC curve (AUROC) of whole-brain DWI-ASPECTS was 0.957 (95% confidence interval [CI] 0.928–0.977). A cut-off value of ≥8 for unfavourable neurological outcomes had specificity and sensitivity of 100% (95% CI 96.6–100) and 89.6% (95% CI 84.4–93.6), respectively. The mean AUROC was 0.956.

Conclusion

More extensive diffusion restriction on DWI-ASPECTS in patients with OHCA who underwent TTM was associated with 6-month unfavourable neurological outcomes.

Running title: Diffusion restriction and neurological outcomes after cardiac arrest.

Introduction

A substantial proportion of patients who experienced out-of-hospital cardiac arrest (OHCA) die because of hypoxic-ischaemic brain injury. In these patients, the neurological prognosis should be evaluated when making decisions on care, including the continuation of critical care or the withdrawal of life-sustaining therapy.1

Among the modalities used for neurologic prognostication in patients with cardiac arrest, brain magnetic resonance imaging (MRI) interprets the degree of hypoxic-ischaemic brain injury.2, 3 Several studies have shown an association between unfavourable neurological outcomes and the burden of injury on fluid-attenuated inversion recovery (FLAIR) and diffusion MRI.2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 However, previous studies have small sample sizes, and the assessment methods used were not standardised. Furthermore, automated analysis methods such as apparent diffusion coefficient (ADC) metrics are difficult to directly apply to clinical practice due to the need for specific software and complex pre-processing of measurements in some software.4 If a standardised analysis method that can be easily used for obtaining measurements is developed, the clinical usefulness of brain MRI in evaluating the neurological prognosis of patients with OHCA could increase.

The Alberta Stroke Program Early Computed Tomography Score (ASPECTS) was used to rapidly screen the extent of early ischaemic changes on brain computed tomography (CT) scans of patients with stroke.15 This tool is a semi-quantitative method for measuring scores by dividing the territory of the middle cerebral artery.15 Considering that global hypoxic-ischaemic brain injury commonly occurs, the ASPECTS can be used to assess for the presence of injury from the middle cerebral artery to the territory of other cerebral arteries. Thus, estimating the volume of cytotoxic oedema observed on brain MRI may be possible. It may also be an alternative to standardisation because it is a simple modification of the existing method. Previous studies have used a modified ASPECTS version to screen the extent of ischaemic changes on brain CT scans and evaluate the neurological prognosis of patients with OHCA.16, 17, 18 However, this novel scoring method has not yet been used for acute brain MRI.

Thus, this study aimed to evaluate the association between the extent of diffusion restriction using modified ASPECTS on brain diffusion-weighted imaging (DWI) and neurological outcomes in patients who underwent targeted temperature management (TTM) after an OHCA.

Section snippets

Study design and population

This retrospective observational study used a prospectively maintained registry of patients admitted to the intensive care unit of Samsung Changwon Hospital for post-cardiac arrest care between January 2012 and September 2021. This registry enrolled patients who underwent TTM after an OHCA.

Participants

Patients aged >15 years who experienced OHCA and underwent TTM were included. Patients who did not undergo a brain MRI were excluded. In addition, considering the possibility of pseudo-normalisation, patients

Results

During the study period, 449 patients who underwent TTM after OHCA were enrolled in the hospital registry. Among them, 1 patient aged <15 years, 141 who did not undergo MRI, and 6 who underwent MRI 10 days after the ROSC were excluded. MRI was not performed for the following reasons: death prior to MRI (n = 97), early awakening (n = 27), refusal of examination (n = 15), discretion of the treating physician (n = 9), unstable vital signs (n = 5) and organ donation (n = 3). The remaining 301

Discussion

This study showed that the extent of diffusion restriction using a semi-quantitative scoring system for assessing the extent of ischaemic changes on brain DWI after an OHCA is associated with neurological outcomes at 6 months.

In this study, DWI showed clear diffusion restrictions due to hypoxic injury in the cerebral cortex and deep grey nuclei. The distribution of whole-brain DWI-ASPECTS according to the neurological outcomes at 6 months had an almost “U”-shaped appearance (Fig. 2). That is,

Conclusion

The DWI-ASPECTS showed a high degree of accuracy in predicting unfavourable neurological outcomes in patients with OHCA who underwent TTM. This finding requires external validation in other study settings.

CRediT authorship contribution statement

Jong Yoon Park: Methodology, Formal analysis. Yong Hwan Kim: Conceptualization, Data curation, Writing – original draft. Seong Jun Ahn: Writing – original draft. Jun Ho Lee: Investigation. Dong Woo Lee: Conceptualization, Methodology. Seong Youn Hwang: Supervision. Yun Gyu Song: Validation, Investigation, Project administration.

Conflicts of interest

None.

Acknowledgements

The authors thank Mi Hyeon Jin for providing statistical advice for this study.

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