Introduction

In Sweden, head computed tomography (CT) is commonly used for prediction of neurological outcome after cardiac arrest, as recommended by guidelines. We compare the prognostic ability and interrater variability of routine and novel CT methods for prediction of poor outcome.

Methods

Retrospective study including patients from Swedish sites within the Target Temperature Management after out-of-hospital cardiac arrest trial examined with CT. Original images were assessed by two independent radiologists blinded from clinical data with eye-balling without pre-specified criteria, and with a semi-quantitative assessment. Grey-white-matter ratios (GWR) were quantified using models with 4–20 manually placed regions of interest. Prognostic abilities and interrater variability were calculated for prediction of poor outcome (modified Rankin Scale 4–6 at 6 months) for early (<24 h) and late (≥24 h) examinations.

Results

68/106 (64 %) of included patients were examined < 24 h post-arrest. Eye-balling predicted poor outcome with 89–100 % specificity and 15–78 % sensitivity. GWR < 24 h predicted neurological outcome with unsatisfactory to satisfactory Area Under the Receiver Operating Characteristics Curve (AUROC: 0.54–0.64). GWR ≥ 24 h yielded very good to excellent AUROC (0.80–0.93). Sensitivities increased > 2–3-fold in examinations performed after 24 h compared to early examinations. Combining eye-balling with GWR < 1.15 predicted poor outcome without false positives with sensitivities remaining acceptable.

Conclusion

In our cohort, qualitative and quantitative CT methods predicted poor outcome with high specificity and low to moderate sensitivity. Sensitivity increased relevantly after the first 24 h after CA. Interrater variability poses a problem and indicates the need to standardise brain CT evaluation to increase the methods’ safety.

中文翻译：

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心脏骤停后头部计算机断层扫描预测不良结果方法的初步研究

介绍

在瑞典，根据指南的建议，头部计算机断层扫描 (CT) 通常用于预测心脏骤停后的神经系统结果。我们比较了常规和新型 CT 方法在预测不良结果方面的预后能力和测量者间变异性。

方法

一项回顾性研究，包括在使用 CT 检查的院外心脏骤停试验后，目标温度管理范围内的瑞典站点的患者。原始图像由两名对临床数据不知情的独立放射科医师在没有预先指定标准的情况下使用眼球法进行评估，并进行半定量评估。使用具有 4-20 个手动放置的感兴趣区域的模型对灰白质比 (GWR) 进行量化。计算预后能力和测量者间变异性以预测早期（<24 小时）和晚期（≥24 小时）检查的不良结果（6 个月时改良 Rankin 量表 4-6）。

结果

68/106 (64 %) 的患者在逮捕后 24 小时内接受了检查。目测以 89-100% 的特异性和 15-78% 的敏感性预测不良结果。GWR < 24 小时预测神经系统结果，接受者操作特征曲线下的面积不令人满意（AUROC：0.54-0.64）。GWR ≥ 24 小时产生非常好到极好的 AUROC (0.80–0.93)。与早期检查相比，24 小时后进行的检查的敏感性增加了 > 2-3 倍。将眼球检查与 GWR < 1.15 相结合，预测结果不佳，没有误报，敏感性仍然可以接受。

结论

在我们的队列中，定性和定量 CT 方法以高特异性和低至中等敏感性预测不良结果。CA 后第一个 24 小时后敏感性相应增加。评估者间的变异性带来了一个问题，表明需要标准化脑 CT 评估以提高方法的安全性。