# Comparison of non-contrast CT, CT perfusion, and CT angiography for predicting delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage

## TL;DR

Non-contrast CT scans at admission are better than other imaging methods for predicting delayed cerebral ischemia in aneurysmal subarachnoid hemorrhage patients.

## Contribution

This study compares the predictive accuracy of non-contrast CT, CT perfusion, and CT angiography for delayed cerebral ischemia in aneurysmal subarachnoid hemorrhage patients.

## Key findings

- The NCCT model had the highest predictive accuracy (AUC: 0.837) compared to CTP and CTA models.
- All three models showed good calibration and reliable internal validation results.
- In poor-grade aSAH patients, NCCT and CTP models had similar predictive abilities.

## Abstract

Non-contrast CT (NCCT), CT perfusion (CTP), and CT angiography (CTA) are recommended for predicting delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH). However, not all patients can undergo all three examinations on admission. We aimed to compare the predictive abilities of NCCT, CTP, and CTA for DCI.

This retrospective study enrolled consecutive aSAH patients admitted to our center between November 2015 and September 2023. NCCT, CTP, and CTA models were constructed using logistic regression analyses adjusted for confounders. The model performances were assessed by discrimination and calibration. Internal validation was conducted using bootstrapping. The predictive abilities were further evaluated in subgroup analyses.

A total of 950 patients (median [IQR] age: 59 [51–68] years; 651 women) were enrolled, of whom 246 (25.9%) developed DCI. The NCCT model had an area under the curve (AUC) of 0.837 (95% CI: 0.808–0.866), and was superior to the CTP (AUC: 0.783; 95% CI: 0.748–0.818; p < 0.001) and CTA (AUC: 0.760; 95% CI: 0.723–0.797; p < 0.001) models. All three models had good calibration ability (all p > 0.05). Internal validation showed satisfactory discrimination ability (optimism-adjusted AUC: 0.840 for the NCCT model, 0.785 for the CTP model, and 0.761 for the CTA model). The NCCT and CTP models exhibited similar predictive abilities (AUC: 0.763 vs. 0.735; p = 0.399) in the poor-grade aSAH (World Federation of Neurological Surgeons 4–5) group.

The NCCT model performed better than the CTP and CTA models for predicting DCI and was comparable to the CTP model in poor-grade aSAH patients.

For most aneurysmal subarachnoid hemorrhage patients, non-contrast CT performed at emergency admission is sufficient to evaluate disease severity and reliably predict the risk of delayed cerebral ischemia.

More straightforward and reliable indicators are required to facilitate early delayed cerebral ischemia prediction.The non-contrast CT model, utilizing admission variables, was most predictive of delayed cerebral ischemia.Non-contrast CT at admission reliably predicts delayed cerebral ischemia risk and severity in most aneurysmal subarachnoid hemorrhage patients.

More straightforward and reliable indicators are required to facilitate early delayed cerebral ischemia prediction.

The non-contrast CT model, utilizing admission variables, was most predictive of delayed cerebral ischemia.

Non-contrast CT at admission reliably predicts delayed cerebral ischemia risk and severity in most aneurysmal subarachnoid hemorrhage patients.