Role of Computed Tomography Angiography Enhancement Ratio in Predicting Prognosis in Patients With Stroke Undergoing Endovascular Treatment

Abstract

Background

The computed tomography angiography enhancement ratio (CTA‐ER), calculated through the net water uptake formula, is a valuable predictive tool for detecting adverse events after stroke. However, limited research has investigated the correlation between CTA‐ER and the prognosis of patients receiving endovascular treatment. Therefore, we aimed to examine whether CTA‐ER could predict favorable outcomes in patients undergoing endovascular treatment.

Methods

We conducted a retrospective study enrolling patients with acute anterior circulation large‐vessel occlusive stroke undergoing endovascular treatment between January 2016 and January 2023. All patients received noncontrast computed tomography and computed tomography angiography scans upon admission. Multivariate logistic regression analysis and receiver operator characteristic curve were used to assess the predictive efficacy in determining favorable outcomes. The favorable outcome at 90 days was a modified Rankin scale score of 0 to 2.

Results

A total of 206 participants (median age, 68 [60–77] years; 77 women) were included in the study, with 82 (39.8%) individuals demonstrating favorable outcomes. Patients with favorable outcomes had lower noncontrast computed tomography net water uptake (6.42% versus 7.76%; P < 0.001) and CTA‐ER (8.31% versus 10.56%; P < 0.001). Multivariate logistic regression analysis identified that CTA‐ER was a significant predictor for favorable outcomes (P<0.05 in all models). Furthermore, the receiver operator characteristic analysis revealed that CTA‐ER exhibited superior predictive performance, surpassing noncontrast computed tomography net water uptake (area under the curve, 0.707 versus 0.636, Delong test; P = 0.046).

Conclusion

CTA‐ER is a significant predictor of favorable outcomes in patients with acute large‐vessel occlusion stroke undergoing endovascular treatment.

Nonstandard Abbreviations and Acronyms

ASPECTS

The Alberta Stroke Program Early CT Score

CTA‐ER

computed tomography angiography enhancement ratio

EVT

endovascular treatment

HU

Hounsfield unit

NCCT

noncontrast computed tomography

NIHSS

National Institutes of Health Stroke Scale

NWU

net water uptake

Clinical Perspective

What Is New?

• The computed tomography angiography enhancement ratio offers a novel perspective for the early evaluation of patients with acute large‐vessel occlusion stroke.

What Are the Clinical Implications?

• The computed tomography angiography enhancement ratio can predict the prognosis of patients with stroke undergoing endovascular treatment.

In recent years, several randomized controlled studies have provided evidence that endovascular treatment (EVT) has emerged as the primary therapeutic approach for patients with acute large‐vessel occlusion stroke within the 6‐hour time window. ¹ , ² The DAWN (DWI or CTP Assessment With Clinical Mismatch in the Triage of Wake Up and Late Presenting Strokes Undergoing Neurointervention With Trevo) and DEFUSE3 (Endovascular Therapy Following Imaging Evaluation for Ischemic Stroke) trials have effectively expanded the allowable time window for EVT implementation to 24 hours. ³ , ⁴ , ⁵ Nevertheless, despite the early adoption of EVT, a significant proportion of treated patients continue to face unfavorable outcomes. ⁶ , ⁷ Therefore, effective early warning indicators are imperative for patients undergoing EVT.

Neuroimaging plays a pivotal role in the early stratification of patients with acute ischemic stroke, thereby effectively enhancing the favorable prognosis rate among individuals undergoing EVT. ⁵ , ⁸ Net water uptake (NWU) is an innovative method based on noncontrast computed tomography (NCCT) density alterations, which is employed to quantify water absorption in ischemic tissue and quantitatively evaluate the extent of brain edema and tissue injury. ⁹ , ¹⁰ NWU can effectively predict adverse events following stroke, such as malignant infarction and symptomatic intracranial hemorrhage. ¹¹ , ¹² However, identifying ischemic changes in computed tomography (CT) density is challenging during the initial acute phase after a stroke. The computed tomography angiography enhancement ratio (CTA‐ER) is a quantitative neuroimaging index calculated using the NWU formula based on the attenuation changes of CTA source images, ¹³ and it plays a pivotal role in the early stages following a stroke. Previous studies have demonstrated that CTA‐ER outperforms NWU based on NCCT in predicting malignant cerebral edema and hemorrhagic transformation. ¹² , ¹⁴ Moreover, the correlation between CTA‐ER and prognosis has received limited attention in previous research. Therefore, our objective is to examine the potential of CTA‐ER as a neuroimaging biomarker for predicting favorable outcomes in individuals diagnosed with acute ischemic stroke undergoing EVT.

Methods

The data are accessible from the corresponding author upon reasonable request.

Study Population

Patients with acute ischemic stroke undergoing EVT were retrospectively investigated at Nanjing Jinling Hospital from January 2016 to January 2023. Patients were screened according to the following predetermined inclusion criteria: (1) age ≥18 years; (2) large‐vessel occlusion in the anterior circulation confirmed by CTA, magnetic resonance angiography, or digital subtraction angiography; (3) EVT within 24 hours of stroke onset; and (4) underwent CT and CTA scans before EVT. The exclusion criteria were (1) missed clinical and imaging data; (2) software segmentation errors due to old cerebral infarction, motion artifacts, and poor image quality; (3) prestroke modified Rankin scale score >2; and (4) lost to follow‐up.

Baseline Characteristics

The patient characteristics were collected from medical records, including age, sex, hypertension, diabetes, stroke or transient ischemia attack history, coronary heart disease, atrial fibrillation, smoking history, and drinking status. Baseline clinical data, such as baseline National Institutes of Health Stroke Scale (NIHSS) score, glucose, and intravenous thrombolysis, were obtained. Time information encompasses onset to puncture time, time from puncture to reperfusion, or the end of the procedure without recanalization. The occlusion sites were confirmed by digital subtraction angiography, encompassing the internal carotid artery M1 segment, and proximal M2 segment of the middle cerebral artery. The grading of collateral status was conducted using the American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology scale. ¹⁵ Collateral circulation status was divided into poor, moderate, and good, defined as a American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology score of 0 to 1, 2, and 3 to 4, respectively. The reperfusion status was categorized on the based of the modified Treatment in Cerebral Infarction scale. ¹⁶ Successful recanalization was defined as a modified Treatment in Cerebral Infarction score of 2b or 3.

The favorable outcome was defined as modified Rankin scale score of 0 to 2 at 90 days, assessed by a proficient neurology physician via telephone or during an outpatient follow‐up. According to the prognosis, we divided the patients into a favorable outcome group (modified Rankin scale score, 0 to 2) and an unfavorable outcome group (modified Rankin scale score, 3–6).

Image Acquisition and Protocols

Patients underwent NCCT and a multiphase CTA on dual‐source CT scanners at admission (Somatom Definition, Siemens Healthineers, Forchheim, Germany). The NCCT scan ranged from the skull base to the cranium, with the following parameters: 120 kV, 250 mA, and 5.0 mm layer thickness. CTA images were obtained after 70 mL single bolus contrast material in combination with physiological saline 40 mL injected intravenously at a rate of 4.0 mL/s using a double‐tube high‐pressure syringe. The parameters of CTA were 120 kV and 280 mA with 0.5 mm slice thickness.

Image Analysis

The Alberta Stroke Program Early CT Score (ASPECTS) was acquired through an automated software–based analysis (syngo. via Research Frontier, ASPECT Score‐Tool version 2.0.3; Siemens Healthineers, Forchheim, Germany). The software uses a brain atlas with probabilistic maps of the ASPECTS regions to perform region segmentation and automate atlas fitting. ¹⁷ , ¹⁸ The average Hounsfield unit (HU) value was then calculated for each area, including only voxels that might belong to soft tissue in this process. HU values that are too high (eg, bone, calcifications) or too low (eg, cerebrospinal fluid, ventricle) are not considered. The affected and unaffected regions are subsequently determined on the basis of the preset threshold. ¹⁴ , ¹⁹ To ensure accurate segmentation and identification of ASPECTS areas, 2 experienced neuroradiologists validated all affected ASPECTS areas. The disparity in HU values between the corresponding regions of the bilateral hemispheres was determined and expressed as a percentage (Figure 1). The calculation of NCCT‐NWU and CTA‐ER were performed using the formula below:

$$\begin{array}{ccc}& & NCCT-NWU\mathrm{or}CTA-ER\hfill \\ & & =\left[1-\left(H{U}_{affected}/H{U}_{corresponding}\right)\right]\times 100\%\hfill \end{array}$$

where HU_affected is mean HUs of each affected ASPECTS region and HU_{corresponding} is the mean HUs of each corresponding ASPECTS region.

Figure 1.

A 69‐year‐old man was admitted for right limb weakness with a baseline NIHSS score of 19, an ASPECTS of 6, and a time from symptom onset to puncture of 228 min. A, The automated ASPECTS software identified the affected regions as C, INS, L, and M1. Subsequently, individual NWU values were computed for each affected region and then averaged. According to the prescribed formula, the software determined that the overall NCCT‐NWU value was 5.1%. B, The CTA‐ER was determined to be 10.4% using the calculation methods and formulas above. C, The DSA showed an occlusion of the C7 segment of the internal carotid artery on the left side. D, After endovascular treatment, the patient achieved successful recanalization (mTICI 3). The patient had an mRS score of 4 at 90 days. ASPECTS indicates Alberta Stroke Program Early CT Score; CTA‐ER, computed tomography angiography enhancement ratio; mRS, modified Rankin scale; mTICI, modified Treatment in Cerebral Infarction scale; NCCT‐NWU, noncontrast computed tomography net water uptake; and NIHSS, National Institutes of Health Stroke Scale.

Statistical Analysis

The Kolmogorov–Smirnov test assessed the normality of the data. Measurement data that exhibited a normal distribution were presented as mean (standard deviation), while data that displayed a nonnormal distribution were represented using the interquartile range. Categorical variables were expressed as numbers (percentages). The comparison of the numerical variable between the 2 groups was using either the 2‐independent‐samples t test or the Mann–Whitney U test. For categorical variables, either the χ² test or Fisher's exact test was used. Variables with a significance level of <0.1 in the univariate logistic regression analyses were included in the multivariable model. Model 1 adjusted for clinical variables, while model 2 expanded upon model 1 by incorporating additional imaging variables. In model 3, a forward selection procedure was used to select variables with a univariate P value of <0.1.

Additionally, we evaluated the predictive ability of NCCT‐NWU and CTA‐ER using the receiver operating characteristic curve. The Delong test was used to compare the area under the curve (AUC) of NCCT‐NWU and CTA‐ER. Subsequently, we further compared the predictive efficacy of model 3+NCCT‐NWU with that of model 3+CTA‐ER for favorable outcomes.

Subgroup analyses were performed for each stratified group on the basis of onset to puncture time (onset to puncture time<360 minutes or ≥360 minutes), NIHSS score (<16 or ≥16), ASPECTS (<6 or ≥6), and successful recanalization (yes or no). The statistical analyses were conducted using R (R Foundation for Statistical Computing, Vienna, Austria) or SPSS (IBM, Armonk, NY).

Results

Patient Characteristics

A total of 206 patients fulfilling the inclusion and exclusion criteria were recruited for our study (Figure 2), comprising 77 female participants (37.4%) with a median age of 68 (60–77) years. The median baseline NIHSS score was 16 (12–20). Of the total patients, 64 (31.1%) received intravenous thrombolysis. The median NCCT‐NWU was calculated to be 7.16% (5.27%–8.83%), while the median CTA‐ER was 9.01% (7.56%–11.66%). Successful recanalization was achieved in 161 (78.2%) patients. A total of 82 patients (39.8%) exhibited favorable outcomes. The comparison between the 2 groups revealed that patients with favorable outcomes showed younger age (65 versus 71 years; P < 0.001), lower baseline NIHSS score (15 versus 17; P < 0.001), lower glucose levels (6.6 versus 7.4 mmol/L; P < 0.001), procedure without recanalization (64 versus 88 minutes; P = 0.002), and higher ASPECTS (7 versus 6; P < 0.001). Moreover, statistically significant differences were observed between the 2 groups in relation to sex, stroke or transient ischemia attack history, occlusion site, collateral circulation, and successful recanalization (all P<0.05). Additionally, the favorable outcome group exhibited lower NCCT‐NWU (6.42% versus 7.76%; P < 0.001) and CTA‐ER (8.31% versus 10.56%; P < 0.001; Table 1).

Figure 2.

Flowchart of patient selection. mRS indicates modified Rankin scale.

Table 1.

Patient Characteristics Stratified by Clinical Outcome

Characteristics	Favorable outcome (n = 82)	Unfavorable outcome (n = 124)	P value
Female sex, n (%)	22 (26.8)	55 (44.4)	0.011 *
Age, y, median (IQR)	65.0 (55.8–71.0)	71.0 (64.3–79.0)	<0.001 *
Hypertension, n (%)	48 (58.5)	80 (64.5)	0.386
Diabetes, n (%)	15 (18.3)	28 (22.6)	0.459
Stroke or TIA history, n (%)	7 (8.5)	25 (20.2)	0.024 *
Coronary heart disease, n (%)	12 (14.6)	28 (22.6)	0.158
Atrial fibrillation, n (%)	21 (25.6)	48 (38.7)	0.051
Smoking history, n (%)	31 (37.8)	37 (29.8)	0.234
Drinking status, n (%)	23 (28.0)	26 (21.0)	0.243
Baseline NIHSS score, median (IQR)	15 (10–18)	17 (13–21)	<0.001 *
Occlusion site, n (%)			0.008 *
ICA	23 (28.0)	60 (48.4)
MCA M1	51 (62.2)	59 (47.6)
MCA M2 proximal	8 (9.8)	5 (4.0)
Glucose, median (IQR)	6.6 (5.7–7.5)	7.4 (6.4–8.9)	<0.001 *
ASPECTS, median (IQR)	7 (6–8)	6 (3–7)	<0.001 *
NCCT‐NWU (%), median (IQR)	6.42 (5.01–7.95)	7.76 (5.65–9.45)	<0.001 *
CTA‐ER, %, median (IQR)	8.31 (6.93–9.53)	10.56 (8.05–12.72)	<0.001 *
Intravenous thrombolysis, n (%)	31 (37.8)	33 (26.6)	0.089
OTP, min, median (IQR)	284 (190–378)	303 (228–400)	0.103
PTR, min, median (IQR)	64 (53–104)	88 (60–139)	0.002 *
Collateral circulation, n (%)			<0.001 *
Poor	10 (12.2)	45 (36.3)
Moderate	25 (30.5)	31 (25.0)
Good	47 (57.3)	48 (38.7)
Successful recanalization, n (%)	73 (89.0)	88 (71.0)	0.002 *

ASPECTS indicates Alberta Stroke Program Early CT Score; CTA‐ER, computed tomography angiography enhancement ratio; ICA, internal carotid artery; IQR, interquartile range; MCA, middle cerebral artery; NCCT‐NWU, noncontrast computed tomography net water uptake; NIHSS, National Institutes of Health Stroke Scale; OTP, onset to groin puncture time; PTR, puncture to reperfusion/end of the procedure time; and TIA, transient ischemia attack.

^* P<0.05.

Independent Predictors of Favorable Outcome

Model 1 was adjusted for clinical variables such as age, sex, stroke or transient ischemia attack history, atrial fibrillation, NIHSS, glucose, and procedure without recanalization. Model 2 expanded upon model 1 by including additional variables, including ASPECTS, occlusion site, collateral circulation, and successful recanalization. Model 3 was determined through a forward selection procedure, including age, NIHSS score, glucose, ASPECTS, occlusion site, and successful recanalization. After adjusting for confounding variables, there is no significant correlation between NCCT‐NWU and a favorable outcome (P>0.05 in all models). Conversely, CTA‐ER consistently emerged as a significant predictor for a favorable outcome across all models (all P<0.05; Table 2).

Table 2.

Predicting Favorable Prognosis With the Multivariable Logistic Regression Model

Variables	Model 1		Model 2		Model 3
	OR (95% CI)	P value	OR (95% CI)	P value	OR (95% CI)	P value
NCCT‐NWU	0.872 (0.759–1.001)	0.052	0.948 (0.814–1.104)	0.491	0.928 (0.808–1.066)	0.289
CTA‐ER	0.789 (0.694–0.897)	<0.001	0.854 (0.736–0.991)	0.037	0.868 (0.756–0.995)	0.042

Model 1: adjusted for age, sex, stroke or TIA history, atrial fibrillation, NIHSS score, glucose, intravenous thrombolysis, and PTR; Model 2: adjusted for age, sex, stroke or TIA history, atrial fibrillation, NIHSS score, glucose, intravenous thrombolysis, PTR, ASPECTS, occlusion site, collateral circulation, and successful recanalization; Model 3: adjusted for variables finally included in the model after forward selection: age, NIHSS score, glucose, ASPECTS, occlusion site, and successful recanalization. ASPECTS indicates Alberta Stroke Program Early CT Score; CTA‐ER, computed tomography angiography enhancement ratio; NCCT‐NWU, noncontrast computed tomography‐net water uptake; NIHSS, National Institutes of Health Stroke Scale; OR, odds ratio; PTR, puncture to reperfusion/end of the procedure time; and TIA, transient ischemia attack.

The receiver operating characteristic analysis revealed that NCCT‐NWU exhibited an AUC of 0.636 (95% CI, 0.559–0.713) in predicting a good prognosis, with a sensitivity of 0.707 (95% CI, 0.601–0.795) and a specificity of 0.581 (95% CI, 0.493–0.664) at the optimal cutoff value of 7.46%. CTA‐ER demonstrated an AUC of 0.707 (95% CI, 0.637–0.778), a sensitivity of 0.829 (95% CI, 0.734–0.895), and a specificity of 0.556 (95% CI, 0.469–0.641) at the optimal cutoff value of 10.20%. Compared with NCCT‐NWU, CTA‐ER displayed superior predictive performance (Delong test, P = 0.046; Table 3, Figure 3). Furthermore, when model 3 was combined with NCCT‐NWU, the AUC was 0.824 (95% CI, 0.767–0.881), sensitivity was 0.927 (95% CI, 0.849–0.966), and specificity was 0.653 (95% CI, 0.566–0.731). Similarly, after adding CTA‐ER in model 3, the AUC was found to be 0.828 (95% CI, 0.773–0.883), sensitivity was 0.902 (95% CI, 0.819–0.950), and specificity was 0.677 (95% CI, 0.591–0.753). However, it is worth noting that the predictive efficacy of CTA‐ER+model 3 is comparable to that of NCCT+model 3 (Delong test, P = 0.561; Table S1, Figure S1).

Table 3.

Receiver Operating Characteristic Analysis Predicting Favorable Outcomes

Variables	AUC (95% CI)	Cutoff	Sensitivity (95% CI)	Specificity (95% CI)
NCCT‐NWU	0.636 (0.559–0.713)	7.46	0.707 (0.601–0.795)	0.581 (0.493–0.664)
CTA‐ER	0.707 (0.637–0.778)	10.20	0.829 (0.734–0.895)	0.556 (0.469–0.641)

ASPECTS indicates Alberta Stroke Program Early CT Score; AUC, area under the curve; CTA‐ER, computed tomography angiography enhancement ratio; NCCT‐NWU, noncontrast computed tomography net water uptake; and NIHSS, National Institutes of Health Stroke Scale.

Figure 3.

ROC curves showed the predictive ability of NCCT‐NWU and CTA‐ER for favorable outcomes. ROC analyses indicated that the predictive efficacy of CTA‐ER was better than NCCT‐NWU (Delong test, P = 0.046). CTA‐ER indicates, computed tomography angiography enhancement ratio; NCCT‐NWU, noncontrast computed tomography net water uptake; and ROC receiver operating characteristic.

Subgroup Analysis

Analyses of forest plots were conducted to assess the predictive efficacy of CTA‐ER and NCCT‐NWU across diverse populations. Through the forest plot of subgroup analysis, we can observe that CTA‐ER and NCCT‐NWU generally maintain a negative correlation with favorable outcomes. However, given that the subgroup analysis in this study was not predefined, we exercise caution regarding the findings of the subgroup analysis (Figure 4).

Figure 4.

Forest maps of subgroup analysis for CTA‐ER and NCCT‐NWU. Subgroup analyzed by OTP, NIHSS score, ASPECTS, and successful recanalization. ASPECTS indicates Alberta Stroke Program Early CT Score; CTA‐ER, computed tomography angiography enhancement ratio; NCCT‐NWU, noncontrast computed tomography net water uptake; NIHSS, National Institutes of Health Stroke Scale; and OTP, onset to puncture time.

Discussion

Our study aimed to investigate the potential utility of CTA‐ER as a quantitative imaging biomarker for predicting favorable outcomes. The main finding of this study was that CTA‐ER serves as a reliable predictor of favorable outcomes in patients with acute anterior circulation large‐vessel occlusive stroke following EVT, surpassing the predictive efficacy of NCCT‐NWU.

NWU, a quantitative imaging parameter, is employed to evaluate the water absorption capacity of ischemic brain tissue through the measurement of density alterations. ⁹ The observed changes in NCCT density are hypothesized to be associated with cytotoxic edema, characterized by cerebral cell swelling caused by ischemia. ²⁰ Thereby, as the CT density decreases, there is a corresponding increase in the NWU value, suggesting compromised viability of the brain tissue. ²⁰ , ²¹ , ²² , ²³ NWU can serve as a “tissue clock” for estimating the age of ischemic lesions and is strongly associated with malignant infarction and malignant edema. ¹⁰ , ¹¹ , ²⁴ Several studies have investigated the correlation between NWU and prognosis. Nawabi et al observed a positive correlation between elevated NWU values and futile recanalization after successful recanalization. ¹⁰ Broocks et al demonstrated the predictive value of NWU in patients undergoing EVT within an extended time window (4.5–24 hours after stroke onset) or with low ASPECTS scores (ASPECTS<6). ²⁵ , ²⁶ In addition, the study conducted by Lu et al confirmed a significant correlation between the automated ASPECTS software–calculated NWU and favorable prognosis in patients with large‐vessel occlusion. ²⁷ However, our findings differ from theirs, possibly due to using different imaging analysis software and differences in the study population, as we included patients with more severe stroke and only those who underwent EVT. Moreover, a study conducted by the same research group on patients undergoing reperfusion therapy with the same software did not find a significant association between NWU and positive outcomes, ²⁸ similar to our results. In our study, the AUC value of NCCT‐NWU was comparatively lower than that reported in previous studies. ¹⁰ We attribute this discrepancy to several potential factors. When the infarct area is small, the calculated value may underestimate the actual value due to the averaging of HU values by automated ASPECTS software for each ASPECTS region. Conversely, CTA‐ER may improve performance in patients with small infarcts owing to its more precise depiction of ischemic areas and earlier detection of changes. ²⁹ , ³⁰ , ³¹ , ³² Successful recanalization may influence NWU's predictive effect by changing edema progression. With unsuccessful recanalization, patients may experience faster edema progression, suggesting dynamic monitoring of edema changes may be a more useful approach than analyzing at a single time point. ³³

The results of our study indicate that CTA‐ER exhibits superior predictive efficacy compared with NCCT‐NWU. Furthermore, it consistently demonstrates reliable predictive performance across all models, establishing itself as an independent prognostic indicator of favorable outcomes. This phenomenon can potentially be attributed to the enhanced ability of CTA to delineate the distinction between normal and pathological tissue in a more distinct manner than NCCT, thereby facilitating a more precise determination of the ultimate infarct area. ²⁹ , ³⁰ , ³¹ , ³² The alteration in NCCT density is contingent upon the water content of ischemic tissue, while the attenuation of the CTA signal is predominantly influenced by the diminished ability of ischemic brain tissue to uptake contrast agents. ³⁴ Consequently, CTA‐ER can accurately depict the ischemic alterations in brain tissue within a brief timeframe, and it can compensate for the lack of significant ischemic modifications during the initial acute phase following a stroke in NCCT. ¹³ , ²⁹ Furthermore, it is observed that CTA hypoattenuation exhibits a stronger correlation with cerebral blood flow compared with cerebral blood volume, and it is suggested that the ASPECTS based on CTA may also serve as an indicator of the ischemic penumbra region. ²⁹ , ³⁵ , ³⁶ Based on the findings above, we consider that the ASPECTS region derived from CTA exhibits a higher degree of similarity to the ischemic region. ³⁵ , ³⁷ This observation explains why CTA‐ER can serve as a more practical alternative tool to NWU based on CTP.

Presently, most studies about NWU rely on semiautomated software and necessitate CTP for assistance in demarcating the infarct region, thereby constraining the utilization of NWU in emergency or primary stroke centers. This study uses fully automated ASPECTS software to autonomously segment the infarct area and compute the NCCT‐NWU and CTA‐ER, obviating the need for advanced imaging aid, rendering the process more straightforward, expeditious, and applicable across more centers. Moreover, this study encompasses a broader array of patients, thereby facilitating the identification of more individuals who would benefit from EVT.

There were several limitations to our study. First, our study was a single‐center retrospective study that exclusively enrolled Han Chinese. This may restrict the extrapolation of our findings, necessitating large‐scale prospective trials to validate. Second, we solely included patients who underwent EVT and adhered strictly to guideline‐based screening criteria for identifying potential beneficiaries of this intervention, which might introduce inherent selection bias. Third, our image analysis relied on software to divide the infarct area automatically, which may be affected by midline deviation or motion artifact interference, leading to incorrect segmentation. Finally, the NCCT‐NWU and CTA‐ER values calculated by the software in our study may exhibit a slight underestimation compared with the actual value, likely since the actual infarct area is only a component of the area defined by ASPECTS.

Conclusions

CTA‐ER is a significant predictor of 90‐day favorable outcomes in patients with acute anterior circulation large‐vessel occlusive stroke undergoing EVT. The application value of CTA‐ER in the treatment decision making for patients undergoing EVT needs to be further validated through prospective studies.

Sources of Funding

This study was supported by National Natural Science Foundation of China (82271361, 82271983, and 82001260), Clinical Research Project of Jinling Hospital (22LCYY‐XH4), and Jiangsu Funding Program for Excellent Postdoctoral Talent (2022ZB752).

Disclosures

None.

Supporting information

Supplementary Figure S1 ROC curves illustrate the predictive performance of Model 3 + NCCT‐NWU and Model 3 + CTA‐ER concerning favorable outcomes. ROC analysis revealed no significant difference in the predictive performance between Model 3 + CTA‐ER and Model 3 + NCCT‐NWU (Delong test, p =0.561). Model 3: adjusted for variables finally included in the model after forward selection: age, NIHSS, glucose, ASPECTS, successful recanalization, occlusion site. NCCT‐NWU indicates noncontrast computed tomography net water uptake; CTA‐ER, computed tomography angiography enhancement ratio; NIHSS, National Institutes of Health Stroke Scale; and ASPECTS, Alberta Stroke Program Early CT Score

Supplementary Table S1 ROC analysis predicting favorable outcomes