Data of patients with acute ischemic stroke due to anterior circulation large vessel occlusion and received successful interventional recanalization in our single comprehensive stroke center from January 2019 to December 2023 was retrospectively collected. This research plan had been approved by the Medical Ethics Committee of Heyuan People’s Hospital (YXYJLL-YJZFQ33). Our study complied with the Declaration of Helsinki. Because this study only collected clinical data and conducted retrospective analysis without any form of intervention on the treatment plan of patients, the Medical Ethics Committee approved the exemption of patients’ informed consent in this study.

Inclusion criteria for this study: (1) It was confirmed occlusion of major blood vessels in the anterior circulation by preoperative imaging examination, including the internal carotid artery, M1 segment of the middle cerebral artery, and M2 segment of the middle cerebral artery; (2) National Institute of Health stroke scale (NIHSS) score ≥ 6 points at the time of onset; (3) Preoperative Alberta Stroke Program Early Computed Tomography (ASPECT) score ≥ 6 points; (4) Age ≥ 18 years old; (5) Pre onset modified Rankin Scale (mRS) score ≤ 2 points; (6) The time from onset to femoral artery puncture ≤ 24 h; (7) The patient’s family members signed and agreed to undergo interventional recanalization treatment; (8) Received immediate postoperative CT scan. Exclusion criteria: (1) Acute ischemic stroke with posterior circulation large vessel occlusion; (2) Occlusion of anterior cerebral artery; (3) Pre onset mRS score > 2 points; (4) The vital signs were unstable during the onset of the disease. The modified Rankin Scale is a scale used to evaluate the neurological recovery status of stroke patients, with a score range of 0 to 6 points. The higher the score, the worse the prognosis, point of 0 represents no symptoms at all, and point of 6 represents death. The research flowchart is shown in Figure 1.

Patients or the public WERE NOT involved in the design, or conduct, or reporting, or dissemination plans of our research.

After imaging evaluation, it was confirmed that the acute ischemic stroke was caused by occlusion of large blood vessels in the anterior circulation, and there was a salvageable ischemic penumbra. After the patient’s family members signed and agreed to perform interventional recanalization, the treatment was carried out under local anesthesia and sedation. If the patient’s condition required, endotracheal intubation and general anesthesia can be administered. The interventional physicians selected one or more methods of stent thrombectomy, thrombus aspiration, balloon dilation, stent implantation, etc. for interventional recanalization based on the patient’s lesion location, nature, and vascular pathway during the operation. The thrombectomy stents we used included Solitaire AB, RECO, TREVO, the suction catheters we used included Sofia, ACE Penumbra, and Tianxun distal access catheter, the balloon we used was Gateway balloon dilation catheter, the carotid stent we used was Protege stent, and the intracranial stent we used was Apollo intracranial vascular stent. In terms of postoperative management, each group of patients would be monitored and their blood pressure and blood sugar would be controlled according to the latest guidelines, and received at least 24 h of electrocardiogram monitoring to closely monitor their vital signs. After surgery, appropriate antithrombotic drugs would be selected based on the patient’s pathogenesis, and the appropriate timing for initiating antithrombotic drugs would be used to treat the patient with antithrombotic therapy. Early postoperative prevention of deep vein thrombosis would be routinely performed on patients. According to the presence or absence of high-density shadows on the immediate postoperative cerebral CT, we divided the patients into a group with high-density shadow and a group without high-density shadow.

After successful interventional recanalization, immediate cerebral CT examination should be performed to determine whether the patient had high-density shadow. Referring to a previous classification method for high-density shadow of immediate cerebral CT after arterial thrombolysis in patients with acute ischemic stroke (15), we had made some improvements to it. Based on the distribution, density, volume, and other information of high-density shadow, we had classified them into four types: (1) Cortical high-density shadow: focal high-density shadow limited to the cortex without occupying space effect. (2) Soft high-density shadow: a high-density shadow limited to the brain parenchyma, with a density of less than 80 HU, a volume of less than one-third of the cerebral hemisphere, no occupying effect, and no high-density shadows in the sulci, gyrus, or ventricles. (3) Metal high-density shadow: a high-density shadow confined to the brain parenchyma, with a density greater than or equal to 80 HU, a large volume but less than one-third of the cerebral hemisphere, no high-density shadow in the sulci, gyrus, or ventricles, and may be accompanied by mild space occupying effect. (4) Diffuse high-density shadow: the high-density shadow has a large volume and may not be limited to the brain parenchyma. It may be accompanied by obvious occupying effects and may be accompanied by high-density shadow in the sulci, gyrus, and ventricles. The typical cases of high-density shadow in four types of immediate cerebral CT are shown in Figure 2. The classification of high-density shadow on immediate CT after successful interventional recanalization was evaluated by two imaging experts who were unaware of the patient’s condition. When there was a disagreement in the evaluation, the third expert should conduct the evaluation. When three experts had different opinions, a final consensus would be reached through thorough discussion.

Demographic, medical history, NIHSS score, preoperative ASPECT score, collateral circulation score, surgical process characteristics, and other information of all patients were collected. The American Society of Interventional and Therapeutic Neuroradiology/ Society of Interventional Radiology (ASTIN/SIR) scoring system was used to score collateral circulation (16), with a score of 0: no collateral blood flow reached the ischemic area. 1 point: There is slow collateral blood flow reaching the ischemic peripheral area. 2 points: There is rapid collateral blood flow reaching the ischemic peripheral area, but only a portion reaches the ischemic area. 3 points: Slow but complete blood flow can be seen throughout the entire ischemic area in the late venous stage. 4 points: Through retrograde perfusion, blood flow rapidly and completely perfuses the entire ischemic area. Symptomatic intracranial hemorrhage is defined as bleeding visible on the patient’s cerebral CT scan, and an increase of ≥ 4 points in the patient’s NIHSS score (17, 18). The definition of futile recanalization is that the mRS score of the patient is greater than 2 points 3 months after successful interventional recanalization, and no independent neurological function has been achieved (19, 20). The characteristics of the surgical process included the time from femoral artery puncture to recanalization of occluded blood vessels, and the time from onset to recanalization of occluded blood vessels. The extended thrombolysis in cerebral infarction (eTICI) blood flow grading is used to evaluate the recanalization of occluded vessels. Levels 0 to 2a are defined as failed intervention recanalization, while levels 2b to 3 are defined as successful intervention recanalization.

All statistical analyses were conducted using SPSS 26.0 software. Measurement data was expressed as mean ± standard deviation or median (interquartile range). Statistical analysis was performed using t-test for measurement data that conformed to normal distribution, and rank sum test was used for measurement data that did not conform to normal distribution. Count data was expressed in frequency and percentage, and statistical analysis was performed using chi square test. Factors found to be associated with high-density shadow on immediate cerebral CT after successful interventional recanalization in univariate analysis were included into univariate and multivariate logistic regression analysis to determine independent related factors.

The average age of all patients was 66.89 ± 11.69 years, with 271 males (64.71%). At the onset of the disease, the NIHSS score was 12.00, the preoperative ASPECT score was 7.00, the collateral circulation score was 3.00, and the time from femoral artery puncture to recanalization of occluded blood vessels was 95.00 min. All patients underwent a 3-month follow-up after surgery.

We included a total of 402 patients, according to whether there was a high-density shadow on the immediate cerebral CT after successful interventional recanalization, the patients were divided into a group with high-density shadow and a group without high-density shadow, with 318 cases (79.10%) in the high-density shadow group and 84 cases (20.90%) in the without high-density shadow group. There were statistically significant differences (p < 0.05) in hypertension, preoperative ASPECT score, collateral circulation score, surgical methods and time from femoral artery puncture to recanalization of occluded vessels between the two groups of patients. Compared with the group without high-density shadow, patients in high-density shadow group had a lower rate of history of hypertension, lower preoperative ASPECT scores, lower proportion of mere use of balloon angioplasty, lower proportion of combination of balloon angioplasty and stent implantation and longer time from femoral artery puncture to recanalization of occluded vessels. There was no statistical difference between the two groups in age, sex, history of diabetes, history of coronary heart disease, history of atrial fibrillation, history of cerebral infarction, history of smoking, history of drinking, pre onset mRS score, rate of receiving intravenous thrombolysis treatment, location of occluded vessels, time from onset to recanalization of occluded vessels, and pathogenesis (p > 0.05). The baseline clinical data of two groups of patients with and without high-density shadow on immediate cerebral CT after successful interventional recanalization are shown in Table 1.

The indicators with statistical differences in chi square test, t-test, and non parametric test were included in univariate and multivariate logistic regression analysis. After adjusting for confounding factors, it was found that the history of hypertension (OR = 0.479; 95% CI 0.283–0.810; p = 0.006), preoperative ASPECT score (OR = 0.748; 95% CI 0.571–0.979; p = 0.034), mere use of balloon angioplasty (OR = 0.150; 95% CI 0.038–0.602; p = 0.007) and combination of balloon angioplasty and stent implantation (OR = 0.216; 95% CI 0.070–0.663; p = 0.007) were independently correlated with high-density shadow on immediate cerebral CT after successful interventional recanalization in patients with acute anterior circulation cerebral infarction caused by large vessel occlusion. The univariate and multivariate logistic regression analyses are shown in Table 2.

In terms of prognosis and complications, compared with patients without high-density shadow, patients in the high-density shadow group had higher mRS scores, higher incidence of futile recanalization, symptomatic intracranial hemorrhage and malignant brain edema, higher mortality rate within 3 months after surgery, and a lower proportion of mRS ≤ 1 at 3 months after surgery (p < 0.05). The comparison of prognosis and complications between the two groups of patients is shown in Table 3. The distribution of mRS scores between the two groups of patients 3 months after surgery is shown in Figure 3.

The high-density shadow on immediate cerebral CT after successful interventional recanalization were divided into four types: cortical type in 16 cases (5.03%), soft type in 85 cases (26.73%), metallic type in 80 cases (25.16%), and diffuse type in 137 cases (43.08%). There were statistically significant differences (p < 0.05) in NIHSS score at the time of onset, preoperative ASPECT score, and collateral circulation score among the four types of high-density shadow of patients. There was no significant difference in age, sex, hypertension, diabetes, coronary heart disease, atrial fibrillation, cerebral infarction, smoking, drinking, pre onset mRS score, rate of receiving intravenous thrombolysis treatment, location of occluded vessels, time from onset to recanalization of occluded vessels, time from femoral artery puncture to recanalization of occluded vessels, and pathogenesis among four types of high-density shadow of patients (p > 0.05). The baseline clinical data of four types of high-density shadow of patients are shown in Table 4.

In terms of prognosis and complications, patients with diffuse high-density shadow had the highest mRS score, highest incidence of futile recanalization, symptomatic intracranial hemorrhage and malignant brain edema, highest mortality rate within 3 months after surgery, and lowest proportion of mRS ≤ 1 was at 3 months after surgery (p < 0.05). The mRS score, incidence of futile recanalization, symptomatic intracranial hemorrhage and malignant brain edema were the lowest and proportion of mRS ≤ 1 was the highest in patients with cortical high-density shadow at 3 months after surgery (p < 0.05). The comparison of prognosis and complications of four types of high-density shadow of patients are shown in Table 5. The distribution of mRS scores of four types of high-density shadow of patients at 3 months after surgery is shown in Figure 4.