Contrast staining on CT after DSA in ischemic stroke patients progresses to infarction and rarely hemorrhages

Incidence, Risk Factors, and Clinical Implications of Subarachnoid Hyperdensities on Flat-Panel Detector CT following Mechanical Thrombectomy in Patients with Anterior Circulation Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Flat-panel detector CT immediately after mechanical thrombectomy can detect complications, including early hemorrhagic transformation and subarachnoid hyperdensities. The clinical significance of subarachnoid hyperdensities in patients undergoing mechanical thrombectomy remains unclear.

MATERIALS AND METHODS

We studied 223 patients who underwent mechanical thrombectomy for anterior circulation stroke who had flat-panel detector CT performed immediately after the procedure and had follow-up imaging within 24 hours. Subarachnoid hyperdensity severity was categorized into 5 grades (subarachnoid hyperdensities, 0: absent to subarachnoid hyperdensities, IV: extensive). Baseline and procedural characteristics as well as outcome measures were analyzed using group comparisons and multivariable logistic regression analyses.

RESULTS

Overall, 100/223 (45%) patients showed subarachnoid hyperdensities on immediate postinterventional flat-panel detector CT. The factors associated with an increased subarachnoid hyperdensity risk were the following: medium-vessel occlusion or distal-vessel occlusion compared with a large-vessel occlusion, a more distal device position, a higher number of device passes, a larger volume of contrast applied, worse final reperfusion expanded TICI, and after receiving IV thrombolysis. The occurrence of subarachnoid hyperdensity grades II-IV was independently associated with worse functional outcomes (adjusted OR for mRS, 3-6: 2.2; 95% CI 1.1-4.3), whereas patients with subarachnoid hyperdensity grade I had outcomes similar to those in patients without subarachnoid hyperdensities.

CONCLUSIONS

Our study identified risk factors for subarachnoid hyperdensities, most of which reflect increasingly challenging procedures or more peripheral recanalization attempts. The presence of subarachnoid hyperdensity grades II-IV was associated with poorer outcomes, suggesting the need for personalized strategies to reduce its incidence and severity or potentially improve recovery after subarachnoid hyperdensities.

Association between CT Perfusion Parameters and Hemorrhagic Transformation after Endovascular Treatment in Acute Ischemic Stroke: Results from the ESCAPE-NA1 Trial

BACKGROUND AND PURPOSE

Hemorrhagic transformation can occur as a complication of endovascular treatment for acute ischemic stroke. This study aimed to determine whether ischemia depth as measured by admission CTP metrics can predict the development of hemorrhagic transformation at 24 hours.

MATERIALS AND METHODS

Patients with baseline CTP and 24-hour follow-up imaging from the ESCAPE-NA1 trial were included. RAPID software was used to generate CTP volume maps for relative CBF, CBV, and time-to-maximum at different thresholds. Hemorrhage on 24-hour imaging was classified according to the Heidelberg system, and volumes were calculated. Univariable and multivariable regression analyses assessed the association between CTP lesion volumes and hemorrhage/hemorrhage subtypes.

RESULTS

Among 408 patients with baseline CTP, 142 (35%) had hemorrhagic transformation at 24-hour follow-up, with 89 (63%) classified as hemorrhagic infarction (HI1/HI2), and 53 (37%), as parenchymal hematoma (PH1/PH2). Patients with HI or PH had larger volumes of low relative CBF and CBV at each threshold compared with those without hemorrhage. After we adjustied for baseline and treatment variables, only increased relative CBF <30% lesion volume was associated with any hemorrhage (adjusted OR, 1.14; 95% CI, 1.02-1.27 per 10 mL), as well as parenchymal hematoma (adjusted OR, 1.23; 95% CI, 1.06-1.43 per 10 mL). No significant associations were observed for hemorrhagic infarction.

CONCLUSIONS

Larger "core" volumes of relative CBF <30% were associated with an increased risk of PH following endovascular treatment. This particular metric, in conjunction with other clinical and imaging variables, may, therefore, help estimate the risk of post-endovascular treatment hemorrhagic complications.

Contrast Staining in Noninfarcted Tissue after Endovascular Treatment of Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Contrast staining is a common finding after endovascular treatment of acute ischemic stroke. It typically occurs in infarcted tissue and is considered an indicator of irreversible brain damage. Contrast staining in noninfarcted tissue has not been systematically investigated. We sought to assess the incidence, risk factors, and clinical significance of contrast staining in noninfarcted tissue after endovascular treatment.

MATERIALS AND METHODS

We conducted a retrospective review of consecutive patients who underwent endovascular treatment for anterior circulation large-vessel occlusion acute ischemic stroke. Contrast staining, defined as new hyperdensity on CT after endovascular treatment, was categorized as either contrast staining in infarcted tissue if the stained region demonstrated restricted diffusion on follow-up MR imaging or contrast staining in noninfarcted tissue if the stained region demonstrated no restricted diffusion. Baseline differences between patients with and without contrast staining in noninfarcted tissue were compared. Logistic regression was used to identify independent associations for contrast staining in noninfarcted tissue after endovascular treatment.

RESULTS

Among 194 patients who underwent endovascular treatment for large-vessel occlusion acute ischemic stroke and met the inclusion criteria, contrast staining in infarcted tissue was noted in 52/194 (26.8%) patients; contrast staining in noninfarcted tissue, in 26 (13.4%) patients. Both contrast staining in infarcted tissue and contrast staining in noninfarcted tissue were noted in 5.6% (11/194). Patients with contrast staining in noninfarcted tissue were found to have a higher likelihood of having an ASPECTS of 8-10, to be associated with contrast staining in infarcted tissue, and to achieve successful reperfusion compared with those without contrast staining in noninfarcted tissue. In contrast staining in noninfarcted tissue regions, the average attenuation was 40 HU, significantly lower than the contrast staining in infarcted tissue regions (53 HU). None of the patients with contrast staining in noninfarcted tissue had clinical worsening during their hospital stay. The median discharge mRS was significantly lower in patients with contrast staining in noninfarcted tissue than in those without (3 versus 4; P = .018). No independent predictors of contrast staining in noninfarcted tissue were found.

CONCLUSIONS

Contrast staining can be seen outside the infarcted tissue after endovascular treatment of acute ischemic stroke, likely attributable to the reversible disruption of the BBB in ischemic but not infarcted tissue. While generally benign, understanding its characteristics is important because it may mimic pathologic conditions such as infarcted tissue and cerebral edema.

Assessment of post-thrombectomy brain hemorrhage in acute ischemic stroke with dual-energy CT: how reliable is it in clinical practice?

PURPOSE

Acute ischemic stroke is currently among the main causes of mortality in Western countries. The current guidelines suggest different flowcharts of diagnostic work-up and treatment modalities, including endovascular thrombectomy. Immediately after intra-arterial recanalization, a brain CT scan is usually performed to assess for the presence of peri-procedural complications; in this setting, it is very hard, if possible, to differentiate blood from iodinated contrast material, which is normally present in ischemic tissue because of BBB disruption. Dual-energy CT may be used for this purpose, exploiting its ability to discriminate different materials.

MATERIALS AND METHODS

We retrospectively studied 44 patients with acute ischemic stroke who were treated with endovascular recanalization at San Giovanni Bosco Hospital in Turin and were then scanned with DECT technology. Subsequent scan was used as standard, since iodine from contrast staining is usually reabsorbed in 24 h and blood persists longer. A χ2 test of independence was performed to examine the relationship between blood detected by DECT scan after the endovascular procedure and the presence of blood in the same areas on the following scans, with a significant result: χ2 (1, N = 37) = 10.7086, p = 0.0010.

RESULTS

Patients with blood detected on DECT scans had a double chance of having hemorrhagic infarction in follow-up scans, (RR 2.02). The sensitivity and specificity of DECT were respectively 70% and 90%, with an overall diagnostic accuracy of 76% and a positive and negative predictive value, respectively, of 95% and 53%.

CONCLUSION

Dual-energy CT scan after endovascular recanalization in ischemic stroke identifies early hemorrhagic infarction with excellent specificity and good overall diagnostic accuracy, representing a reliable diagnostic tool in everyday clinical practice.

Determinants and Clinical Relevance of Iodine Contrast Extravasation after Endovascular Thrombectomy: A Dual-Energy CT Study

BACKGROUND AND PURPOSE

Iodine contrast extravasation (ICE) is common in patients with acute ischemic stroke (AIS) after endovascular-thrombectomy (EVT). The aim of our study was to evaluate the incidence of ICE assessed by dual-energy CT (DECT), its determinants, and associations with clinical outcome.

MATERIALS AND METHODS

We retrospectively examined imaging parameters and clinical factors from consecutive patients with AIS treated with EVT who had a DECT 24 hours thereafter, identified at a single academic center. Associations between ICE, clinical, imaging, and procedural parameters, as well as clinical outcome were explored by using univariable and multivariable models.

RESULTS

A total of 197 consecutive patients were included (period 2019-2020), of which 53 (27%) demonstrated ICE that was pure ICE in 30/53 (57%) and mixed with intracranial hemorrhage (ICH) in 23/53 (43%). Low initial-ASPECTS, high per-procedural-contrast volume injected, and high admission-glycemia were independently associated with ICE (respectively, OR = 0.43, 95% CI, 0.16-1.13, P = .047; OR = 1.02, 95% CI, 1.00-1.04, P = .003; OR = 8.92, 95% CI, 0.63-125.77, P = .043). ICE was independently associated with ICH (P = .047), but not with poorer clinical outcome (6-month mRS >2, P = .223). Univariate analysis demonstrated that low ADC, higher ischemic volume, ICA occlusion, mass effect, longer procedure duration, combined thrombectomy technique, higher number of device passes, and lower recanalization rate were associated with ICE (respectively, P = .002; <.001; .002; <.001; .002; 0.011; <0.001; 0.015).

CONCLUSIONS

ICE evaluated with DECT is a relatively frequent finding after EVT, present in almost one-third of patients. Lower admission ASPECTS, higher glycemia, and high contrast volume injected per procedure were associated with ICE. We also found an association between ICE and ICH, confirming blood-brain barrier alteration as a major determinant of ICH.

Early antithrombotic therapy in patients with postinterventional cerebral hyperdensity reduces early neurological deterioration after mechanical thrombectomy

BACKGROUND

Initiation of early antithrombotic therapy after acute ischemic stroke (AIS) is crucial. We aimed to investigate whether early antithrombotic therapy influences early neurological deterioration (END) in AIS patients with postinterventional cerebral hyperdensity (PCHD) immediately after mechanical thrombectomy (MT).

METHODS

We retrospectively analyzed 108 consecutive anterior circulation AIS patients with PCHD immediately after MT. All patients were divided into END group and non-END group and END was defined as an increase of four points or more on the postinterventional National Institutes of Health Stroke Scale (NIHSS) score within the first 72 h after MT. Early antithrombotic therapy was defined as patients with PCHD who received antithrombotic therapy within 24 h after MT. Statistical analyses were performed to evaluate the association between early antithrombotic therapy and the risk of END.

RESULTS

Among 108 patients, 27 (25%) patients developed END. Multivariate regression analysis revealed that early use of antithrombotic therapy (OR = 0.229, 95%CI = 0.083-0.626, P = 0.004) was an independent protector of END and postinterventional low density shadow exceeding 1/3 of the vascular territory (OR = 4.000, 95%CI = 1.157-13.834, P = 0.029) was an independent risk factor for END.

CONCLUSION

Antithrombotic therapy within 24 h after MT maybe associated with the reduced risk of END in anterior circulation AIS patients with PCHD.

Associations between multiple sclerosis and in-hospital outcomes of patients with hemorrhagic stroke

OBJECTIVE

To determine the influence of multiple sclerosis (MS) on in-hospital outcomes of patients with hemorrhagic strokes using a large, nationally representative database.

MATERIALS AND METHODS

This population-based, retrospective study extracted data of adults with hemorrhagic stroke from the US Nationwide Inpatient Sample (NIS) database from 2016 to 2018. Patients with/without MS were then compared. Hemorrhagic stroke and MS were identified by the International Classification of Diseases, Tenth editions (ICD-10) codes. In-hospital outcomes (i.e., in-hospital mortality, discharge destination, length of stay [LOS], total hospital cost, and major complications) were compared between subjects with and without MS using logistic regression analysis.

RESULTS

Among 107,573 patients with hemorrhagic stroke, 0.3% (n=337) had MS. After 1:10 propensity-score (PS) matching, 3,707 patients remained in the analytic sample. Multivariable analysis revealed that patients with MS had significantly shorter LOS (adjusted β=-1.34 days; 95% CI: -2.41 to -0.26, p=0.015), and lower total hospital costs (adjusted β=-28.82; 95% CI: -43.57 to -14.06, p<0.001) than those without MS. No significant different risks of any major complications, in-hospital mortality, or transfer to nursing homes/long-term care facilities were observed. For major complications, patients with MS had a significantly lower risk of cerebral edema than those without MS (adjusted odds ratio [aOR] = 0.66, 95%CI: 0.51 to 0.86, p =0.002) CONCLUSIONS: In hospitalized patients with hemorrhagic stroke, those with MS have shorter LOS, lower costs, and a lower risk of cerebral edema compared to no MS. More relevant experiments and studies are needed to confirm results of this study.

The clinical utility of dual-energy CT in post-thrombectomy care: Part 2, the predictive value of contrast density and volume for delayed hemorrhagic transformation

OBJECTIVES

Dual-energy CT allows differentiation between blood and iodinated contrast. This study aims to determine the predictive value of contrast density and volume on post-thrombectomy dual-energy CT for delayed hemorrhagic transformation and its impact on 90-day outcomes.

MATERIALS AND METHODS

A retrospective analysis was performed on patients who underwent thrombectomy for anterior circulation large-vessel occlusion at a comprehensive stroke center from 2018-2021. Per institutional protocol, all patients underwent dual-energy CT immediately post-thrombectomy and MRI or CT 24 hours afterward. The presence of hemorrhage and contrast staining was evaluated by dual-energy CT. Delayed hemorrhagic transformation was determined by 24-hour imaging and classified into petechial hemorrhage or parenchymal hematoma using ECASS III criteria. Univariable and multivariable analyses were performed to determine predictors and outcomes of delayed hemorrhagic transformation.

RESULTS

Of 97 patients with contrast staining and without hemorrhage on dual-energy CT, 30 and 18 patients developed delayed petechial hemorrhage and delayed parenchymal hematoma, respectively. On multivariable analysis, delayed petechial hemorrhage was predicted by anticoagulant use (OR,3.53;p=0.021;95%CI,1.19-10.48) and maximum contrast density (OR,1.21;p=0.004;95%CI,1.06-1.37;per 10 HU increase), while delayed parenchymal hematoma was predicted by contrast volume (OR,1.37;p=0.023;95%CI,1.04-1.82;per 10 mL increase) and low-density lipoprotein (OR,0.97;p=0.043;95%CI,0.94-1.00;per 1 mg/dL increase). After adjusting for potential confounders, delayed parenchymal hematoma was associated with worse functional outcomes (OR,0.07;p=0.013;95%CI,0.01-0.58) and mortality (OR,7.83;p=0.008;95%CI,1.66-37.07), while delayed petechial hemorrhage was associated with neither.

CONCLUSION

Contrast volume predicted delayed parenchymal hematoma, which was associated with worse functional outcomes and mortality. Contrast volume can serve as a useful predictor of delayed parenchymal hematoma following thrombectomy and may have implications for patient management.

Reperfusion Injury Is Associated With Poor Outcome in Patients With Recanalization After Thrombectomy

BACKGROUND

The existence of cerebral reperfusion injury in human beings remains controversial. Thus, we aimed to explore the presence of reperfusion injury in acute ischemic stroke patients with recanalization after mechanical thrombectomy and analyzed its impact on neurological outcome.

METHODS

We reviewed our prospectively collected database CIPPIS (Comparison Influence to Prognosis of CTP and MRP in AIS Patients, NCT03367286), and enrolled anterior circulation large artery occlusion patients with recanalization after mechanical thrombectomy who underwent (1) computed tomography (CT) perfusion on admission and immediately after recanalization to determine reperfusion region, and (2) CT and/or magnetic resonance imaging (MRI) immediately and 24 hours after recanalization to determine lesion areas. The expansion of lesion between recanalization and 24 hours within reperfusion region was potentially caused by reperfusion, thus termed as radiological observed reperfusion injury (RORI). Based on the imaging modality immediately after recanalization, RORI was further divided into RORI_CT and RORI_MRI. We first included a small cohort who had performed both CT and MRI immediately after recanalization to validate the consistency between RORI_CT and RORI_MRI (Study 1). Then the association with RORI_CT and poor outcome, defined as 3-month modified Rankin Scale score of 3 to 6, was explored in a larger cohort (Study 2).

RESULTS

Study 1 included 23 patients and good consistency was found between RORI_CT and RORI_MRI (intraclass correlation=0.97, P<0.001). Among 226 patients included in Study 2, a total of 106 (46.9%) were identified with RORI. The ratio of RORI to reperfusion region was 30.1 (16.2, 51.0)% and was independently associated with poor outcome (odds ratio=1.55 per 10% [95% CI' 1.30-1.84]; P<0.001).

CONCLUSIONS

Our findings suggested that RORI was relatively frequent in stroke patients with recanalization after mechanical thrombectomy and associated with poor outcome despite successful recanalization.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT03367286.

Quantitative Intracerebral Iodine Extravasation in Risk Stratification for Intracranial Hemorrhage in Patients with Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Intracerebral hemorrhage poses a severe threat to the outcomes in patients with postthrombectomy acute stroke. We aimed to compare the absolute intracerebral iodine concentration and normalized iodine concentration ratio in predicting intracerebral hemorrhage in patients postthrombectomy.

MATERIALS AND METHODS

Patients with acute anterior circulation large-vessel occlusion who underwent mechanical thrombectomy and had successful recanalization were retrospectively included in the study. Dual-energy CT was performed within 1 hour after mechanical thrombectomy. Postprocessing was performed to measure the absolute intracerebral iodine concentration and the normalized iodine concentration ratio. The correlation between the absolute intracerebral iodine concentration and the normalized iodine concentration ratio was analyzed using the Spearman rank correlation coefficient. We compared the area under the receiver operating characteristic curve of the absolute intracerebral iodine concentration and the normalized iodine concentration ratio using the DeLong test.

RESULTS

We included 138 patients with successful recanalization. Of 43 patients who did not have parenchymal contrast staining on postthrombectomy dual-energy CT, 5 (11.6%) developed intracerebral hemorrhage. Among patients (95/138, 68.8%) with parenchymal contrast staining, 37 (38.9%, 37/95) developed intracerebral hemorrhage. The absolute intracerebral iodine concentration was significantly correlated with the normalized iodine concentration ratio (ρ = 0.807; 95% CI, 0.718-0.867; P < .001). The cutoffs of the normalized iodine concentration ratio and absolute intracerebral iodine concentration for identifying patients with intracerebral hemorrhage development were 222.8%, with a sensitivity of 67.6% and specificity of 76.4%, and 2.7 mg I/mL, with a sensitivity of 75.7% and specificity of 65.5%, respectively. No significant difference was found between the areas under the receiver operating characteristic curve for the absolute intracerebral iodine concentration and the normalized iodine concentration ratio (0.753 versus 0.738) (P = .694).

CONCLUSIONS

The hemorrhagic transformation predictive power of the normalized iodine concentration ratio is similar to that of the absolute intracerebral iodine concentration in patients with successful recanalization.

Alberta Stroke Program Early CT Score applied to hyperdense lesion on noncontrast CT immediately post-thrombectomy is a predictor of poor outcome in acute ischemic stroke: A case-control study

We aimed to evaluate whether Alberta Stroke Program Early CT Score (ASPECTS) applied to hyperdense lesion on noncontrast CT obtained immediately post-thrombectomy (post-ASPECTS) is useful for predicting poor outcome. We retrospectively reviewed patients who underwent noncontrast CT (NCCT) immediately after mechanical thrombectomy between January 2017 and July 2020 in our comprehensive stroke center. We collected baseline NCCT and post-ASPECTS score. The sensitivity, specificity, and positive and negative predictive values of the post-ASPECTS in predicting clinical outcome were calculated. A total of 223 patients were included. The hyperdense lesion on NCCT immediately after endovascular thrombectomy presented in 85.7% (191/223) patients, poor clinical outcome was in 56.1% (112/191) of hyperdense lesion patients. Low post-ASPECTS was associated with poor outcome (OR 0.390; 95% CI 0.258-0.589; P = .001), with an AUCROC curve of 0.753 (95% CI 0.684-0.822), while baseline NCCT-ASPECTS was not (OR 0. 754; 95% CI 0. 497-1.144; P = .185). A score ≤ 7 in post-ASPECTS was the best cut-off to poor clinical outcome (sensitivity 84.8%; specificity 52.7%; positive predictive value 68.4%; negative predictive value 73.8%). Our results point to the proportion of patients who present hyperdense lesion on NCCT is very high, post-ASPECTS could predict poor clinical outcomes in patients with stroke treated with endovascular mechanical thrombectomy, and post-ASPECTS may achieved better predictive value than baseline ASPECTS.

Automated Measurement of Net Water Uptake From Baseline and Follow-Up CTs in Patients With Large Vessel Occlusion Stroke

Quantifying the extent and evolution of cerebral edema developing after stroke is an important but challenging goal. Lesional net water uptake (NWU) is a promising CT-based biomarker of edema, but its measurement requires manually delineating infarcted tissue and mirrored regions in the contralateral hemisphere. We implement an imaging pipeline capable of automatically segmenting the infarct region and calculating NWU from both baseline and follow-up CTs of large-vessel occlusion (LVO) patients. Infarct core is extracted from CT perfusion images using a deconvolution algorithm while infarcts on follow-up CTs were segmented from non-contrast CT (NCCT) using a deep-learning algorithm. These infarct masks were flipped along the brain midline to generate mirrored regions in the contralateral hemisphere of NCCT; NWU was calculated as one minus the ratio of densities between regions, removing voxels segmented as CSF and with HU outside thresholds of 20-80 (normal hemisphere and baseline CT) and 0-40 (infarct region on follow-up). Automated results were compared with those obtained using manually-drawn infarcts and an ASPECTS region-of-interest based method that samples densities within the infarct and normal hemisphere, using intraclass correlation coefficient (ρ). This was tested on serial CTs from 55 patients with anterior circulation LVO (including 66 follow-up CTs). Baseline NWU using automated core was 4.3% (IQR 2.6-7.3) and correlated with manual measurement (ρ = 0.80, p < 0.0001) and ASPECTS (r = -0.60, p = 0.0001). Automatically segmented infarct volumes (median 110-ml) correlated to manually-drawn volumes (ρ = 0.96, p < 0.0001) with median Dice similarity coefficient of 0.83 (IQR 0.72-0.90). Automated NWU was 24.6% (IQR 20-27) and highly correlated to NWU from manually-drawn infarcts (ρ = 0.98) and the sampling-based method (ρ = 0.68, both p < 0.0001). We conclude that this automated imaging pipeline is able to accurately quantify region of infarction and NWU from serial CTs and could be leveraged to study the evolution and impact of edema in large cohorts of stroke patients.

Hemorrhagic Transformation Rates following Contrast Media Administration in Patients Hospitalized with Ischemic Stroke

BACKGROUND AND PURPOSE

Hemorrhagic transformation is a critical complication associated with ischemic stroke and has been associated with contrast media administration. The objective of our study was to use real-world in-hospital data to evaluate the correlation between contrast media type and transformation from ischemic to hemorrhagic stroke.

MATERIALS AND METHODS

We obtained data on inpatient admissions with a diagnosis of ischemic stroke and a record of either iso-osmolar or low-osmolar iodinated contrast media for a stroke-related diagnostic test and a treatment procedure (thrombectomy, thrombolysis, or angioplasty). We performed multivariable regression analysis to assess the relationship between contrast media type and the development of hemorrhagic transformation during hospitalization, adjusting for patient characteristics, comorbid conditions, procedure type, a threshold for contrast media volume, and differences across hospitals.

RESULTS

Inpatient visits with exclusive use of either low-osmolar (n = 38,130) or iso-osmolar contrast media (n = 4042) were included. We observed an overall risk reduction in hemorrhagic transformation among patients who received iso-osmolar compared with low-osmolar contrast media, with an absolute risk reduction of 1.4% (P = .032), relative risk reduction of 12.5%, and number needed to prevent harm of 70. This outcome was driven primarily by patients undergoing endovascular thrombectomy (n = 9211), in which iso-osmolar contrast media was associated with an absolute risk reduction of 4.6% (P = .028), a relative risk reduction of 20.8%, and number needed to prevent harm of 22, compared with low-osmolar contrast media.

CONCLUSIONS

Iso-osmolar contrast media was associated with a lower rate of hemorrhagic transformation compared with low-osmolar contrast media in patients with ischemic stroke.

Hyperattenuations on flat-panel computed tomography after successful recanalization of mechanical thrombectomy for anterior circulation occlusion

Background

To evaluate intraparenchymal hyperattenuation (IPH) on flat-panel computed tomography (FPCT) findings and their clinical usefulness for predicting prognosis after successful mechanical thrombectomy (MT) for acute occlusion of anterior circulation.

Methods

A retrospective review was conducted for 158 consecutive patients undergoing mechanical thrombectomy during the last six years. After excluding those with posterior circulation occlusion or incomplete recanalization and those without FPCT, 82 patients were finally included. Immediate post-procedural IPH on FPCT was categorized into four patterns (none, striatal, cortical, or combined pattern). Follow-up magnetic resonance images or CT scans after 48 hours from MT were analyzed according to FPCT findings. The existence of hemorrhagic transformation, intracerebral hemorrhage, and brain swelling was evaluated. Functional clinical outcomes were accessed with post-procedural 3-month modified Rankin scales (mRS).

Results

Of 82 patients, 34 patients were found to have IPH (16 with a striatal pattern, 8 with a cortical pattern, and 10 with a combined pattern). Hemorrhagic complication (P<0.001), brain swelling (P<0.001), and poor mRS scores (P=0.042) showed significant differences according to IPH patterns. Multivariate logistic regression analysis revealed that the presence of a striatal pattern (OR: 13.26, P<0.001), cortical pattern (OR: 11.61, P=0.009), and combined pattern (OR: 45.34, P<0.001) independently predicted hemorrhagic complications. The location of the occlusion (OR: 4.13, P=0.034), cortical pattern (OR: 5.94, P=0.039), and combined pattern (OR: 39.85, P=0.001) predicted brain swelling. Age (OR: 1.07, P=0.006) and the presence of a combined pattern (OR: 10.58, P=0.046) predicted poor clinical outcomes.

Conclusions

FPCT is a rapid and effective tool for a prompt follow-up just after MT to predict prognosis. Those with striatal patterns showed relatively good clinical outcomes despite significant hemorrhage. Cortical IPH patterns independently predicted a high rate of post-procedural hemorrhage or brain swelling. Combined pattern is a strong predictor for both radiologic and poor clinical outcomes.

Association between flat-panel computed tomography hyperattenuation and clinical outcome after successful recanalization by endovascular treatment

OBJECTIVE

Hyperattenuation on CT scanning performed immediately after endovascular treatment (EVT) is known to be associated with the final infarct. As flat-panel CT (FPCT) scanning is readily accessible within their angiography suite, the authors evaluated the ability of the extent of hyperattenuation on FPCT to predict clinical outcomes after EVT.

METHODS

Patients with successful recanalization (modified Thrombolysis in Cerebral Infarction grade 2b or 3) were reviewed retrospectively. The extent of hyperattenuation was assessed by the Alberta Stroke Program Early CT Score on FPCT (FPCT-ASPECTS). FPCT-ASPECTS findings were compared according to functional outcome and malignant infarction. The predictive power of the FPCT-ASPECTS with initial CT images before EVT (CT-ASPECTS) and follow-up diffusion-weighted images (MR-ASPECTS) was also compared.

RESULTS

A total of 235 patients were included. All patients were treated with mechanical thrombectomy, and 45.5% of the patients received intravenous tissue plasminogen activator. The mean (± SD) time from stroke onset to recanalization was 383 ± 290 minutes. The FPCT-ASPECTS was significantly different between patients with a favorable outcome and those without (mean 9.3 ± 0.9 vs 6.7 ± 2.6) and between patients with malignant infarction and those without (3.4 ± 2.9 vs 8.8 ± 1.4). The FPCT-ASPECTS was an independent factor for a favorable outcome (adjusted OR 3.28, 95% CI 2.12-5.01) and malignant infarction (adjusted OR 0.42, 95% CI 0.31-0.57). The area under the curve (AUC) of the FPCT-ASPECTS for a favorable outcome (0.862, cutoff ≥ 8) was significantly greater than that of the CT-ASPECTS (0.637) (p < 0.001) and comparable to that of the MR-ASPECTS (0.853) (p = 0.983). For malignant infarction, the FPCT-ASPECTS was also more predictive than the CT-ASPECTS (AUC 0.906 vs 0.552; p = 0.001) with a cutoff of ≤ 5.

CONCLUSIONS

The FPCT-ASPECTS was highly predictive of clinical outcomes in patients with successful recanalization. FPCT could be a practical method to immediately predict clinical outcomes and thereby aid in acute management after EVT.

Cerebral contrast staining mimicking parenchymal haemorrhage in a stroke patient

A 75-year-old female patient presented with signs and symptoms of a right hemispheric syndrome. A CT scan of the brain with angiogram showed an acute infarct in the right middle cerebral artery (MCA) territory secondary to thromb-occlusion of the M1 segment of the right MCA. A follow-up CT scan 2 weeks later showed a large hyperdense region in the infarcted area. With the aid of a dual-energy CT scan, this was eventually shown to be due to contrast staining from an earlier administration of iodinated contrast on the same day, rather than frank haemorrhagic conversion of the recent right MCA infarct.

Value of high-density sign on CT images after mechanical thrombectomy for large vessel occlusion in predicting hemorrhage and unfavorable outcome

PURPOSE

Cerebral hyperdensities can appear on head computed tomography (CT) images performed early after endovascular treatment (EVT) in patients with acute ischemic stroke and may be secondary to contrast staining or hemorrhagic transformation. The aim of this study was to determine how the high-density sign on CT affects mortality and clinical outcome and whether CT parameters predict hemorrhagic conversion or unfavorable outcome.

METHODS

We retrospectively reviewed a database of patients who underwent EVT with mechanical thrombectomy for acute ischemic stroke over 7 years. Included were acute stroke patients with a CT examination within 24 h post-EVT with mechanical thrombectomy, demonstrating areas of hyperdensity. We evaluated morphologic characteristics of these lesions, location, CT Hounsfield units and largest area, as well as patient demographics, EVT methods and patient outcome.

RESULTS

A total of 29 patients met the strict inclusion criteria. Complete recanalization was achieved in 58.6% (17/29). Seventeen (58.6%) cases of post-intervention cerebral hyperdensities were related to contrast staining and 12 (41.4%) cases to contrast staining and hemorrhage. Patient mortality was significantly higher in the hemorrhagic group (50.0% versus 5.9%, p = 0.003). The increased density on CT was associated with higher hemorrhagic risk (odds ratio 1.05, p = 0.036).

CONCLUSION

Patients with the high-density sign on CT images after mechanical thrombectomy for acute ischemic stroke demonstrated increased mortality and worse clinical outcome, primarily when these hyperdensities were related to hemorrhage. CT imaging parameters as higher density areas can help in the differentiation of hemorrhage from contrast staining.

Recent Administration of Iodinated Contrast Renders Core Infarct Estimation Inaccurate Using RAPID Software

BACKGROUND AND PURPOSE

Automated CTP software is increasingly used for extended window emergent large-vessel occlusion to quantify core infarct. We aimed to assess whether RAPID software underestimates core infarct in patients with an extended window recently receiving IV iodinated contrast.

MATERIALS AND METHODS

We reviewed a prospective, single-center data base of 271 consecutive patients who underwent CTA ± CTP for acute ischemic stroke from May 2018 through January 2019. Patients with emergent large-vessel occlusion confirmed by CTA in the extended window (>6 hours since last known well) and CTP with RAPID postprocessing were included. Two blinded raters independently assessed CT ASPECTS on NCCT performed at the time of CTP. RAPID software used relative cerebral blood flow of <30% as a surrogate for irreversible core infarct. Patients were dichotomized on the basis of receiving recent IV iodinated contrast (<8 hours before CTP) for a separate imaging study.

RESULTS

The recent IV contrast and contrast-naïve cohorts comprised 23 and 15 patients, respectively. Multivariate linear regression analysis demonstrated that recent IV contrast administration was independently associated with a decrease in the RAPID core infarct estimate (proportional increase = 0.34; 95% CI, 0.12-0.96; P = .04).

CONCLUSIONS

Patients who received IV iodinated contrast in proximity (<8 hours) to CTA/CTP as part of a separate imaging study had a much higher likelihood of core infarct underestimation with RAPID compared with contrast-naïve patients. Over-reliance on RAPID postprocessing for treatment disposition of patients with extended window emergent large-vessel occlusion should be avoided, particularly with recent IV contrast administration.

Contrast Extravasation Post Thrombectomy in Patients With Acute Cerebral Stroke: A Review and Recommendations for Future Studies

Mechanical thrombectomy (MT) for cerebral revascularization in acute stroke is now considered standard of care in select patients. Patients are assessed routinely after MT with CT scanning. The phenomenon of contrast staining is well documented in the literature and is posited to be related to increased blood-brain barrier (BBB) permeability of susceptible and/or infarcting brain tissue allowing angiographic contrast to be visualized outside the normal cerebral vasculature. In some cases, this can progress to include frank blood/contrast extravasation or even more seriously lead to intraparenchymal hemorrhage (IPH) with less favorable clinical outcomes. The relationship of this staining phenomenon and how it may have a cause or effect relationship with progression to hemorrhage is unclear. Many studies have been performed trying to better characterize this radiographic finding in terms of accurate diagnosis and potential for influencing prognosis. A literature review included a glaring lack of standardization in the application of terminology and quantitative/qualitative analysis. Dual energy CT (DECT) appears to be the best imaging modality to differentiate blood from contrast, but its application is limited since it is not as available as conventional CT. The possibility that risk factors are associated with progression of mixed density (blood and contrast) extravasations to frank IPH with resultant poorer outcomes is suggested in some studies. Overall, there remains a lack of consensus on how to best interpret this radiographic finding in altering any future stroke treatment(s). Recommendations of how to overcome this are postulated by the authors, which include standardization of terminology, progression toward more DECT use.

Neuroimaging of Patients in the Intensive Care Unit: Pearls and Pitfalls

A brief introduction is provided of the different imaging modalities encountered in the intensive care unit (ICU). The spectrum of intracranial pathology as well as potential postsurgical complications is reviewed, with a focus on pearls and pitfalls. A brief overview also is provided of imaging of the spine in an ICU patient.

Iodine-stained fragmented thromboembolism

AIM

Iodine-stained fragmented thromboembolism (ISFT) is a rare phenomenon encountered in the immediate aftermath of mechanical thrombectomy or rarely as a complication of post-carotid stenting. The aim was to describe the imaging appearance and discuss its pathophysiology.

METHOD

This is a retrospective review of patients who underwent mechanical thrombectomy for acute stroke at a single institution over the period of one year. All patients underwent the standard acute stroke imaging protocol (CT head, CT angiogram (CTA) and CT brain perfusion) and when clinically appropriate followed by catheter angiogram and mechanical thrombectomy. ISFT was defined as an arterial luminal filling defect with Hounsfield density equal to or greater than iodine seen on the biplanar CT or conventional CT. The presence and location of ISFT were documented. Standard CT angiogram (CTA) or magnetic resonance angiogram (MRA) was performed 24-48 hours after the neurointerventional procedure to assess for recanalization, volume of infarction and the fate of the ISFT.

RESULTS

ISFTs were identified in eight (five males and three females, age range 18-80 years) out of 49 patients in the following locations: distal M1 (n = 1), M2 (n = 4), M3 (n = 1), A1 (n = 1), distal A2 (n = 1). ISFT and vessel recanalization occurred in five patients on follow-up. ISFT and vessel occlusion persisted in two patients.

CONCLUSION

ISFT is likely the result of mechanical disruption of a thromboembolus, and porosity of the thromboembolus fragment may transiently retain iodinated contrast. Recognition of this entity may be important to aid detection of residual thromboembolism and avoid misinterpretation as calcified thromboembolism.

Parenchymal hyperdensity on C-arm CT images after endovascular therapy for acute ischaemic stroke predicts a poor prognosis

AIM

To investigate whether hyperdense areas (HDAs) observed after endovascular treatment on multisection computed tomography (CT) are related to outcome.

MATERIALS AND METHODS

Data on 82 patients with acute anterior circulation ischaemic stroke resulting from intracranial large artery occlusion were analysed retrospectively All patients underwent mechanical thrombectomy and/or emergency angioplasty, and partial or complete recanalisation was successfully achieved. C-arm CT was performed immediately after endovascular treatment for all patients. Clinical and radiological data were compared between patients with and those without HDA and between patients with good and those with poor outcomes.

RESULTS

Compared with non-HDA patients, HDA patients were more likely to present with severe neurological deficits (admission National Institutes of Health Stroke Scale [NIHSS] score: 18 versus 16, p=0.037) and had a higher number of stent retriever passes performed (2.9±1.3 versus 1.4±1, p<0.001), longer onset-to-presentation times (229±78 versus 171±90 minutes; p=0.002), longer onset-to-recanalisation times (418±94 versus 331±105 minutes; p<0.001), and longer puncture-to-recanalisation times (103±47 versus 69±42 minutes; p=0.001). Fewer HDA patients had a good prognosis (35.7% versus 70%, p<0.001). Multivariate analysis showed the presence of HDAs was an independent negative prognostic factor (OR=0.208; p=0.002).

CONCLUSION

HDAs on C-arm CT appear to be common in patients with acute ischaemic stroke who underwent successful endovascular treatment. HDA presence suggests a poor prognosis despite successful reperfusion.

MR Imaging for Differentiating Contrast Staining from Hemorrhagic Transformation after Endovascular Thrombectomy in Acute Ischemic Stroke: Phantom and Patient Study

BACKGROUND AND PURPOSE

Early differentiation of contrast staining from hemorrhagic transformation in patients with acute ischemic stroke who have undergone endovascular treatment is critical in preventing the delayed administration of antiplatelet agents. We aimed to demonstrate the usefulness of an immediate postinterventional DWI protocol including B₀ and gradient recalled-echo sequences to discriminate those 2 conditions through phantom and preliminary retrospective patient studies.

MATERIALS AND METHODS

On 3T MR imaging, the signal intensities of the phantom models consisting of iodinated contrast agents diluted with normal saline and arterial blood were compared using T1WI, T2WI, and gradient recalled-echo sequences. A total 17 patients (8 with hemorrhagic transformation and 9 with contrast staining; 8 men and 9 women; mean age, 72.00 ± 10.91 years; range, 52-90 years) who underwent mechanical thrombectomy for acute ischemic stroke and showed newly appearing hyperdense lesions on immediate (<24 hours) postinterventional nonenhanced CT scans were included in this study. Immediate postinterventional DWI of patients were compared.

RESULTS

In the phantom study, iodinated contrast agents diluted with normal saline showed minimal signal drop, while those diluted with arterial blood demonstrated dark signal intensity in the T2WI and gradient recalled-echo sequences. In the patient study, all hemorrhagic transformations and none of the contrast staining demonstrated dark or low signal (<gray matter) intensities similar to those of the vessel in the B₀-DWI and gradient recalled-echo images.

CONCLUSIONS

According to our preliminary results, contrast staining might be differentiated from hemorrhagic transformation using an immediate postinterventional DWI protocol including gradient recalled-echo sequences. It might be possible to expedite establishment of postinterventional medical treatment strategy.

Another Endovascular Therapy Strategy for Acute Tandem Occlusion: Protect-Expand-Aspiration-Revascularization-Stent (PEARS) Technique

OBJECTIVE

Initial stenotic occlusion of the internal carotid artery with intracranial artery occlusion in acute ischemic stroke is associated with high morbidity and can benefit from endovascular therapy. However, the optimal endovascular strategy is unclear. This study aimed to evaluate the feasibility of the "half" anterograde approach and clinical outcome of treated patients. Revascularization validity of the 2 "half" anterograde approach with (Protect-Expand-Aspiration-Revascularization-Stent [PEARS] technique) or without (plain technique) using an embolic prevention device and aspiration was also compared.

METHODS

Data on initial stenotic occlusion of the internal carotid artery with intracranial artery occlusion in our prospective stroke registry database between January 2015 and February 2017 were collected. Clinical and angiographic data were retrospectively analyzed. Clinical outcome was evaluated at 3 months, defined as a modified Rankin scale ≤2 as a good clinical outcome.

RESULTS

Overall, 26 patients with tandem occlusion were included; 96.3% of patients had successful recanalization. The rate of a good clinical outcome was 61.8%, symptomatic parenchymal hemorrhage was 7.7%, and mortality was 15.4%. The PEARS technique took less time (56 ± 14 vs. 97 ± 31 minutes; P = 0.002) and had less embolic events (0 vs. 30.8%; P = 0.012) compared with the plain technique. Use of the PEARS technique was an independent predictor for shortening revascularization time (β = -0.651, P = 0.001).

CONCLUSIONS

The half anterograde approach technique is feasible and safe for treating tandem occlusion. Furthermore, the PEARS technique is associated with a shorter reperfusion time and less embolic events than the plain technique, and should be recommended in tandem occlusion.

Microcatheter contrast injection in stent retriever neurothrombectomy is safe and useful: insights from SWIFT PRIME

Microcatheter contrast injection (MCI) prior to stent retriever deployment for the treatment of acute ischemic stroke may be useful for evaluation of distal anatomy and flow patterns beyond the occlusion. However, prior data from intra-arterialthrombolysis suggested that MCI increases the risk of intracranial hemorrhage (ICH). The safety and utility of MCI has not been investigated in the setting of thrombectomy.

Methods

We analyzed the Solitaire With the Intention For Thrombectomy as Primary Endovascular Treatment (SWIFT PRIME) trial to correlate pre-intervention MCI flow with collateral flow, and to investigate its impact on ICH and clinical outcome after thrombectomy with the Solitaire device.

Results

MCI was noted in 52% (n=51) of patients with a prevalence for the M2 location of 71% (n=36). Dichotomized correlation demonstrated a strong inverse relationship for partial collaterals with good MCI flow (p=0.004; OR 8.25). None of the MCI variables (presence, number, or grades) correlated with ICH and clinical outcome. The most significant predictors of non-disabled outcome were higher Alberta Stroke Program early CT Score (ASPECTS) (OR 1.61; p=0.0361) and younger age (OR 0.922; p = 0.0109). Higher ASPECTS was also a strong predictor of lower ICH risk (OR 0.501, p=0.0078).

Conclusions

Collateral flow inversely correlated with MCI flow in the endovascular arm of the SWIFT PRIME trial. This finding warrants further validation in larger cohorts as MCI may be influenced by individual operator’s technique and choice of syringe size. Evaluation of flow and distal anatomy with MCI prior to stent retriever deployment is safe with no evidence of an impact on ICH or clinical outcome.

Clinical trial registration

NCT01657461: Post- results

Contrast Extravasation versus Hemorrhage after Thrombectomy in Patients with Acute Stroke

BACKGROUND AND PURPOSE

Intra-arterial recanalization postprocedural imaging in stroke patients can result in diagnostic complications due to hyperdensities on noncontrast computed tomography (CT), which may represent either contrast extravasation or intracranial hemorrhage. If these lesions are hemorrhage, then they are risk factors becoming symptomatic, which, if not distinguished, can alter clinical management. We investigate the effects of iodinated contrast on postprocedural magnetic resonance imaging (MRI) and prevalence of equivocal imaging interpretations of postprocedural extravasated contrast versus hemorrhage while identifying protocol pitfalls.

METHODS

We identified 10 patients diagnosed with ischemic stroke who underwent intra-arterial recanalization in a 5-year period. These patients demonstrated a hyperdensity on a postprocedural CT within 24 hours, underwent an MRI within 48 hours, and an additional confirmatory noncontrast CT at least 72 hours postprocedure.

RESULTS

Postprocedural MRI in all 10 stroke patients demonstrated T1 - and T2 -relaxation time changes due to residual iodine contrast agents. This lead to false positive postprocedural hemorrhage MRI interpretations in 2/10 patients, 3/10 false negative interpretations of contrast extravasation, and 5/10 equivocal interpretations suggesting extravasation or hemorrhage. Of these five cases, two were performed with gadolinium.

CONCLUSION

MRI done within 48 hours postprocedure can lead to false positive hemorrhage or false negative contrast extravasation interpretations in stroke patients possibly due to effects from the administered angiographic contrast. Additionally, MRI should be done both after 72 hours for confirmation and without gadolinium contrast as the effects of the gadolinium contrast and residual angiographic contrast could lead to misdiagnosis.

Variable MR and pathologic patterns of hemorrhage after iodinated contrast infusion in MCA occlusion/reperfusion model

OBJECTIVE

To examine the hypothesis that IA reperfusion with iso-osmolar iodixanol, low-osmolar iopamidol, or saline causes different effects on MR signal changes and pathologic cut-brain section related to hemorrhagic transformation (HT) or iodinated radiographic contrast media (IRCM) deposition.

METHODS

Infarct was induced in 30 rats by middle cerebral artery suture occlusion. Reperfusion was performed after 5 hours with iso-osmolar iodixanol (n=9), low-osmolar iopamidol (n=12) or saline (n=9). MR images were obtained immediately after reperfusion and rats were sacrificed at 24 hours. Hypointense areas within the infarction on T2-weighted (T2-WI) or gradient echo (GRE) images were recorded and compared with HT on pathology. Fisher's exact test was used for proportions, and receiver operator curve analysis to evaluate MRI discrimination of hemorrhage.

RESULTS

Two types of HT were noted on pathology: confluent >0.2 mm petechial hemorrhage (PeH, 78%) or well-defined ≤0.2 mm hemorrhagic focus (HF, 22%). PeH was least common in the iodixanol subgroup (p<0.02). HF was more common in the IRCM group. Hypointense areas on T2-WI but not on GRE were significantly more common in the IRCM group (p<0.05). Hypointense areas on T2-WI and GRE discriminated HT (area under the curve: 0.714, p<0.002).

CONCLUSIONS

IRCM and saline induced different MRI signal and pathologic patterns in our sample. We postulate that T2 hypointensity with no GRE hypointensity might be associated with IRCM deposition; and decreased frequency of PeH after iodixanol infusion and the presence of HF almost exclusively in the IRCM group might represent a direct/indirect effect of contrast infusion/deposition in the brain parenchyma after reperfusion. Our results support previous observations in IMS III and are hypothesis generating.

Intraparenchymal Hyperattenuations on Flat-Panel CT Directly After Mechanical Thrombectomy are Restricted to the Initial Infarct Core on Diffusion-Weighted Imaging

PURPOSE

The presence of intraparenchymal hyperattenuations (IPH) on flat-panel computed tomography (FP-CT) after endovascular recanalization in stroke patients is a common phenomenon. They are thought to occur in ischemic areas with breakdown of the blood-brain barrier but previous studies that investigated a mutual interaction are scarce. We aimed to assess the relationship of IPH localization with prethrombectomy diffusion-weighted imaging (DWI) lesions.

METHODS

This retrospective multicenter study included 27 acute stroke patients who underwent DWI prior to FP-CT following mechanical thrombectomy. After software-based coregistration of DWI and FP-CT, lesion volumetry was conducted and overlapping was analyzed.

RESULTS

Two different patterns were observed: IPH corresponding to the DWI lesion and IPH exceeding the DWI lesion. The latter showed demarcated infarction of DWI exceeding IPH at 24 h. No major hemorrhage following IPH was observed. Most IPH were manifested within the basal ganglia and insular cortex.

CONCLUSION

The IPH primarily appeared within the initial ischemic core and secondarily within the penumbral tissue that progressed to infarction. The IPH represent the minimum final infarct volume, which may help in periinterventional decision making.

Distinction between contrast staining and hemorrhage after endovascular stroke treatment: one CT is not enough

BACKGROUND

Postinterventional cerebral hyperdensities (PCHDs) are a common finding after endovascular stroke treatment. There is uncertainty about the extent to which PCHDs correspond to hemorrhage or contrast staining. Our aim was to evaluate the use of PCHD density on immediate postinterventional CT, and PCHD evolution on follow-up CT for differentiating contrast staining from hemorrhage after endovascular treatment.

METHODS

We retrospectively reviewed the imaging data of 84 patients who underwent endovascular treatment for acute arterial ischemic stroke in the anterior circulation and who received an immediate postinterventional CT, a follow-up CT within 36 h, and a follow-up MRI within 10 days.

RESULTS

PCHDs were seen in 62 of 84 patients in a total of 130 Alberta Stroke Program Early CT Score (ASPECTS) areas. A specificity of 100% to predict hemorrhage was only seen for PCHDs with densities <40 HU (for ruling hemorrhage out) and ≥140 HU (for ruling hemorrhage in), at the cost of a low sensitivity of 1.1% and 2.4%, respectively. Persisting PCHDs correlated with hemorrhage with a specificity of 93.3% and a sensitivity of 62.5%. When follow-up CT was performed at least 19 h after the first CT, persisting PCHDs correlated with hemorrhage with a specificity of 100% and a sensitivity of 62.5%.

CONCLUSIONS

There are no density thresholds for PCHDs that allow predicting the absence or presence of hemorrhage with 100% specificity and acceptable sensitivity. A CT scan performed at least 19-24 h after endovascular therapy is the only reliable method to differentiate contrast staining from hemorrhage.

Initial factors affecting the clinical outcome after successful recanalization via MR-based mechanical thrombectomy in patients with acute ischemic stroke due to basilar artery occlusion

Background and purpose

To determine the initial factors, including patient characteristics, stroke etiology and severity, time factors, and imaging findings, that could affect the clinical outcome of patients with acute ischemic stroke (AIS) caused by basilar artery occlusion (BAO) where successful recanalization was achieved via mechanical thrombectomy.

Methods

Between March 2011 and December 2014, 35 patients with AIS caused by BAO received MRI/MR angiography-based mechanical thrombectomies, and recanalization was achieved with a Thrombolysis In Cerebral Infarction score of >2b. The patients were divided into a good outcome group (n=19), defined as those with a modified Rankin Scale (mRS) score of 0–2 at 3 months after stroke onset, and a poor outcome group (n=16), defined as a mRS score of 3–6. The differences between the groups were analyzed.

Results

Initial National Institutes of Health Stroke Scale (NIHSS) score (good vs poor: 17.9±8.9 vs 27.6±8.5, p=0.003), posterior circulation Acute Stroke Prognosis Early CT Score (pc-ASPECTS) based on initial diffusion-weighted images (DWI) (good vs poor: 7.8±1.6 vs 5.4±1.8, p=0.001), pc-ASPECTS based on contrast staining on the post-thrombectomy control CT (good vs poor: 9.2±1.5 vs 6.3±2.2, p<0.001), and presence of contrast staining in the brainstem on that CT (good vs poor: 15.8% vs 81.6%, p<0.001) were significantly different between the groups.

Conclusions

Patients with AIS caused by BAO with a lower initial NIHSS score, fewer lesions on initial DWI, and less contrast staining on the post-thrombectomy control CT have higher probabilities of a good clinical outcome after successful recanalization via a mechanical thrombectomy.