Clinical significance of post-interventional cerebral hyperdensities after endovascular mechanical thrombectomy in acute ischaemic stroke

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.

The ACORNS grading scale: a novel tool for the prediction of malignant brain edema after endovascular thrombectomy

BACKGROUND

To develop and validate a novel tool for predicting the development of malignant brain edema (MBE) in large vessel occlusion stroke patients after endovascular thrombectomy (EVT).

METHODS

We used a prospectively registered population of EVT patients from three comprehensive stroke centers. The population was randomly divided into two subsets (7:3): a training cohort and an internal validation cohort. External validation was performed using the Endovascular Treatment for Acute Anterior Circulation Ischemic Stroke Registry in China (ACTUAL) database. MBE was defined as (1) hypodense parenchyma in at least 50% of the middle cerebral artery and signs of local brain swelling, and (2) a midline shift of ≥5 mm at the septum pellucidum or pineal gland with obliteration of the basal cisterns. The model was constructed using logistic regression analysis. The performance of the model was examined in terms of discrimination and calibration.

RESULTS

After adjusting for other confounders, baseline National Institutes of Health Stroke Scale (NIHSS) and Alberta Stroke Program Early CT (ASPECT) scores, a clinical history of hypertension, collateral status, intravenous thrombolysis before thrombectomy, fasting blood glucose, reperfusion status, and occlusion site were found to be independent predictors of MBE. These variables were combined to create the ACORNS grading scale. The areas under the curve in receiver operating curve analysis were 0.850 (95% CI 0.816 to 0.884), 0.874 (95% CI 0.821 to 0.926), and 0.785 (95% CI 0.740 to 0.829) for the training, internal validation, and external validation cohorts, respectively, indicating good discriminative performance in the validation cohorts.

CONCLUSIONS

The ACORNS grading scale is an accurate and easily applicable model for the prediction of the development of MBE after EVT.

Prognostic value of contrast staining on dual-energy CT after endovascular therapy in acute ischemic stroke: a meta-analysis

BACKGROUND

Contrast staining (CS) on dual-energy CT (DECT) is common after endovascular therapy (EVT) in acute ischemic stroke (AIS). We performed a meta-analysis to investigate the prognostic significance of CS detected by DECT after EVT in AIS.

METHOD

MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Web of Science and Scopus databases were searched from inception to July 2023 for publications on the prognostic significance of CS on DECT after EVT in patients with AIS. Prognostic outcomes were hemorrhage transformation (HT) and poor functional outcome (modified Rankin Scale [mRS] Score of 3-6 at the 90-day follow-up). Data are presented as odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

Eleven studies including 1123 cases of AIS were included. Pooled results indicated a higher risk of HT in patients with CS than in those without CS (OR = 2.22; 95% CI 1.41-3.51, P = 0.001; I2 = 45.4%). No association between CS and symptomatic HT was observed (OR = 2.10; 95% CI 0.64-6.95, P = 0.223; I2 = 67.3%). Moreover, there was also higher odds of poor functional outcome in patients with CS than in those without CS (OR = 2.76; 95% CI 1.53-4.97, P = 0.001; I2 = 44.9%).

CONCLUSIONS

The presence of contrast staining on DECT after EVT is associated with a higher risk of hemorrhage transformation and poor functional outcome. However, further high-quality studies with standardized processes are required to confirm these results.

Clinical significance and prevalence of subarachnoid hyperdensities on flat detector CT after mechanical thrombectomy: does it really matter?

BACKGROUND

Subarachnoid hyperdensities after mechanical thrombectomy (MT) are a common finding. However, it is often regarded as clinically insignificant.

OBJECTIVE

With this single-center investigation, to identify the prevalence of subarachnoid hyperdensities following MT, associated predictors, and the impact on the clinical outcome of the patients.

METHODS

383 patients from the stroke registry were analyzed for the presence of subarachnoid hyperdensities on flat detector CT (FDCT) directly after the completion of MT, and on follow-up dual-energy CT, then classified according to a visual grading scale. 178 patients were included with anterior circulation occlusions. Regression analysis was performed to identify significant predictors, and Kruskal-Wallis analysis and Χ2 test were performed to test the variables among the different groups. The primary outcome was the modified Rankin Scale (mRS) score at 90 days and was analyzed with the Wilcoxon-Mann-Whitney rank-sum test.

RESULTS

The prevalence of subarachnoid hyperdensities on FDCT was (66/178, 37.1%) with patients experiencing a significant unfavorable outcome (P=0.035). Significantly fewer patients with subarachnoid hyperdensities achieved a mRS score of ≤3 at 90 days 25/66 (37.9%) vs 60/112 (53.6%), P=0.043). In addition, mortality was significantly higher in the subarachnoid hyperdensities group (34.8% vs 19.6%, P=0.024). Distal occlusions and a higher number of device passes were significantly associated with subarachnoid hyperdensities (P=0.026) and (P=0.001), respectively. Patients who received intravenous tissue plasminogen activator had significantly fewer subarachnoid hyperdensities (P=0.029).

CONCLUSIONS

Postinterventional subarachnoid hyperdensities are a frequent finding after MT and are associated with neurological decline and worse functional outcome. They are more common with distal occlusions and multiple device passes.

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.

Immediate postinterventional flat-panel CT: Differentiation of hemorrhagic transformation from contrast exudation of acute ischemic stroke patients after thrombectomy

BACKGROUND

Flat-panel computed tomography (CT) is an available imaging modality immediately after endovascular thrombectomy without transferring patients to the CT room.

PURPOSE

To determine the accuracy of flat-panel CT scans in differentiating hemorrhagic transformation (HT) from contrast exudation after thrombectomy in patients with acute ischemic stroke (AIS).

MATERIAL AND METHODS

From January 2019 to December 2021, consecutive patients with AIS who received an immediate flat-panel CT scan and follow-up neuroimaging after thrombectomy were enrolled in our study. The receiver operating characteristic curve was adopted to assess the discriminating accuracy of characteristics of flat-panel CT for HT.

RESULTS

A total of 108 patients were enrolled in the study; 58 (53.7%) patients presented with hyperdense lesions on flat-panel CT. Patients with hyperdense lesions experienced a higher proportion of HT than patients without (58.7% vs. 10.0%; P < 0.001). Among all patients with hyperdensity on flat-panel CT, patients who experienced HT had higher average Hounsfield units (HUavg) (125 vs. 93; P = 0.001) and a higher proportion of mass effect (67.6 vs. 12.5; P < 0.001). The flat-panel CT differentiating HT from contrast exudation yielded a sensitivity of 87.2% and a negative predictive value of 90.0%. The area under the curve of HUavg, mass effect, and combination for differentiation of HT were 0.74, 0.78, and 0.83, respectively.

CONCLUSION

The hyperdensity on immediately post-thrombectomy flat-panel CT could differentiate HT from contrast exudation with an excellent negative predictive value. The ability of flat-panel CT in differentiating HT from contrast exudation was improved when combined with HUavg and mass effect.

Post-ASPECTS based on hyperdensity in NCCT immediately after thrombectomy is an ultra-early predictor of hemorrhagic transformation and prognosis

Background and Purpose

Almost half of the patients exhibit futile recanalization after thrombectomy; however, the early postoperative predictors of futile recanalization remain unclear. We analyzed the relationship of post-thrombectomy ASPECTS (Post-ASPECTS) with 90-day prognosis and hemorrhagic transformation (HT).

Methods

We collected data from patients with acute ischemic stroke (AIS) with anterior-circulation large vessel occlusion (ACLVO) who were treated via thrombectomy within 10 h in 3 hospitals. Successful endovascular recanalization was achieved (modified thrombolysis in cerebral ischemia [mTICI] 2b/3). Non-contrast computed tomography (NCCT) examination was performed immediately (within 1 h) after thrombectomy. Post-ASPECTS were scored based on the brain parenchymal hyperdensity in NCCT according to the ASPECTS scoring method. HT was defined according to the ECASS II classification criteria. Linear correlation, logistic regression, and receiver operating characteristic curve analyses were used to determine the influencing factors and best predictive value of 90-day prognosis, 90-day death, and HT.

Results

A total of 231 patients were enrolled. The good prognosis rate, mortality rate, and HT rate were 57.1, 9.5, and 38.3%, respectively. The Post-ASPECTS affected poor prognosis, death, and HT. The best predictive value of Post-ASPECTS for poor prognosis, death, and HT was 7. The specificities of Post-ASPECTS for predicting HT, poor prognosis, and death were 87.6% (AUC, 0.811; P &lt; 0.001), 87.1% (AUC, 0.768; P &lt; 0.001), and 73.7% (AUC, 0.748; P &lt; 0.001), with positive predictive values of 74.2, 75.7, and 21.4%, respectively.

Conclusion

Post-ASPECTS predicted 90-day prognosis, death, and HT with high specificity and high positive predictive value in patients with AIS with ACLVO. Post-ASPECTS may be an ultra-early predictor of prognosis after thrombectomy.

Early Prediction of Malignant Edema After Successful Recanalization in Patients with Acute Ischemic Stroke

BACKGROUND

Postinterventional cerebral hyperdensities are common on non-contrast-enhanced computed tomography (CT) after endovascular thrombectomy in patients with acute ischemic stroke, which may reflect blood-brain barrier damage. The disruption of the blood-brain barrier may lead to malignant brain edema. The relationship between the extent of postinterventional cerebral hyperdensities and malignant brain edema is unclear.

METHODS

Patients with middle cerebral artery territory infarction and successful recanalization were consecutively enrolled. Postinterventional non-contrast-enhanced CT was performed to evaluate postinterventional cerebral hyperdensities within 24 h after endovascular thrombectomy. On the basis of the areas of the Alberta Stroke Program Early CT Score, we devised the Hyperdensity on CT Score to evaluate the extent of postinterventional cerebral hyperdensities. The primary outcome was malignant brain edema, defined as the development of clinical signs of herniation (including a decrease in consciousness and/or anisocoria), accompanied by imaging evidence of brain swelling. The component of postinterventional cerebral hyperdensities was divided into contrast staining and hemorrhage on the basis of persistency.

RESULTS

Three hundred sixty patients were included (50.6% male, mean age 67.9 years), of whom 247 (68.6%) developed postinterventional cerebral hyperdensities and 66 (18.3%) developed malignant brain edema. After adjustment for confounders, including the component of postinterventional cerebral hyperdensities, the extent of postinterventional cerebral hyperdensities assessed by the Hyperdensity on CT Score was significantly associated with malignant brain edema (odds ratio 1.46, 95% confidence interval 1.20-1.77, p < 0.001). A Hyperdensity on CT Score greater than 3 had a sensitivity of 0.73 and a specificity of 0.87 for predicting malignant brain edema.

CONCLUSIONS

The extent of postinterventional cerebral hyperdensities on postinterventional non-contrast-enhanced CT was associated with malignant brain edema. The Hyperdensity on CT Score could be used to predict malignant brain edema regardless of the component of postinterventional cerebral hyperdensities.

Association between pre-treatment perfusion profile and cerebral edema after reperfusion therapies in ischemic stroke

The relationship between reperfusion and edema is unclear, with experimental and clinical data yielding conflicting results. We investigated whether the extent of salvageable and irreversibly-injured tissue at baseline influenced the effect of therapeutic reperfusion on cerebral edema. In a pooled analysis of 415 patients with anterior circulation large vessel occlusion from the Tenecteplase-versus-Alteplase-before-Endovascular-Therapy-for-Ischemic-Stroke (EXTEND-IA TNK) part 1 and 2 trials, associations between core and mismatch volume on pre-treatment CT-Perfusion with cerebral edema at 24-hours, and their interactions with reperfusion were tested. Core volume was associated with increased edema (p < 0.001) with no significant interaction with reperfusion (p = 0.82). In comparison, a significant interaction between reperfusion and mismatch volume (p = 0.03) was observed: Mismatch volume was associated with increased edema in the absence of reperfusion (p = 0.009) but not with reperfusion (p = 0.27). When mismatch volume was dichotomized at the median (102 ml), reperfusion was associated with reduced edema in patients with large mismatch volume (p < 0.001) but not with smaller mismatch volume (p = 0.35). The effect of reperfusion on edema may be variable and dependent on the physiological state of the cerebral tissue. In patients with small to moderate ischemic core volume, the benefit of reperfusion in reducing edema is related to penumbral salvage.

Clinical Significance of Hyperdense Lesions on Non-enhanced Brain CT Obtained Immediately after Arterial Revascularization in Acute Ischemic Stroke Patients

Purpose

To analyze the characteristics of hyperdense lesions on brain CT conducted immediately after arterial revascularization (AR) in patients with acute ischemic stroke (AIS), track the outcome of those lesions and investigate their clinical significance.

Materials and Methods

97 AIS patients were enrolled in our study. Among them, 52 patients showed hyperdense lesions and were divided into three categories: type I, type II and type III according to the morphologic characteristics of hyperdense lesions. All patients underwent several follow-up CT/MR examinations to visualize the outcomes of the lesions.

Results

Among the 52 patients, 22 showed contrast extravasation, 23 displayed contrast extravasation combined with hemorrhagic transformation (HT) and 7 confirmed symptomatic intracranial hemorrhage (SICH) in follow-up CT/MR. Among the without hyperdense lesions group, only 7 converted to hemorrhage, and no SICH occurred. All type I lesions showed contrast extravasation; 23 type II lesions turned to hemorrhage, 2 revealed SICH and 6 were pure contrast extravasation; all of the type III developed into SICH.

Conclusion

Hyperdense lesions on non-enhanced brain CT obtained immediately after arterial revascularization (AR) exhibited varying features. Type I indicated a pure contrast extravasation. Type II and type III hyperdense lesions suggested higher incidence of HT, the presence of type III lesions indicated an ominous outcome.

Hyperattenuated Lesions on Immediate Non-contrast CT After Endovascular Therapy Predict Intracranial Hemorrhage in Patients With Acute Ischemic Stroke: A Retrospective Propensity Matched Study

Background and Purpose: This study aimed to analyze the association between hyperattenuated lesions (HALs) and postoperative intracranial hemorrhage (IH) and predict perioperative IH through quantitative analysis of HALs in acute ischemic stroke (AIS) with anterior large vessel occlusion (LVO) after endovascular therapy (ET).

Materials and Methods: This retrospective, propensity-matched study enrolled AIS who received ET from a single-center registry study between August 2017 and May 2020. The enrolled patients were divided into two groups: IH and non-IH, by follow-up postoperative CT. The occurrences of HALs on immediate CT after ET were also recorded. The association between IH and HALs after propensity score matching (PSM) was determined by binary logistic regression models. The receiver operating characteristic (ROC) curve was used to determine the predictive value of the highest CT Hounsfield units (HU) value on immediate CT.

Results: Initially, 1,418 patients who underwent digital subtraction angiography were reviewed and 114 AIS patients with immediate postoperative CT and follow-up CT after ET were enrolled. Forty-nine out of the 114 patients developed IH after therapy. After PSM analysis, patients with IH were more likely to have HALs on immediate CT (Odds Ratio, OR 11.9, P = 0.002, and 95% CI: 2.485–57.284). For 80 patients with HALs, ROC analysis of the highest CT value in the HALs territory showed that the cut-off value was 97 HU, the sensitivity was 70.21%, and the specificity was 81.82%.

Conclusions: Patients with HALs after ET are more likely to have perioperative IH. The highest CT value in the HALs area might be used to predict IH.

Clinical Significance of Hyperdense Area after Endovascular Therapy in Patients with Acute Ischemic Stroke: A Systematic Review and Meta-Analysis

OBJECTIVE

We performed a systematic review and meta-analysis to investigate the clinical significance of hyperdense area after thrombectomy in patients with acute ischemic stroke (AIS).

METHODS

We searched Ovid MEDLINE(R) and Epub Ahead of Print, In-Process and other Non-Indexed, Cochrane Library Clinical Controlled Trials and Embase from inception to September 2020 and collected the cohort and case-control studies about the clinical significance of hyperdense area on different types of computed tomography (CT) after thrombectomy in patients with AIS. Outcomes were poor functional outcome (modified Rankin Scale [mRS] Score 3-6 at discharge or 90-day), mortality and subtypes of hemorrhage according to the European Cooperative Acute Stroke Study (ECASS).

RESULTS

1,999 patients from 16 studies were included in this meta-analysis. Pooled results indicated higher risk of symptomatic intracerebral hemorrhage (odds ratio [OR] = 3.02; 95% confidence interval [CI] 1.84-4.95; p < 0.0001, I2 = 0%) in patients with hyperdense area, and the subtype of parenchymal hematoma as well. There was also higher odds of poor functional outcome based on the mRS 3-6 at discharge or 90-day (OR = 1.92; 95% CI 1.35-2.73; p = 0.0003, I2 = 31%) and mortality (OR = 2.06; 95% CI 1.41-3.02; p = 0.0002, I2 = 0%) in patients with hyperdense area after thrombectomy compared with those without hyperdense area.

CONCLUSIONS

Our results indicated that the presence of hyperdense area on CT after thrombectomy was associated with high risk of symptomatic intracerebral hemorrhage, poor functional outcome, as well as mortality in patients with AIS. However, further studies were needed to confirm these results. The meta-analysis was conducted in adherence with the PRISMA Statement and was registered at the International Prospective Register of Systematic Reviews (CRD42020164165). To the best of our knowledge, this study is the first meta-analysis investigating the effect of hyperdense area after endovascular therapy in patients with AIS.

Initial experience with dual-layer detector spectral CT for diagnosis of blood or contrast after endovascular treatment for ischemic stroke

PURPOSE

To determine whether spectral detector CT (SDCT) with a plain non-enhanced monochromatic CT, a water-weighted image after iodine removal, an iodine map, and Mono energetic images changes the diagnosis and classification of intracranial hemorrhage based on single energy CT after endovascular treatment (EVT) for ischemic stroke.

METHODS

Two readers evaluated single energy and SD CT data collected from 63 patients within one week after EVT. They diagnosed ICH or contrast staining, and graded ICH according to the Heidelberg and Safe Implementation of Thrombolysis in Stroke-Monitoring Study (SITS-MOST) classification. Differences in diagnosis between single energy and SD CT were tested with Pearson's chi-squared test. Diagnostic values of single energy CT were calculated. Interrater agreement was based on Cohen's Kappa.

RESULTS

When spectral data were added to single energy CT, the diagnosis of ICH changed in 8 CT scans (13%): in 4, the diagnosis of ICH was rejected and in 4, initially undetected ICH was diagnosed. In an additional 3 patients, the ICH grade was modified. CT alone had 88% sensitivity, 87% specificity, 88% positive diagnostic value, 87% negative diagnostic value, and 87% overall accuracy for ICH compared to SDCT. Interreader agreement on the presence of ICH was 0.84 (95% CI 0.51-0.86) for spectral CT and 0.84 (95% CI 0.73-0.97) for single energy CT.

CONCLUSION

SD CT after endovascular treatment contributes to the distinction between intracranial hemorrhage and contrast staining.

Flat Panel CT Scanning Is Helpful in Predicting Hemorrhagic Transformation in Acute Ischemic Stroke Patients Undergoing Endovascular Thrombectomy

Purpose

Hyperdense lesions are frequently revealed on flat panel CT (FP-CT) immediately after endovascular thrombectomy in patients with acute ischemic stroke. This study is aimed at discriminating hyperdense lesions caused by extravasation plus hemorrhage from those caused by contrast extravasation alone.

Methods

We retrospectively analyzed clinical and radiological data of patients who underwent an immediate postprocedure FP-CT scan and a follow-up noncontrast CT 24 hours after thrombectomy. We especially focused on the Maximum Hounsfield Units (HU_max) of each hyperdense lesion. A hyperdense lesion was judged to be hemorrhagic when it persisted on noncontrast CT and/or developed a mass effect.

Results

Of 81 patients included in this study, 32 (39.5%) patients presented 41 hyperdense lesions on FP-CT. The chance of hemorrhagic transformation is higher in patients with hyperdense lesions on FP-CT than that in patients without hyperdense lesions (23/32 vs. 1/49, p < 0.001). The HU_max of hyperdensity on FP-CT can predict hemorrhagic transformation with an area under the curve of 0.805 (95% CI: 0.67-0.94, p = 0.02). The sensitivity, specificity, positive, and negative predictive values of hyperdensity on FP-CT for hemorrhagic transformation were 96%, 84%, 72%, and 98%, respectively. A HU_max of >600 predicted hemorrhagic transformation with a sensitivity of 50% and a specificity of 100%.

Conclusions

The presence of hyperdensity on FP-CT can predict hemorrhagic transformation with a high sensitivity and negative predictive value. The measurement of HU_max of hyperdense lesion on FP-CT can be applied to the management of patients undergoing endovascular recanalization.

Hyperattenuating lesions after mechanical thrombectomy in acute ischaemic stroke: factors predicting symptomatic haemorrhage and clinical outcomes

AIM

To evaluate the clinical significance of hyperattenuating lesions on CT after mechanical thrombectomy for acute ischaemic stroke, and to identify imaging factors that predict symptomatic haemorrhage and unfavourable outcomes.

MATERIALS AND METHODS

Seventy-eight patients with acute ischaemic stroke in the anterior circulation who underwent mechanical thrombectomy were evaluated. All patients underwent post-interventional unenhanced computed tomography (CT) within 24 h and follow-up CT or magnetic resonance imaging (MRI) within 7 days. Baseline characteristics and clinical outcomes were compared between patients with and without hyperattenuating lesions. In patients with hyperattenuating lesions, clinical and imaging factors that predict symptomatic haemorrhage and unfavourable outcomes were determined.

RESULTS

Fifty-six of 78 patients (71.8%) demonstrated hyperattenuating lesions on post-interventional CT. Patients with hyperattenuating lesions showed lower Alberta Stroke Program Early CT score (ASPECTS), persistent/symptomatic haemorrhage, and unfavourable outcomes than those without. In patients with hyperattenuating lesions, larger hyperattenuating lesion volume (>21.3 ml; OR, 55.60, p<0.001) and perilesional oedema (OR, 46.04, p=0.015) were independent factors predicting symptomatic haemorrhage. Older age (OR, 1.2, p=0.006) and lower ASPECTS (OR, 0.45, p=0.046) were independent factors predicting unfavourable outcomes in patients with hyperattenuating lesions. Adding the volume of the hyperattenuating lesion to age and ASPECTS increased the predictive performance of unfavourable outcomes (area under the curve 0.874 versus 0.934, p=0.043).

CONCLUSIONS

Hyperattenuating lesions on post-interventional CT are associated with increased risk of symptomatic haemorrhage and unfavourable outcomes. Larger hyperattenuating lesion volume is an independent factor of symptomatic haemorrhage and it has added predictive value for unfavourable outcomes.

Contrast Extravasation is Predictive of Poor Clinical Outcomes in Patients Undergoing Endovascular Therapy for Acute Ischemic Stroke in the Anterior Circulation

OBJECTIVE

To investigate whether contrast extravasation on dual-energy computed tomography (DECT) in patients with acute ischemic stroke (AIS) after endovascular therapy (EVT) are related to hemorrhagic transformation (HT) and poor short-term clinical outcomes.

METHODS

A retrospective analysis was conducted on AIS patients who underwent EVT at Xuanwu hospital between November 2016 and January 2019. DECT was performed on all patients within 24 hours after EVT. Baseline demographic and clinical data were analyzed between patients with and without contrast extravasation and between patients with HT and non-HT, good and poor outcomes at 3 months post-EVT.

RESULTS

A total of 166 patients were included in the study with 51 (30.7%) patients experiencing contrast extravasation. Compared to patients without contrast extravasation, patients with contrast extravasation had longer onset to reperfusion time (444.8 minutes versus 374.0 minutes, P = .044) and higher percentages of greater than 3 retriever passes (16.7% versus 31.4%, P = .030). Contrast extravasation was associated with higher risk of HT (P = .038), poor outcome after discharge (P = .030), and longer hospital stay (P = .034). Multivariate analysis showed that contrast extravasation occurrence was an independent factor for HT (OR = 2.150, 95% CI 1.060-4.360, P = .034) and poor short-term outcome (OR = 2.936; 95% CI 1.147-7.518, P = .025).

CONCLUSIONS

The presence of contrast extravasation within 24 hours of EVT may be associated with higher risks of HT and may be predictive of unfavorable functional outcomes in AIS patients.

Dual energy CT after stroke thrombectomy alters assessment of hemorrhagic complications

Objective

To determine whether dual energy CT with a combined approach (cDECT) using a plain noncontrast monochromatic CT (pCT), a water-weighted image after iodine removal, and an iodine-weighted image changes the diagnosis and classification of intracranial hemorrhage (ICH) after endovascular thrombectomy (EVT) in acute ischemic stroke compared to a pCT image alone without separate water and iodine weighting.

Method

During 2012 to 2016, 372 patients at our comprehensive stroke center underwent DECT scans within 36 hours after EVT. Two readers evaluated pCT compared to a second reading with cDECT, establishing the diagnosis of ICH and grading it per the Heidelberg and Safe Implementation of Thrombolysis in Stroke–Monitoring Study (SITS-MOST) classifications.

Result

Using cDECT changed the ICH diagnosis to contrast staining only in 34% (52 of 152), modified the ICH grade in 10% (15 of 152), and diagnosed initially undetected ICH in 2% (5 of 220). pCT alone had 95% sensitivity, 80% specificity, 66% positive predictive value, 98% negative predictive value, and 85% accuracy for ICH compared to cDECT. Interreader agreement on the presence of ICH increased with cDECT compared to pCT (Cohen κ = 0.77 [95% confidence interval 0.69–0.84] vs 0.68 [0.61–0.76]).

Conclusion

cDECT within 36 hours after EVT changes the radiologic report regarding posttreatment ICH in a considerable proportion of patients undergoing EVT compared to pCT alone. This could affect decision-making regarding monitoring, secondary prevention, and prognostication. The cDECT scan could improve the interpretation consistency of high-attenuating changes on post-EVT images.

Contrast Staining may be Associated with Intracerebral Hemorrhage but Not Functional Outcome in Acute Ischemic Stroke Patients Treated with Endovascular Thrombectomy

To evaluate the incidence of post-interventional contrast staining (PICS) in acute ischemic stroke (AIS) Chinese patients who were treated with endovascular thrombectomy (ET) and investigate potential association of PICS with functional outcome and intracerebral hemorrhage (ICH). This observational study was based on a single-center prospective registry study. AIS patients who underwent ET from January 2013 to February 2017 were recruited into this study. All patients had dual-energy CT (DECT) scan of the head at 12 to 24 hours post-ET. The primary outcome was the incidence of PICS. Secondary outcomes were total ICH, symptomatic ICH (sICH), 3-month functional outcome, and long-term functional outcome. One hundred and eighty patients were enrolled in this study. PICS was detected in 50 patients (28%) based on the post-interventional CT scan. We first used basic statistical analyses, showing that the incidence of both total ICH (60% vs. 25%, p<0.001) and sICH (18% vs. 8%, p=0.044) were higher in patients with PICS than those without, and fewer patients achieved no disability (mRS≤1) in the PICS group compared to the control group at both 3-month and long-term follow-up (p<0.01 each). However, multivariate regression analysis further revealed that PICS only increased total (adjusted odds ratio, 7.38; 95% confidence interval 1.66 to 32.9; p=0.009) but not sICH risk. Furthermore, the logistic regression analyses did not show statistical difference in good clinical outcomes or mortality between the two groups. PICS is a common phenomenon in Chinese AIS patients. It is associated with total ICH after ET, but it seems to have no effect on functional outcome and sICH. Further large-scale studies are warranted to validate these results.

Preventing vessel perforations in endovascular thrombectomy: feasibility and safety of passing the clot with a microcatheter without microwire: the wireless microcatheter technique

BACKGROUND

To place a stent retriever for thrombectomy in acute ischemic stroke, the clot has to be passed first. A microwire is usually used for this maneuver. As an alternative, a wireless microcatheter can be used to pass the clot.

OBJECTIVE

To analyze the feasibility and complication rates of passing the clot using either a microwire or a wireless microcatheter.

METHODS

A retrospective non-randomized analysis of 110 consecutive patients with acute ischemic stroke in the anterior circulation was performed, in whom video recordings of mechanical thrombectomies were available. In total, 203 attempts at mechanical recanalization were performed.

RESULTS

Successful recanalization (TICI 2b-3) was achieved in 97.3% of patients. In 71.8% of attempts the clot was successfully passed using a wireless microcatheter only. When a microwire was used initially, clot passage was successful in 95.3% of attempts. Complication rates for angiographically detectable subarachnoid hemorrhage were 6.1% when a microwire was used to pass the clot compared with 0% when a wireless microcatheter was used (p<0.001). Complication rates for angiographically occult circumscribed subarachnoid contrast extravasation observed on post-interventional CT scans were 18.2% when a microwire was used to pass the clot and 4.5% when a wireless microcatheter was used (p<0.001).

CONCLUSIONS

In most cases of mechanical recanalization the clot can be passed with a wireless microcatheter instead of a microwire. In our study this method significantly reduced the risk for vessel perforation and subarachnoid hemorrhage. We therefore recommend the use of this technique whenever possible.

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.

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.

Hyper-attenuating brain lesions on CT after ischemic stroke and thrombectomy are associated with final brain infarction

Purpose Hyper-attenuating lesions, or contrast staining, on a non-contrast brain computed tomography (NCCT) scan have been investigated as a predictor for hemorrhagic transformation after endovascular treatment of acute ischemic stroke (AIS). However, the association of hyper-attenuating lesions and final ischemic areas are poorly investigated in this setting. The aim of the present study was to assess correlations between hyper-attenuating lesions and final brain infarcted areas after thrombectomy for AIS. Methods Data from patients with AIS of the anterior circulation who underwent endovascular treatment were retrospectively assessed. Images of the brain NCCT scans were analyzed in the first hours and late after treatment. The hyper-attenuating areas were compared to the final ischemic areas using the Alberta Stroke Program Early CT Score (ASPECTS). Results Seventy-one of the 123 patients (65.13%) treated were included. The association between the hyper-attenuating region in the post-thrombectomy CT scan and final brain ischemic area were sensitivity (58.3% to 96.9%), specificity (42.9% to 95.6%), positive predictive values (71.4% to 97.7%), negative predictive values (53.8% to 79.5%), and accuracy values (68% to 91%). The highest sensitivity values were found for the lentiform (96.9%) and caudate nuclei (80.4%) and for the internal capsule (87.5%), and the lowest values were found for the M1 (58.3%) and M6 (66.7%) cortices. Conclusions Hyper-attenuating lesions on head NCCT scans performed after endovascular treatment of AIS may predict final brain infarcted areas. The prediction appears to be higher in the deep brain regions compared with the cortical regions.

Infarct fogging on immediate postinterventional CT-a not infrequent occurrence

PURPOSE

A pseudo-normalization of infarcted brain parenchyma, similar to the "fogging effect" which usually occurs after 2-3 weeks, can be observed on CT performed immediately after endovascular stroke treatment (EST). Goal of this study was to analyze the incidence of this phenomenon and its evolution on follow-up imaging.

METHODS

One hundred fifty-two patients in our database of 949 patients, who were treated for acute stroke between January 2010 and January 2015, fulfilled the inclusion criteria of (a) EST for an acute stroke in the anterior circulation, (b) an ASPECT-score < 10 on pre-interventional CT, and (c) postinterventional CT imaging within 4.5 h after the procedure. Two independent reviewers analyzed imaging data of these patients.

RESULTS

Transformation of brain areas from hypoattenuated on pre-interventional CT to isodense on postinterventional CT was seen in 37 patients in a total of 49 ASPECTS areas (Cohen's kappa 0.819; p < 0.001). In 17 patients, the previously hypoattenuated brain areas became isodense, but appeared swollen. In 20 patients (13%), the previously hypodense brain area could not be distinguished from normal brain parenchyma. On follow-up imaging, all isodense brain areas showed signs of infarction.

CONCLUSION

Pseudo-normalization of infarct hypoattenuation on postinterventional CT is not infrequent. It is most likely caused by contrast leakage in infarcted parenchyma and does not represent salvage of ischemic brain parenchyma.

Relationship between Hemorrhagic Complications and Target Vessels in Acute Thrombectomy

PURPOSE

Intracranial hemorrhage after thrombectomy using a catheter to treat acute major cerebral artery occlusion is known to exacerbate patient outcomes. This study was performed to determine the relationship between middle cerebral artery (MCA) tortuosity and postoperative hemorrhage.

METHODS

We examined 111 consecutive patients who underwent acute thrombectomy for major intracranial artery occlusion in the anterior circulation at our hospital between September 2013 and June 2016. Patients in whom intracranial hemorrhage or subarachnoid hemorrhage was seen on head computed tomography 12-24 hours after surgery were assigned to the hemorrhagic group, whereas all the other patients were assigned to the nonhemorrhagic group. The groups were compared for tortuosity of the MCA, which was evaluated by finding the top-to-bottom (TB) distance of the M1 segment on anterior-posterior view angiograms. A modified Rankin scale score of 0-2 at 3 months after onset was considered a favorable prognosis.

RESULTS

The hemorrhagic group comprised 28 patients (25.2%) and the nonhemorrhagic group comprised 83 patients (74.8%). No significant difference in patient characteristics was seen between the groups. The hemorrhagic group displayed significantly fewer patients with a favorable prognosis (17.9% versus 43.4%, P = .016). The TB distance was significantly greater in the hemorrhagic group (hemorrhagic group, 9.7 mm; nonhemorrhagic group, 7.6 mm; P = .002); multivariate analysis also identified a TB distance over 8.8 mm as a factor independently associated with postoperative intracranial hemorrhage (P = .001).

CONCLUSIONS

Post-thrombectomy hemorrhage was significantly correlated with TB distance. A solution is needed for selecting and combining devices used in patients with a TB distance over 8.8 mm.

[Mechanical thrombectomy: Acute complications and delayed sequelae]

BACKGROUND

Due to the positive evidence for mechanical thrombectomy (mTE), it will be increasingly used in future. Profound knowledge of potential complications, prevention and management of complications is necessary to safely implement mTE into clinical practice.

AIM

Description of specific complications of mTE and their clinical relevance, measures for prevention and management. Summary of the current knowledge on long-term side effects of mTE.

MATERIAL AND METHODS

Analysis of current trial results and selected case series to address specific topics. Summary of own practical clinical experience.

RESULTS

Vascular injury (1-5%) and emboli (5-9%) are the most relevant intraprocedural complications but the clinical outcome is variable. Measures for prevention and management are described in detail. Vasospasms frequently occur (20-26%) but rarely need specific treatment and do not affect the clinical course. In the case of restrictive indications the frequency of symptomatic hemorrhage is similar to that for medicinal treatment (up to 8%). Contrast medium enhancement in the area of the infarction on post-treatment imaging should not be mistaken for hemorrhages. Focal subarachnoid contrast medium enhancement or hemorrhage occurs in up to 24% of cases and is predominantly benign. In follow-up imaging stenoses or occlusions can be detected in 4-10% of the treated vessels, most of which are asymptomatic. They are considered to be caused by microtrauma to the vascular wall.

CONCLUSION

Clinically relevant complications of mTE are rare. Preventive measures and effective management of complications may even increase safety. Stenoses occasionally occur as a long-term side effect but are asymptomatic in the majority of cases.

MRI Appearance of Intracerebral Iodinated Contrast Agents: Is It Possible to Distinguish Extravasated Contrast Agent from Hemorrhage?

BACKGROUND AND PURPOSE

Hyperattenuated cerebral areas on postinterventional CT are a common finding after endovascular stroke treatment. There is uncertainty about the extent to which these hyperattenuated areas correspond to hemorrhage or contrast agent that extravasated into infarcted parenchyma during angiography. We evaluated whether it is possible to distinguish contrast extravasation from blood on MR imaging.

MATERIALS AND METHODS

We examined the influence of iodinated contrast agents on T1, T2, and T2* and magnetic susceptibility in a phantom model and an ex vivo animal model. We determined T1, T2, and T2* relaxation times and magnetic susceptibility of iopamidol and iopromide in dilutions of 1:1; 1:2; 1:4; 1:10; and 1:100 with physiologic saline solution. We then examined the appearance of intracerebral iopamidol on MR imaging in an ex vivo animal model. To this end, we injected iopamidol into the brain of a deceased swine.

RESULTS

Iopamidol and iopromide cause a negative susceptibility shift and T1, T2, and T2* shortening. The effects, however, become very small in dilutions of 1:10 and higher. Undiluted iopamidol, injected directly into the brain parenchyma, did not cause visually distinctive signal changes on T1-weighted spin-echo, T2-weighted turbo spin-echo, and T2*-weighted gradient recalled-echo imaging.

CONCLUSIONS

It is unlikely that iodinated contrast agents extravasated into infarcted brain parenchyma cause signal changes that mimic hemorrhage on T1WI, T2WI, and T2*WI. Our results imply that extravasated contrast agents can be distinguished from hemorrhage on MR imaging.

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.