Time dependency of automated collateral scores in computed tomography angiography and computed tomography perfusion images in patients with intracranial arterial occlusion.

PURPOSE: The assessment of collateral status may depend on the timing of image acquisition. The purpose of this study is to investigate whether there are optimal time points in CT Perfusion (CTP) for collateral status assessment, and compare collaterals scores at these time points with collateral scores from multiphase CT angiography (mCTA). METHODS: Patients with an acute intracranial occlusion who underwent baseline non-contrast CT, mCTA and CT perfusion were selected. Collateral status was assessed using an automatically computed Collateral Ratio (CR) score in mCTA, and predefined time points in CTP acquisition. CRs extracted from CTP were correlated with CRs from mCTA. In addition, all CRs were related to baseline National Institutes of Health Stroke Scale (NIHSS) and Alberta Stoke Program Early CT Score (ASPECTS) with linear regression analysis to find the optimal CR. RESULTS: In total 58 subjects (median age 74 years; interquartile range 61-83 years; 33 male) were included. When comparing the CRs from the CTP vs. mCTA acquisition, the strongest correlations were found between CR from baseline mCTA and the CR at the maximal intensity projection of time-resolved CTP (r = 0.81) and the CR at the peak of arterial enhancement point (r = 0.78). Baseline mCTA-derived CR had the highest correlation with ASPECTS (ß = 0.36 (95%CI 0.11, 0.61)) and NIHSS (ß = - 0.48 (95%CI - 0.72, - 0.16)). CONCLUSION: Collateral status assessment strongly depends on the timing of acquisition. Collateral scores obtained from mCTA imaging is close to the optimal collateral score obtained from CTP imaging.

Association of the careggi collateral score with radiological outcomes after thrombectomy for stroke with an occlusion of the middle cerebral artery.

We aimed to examine the association between Careggi Collateral Score (CCS) and radiological outcomes in a large multicenter cohort of patients receiving thrombectomy for stroke with occlusion of middle cerebral artery (MCA). We conducted a study on prospectively collected data from 1785 patients enrolled in the Italian Registry of Endovascular Treatment in Acute Stroke. According to the extension of the retrograde reperfusion in the cortical anterior cerebral artery-MCA territories, CCS ranges from 0 (absence of retrograde filling) to 4 (visualization of collaterals until the alar segment of the MCA). Radiological outcomes at 24 h were the presence and severity of infarct growth defined by the absolute change in ASPECTS from baseline to 24 h; presence and severity of cerebral bleeding defined as no ICH, HI-1, HI-2, PH-1, or PH-2; presence and severity of cerebral edema (CED) defined as no CED, CED-1, CED-2, or CED-3. Using CCS = 0 as reference, ORs of CCS grades were significantly associated in the direction of better radiological outcome on infarct growth (0.517 for CCS = 1, 0.413 for CCS = 2, 0.358 for CCS = 3, 0.236 for CCS = 4), cerebral bleeding grading (0.485 for CCS = 1, 0.445 for CCS = 2, 0.400 for CCS = 3, 0.379 for CCS = 4), and CED grading (0.734 for CCS = 1, 0.301 for CCS = 2, 0.295 for CCS = 3, 0.255 for CSS = 4) shift in ordinal regression analysis after adjustment for pre-defined variables (age, NIHSS score, ASPECTS, occlusion site, onset-to-groin puncture time, procedure time, and TICI score). Using CCS = 4 as reference, ORs of CCS grades were significantly associated in the direction of worse radiological outcome on infarct growth (1.521 for CCS = 3, 1.754 for CCS = 2, 2.193 for CCS = 1, 4.244 for CCS = 0), cerebral bleeding grading (2.498 for CCS = 0), and CED grading (1.365 for CCS = 2, 2.876 for CCS = 1, 3.916 for CCS = 0) shift. The CCS could improve the prognostic estimate of radiological outcomes in patients receiving thrombectomy for stroke with MCA occlusion.

Favourable collaterals according to the Careggi Collateral Score grading system in patients treated with thrombectomy for stroke with middle cerebral artery occlusion.

The ability of the current grading systems to predict optimal outcomes in stroke patients with favourable collaterals remains unexplored. We evaluated differences in the performance of grading systems between Careggi Collateral Score and ASITN/SIR collateral score to predict clinical and radiological outcomes in stroke patients with favourable collaterals who underwent thrombectomy. We included stroke patients receiving thrombectomy within 360 min after symptom onset with MCA occlusion and favourable collaterals (i.e., without poor collaterals) defined by ASITN/SIR collateral score between 2 and 4. Using ordinal regression, we estimated the association of each CCS and ASITN/SIR grade with mRS shift (0-6) at 3 months, NIHSS score (0-42) and ASPECT score (10-0) at baseline, TICI score (3-0), infarct growth, cerebral bleeding, and cerebral edema grading at 24 h by calculating the odds ratios (ORs) with two-sided 95% confidence intervals after adjustment for predefined variables. Using the best collateral grade (CCS = 4) as reference, ORs of the CCS grades were associated in the direction of unfavourable outcome on 3-month mRS shift (2.325 for CCS = 3; 5.092 for CCS = 2), in the direction of more severe baseline NIHSS score (5.434 for CCS = 3; 16.041 for CCS = 2), 24-h infarct growth (2.659 for CCS = 3; 8.288 for CCS = 4) and 24-h cerebral edema (1.057 for CCS = 3; 5.374 for CCS = 2) shift. ORs of the ASITN/SIR grades were associated in the direction of more severe baseline NIHSS score (4.332 for ASITN/SIR = 3; 16.960 for ASITN/SIR = 2) and 24-h infarct growth (2.138 for ASITN/SIR = 3; 7.490 for ASITN/SIR = 2) shift. The AUC ROC of CCS and ASITN/SIR for predicting 3-month mRS score 0-1 were 0.681 (95% CI: 0.562-0.799; p = 0.009) and 0.599 (95% CI: 0.466-0.73; p = 0.156), respectively. CCS = 4 and ASITN/SIR ≥ 3 were the optimal cut-offs to predict 3-month mRS score 0-1, respectively. CCS grading system performed better than the ASITN/SIR collateral score predicting 3-month mRS score and 24-h CED grading in stroke patients with favourable collaterals who received thrombectomy for MCA occlusion.

Bio-clinical evaluation of collateral score in acute middle cerebral artery occlusion.

BACKGROUND: Acute ischemic stroke (AIS) is characterized as a neurological deficit owing to an acute focal damage to the brain by cerebral infarction. A collateral score is the most significant factor evaluating the prognosis of AIS, its relationship with demographic data, serum biochemical parameters, and clinical disability in this field. METHODS: We conducted a single-center retrospective study with 100 patients with AIS within the first 6 h of ischemic stroke. Data for consecutive AIS patients were collected from February 2019 to May 2020. The collateral score was assessed by using developed scoring systems defined by Maas et al. The correlations between collateral score and demographic data, biochemical parameters, NIHSS scores (National Institutes of Health Stroke Scale), mRS (modified Rankin scale) scores were recorded. RESULTS: The research was performed in 100 patients (median age, 71.55 ± 11.46 years), and there was a statistically significant difference between elevated erythrocyte distribution width (RDW) and Maas collateral score (insular cortex) (p = 0.024) and lymphocyte/ monocyte ratio (LMO) and Maas collateral (leptomeningeal) score (p = 0.025).

Rapid Infarct Progression in Anterior Circulation Large Vessel Occlusion Ischemic Stroke Patients During Inter-Facility Transfer.

INTRODUCTION: We aimed to identify factors associated with rapid infarct progression during inter-facility transfer for endovascular thrombectomy evaluation and its impact on clinical outcomes. METHODS: Patients with anterior circulation large artery occlusion within 24 h of onset transferred within our 17 hospital tele-stroke network were retrospectively analyzed. Patients were divided into fast progressors and slow progressors. Fast progressors were defined as CT ASPECTS score of ≥6 at the referring hospital (RH) and <6 at the hub hospital. Good clinical outcomes were defined as modified Rankin Scale score (mRS) 0-2 at 90 days. Demographic, clinical and radiologic variables associated with fast progressors and good clinical outcomes were identified using multivariable regression models. RESULTS: Among the 190 patients, 44 (23%) patients underwent rapid infarct progression. Higher stroke severity at presentation [aOR, 1.096, 95% CI,1.023, 1.174; p = 0.009], presence of early ischemic changes (CT ASPECT 6-9) at the RH [aOR, 2.721, 95% CI, 1.22, 6.071; p = 0.014] were positively associated, whereas prior ischemic stroke [aOR, 0.272, 95% CI, 0.078, 0.948; p = 0.04] and higher collateral score (2,3,4) [aOR, 0.138, 95%CI, 0.059, 0.324, p=<0.0001] were negatively associated with rapid infarct progression. Fifty-eight (31%) transferred patients had good outcomes. After adjusting for reperfusion status, age [aOR, 0.96, 95% CI, 0.93, 0.98; p=<0.001], initial stroke severity [aOR, 0.87, 95% CI, 0.81, 0.93; p=<0.001], absolute rate of decrease in CT ASPECTS [aOR, 0.38, 95% CI, 0.19, 0.77; p = 0.007] and internal carotid artery (ICA) occlusion [aOR, 0.34, 95 %CI, 0.12, 0.94; p = 0.038] were negatively associated with good outcome. CONCLUSION: Higher stroke severity, presence of early ischemic changes at the referring facility, absence of prior stroke, and poor collateral scores (CS 0-1) are the factors associated with rapid infarct progression in the telemedicine transfer cohort. Increasing age, higher stroke severity, higher absolute decrease in CT ASPECTS and ICA occlusion determine poor clinical outcomes.

The Relative Cerebral Blood Volume (rCBV) < 42% Is Independently Associated with Collateral Status in Anterior Circulation Large Vessel Occlusion.

Background: The pretreatment CT perfusion (CTP) marker the relative cerebral blood volume (rCBV) < 42% lesion volume has recently been shown to predict 90-day functional outcomes; however, studies assessing correlations of the rCBV < 42% lesion volume with other outcomes remain sparse. Here, we aim to assess the relationship between the rCBV < 42% lesion volume and the reference standard digital subtraction angiography (DSA)-derived American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology (ASITN) collateral score, hereby referred as the DSA CS. Methods: In this retrospective evaluation of our prospectively collected database, we included acute stroke patients triaged by multimodal CT imaging, including CT angiography and perfusion imaging, with confirmed anterior circulation large vessel occlusion between 1 September 2017 and 1 October 2023. Group differences were assessed using the Student's t test, Mann-Whitney U test and Chi-Square test. Spearman's rank correlation and logistic regression analyses were used to assess associations between rCBV < 42% and DSA CS. Results: In total, 222 patients (median age: 69 years, 56.3% female) met our inclusion criteria. In the multivariable logistic regression analysis, taking into account age, sex, race, hypertension, hyperlipidemia, diabetes, atrial fibrillation, prior stroke or transient ischemic attack, the admission National Institute of Health stroke scale, the premorbid modified Rankin score, the Alberta stroke program early CT score (ASPECTS), and segment occlusion, the rCBV < 42% lesion volume (adjusted OR: 0.98, p < 0.05) was independently associated with the DSA CS. Conclusion: The rCBV < 42% lesion volume is independently associated with the DSA CS.

Inter-Rater Reliability of Collateral Status Assessment Based on CT Angiography: A Retrospective Study of Middle Cerebral Artery Ischaemic Stroke.

The importance of assessing the collateral status (CS) in patients with ischaemic stroke (IS) has repeatedly been emphasised in clinical guidelines. Various publications offer qualitative or semiquantitative scales with gradations corresponding to the different extents of the collaterals, visualised mostly on the basis of CTA images. However, information on their inter-rater reliability is limited. Therefore, the aim of this study is to investigate the inter-rater reliability of the scales for collateral assessment. CTA images of 158 patients in the acute period of IS were used in the study. The assessment of CS was performed by two experts using three methodologies: the modified Tan scale, the Miteff scale, and the Rosenthal scale. Cohen's kappa, weighted kappa and Krippendorff's alpha were used as reliability measures. For the modified Tan scale and the Miteff and Rosenthal scales, the weighted kappa values were 0.72, 0.49 and 0.59, respectively. Although the best measure of consistency was found for the modified Tan scale, no statistically significant differences were revealed among the scales. The impact of the CS on the degree of neurological deficit at discharge was shown for the modified Tan and Rosenthal scales. In conclusion, the analysis showed a moderate inter-rater reliability of the three scales, but was not able to distinguish the best one among them.

Siamese model for collateral score prediction from computed tomography angiography images in acute ischemic stroke.

Introduction: Imaging biomarkers, such as the collateral score as determined from Computed Tomography Angiography (CTA) images, play a role in treatment decision making for acute stroke patients. In this manuscript, we present an end-to-end learning approach for automatic determination of a collateral score from a CTA image. Our aim was to investigate whether such end-to-end learning approaches can be used for this classification task, and whether the resulting classification can be used in existing outcome prediction models. Methods: The method consists of a preprocessing step, where the CTA image is aligned to an atlas and divided in the two hemispheres: the affected side and the healthy side. Subsequently, a VoxResNet based convolutional neural network is used to extract features at various resolutions from the input images. This is done by using a Siamese model, such that the classification is driven by the comparison between the affected and healthy using a unique set of features for both hemispheres. After masking the resulting features for both sides with the vascular region and global average pooling (per hemisphere) and concatenation of the resulting features, a fully connected layer is used to determine the categorized collateral score. Experiments: Several experiments have been performed to optimize the model hyperparameters and training procedure, and to validate the final model performance. The hyperparameter optimization and subsequent model training was done using CTA images from the MR CLEAN Registry, a Dutch multi-center multi-vendor registry of acute stroke patients that underwent endovascular treatment. A separate set of images, from the MR CLEAN Trial, served as an external validation set, where collateral scoring was assessed and compared with both human observers and a recent more traditional model. In addition, the automated collateral scores have been used in an existing functional outcome prediction model that uses both imaging and non-imaging clinical parameters. Conclusion: The results show that end-to-end learning of collateral scoring in CTA images is feasible, and does perform similar to more traditional methods, and the performance also is within the inter-observer variation. Furthermore, the results demonstrate that the end-to-end classification results also can be used in an existing functional outcome prediction model.

Association of the Careggi Collateral Score with 3-month modified Rankin Scale score after thrombectomy for stroke with occlusion of the middle cerebral artery.

BACKGROUND: The Careggi Collateral Score (CCS) (qualitative-quantitative evaluation) was developed from a single-centre cohort as an angiographic score to describe both the extension and effectiveness of the pial collateral circulation in stroke patients with occlusion of the anterior circulation. We aimed to examine the association between CCS (quantitative evaluation) and 3-month modified Rankin Scale (mRS) score in a large multi-center cohort of patients receiving thrombectomy for stroke with occlusion of middle cerebral artery (MCA). METHODS: We conducted a study on prospectively collected data from 1284 patients enrolled in the Italian Registry of Endovascular Treatment in Acute Stroke. According to the extension of the retrograde reperfusion in the cortical anterior cerebral artery (ACA)-MCA territories, CCS ranges from 0 (absence of retrograde filling) to 4 (visualization of collaterals until the alar segment of the MCA). RESULTS: Using CCS of 4 as reference, CCS grades were associated in the direction of unfavourable outcome on 3-month mRS shift (0 to 6); significant difference was found between CCS of 0 and CCS of 1 and between CCS of 3 and CCS of 4. CCS ≥ 3 was the optimal cut-off for predicting 3-month excellent outcome, while CCS ≥ 1 was the optimal cut-off for predicting 3-month survival. CCS of 0 and CCS < 3 were associated in the direction of unfavourable recanalization on TICI shift (0 to 3) compared with CCS ≥ 1 and CCS ≥ 3, respectively. Compared with CCS ≥ 3 as reference, CCS of 0 and CCS 1 to 2 were associated in the direction of unfavourable recanalization on TICI shift. There was no evidence of heterogeneity of effects of successful recanalization and procedure time ≤ 60 min on 3-month mRS shift across CCS categories. CONCLUSION: The CCS could provide a future advantage for improving the prognosis in patients receiving thrombectomy for stroke with M1 or M1-M2 segment of the MCA occlusion.

Thin-slab maximum intensity projection of CT angiography for collateral score and clot burden score evaluation: comparison with conventional CT angiography.

BACKGROUND: This study aimed to exam the effects of thin-slab maximum intensity projection (TS-MIP) of computed tomography angiography (CTA) for collateral score (CS) and clot burden score (CBS) evaluation in patients with large-vessel-occlusion (LVO) stroke in the anterior circulation. METHODS: Of 241 consecutive patients with LVO stroke admitted to our center between August 2015 and June 2020, 187 patients were enrolled. CS and CBS were evaluated on conventional CTA and TS-MIP separately. Outcome at 90 days was classified as good if modified Rankin scale (mRS) was ≤2 and as poor if mRS was >2. The correlations between CS and CBS and clinical outcomes were assessed. Receiver operating characteristic (ROC) curve analysis was used to determine the diagnostic values of CS and CBS. Multivariate logistic regression analysis was performed to identify the independent predictors of 90-day good clinical outcomes. RESULTS: The correlation coefficient for clinical outcomes was significantly better for CS based on TS-MIP than that based on conventional CTA (-0.444 vs. -0.285, P=0.039); no significant difference was found in the CBS evaluation (TS-MIP: -0.356 vs. conventional CTA: -0.320, P=0.348). For predicting good clinical outcomes, TS-MIP-based CS was associated with larger area under the curve (AUC) (0.709 vs. 0.609, P=0.004) and higher sensitivity (69.1% vs. 42.0%, P=0.001) than CS based on CTA. In multivariable logistic regression analysis, the factors independently associated with good outcomes were National Institutes of Health Stroke Scale (NIHSS) score at admission (OR =1.147; P<0.001), TS-MIP-based CS (OR =0.326; P<0.001), final modified treatment in cerebral infarction (mTICI) score of 2b/3 (OR =0.098; P<0.001), and hemorrhagic transformation (OR =3.662; P<0.001). CONCLUSIONS: TS-MIP-CTA is superior to conventional CTA for evaluation CS and CBS, and TS-MIP-based CS may be a useful predictor of clinical outcome.

Quantitative collateral score for the prediction of clinical outcomes in stroke patients: Better than visual grading.

Objectives: To identify preoperative prognostic factors for acute ischemic stroke (AIS) patients receiving mechanical thrombectomy (MT) and compare the performance of quantitative collateral score (qCS) and visual collateral score (vCS) in outcome prediction. Methods: Fifty-five patients with AIS receiving MT were retrospectively enrolled. qCS was defined as the percentage of the volume of collaterals of both hemispheres. Based on the dichotomous outcome assessed using a 90-day modified Rankin Scale (mRS), we compared qCS, vCS, age, sex, National Institute of Health stroke scale score, etiological subtype, platelet count, international normalized ratio, glucose levels, and low-density lipoprotein cholesterol (LDL-C) levels between favorable and unfavorable outcome groups. Logistic regression analysis was performed to determine the effect on the clinical outcome. The discriminatory power of qCS, vCS, and their combination with cofounders for determining favorable outcomes was tested with the area under the receiver-operating characteristic curve (AUC). Results: vCS, qCS, LDL-C, and age could all predict clinical outcomes. qCS is superior over vCS in predicting favorable outcomes with a relatively higher AUC value (qCS vs. vCS: 0.81 vs. 0.74) and a higher sensitivity rate (qCS vs. vCS: 72.7% vs. 40.9%). The prediction power of qCS + LDL-C + age was best with an AUC value of 0.91, but the accuracy was just increased slightly compared to that of qCS alone. Conclusion: Collateral scores, LDL-C and age were independent prognostic predictors for patients with AIS receiving MT; qCS was a better predictor than vCS. Furthermore, qCS + LDL-C + age offers a strong prognostic prediction power and qCS alone was another good choice for predicting clinical outcome.

Role of modified TAN score in predicting prognosis in patients with acute ischemic stroke undergoing endovascular therapy.

OBJECTIVE: The study aimed to evaluate the prognostic role of modified TAN collateral score in predicting functional independence in ischemic stroke patients, who underwent endovascular therapy. INTRODUCTION: Identifying the group of patients, who will benefit most from arterial recanalization in patients with acute ischemic stroke, is the basis of success. Collateral circulation is a physiological condition that protects the brain against ischemia and inhibits the growth of a damaged area. The presence of collaterals is a well-known determinant for functional independence. Numerous collateral scoring systems are used for this purpose. The aim of this study was to evaluate the prognostic role of modified TAN collateral score (MTCS) in predicting functional independence in patients, who received endovascular therapy. MATERIALS AND METHODS: Prospective data of 101 patients, who received endovascular therapy from the stroke team of Eskisehir Osmangazi University (ESOGÜ) between 2016 and 2017, were examined retrospectively for this purpose. Collateral assessments were performed in Computed Tomography Angiography (CTA) according to the modified TAN scoring system (< 50% refers to poor collateral status, ≥ 50% refers to good collateral status). Good clinical outcome was assessed as mRS 0-2 in the 3rd month. The TICI scoring system was used in the evaluation of recanalization. Patients treated within the first 6 h of symptom onset, patients with NCCT and contrast CTA, patients with internal carotid artery and middle cerebral artery occlusion were included in the study. Posterior system stroke was not included in the study. CONCLUSION: Of the 101 patients, 50 (49%) had poor MTCS. Presentation and 24th hour NIHSS values of the patients with poor MTCS were higher (p:0.003). The third month mRS values were low in patients with good MTCS on admission, while these values were high in patients, who presented with poor MTCS. Mortality rates were significantly higher in the patient group with poor collateral circulation score (32-5.9%) (p:0.001). No significant differences were found in the presentation ASPECT values and (TICI 2b/3) recanalization rates of the patients. The rate of futile recanalization was significantly higher in the group with poor collateral circulation (52-8%) (p:0.0001). Presentation glucose, NIHSS, mTAN, symptom-puncture time, and good ASPECT score were found to be predictive markers for good outcome by univariate analysis. The major risk factors were determined by performing multiple logistic regression analysis. Presentation glucose, NIHSS, and mTAN (OR:1.013, 1.29, 0.198, respectively) were found to be strong and independent predictors for good clinical outcome. According to Multiple Binary Logistic Regression analysis Backward-ward model, Baseline NIHSS, poor collaterals and baseline glucose are found as predictors for poor outcome. DISCUSSION: This study shows that good collateral score is associated with good clinical response, small final infarct volume, third month low mRS, low admission, and 24-hour NIHSS rates. The likelihood of having long term prognosis is 7 fold higher in patients with poor collaterals. The use of the MTCS system is recommended and supported due to its easy and rapid applicability.

Regional leptomeningeal collateral score by computed tomographic angiography correlates with 3-month clinical outcome in acute ischemic stroke.

PURPOSE: The aim of the study is to assess the correlation between regional leptomeningeal collateral (rLMC) Scores calculated on computed tomography (CT) angiography following acute anterior circulation ischemic stroke, with 3-month clinical outcome measured as modified Rankin Scale (mRS) and Barthel Index (BI). MATERIALS AND METHODS: A total of thirty patients were studied as per the exclusion and inclusion criteria and after informed consent. Multi-phase CT angiography was carried out within 24 h of stroke onset, and collateral scoring was done using rLMC score along with Alberta stroke programme early CT (ASPECT) scoring. At 3 months, patients were followed up to evaluate the clinical outcome using mRS and BI. Statistical analysis was performed to find out the correlation between rLMC score, ASPECT score, and clinical outcome and for association with demographic parameters and stroke risk factors. RESULTS: A strong correlation was noted between ASPECT and rLMC scores (P < 0.001) and between rLMC scores and clinical outcome at 3 months (mRS and BI). Correlation with mRS (P < 0.001) was nearly as strong as that of BI on follow-up (P < 0.001). The ASPECT score also was a predictor of clinical outcome and showed correlation with mRS (P < 0.001) and BI (P < 0.001). No significant association was found between various stroke risk factors and demographic parameters with rLMC scores. The rLMC scoring system showed substantial inter-rater reliability with Kappa = 0.7. CONCLUSIONS: rLMC score in CT angiography correlates with ASPECT Score and clinical outcome at 3 months. Hence, this scoring system can be used for collateral quantification as may be of use in predicting short-term clinical outcomes.

Cone beam-computed tomography angiography by intravenous contrast injection is reliable to evaluate patients with large vessel occlusion.

PURPOSE: Mechanical thrombectomy (MT) for acute ischemic stroke (AIS) patients due to emergent large vessel occlusion (ELVO) is standard treatment, the benefits, however, are highly time-sensitive. After patient eligibility for reperfusion therapy is determined by conventional radiological examinations, the time to be transferred from the department of radiological examination to angiography-suites is critical. We speculated that the time required for the diagnosis of AIS might be reduced if we could determine MT eligibility in patients with ELVO at angiography-suites. Modern angiography-suites with flat panel detectors can perform cone beam (CB)-CT. We performed CB-CTA using intravenous injection of contrast agent to evaluate occlusion sites, collateral score, and construction of vessels distal to occlusion sites and determined if CB-CTA could be useful to evaluate patients with ELVO. METHODS: We included 15 patients with ELVO diagnosed by conventional MRI or CT/CTA, and investigated whether CB-CTA was reliable to diagnose occlusion sites. We also studied if collateral score on CB-CTA was associated with prognosis after successful reperfusion by MT by comparison between favorable (modified Rankin scale (mRS) 0-2), and unfavorable outcome group (mRS 3-6). RESULTS: There was strong agreement of occlusion sites between CB-CTA and conventional radiological examination (κ = 0.80). Collateral score determined by CB-CTA was significantly different between favorable outcome and unfavorable outcome group (median collateral score 2.3 v.s. 1.3, p = 0.040). CONCLUSIONS: Although prospective study of AIS patients at a radiography department is indispensable, CB-CTA performed in an angiography-suite might be useful to evaluate patients with ELVO.

Cerebral Collateral Circulation: A Review in the Context of Ischemic Stroke and Mechanical Thrombectomy.

The pial (leptomenigeal) collateral circulation is a key determinant of functional outcome after mechanical thrombectomy after large-vessel ischemic stroke. Patients with good collateral blood flow benefit up to 24 hours after stroke onset, whereas those with poor collateral flow evidence less or no benefit. However, clues to why collateral flow varies so widely among patients have remained elusive. Recent findings in animal studies, which are currently being tested for confirmation in humans, have found that naturally occurring variants of a novel "collateral gene," Rabep2, result in large differences in the extent of anatomic collaterals and thus blood flow and infarct size in mice after stroke. The comprehension of collagerogenesis in humans and the evaluation of collateral status could aid in identifying patients who will benefit not only from mechanical thrombectomy in the extended time window but also from any reperfusion strategy. We performed a literature review focused on radiographic, clinical, and genetic aspects of the collateral circulation.

Hemorrhage After Endovascular Recanalization in Acute Stroke: Lesion Extent, Collaterals and Degree of Ischemic Water Uptake Mediate Tissue Vulnerability.

Background and Purpose: Intracranial hemorrhage (ICH) remains a major complication of endovascular treatment (ET) in acute stroke. The aim of this study was to identify clinical and imaging predictors for ICH in patients with acute ischemic stroke undergoing successful ET. Methods: We performed a retrospective analysis of patients with large vessel occlusion in the anterior circulation who underwent successful ET at our university medical center between 2015 and 2018. ICH was diagnosed on non-enhanced CT and a binary outcome was defined: ICH occurrence in the immediate post-interventional phase within 12-36 h (yes/no). The impacts of clinical, radiological, and interventional parameters on outcome were assessed in logistic regression models. Results: One hundred and seven patients fulfilled the inclusion criteria. 37 (34.6%) showed an ICH of which 7 (6.5%) patients were diagnosed as symptomatic and 30 (28.04%) as asymptomatic. Multivariable regression analyses identified a lower ASPECTS (adjusted odds ratio (OR) 1.95, 95%CI: 1.4-3.63, P = 0.037), low collateral score (adjusted OR 0.12, 95%CI: 0.03-0.49, P = 0.003) and high Net Water Uptake (NWU) (adjusted OR 1.56, 95%CI: 2.34-1.03, P = 0.007) as independent predictors of ICH after successful ET. Conclusions: CT-based quantitative NWU, ASPECTS, and collateral score mediate tissue vulnerability and are reliable independent predictors of a bleeding event after successful ET. This imaging-based prediction model might be useful for early stratification of patients at high risk of a bleeding event after ET, especially with low ASPECTS.

Predictors for basal ganglia viability after mechanical thrombectomy in proximal middle cerebral artery occlusion.

BACKGROUND/PURPOSE: In acute proximal middle cerebral artery (MCA) occlusion covering the lenticulostriate arteries (LSA), ischemic tolerance of basal ganglia is limited due to supposed lack of collateral supply. However, in several patients, basal ganglia (BG) infarction was absent after successful mechanical thrombectomy (MTE). Purpose of our study was to evaluate predictors for BG viability in stroke patients despite prolonged MCA mainstem occlusion. MATERIAL/METHODS: We retrospectively reviewed all stroke patients from our local registry with MCA mainstem occlusion after mechanical thrombectomy between November 2009 and October 2016. All patients underwent non-enhanced post-interventional cranial CT imaging (NCCT) and were classified according to 6 patterns of BG viability: complete: putamen (P) and globus pallidus (GP); partial: P or GP, and combination of complete or partial BG and/or adjacent white matter/cortical (WMC) viability. We compared viability patterns with respect to pre-interventional stroke imaging including NCCT, CT-angiography (CTA), CT perfusion (CTP); demographics, pre- and intra-procedural data and occurrence of post-procedural intracerebral hematoma (ICH). CTP imaging of the affected and contralateral BG-territories were obtained separately and CTA-collateral score (CS) was assessed. RESULTS: A significant correlation between higher collateral score and viability of GP (OR = 1.949; p = .011), P (OR = 2.039, p = .011), and the combination of GP, P and WMC (OR = 2.767, p = .007) was revealed. Higher relative CBV ratio (rCBVR) was significantly associated with viability of the pattern GP + WMC (univariate: OR = 3.160, p = .014; multivariate: OR = 6.058; p = .021). CONCLUSION: CTA collateral score and rCBVR were predictive for BG viability in stroke patients after successful MTE in prolonged complete MCA-mainstem and LSA occlusion.

Value of CT angiography in anterior circulation large vessel occlusive stroke: Imaging findings, pearls, and pitfalls.

Hyperacute stroke imaging is playing an increasingly important role in determining management decisions in acute stroke patients, particularly patients with large vessel occlusive stroke who may benefit from endovascular intervention. CT angiography (CTA) is an important tool in the work-up of the acute stroke patient. It reliably detects large occlusive thrombi in proximal cerebral arteries and is a quick and highly accurate method in identifying candidates for endovascular stroke treatment. In this article we review the imaging findings on CTA in acute large vessel occlusive stroke using a pictorial case based approach. We retrospectively reviewed CTA studies in 48 patients presenting with acute anterior circulation large vessel occlusive stroke who were brought for intra-arterial acute stroke intervention. We discuss and illustrate patterns of proximal intracranial arterial occlusion, collateralization to the occluded territory, as well as reviewing some important pearls, pitfalls and teaching points in CTA assessment of the acute stroke patient. Performed from the level of the aortic arch CTA also gives valuable information regarding the state of other vessels in the acute stroke patient, identifying additional significant vascular stenoses or occlusions, and as we illustrate, can demonstrate other clinically significant findings which may impact on patient management and outcome.