Favorable Imaging Profile Research Articles

Abstract TP131: Computed Tomography Perfusion Imaging Patterns Are Similar Before and After Interfacility Transfer of Ischemic Stroke Patients

Background: Large vessel occlusion (LVO) stroke patients are often transferred from regional hospitals to comprehensive stroke centers (CSC) for thrombectomy. The need for repeat imaging at CSCs prior to intervention is unclear. We compared regional hospital and CSC perfusion imaging results for interfacility transfers in a single health system. Methods: We analyzed a cohort of patients in western Michigan who received CT perfusion imaging before and after transfer to a CSC. Perfusion mismatch (MM), core infarct volume (CIV), and favorability of imaging for mechanical thrombectomy (MT) candidacy were compared between the regional and CSC studies. A favorable imaging profile was defined as the presence of LVO, MM volume >10 mL, and MM/CIV ratio of >1.2. Linear regression was used to examine predictors of infarct growth during transfer. Results: Over a 10-month period, 25 patients met inclusion criteria. The median age was 76 (IQR 66-81), 60% were male, median NIHSS was 11 (IQR 2-18), and most patients had occlusion of the internal carotid or middle cerebral arteries (72%). The median time from last known well to initial CT was 250 minutes (IQR 85-620). Regional median MM volume was 52 mL (IQR 8-97), CIV was 0 mL (IQR 0-13), and hypoperfusion intensity ratio (HIR) was 0.25 (IQR 0-0.34). The median time between CTs was 152 minutes (IQR 139-226). The median change in MM volume was -3 mL (IQR -27-3) and median CIV growth rate was 0 mL/hr (IQR 0-2.0). In a multivariable regression model, higher HIR (β=23.2, p=0.012) and minutes between imaging studies (β=0.10, p=0.021) were associated with CIV growth. Sixteen patients (64%) had favorable imaging profiles for MT at the regional hospital. Of these, 15 (93.8%) continued to have a favorable CSC imaging profiles and 9 (56.2%) underwent MT. Of the 9 patients without favorable regional imaging profiles, 1 (11.1%) had a favorable CSC imaging profile and 2 (22.2%) underwent MT. Conclusion: In our sample, regional and CSC perfusion imaging patterns were similar and patients infrequently crossed thresholds for MT candidacy between studies. Initial HIR and longer delays between were independently associated with infarct growth during transfers, however overall infarct growth was very small.

Mechanical thrombectomy for acute large vessel occlusion stroke beyond 24h.

Multiple trials have shown that mechanical thrombectomy (MT) is superior to medical therapy. However, no robust evidence is available regarding MT beyond 24h. In this study, we aimed to determine the safety and efficacy of endovascular stroke therapy in this late window. We conducted a retrospective study of prospectively collected data of patients who met extended window trial criteria, but underwent MT beyond 24h. Safety and efficacy outcomes included symptomatic intracerebral hemorrhage (sICH), procedural complications, number of passes, successful recanalization (mTICI 2b-3), delta (Δ) NIHSS (baseline-discharge), and favorable outcomes (mRS 0-2 at 90days). A total of 39 patients were included with a median age of 69years (IQR 61.5, 73.5); 54% were females. Hypertension was present in 76% of patients; 23% were smokers. Half of the patients had M1 occlusion (48.7%). Median preprocedural NIHSS was 11 (IQR 7.0, 19.5). Successful revascularization was achieved in 87%; median number of passes was 2 (IQR 1.0, 3.0). Median ΔNIHSS was 3.0 (IQR -1.5, 8.0). Favorable outcome was achieved in 49% (95% CI: 34%-64%), and 95% were free of complications. A total of 3 patients (7.7%) had sICH. In an exploratory analysis, posterior circulation occlusion was associated with higher mRS at 90days (OR: 14.7, p=0.016). Favorable discharge facility was associated with lower mRS at 90days (OR: 0.11, p=0.004). Our study showed comparable clinical outcomes of MT beyond 24h compared to MT trials within 24h in patients with favorable imaging profile, especially in anterior circulation occlusions.

Effect of Sex on Clinical Outcome and Imaging after Endovascular Treatment of Large-Vessel Ischemic Stroke

Background and PurposeIt is unclear if sex differences explain some of the variability in the outcomes of stroke patients who undergo endovascular treatment (EVT). In this study we assess the effect of sex on radiological and functional outcomes in EVT-treated acute stroke patients and determine if differences in baseline perfusion status between men and women might account for differences in outcomes. MethodsWe included patients from the CRISP (Computed tomographic perfusion to Predict Response to Recanalization in ischemic stroke) study, a prospective cohort study of acute stroke patients who underwent EVT up to 18 hours after last seen well. We designed ordinal regression and univariable and multivariable regression models to examine the association between sex and infarct growth, final infarct volume and 90-day mRS score. ResultsWe included 198 patients. At baseline, women had smaller perfusion lesions, more often had a target mismatch perfusion profile, and had better collateral perfusion. Women experienced less ischemic core growth (median 15 mL vs. 29 mL, p < 0.01) and had smaller final infarct volumes (median 26 mL vs. 50 mL, p < 0.01). Female sex was associated with a favorable shift on the modified Rankin Scale (adjusted cOR 1.79 [1.04 - 3.08; p = 0.04]) and lower odds of severe disability or death (adjusted OR 0.29 [0.10 – 0.81]; p = 0.02). ConclusionsThe results suggest that women have better collaterals and, therefore, more often exhibit a favorable imaging profile on baseline imaging, experience less lesion growth, and have better clinical outcomes following endovascular therapy.

Insights Into Intra-arterial Thrombolysis in the Modern Era of Mechanical Thrombectomy.

Background and Purpose: The role of intra-arterial (IA) thrombolysis in modern endovascular therapy is not well-understood. Here, we surveyed neurointerventionalists to understand their current clinical practices and opinions of IA thrombolysis in the new era of mechanical thrombectomy (MT).Method: A 24-question anonymous survey was distributed via email to the members of the Society of Vascular and Interventional Neurology.Results: One hundred and four responses were included in the analysis. Most respondents were interventional neurologists (76.9%) and had ≥5-years in neuro-interventional practice (80.8%). IA thrombolytics are presently used by 60.6%. Aspiration plus stent-retriever was the most common MT approach used with IA-thrombolysis (66.0%). IA-thrombolysis was used in mainly three approaches: (1) treatment of primary distal occlusions, (2) as rescue after proximal occlusion thrombectomy, and (3) or as adjunct therapy to primary MT approach. The most frequent IA-rtPA dose was 3–10 mg, with 1 mg/min infusion rate (56.6%). 84.9% do not have a standardized protocol for administering IA-rtPA. About half (50.9%) believed there should be no time limit for administering IA lytic if there is a favorable imaging profile, while 30.2% indicated ≤6 h. Most respondents (76.5%) would consider using IA-tenecteplase in a trial setting. Only 12.9% felt there was no role for IA thrombolysis in modern endovascular practice. Respondents with ≥10-years' experience were less supportive of the future of IA lytic (98.0 vs. 76.4%, p = 0.006).Conclusion: IA-thrombolysis is currently used in clinical practice; however, there is no clear consensus on best practices or criteria for administration. Further studies are needed to define the role of IA-thrombolysis in the context of MT.

Response to Late-Window Endovascular Revascularization Is Associated With Collateral Status in Basilar Artery Occlusion.

Background and Purpose- The benefit of endovascular therapy in extended time windows has been demonstrated in patients with anterior circulation large vessel occlusion ischemic stroke and favorable imaging profile. We evaluated whether collaterals and thrombus burden influence the associations between revascularization, time-to-treatment, and outcome in endovascular therapy-treated patients with basilar artery occlusion. Methods- We retrospectively analyzed clinical and imaging data of consecutive endovascular therapy-treated patients with basilar artery occlusion included in the multicenter Basilar Artery Treatment and Management Collaboration. The BATMAN (Basilar Artery on Computed Tomography Angiography score, which evaluates thrombus burden and collaterals) and the PC-CS (Posterior Circulation Collateral score, which evaluates collaterals) were assessed on computed tomography angiography, blinded to clinical outcome. Good outcome was defined as modified Rankin Scale score of ≤3 within 3 months; revascularization (successful reperfusion) as modified Thrombolysis in Cerebral Infarction 2b-3 (or TIMI [Thrombolysis in Myocardial Infarction] 2-3 in the BASICS [Basilar Artery International Cooperation Study] registry). Results- We included 172 patients with basilar artery occlusion treated with endovascular therapy (124 with mechanical thrombectomy): mean (SD) age 65 (13) years, median National Institutes of Health Stroke Scale 22 (interquartile range 12-30), 64 (37%) treated >6 hours. Revascularization (achieved in 79% of patients) was associated with good outcome (P=0.003). The use of new generation thrombectomy devices was associated with good outcome (P=0.03). In patients who achieved revascularization, 29/46 (63%) of patients with a favorable BATMAN score and 26/51 (51%) with favorable PC-CS had good outcomes. In logistic regression analysis (adjusted for age, National Institutes of Health Stroke Scale, and time-to-treatment ≤6/>6 hours), revascularization was associated with good outcome in patients with favorable BATMAN score (odds ratio, 15.8; 95% CI, 1.4-175; P=0.02) or PC-CS (odds ratio, 9.4; 95% CI, 1.4-64; P=0.02). In patients who achieved revascularization, early (time-to-treatment ≤6 hours) but not late treatment was associated with improved outcome in patients with unfavorable BATMAN score (18/52 [35%]; odds ratio, 15; 95% CI, 1.9-124; P=0.01) or PC-CS (16/44 [36%]; odds ratio, 5.5; 95% CI, 1.4-21; P=0.01). Conclusions- Revascularization is associated with good outcome in patients with basilar artery occlusion with good collaterals and less extensive occlusion, even >6 hours after onset.

Mechanical embolectomy for acute ischemic stroke beyond six hours from symptom onset using MRI based perfusion imaging

IntroductionThere is very limited data on the use of MRI based perfusion imaging to select patients with acute ischemic stroke and large vessel occlusion (LVO) for intraarterial therapy beyond 6h from onset. Our aim is to report the outcome of patients with acute ischemic stroke and large artery occlusion who presented beyond 6h from onset, had favorable MRI imaging profile, and underwent mechanical embolectomy. MethodsThis is a single institution (Rhode Island Hospital) retrospective study between December 1st, 2015, and July 30th, 2016 that included patients with acute ischemic stroke and proximal LVO with CT ASPECTS of 6 or more and 6–24h from symptom onset who were assessed for mechanical embolectomy using MRI based perfusion imaging. Favorable imaging profile was defined based on prior studies as 1) DWI lesion volume (as defined as apparent diffusion coefficient<620×10–6mm2/s) of 70ml or less; 2) Penumbra volume (as defined by volume of tissue with Tmax>6s) of 15ml or greater; 3) A mismatch ratio of 1.8 or more; and 4) Volume of tissue with perfusion lesion with Tmax>10s is <100ml. Good outcome was defined as a 90-day mRS≤2. Results41 patients met the inclusion criteria; 22 (53.7%) had favorable imaging profile and underwent mechanical embolectomy. The rate of good outcomes in this series was similar to that in a patient level pooled meta-analysis of the recent endovascular trials (63.6% vs. 46%, p=0.13). None of the patients in our cohort had symptomatic intracereberal hemorrhage. ConclusionsMRI perfusion based imaging may help select patients with acute ischemic stroke and proximal emergent LVO for embolectomy beyond the treatment window used in most endovascular trials. This provides compelling evidence for stroke centers to participate in ongoing trials using advanced imaging to study endovascular treatment in this patient population.

Abstract WP39: Mechanical Embolectomy for Acute Ischemic Stroke Beyond Six Hours From Symptom Onset Using Advanced MR Imaging

Background: There is very limited data on the use of advanced neuroimaging to select patients with acute ischemic stroke and large vessel occlusion for intraarterial therapy beyond 6 hours from onset. Our aim is to report the outcome of patients with acute ischemic stroke and large artery occlusion who presented beyond 6 hours from onset, had favorable MRI imaging profile, and underwent mechanical embolectomy. Methods: This is a single institution retrospective study between December 1st, 2015, and July 30 th , 2016 with acute ischemic stroke and anterior circulation large vessel occlusion (LVO) with ASPECTS of 6 or more and beyond 6 hours from symptoms onset. Favorable imaging profile was defined as 1) DWI lesion volume (as defined as apparent diffusion coefficient &lt; 620 X 10-6 mm2/s) of 70 mL or less AND 2) Penumbra volume (as defined by volume of tissue with Tmax &gt;6 sec) of 15 mL or greater AND 3) A mismatch ratio of 1.8 or more AND 4) Volume of tissue with perfusion lesion with Tmax &gt; 10 sec is less than 100 mL. Good outcome was defined as a 90 day mRS≤2. Results: In the study period, 41 patients met the inclusion criteria; 22 (53.6%) had favorable imaging profile and underwent mechanical embolectomy. The median age was 75 years (59-92), 68.2% were females; the median time from last known normal to groin puncture was 684.5 minutes (range 363-1628) and the median admission NIHSS score was 17.5 (range 4-28). The rate of good outcomes in this series was similar to that in a patient level pooled meta-analysis of the recent endovascular trials (68.2% vs. 46.0%, p=0.07). The rate of good outcome matches that of the EXTEND-IA trial that selected patients using perfusion imaging (68.2% vs. 71.0%, p = 1.00). None of the patients in our cohort had symptomatic intracereberal hemorrhage. Conclusion: Advanced MR imaging may help select patients with acute ischemic stroke and anterior circulation large vessel occlusion for embolectomy beyond the treatment window used in most endovascular trials.

Abstract TP9: ASPECTS Values in Patients With Large Vessel Occlusion and Time of Arrival to Emergency Department: Estimation of Eligibility for Endovascular Stroke Therapy

Background: Favorable imaging profile according to The Alberta Stroke Program Early CT Score (ASPECTS) is an important selection criterion for endovascular therapy in patients with acute stroke from anterior circulation large vessel occlusion (LVO). The goal of this study was analyze the relationship between ASPECTS values and time of arrival to emergency department (ED) after stroke onset, and its impact on patient’s eligibility for endovascular stroke therapy. Methods: analysts of ASPECTS values in consecutive patients with acute stroke from anterior circulation LVO admitted within 24 hours of onset was performed. Criteria from American Heart Association/American Stroke Association (AHA/ASA) guidelines based on the proposed class I-II recommendations, including the ‘favorable’ ASPECTS range of 6-10 were applied to determine frequency of potentially eligible patients for endovascular stroke therapy. Results: Of 641 patients with acute ischemic stroke presenting within the first 24 hours of onset, 71 (11%) had anterior circulation LVO. Medium time from arrival to ED to noncontrast head CT was 6 minutes. 72% of patients arrived to ED within the first 6 hours, 18% within 6-12 hours, and 10% within 12-24 hours of symptom onset. Based on ‘favorable’ ASPECTS criterion alone, 80% of patients with anterior circulation LVO who arrive to the ED within the first 6 hours of stroke onset would qualify for endovascular therapy. Of those who arrived to ED within 6-24 hours of stroke onset, 50% had ‘favorable’ ASPECTS. Conclusions: 50% of patients with stroke from anterior circulation LVO who arrive to ED within 6-24 hours of onset have ‘favorable’ ASPECTS, making them potentially eligible for endovascular stroke therapy.

Abstract TP6: Factors Influencing Infarct Progression During Ischemic Stroke Patients Transfer: Collaterals Lost is Brain Lost

Introduction: When transferred from a referring hospital (RH) to a thrombectomy capable stroke center (TCSC), patients with initially favorable imaging profile (ASPECT score ≥6) often demonstrate infarct progression significant enough to make them ineligible at arrival. We sought to determine the clinical and imaging factors associated with this phenomenon in transferred ischemic stroke patients. Methods: We identified adult stroke patients transferred from one of 30 RH between 2010 and 2016 for which (1) a RH computed tomography (CT) and (2) a CT Angiography (CTA) at arrival were available for review. ASPECT scores were evaluated by 2 raters. The adequacy of leptomeningeal collateral flow was rated as none/poor, decreased, adequate or augmented per the Maas et al (Stroke 2009), modified scale. ASPECTS decay was defined as an ASPECT initial score ≥6 worsening between RH and TCSC CTs to a score &lt;6. Results: A total of 330 patients were included in the analysis (mean age 70.2 ± 14.2, 43.3% females). Univariable subgroup analyses showed that patients with ASPECTs decay were more likely to be females (55% vs 40%, p=0.02), not on anticoagulants (4% vs 15%, p=0.01), and with higher initial NIHSS (Median [IQR] 19 [15.3-22] vs 11 [6-17], p&lt;0.001), hyperdense vessel sign on initial CT (71% vs 26%, p&lt;0.001) and poor collaterals on CTA (72% vs 19%, p&lt;0.001). In multivariable models, higher NIHSS, lower baseline ASPECTs, CTA evidence of a proximal occlusion, and none/poor collaterals were strong predictors of ASPECTs decay, with collateral status demonstrating the highest odds ratio (aOR 10.3, 95%CI: [4.1-29], p&lt;0.001). Similar results were found after stratification by vessel occlusion level. Conclusion: In ischemic stroke patients transferred for thrombectomy, poor collateral flow, stroke severity and proximal vascular occlusion, but not time interval, are the main determinants of ASPECTs decay.

ASPECTS decay during inter-facility transfer in patients with large vessel occlusion strokes

BackgroundFavorable imaging profile according to the Alberta Stroke Program Early CT Score (ASPECTS) on non-contrast head CT is a key criterion for the selection of patients with ischemic stroke from...