Background and purpose
Mechanical thrombectomy (MT) has proven to be the standard of care for patients with acute ischemic stroke due to large vessel occlusion (AIS‐LVO). However, high ...revascularization rates do not necessarily result in favorable functional outcomes. We aimed to investigate imaging biomarkers associated with futile recanalization, defined as unfavorable functional outcome despite successful recanalization in AIS‐LVO patients.
Methods
A retrospective multicenter cohort study was made of AIS‐LVO patients treated by MT. Successful recanalization was defined as modified Thrombolysis in Cerebral Infarction score of 2b–3. A modified Rankin Scale score of 3–6 at 90 days was defined as unfavorable functional outcome. Cortical Vein Opacification Score (COVES) was used to assess venous outflow (VO), and the Tan scale was utilized to determine pial arterial collaterals on admission computed tomography angiography (CTA). Unfavorable VO was defined as COVES ≤ 2. Multivariable regression analysis was performed to investigate vascular imaging factors associated with futile recanalization.
Results
Among 539 patients in whom successful recanalization was achieved, unfavorable functional outcome was observed in 59% of patients. Fifty‐eight percent of patients had unfavorable VO, and 31% exhibited poor pial arterial collaterals. In multivariable regression, unfavorable VO was a strong predictor (adjusted odds ratio = 4.79, 95% confidence interval = 2.48–9.23) of unfavorable functional outcome despite successful recanalization.
Conclusions
We observe that unfavorable VO on admission CTA is a strong predictor of unfavorable functional outcomes despite successful vessel recanalization in AIS‐LVO patients. Assessment of VO profiles could help as a pretreatment imaging biomarker to determine patients at risk for futile recanalization.
Net water uptake (NWU) is a quantitative imaging biomarker used to assess cerebral edema resulting from ischemia via Computed Tomography (CT)-densitometry. It serves as a strong predictor of clinical ...outcome. Nevertheless, NWU measurements on follow-up CT scans after mechanical thrombectomy (MT) can be affected by contrast staining. To improve the accuracy of edema estimation, virtual non-contrast images (VNC-I) from dual-energy CT scans (DECT) were compared to conventional polychromatic CT images (CP-I) in this study. We examined NWU measurements derived from VNC-I and CP-I to assess their agreement and predictive value in clinical outcome. 88 consecutive patients who received DECT as follow-up after MT were included. NWU was quantified on CP-I (cNWU) and VNC-I (vNWU). The clinical endpoint was functional independence at discharge. cNWU and vNWU were highly correlated (r = 0.71, p < 0.0001). The median difference between cNWU and vNWU was 8.7% (IQR: 4.5-14.1%), associated with successful vessel recanalization (mTICI2b-3) (ß: 11.6%, 95% CI 2.9-23.0%, p = 0.04), and age (ß: 4.2%, 95% CI 1.3-7.0%, p = 0.005). The diagnostic accuracy to classify outcome between cNWU and vNWU was similar (AUC:0.78 versus 0.77). Although there was an 8.7% median difference, indicating potential edema underestimation on CP-I, it did not have short-term clinical implications.
BACKGROUND AND OBJECTIVESTime from stroke onset is associated with clinical response to intravenous thrombolysis (IVT) with alteplase and is therefore used to select patients for treatment. ...Alternatively, neuroimaging may be used for treatment in the uncertain or extended time window. We hypothesized that the patient-specific imaging indicator of ischemic lesion progression ("tissue clock") using CT perfusion (CTP) or quantitative net water uptake (NWU) is a predictor of early neurologic improvement (ENI) independent of time.METHODSObservational study of anterior circulation ischemic stroke patients with proximal vessel occlusion and known time from symptom onset triaged by multimodal CT undergoing endovascular treatment. Quantitative NWU using an established threshold (11.5%) or CTP lesion core mismatch (EXTEND criteria) was used to estimate ischemic lesion progression. The treatment effect of IVT depending on lesion progression defined by tissue clock vs time clock was assessed by inverse probability weighting (IPW). End points were binarized ENI and functional independence at day 90.RESULTSFour hundred nine patients were included, of which 223 (54.5%) received IVT. The proportion of patients within an early time window (<4.5 hours), low NWU, and CTP mismatch were 45.0%, 86.5%, and 80.3%. In IPW, IVT was associated with higher rates of ENI (%-difference: 7.3%, p = 0.02). For patients with CTP mismatch or low NWU, IVT was associated with a 9.6% or 7.2% higher rate of ENI, which was different than the effect of IVT in patients without CTP mismatch or high NWU (-9.3%/-7.3%; p = 0.004/p = 0.03), whereas early treatment window did not modify the effect of IVT.DISCUSSIONCT-based measures of the "tissue clock" might identify patients who benefit from IVT more accurately than conventional time windows. Considering the high number of patients with early "tissue clock" (low NWU/CTP mismatch) within an extended time window, considerable benefit from IVT using imaging indicators of the "tissue clock" may be achieved.
BackgroundIn patients suffering from acute ischemic stroke from large vessel occlusion (LVO), mechanical thrombectomy (MT) often leads to successful reperfusion. Only approximately half of these ...patients have a favorable clinical outcome. Our aim was to determine the prognostic factors associated with poor clinical outcome following complete reperfusion.MethodsPatients treated with MT for LVO from a prospective single-center stroke registry between July 2015 and April 2019 were screened. Complete reperfusion was defined as Thrombolysis in Cerebral Infarction (TICI) grade 3. A modified Rankin scale at 90 days (mRS90) of 3–6 was defined as ‘poor outcome’. A logistic regression analysis was performed with poor outcome as a dependent variable, and baseline clinical data, comorbidities, stroke severity, collateral status, and treatment information as independent variables.Results123 patients with complete reperfusion (TICI 3) were included in this study. Poor clinical outcome was observed in 67 (54.5%) of these patients. Multivariable logistic regression analysis identified greater age (adjusted OR 1.10, 95% CI 1.04 to 1.17; p=0.001), higher admission National Institutes of Health Stroke Scale (NIHSS) (OR 1.14, 95% CI 1.02 to 1.28; p=0.024), and lower Alberta Stroke Program Early CT Score (ASPECTS) (OR 0.6, 95% CI 0.4 to 0.84; p=0.007) as independent predictors of poor outcome. Poor outcome was independent of collateral score.ConclusionPoor clinical outcome is observed in a large proportion of acute ischemic stroke patients treated with MT, despite complete reperfusion. In this study, futile recanalization was shown to occur independently of collateral status, but was associated with increasing age and stroke severity.
The effect of mechanical thrombectomy (MT) on functional outcome in patients with ischemic stroke with low ASPECTS is still uncertain. ASPECTS rating is based on the presence of ischemic ...hypoattenuation relative to normal; however, the degree of hypoattenuation, which directly reflects net uptake of water, is currently not considered an imaging biomarker in stroke triage. We hypothesized that the effect of thrombectomy on functional outcome in low ASPECTS patients depends on early lesion water uptake.
For this multicenter observational study, patients with anterior circulation stroke with ASPECTS ≤5 were consecutively analyzed. Net water uptake (NWU) was assessed as a quantitative imaging biomarker in admission CT. The primary end point was the rate of favorable functional outcome defined as modified Rankin Scale score 0-3 at day 90. The effect of recanalization on functional outcome was analyzed according to the degree of NWU within the early infarct lesion.
A total of 254 patients were included, of which 148 (58%) underwent MT. The median ASPECTS was 4 (interquartile range IQR 3-5), and the median NWU was 11.4% (IQR 8.9%-15.1%). The rate of favorable outcome was 27.6% in patients with low NWU (<11.4%) vs 6.3% in patients with high NWU (≥11.4%;
< 0.0001). In multivariable logistic regression analysis, NWU was an independent predictor of outcome, whereas vessel recanalization (modified thrombolysis in cerebral infarction ≥2b) was only significantly associated with better outcomes if NWU was lower than 12.6%. In inverse-probability weighting analysis, recanalization was associated with 20.7% (
= 0.01) increase in favorable outcome in patients with low NWU compared with 9.1% (
= 0.06) in patients with high NWU.
Early NWU was independently associated with clinical outcome and might serve as an indicator of futile MT in low ASPECTS patients. NWU could be tested as a tool to select low ASPECTS patients for MT.
The study is registered within the ClinicalTrials.gov Protocol Registration and Results System (NCT04862507).
Computed tomography perfusion (CTP) imaging is regularly used to guide patient selection for mechanical thrombectomy (MT). However, the effect of MT in patients without salvageable tissue on CTP has ...not been investigated. The purpose of this study was to assess the effect of MT in patients with stroke without perfusion mismatch profiles.
This observational study analyzed patients with ischemic stroke consecutively treated between March 1, 2015, and January 31, 2022, triaged by multimodal-computed tomography undergoing MT. CTP lesion-core mismatch profiles were defined using a mismatch volume/ratio of ≥10 mL/1.2, respectively. The primary end point was the rate of functional independence at 90 days, defined as the modified Rankin Scale score of 0 to 2. Recanalization was evaluated with the modified Thrombolysis in Cerebral Infarction scale. The effect of baseline variables on functional outcome was assessed using multivariable logistic regression analysis. Outcomes of patients with and without CTP-mismatch profiles were compared using 1:1 propensity score matching.
Of 724 patients who met the inclusion criteria of this retrospective observational study, 110 (15%) patients had no CTP mismatch and were analyzed. The median age was 74 (interquartile range, 62-80) years and 53% were women. Successful recanalization (modified Thrombolysis in Cerebral Infarction score, ≥2b) was achieved in 66% (73) and associated with functional independence at 90 days (adjusted odds ratio, 7.33 95% CI, 1.22-43.70;
=0.03). A significant interaction was observed between recanalization and age, as well as the extent of infarction, indicating MT to be most effective in patients <70 years and with a baseline Alberta Stroke Program Early Computed Tomography Score range between 3 and 7. These findings remained stable after propensity score matching, analyzing 152 matched pairs with similar rates of functional independence between patients with and without CTP-mismatch profiles (17% versus 23%;
=0.42).
In patients without CTP-mismatch profiles defined according to the EXTEND (Extending the Time for Thrombolysis in Emergency Neurological Deficits) criteria, recanalization was associated with improved functional outcomes. This effect was associated with baseline Alberta Stroke Program Early Computed Tomography Score and age, but not with the time from onset to imaging.
Background and purpose
Clinical outcome after endovascular thrombectomy in patients with acute ischemic stroke still varies significantly. Higher blood glucose levels (BGL) have been associated with ...worse clinical outcome, but the pathophysiological causes are not yet understood. We hypothesized that higher levels of BGL are associated with more pronounced ischemic brain edema and worse clinical outcome mediated by cerebral collateral circulation.
Methods
178 acute ischemic stroke patients who underwent mechanical thrombectomy were included. Early ischemic brain edema was determined using quantitative lesion water uptake on initial computed tomography (CT) and collateral status was assessed with an established 5-point scoring system in CT-angiography. Good clinical outcome was defined as functional independence (modified Rankin Scale mRS score 0–2). Multivariable logistic regression analysis was performed to predict functional independence and linear regression analyses to investigate the impact of BGL and collateral status on water uptake.
Results
The mean BGL at admission was significantly lower in patients with good outcome at 90 days (116.5 versus 138.5 mg/dl;
p
< 0.001) and early water uptake was lower (6.3% versus 9.6%;
p
< 0.001). The likelihood for good outcome declined with increasing BGL (odds ratio OR per 100 mg/dl BGL increase: 0.15; 95% CI 0.02–0.86;
p
= 0.039). Worse collaterals (1% water uptake per point, 95% CI 0.4–1.7%) and higher BGL (0.6% per 10 mg/dl BGL, 95% CI 0.3–0.8%) were significantly associated with increased water uptake.
Conclusion
Elevated admission BGL were associated with increased early brain edema and poor clinical outcome mediated by collateral status. Patients with higher BGL might be targeted by adjuvant anti-edematous treatment.
Objectives
Triage of patients with basilar artery occlusion for additional imaging diagnostics, therapy planning, and initial outcome prediction requires assessment of early ischemic changes in early ...hyperacute non-contrast computed tomography (NCCT) scans. However, accuracy of visual evaluation is impaired by inter- and intra-reader variability, artifacts in the posterior fossa and limited sensitivity for subtle density shifts. We propose a machine learning approach for detecting early ischemic changes in pc-ASPECTS regions (Posterior circulation Alberta Stroke Program Early CT Score) based on admission NCCTs.
Methods
The retrospective study includes 552 pc-ASPECTS regions (144 with infarctions in follow-up NCCTs) extracted from pre-therapeutic early hyperacute scans of 69 patients with basilar artery occlusion that later underwent successful recanalization. We evaluated 1218 quantitative image features utilizing random forest algorithms with fivefold cross-validation for the ability to detect early ischemic changes in hyperacute images that lead to definitive infarctions in follow-up imaging. Classifier performance was compared to conventional readings of two neuroradiologists.
Results
Receiver operating characteristic area under the curves for detection of early ischemic changes were 0.70 (95% CI 0.64; 0.75) for cerebellum to 0.82 (95% CI 0.77; 0.86) for thalamus. Predictive performance of the classifier was significantly higher compared to visual reading for thalamus, midbrain, and pons (
P
value < 0.05).
Conclusions
Quantitative features of early hyperacute NCCTs can be used to detect early ischemic changes in pc-ASPECTS regions. The classifier performance was higher or equal to results of human raters. The proposed approach could facilitate reproducible analysis in research and may allow standardized assessments for outcome prediction and therapy planning in clinical routine.
Artifacts in computed tomography (CT) and magnetic resonance imaging (MRI) due to titanium implants in spine surgery are known to cause difficulties in follow-up imaging, radiation planning, and ...precise dose delivery in patients with spinal tumors. Carbon fiber–reinforced polyetheretherketon (CFRP) implants aim to reduce these artifacts. Our aim was to analyze susceptibility artifacts of these implants using a standardized in vitro model. Titanium and CFRP screw-rod phantoms were embedded in 3% agarose gel. Phantoms were scanned with Siemens Somatom AS Open and 3.0-T Siemens Skyra scanners. Regions of interest (ROIs) were plotted and analyzed for CT and MRI at clinically relevant localizations. CT voxel–based imaging analysis showed a significant difference of artifact intensity and central overlay between titanium and CFRP phantoms. For the virtual regions of the spinal canal, titanium implants (ti) presented − 30.7 HU vs. 33.4 HU mean for CFRP (
p
< 0.001), at the posterior margin of the vertebral body 68.9 HU (ti) vs. 59.8 HU (CFRP) (
p
< 0.001) and at the anterior part of the vertebral body 201.2 HU (ti) vs. 70.4 HU (CFRP) (
p
< 0.001), respectively. MRI data was only visually interpreted due to the low sample size and lack of an objective measuring system as Hounsfield units in CT. CT imaging of the phantom with typical implant configuration for thoracic stabilization could demonstrate a significant artifact reduction in CFRP implants compared with titanium implants for evaluation of index structures. Radiolucency with less artifacts provides a better interpretation of follow-up imaging, radiation planning, and more precise dose delivery.
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