Abstract 2697: Fully-automated Identification of Acute Stroke Lesion Volumes with CT Perfusion

Stroke ◽  
2012 ◽  
Vol 43 (suppl_1) ◽  
Author(s):  
Matus Straka ◽  
Gregory W Albers ◽  
Maarten G Lansberg ◽  
Stephanie M Kemp ◽  
Michael P Marks ◽  
...  
Keyword(s):  
Acute Stroke ◽  
Ct Perfusion ◽  
Automated Image Analysis ◽  
Great Promise ◽  
Lesion Volume ◽  
Stroke Patients ◽  
Infarct Core ◽  
Median Volume ◽  
Stroke Lesion ◽  
Volume Difference

Purpose: Mismatch between volumes of infarct core and critically hypoperfused tissue (CHT) may be used to identify acute stroke patients who could benefit from reperfusion therapies. We present a fully-automated, operator-free approach for identifying the core and CHT lesion volumes with CT perfusion (CTP). Methods: 31 scans of 25 acute stroke patients who underwent CTP followed by MRI (range: 23-120 min) were analyzed. CTP was obtained as a one or two 2cm slabs. MRI included DWI and PWI. Reference stroke lesion metrics were MRI-based: core via DWI (ADC<615x10 -6 mm 2 /s), and CHT via PWI (Tmax>6s). CTP and PWI scans were processed with an automated image analysis program (RAPID) with delay-independent deconvolution. MRI maps were coregistered to CTP. Contralaterally-relative CBV CT and CBF CT ( cr CBF CT , cr CBF CT ) maps were computed by putting into ratio the original and corresponding laterally-mirrored and smoothed rCBV CT and rCBF CT maps (obtained by vertical flip and coregistration of the anatomic images, see Fig). Stroke core in CTP was delineated by thresholding cr CBV CT and cr CBF CT , and CHT by thresholding Tmax CT . Optimal thresholds were obtained by ROC analysis and minimization of lesion volume differences between CT and MRI. Results: For identification of stroke core in CTP, cr CBF CT performed better than cr CBV CT . Optimal threshold was cr CBF CT < 0.30 with sensitivity 60% (CI 95% 57-63%) and specificity 88%, (CI 95% 87-89%); median volume difference between CBF CT and DWI lesions was 0 ml (IQR: -6ml to 6 ml); correlation of volumes was r 2 =0.72 ( p <0.0001). For identification of CHT, reference MRI lesions (Tmax MR >6s) were most accurately identified by Tmax CT >6s with sensitivity 72% (CI 95% 70-74%), specificity 97% (CI 95% 96-97%); median volume difference between Tmax CT and Tmax MR was -3ml (IQR: -10ml to 0ml); correlation of CHT volumes r 2 =0.89 (p<0.0001). Conclusions: The processing methods and CTP thresholds presented in this study show a great promise for fully-automated outlining of stroke lesions using CTP. Such a technique could be of great value for CTP-based patient selection in clinical trials and clinical practice.

Abstract WP83: Validation of a Relative Non-Contrast CT Map to Detect Early Ischemic Changes in Acute Stroke

Stroke ◽  
2020 ◽  
Vol 51 (Suppl_1) ◽  
Author(s):  
Margy E McCullough-Hicks ◽  
Soren Christensen ◽  
Aditya Srivatsan ◽  
Gregory W Albers ◽  
Maarten Lansberg
Keyword(s):  
Acute Stroke ◽  
Brain Regions ◽  
Lesion Volume ◽  
Stroke Patients ◽  
Infarct Core ◽  
Test Characteristics ◽  
Contrast Ct ◽  
Sensitivity Specificity ◽  
Early Infarction

Background: Discerning signs of early infarct on the non-contrast CT (NCCT) can be difficult. To facilitate interpretation of the NCCT we previously developed a technique to generate symmetry ratio maps of the NCCT (rNCCT maps) on which subtle (≥5%) differences in density between symmetric brain regions are enhanced. We sought to validate the rNCCT map against other measures of early infarction in a large cohort. Methods: rNCCT maps were generated for 146 ischemic stroke patients. We assessed how often a neurologist’s interpretation of the NCCT was changed when provided with the rNCCT map. The neurologist was blinded to CTP and DWI but was given the infarct hemisphere. In addition, using the 24-hour DWI as the gold standard, we assessed the sensitivity, specificity and volumetric accuracy of the rNCCT-defined infarct core and compared this to the test characteristics of CTP-defined infarct core (CBF<38% threshold). Results: Addition of rNCCT overlay map changed clinician’s initial read 64.4% of the time (95% CI 56-72%); the rNCCT identified new areas of ischemia not appreciated on blinded review 86.2% of the time (95% CI 78-92%) and in 35.1% helped rule out early ischemia where the reader was unsure of its presence (95% CI 26-45%). In the 53 patients with reperfusion and follow-up MRI, specificity of rNCCT for final lesion volume was 99.5% for rNCCT [98.5-99.8%] vs. 99.8% [IQR 98.8-99.9%] for CTP (P=0.08). Sensitivity for rNCCT was 19.9% [7.1-28.1%] vs. 17.5% [4.7-32.2%] for CTP (P=0.56). Conclusions: This study validates the rNCCT map for detection of early ischemic changes. It is more quantitative and objective than a clinician’s read of the NCCT alone. The sensitivity and specificity for detecting early ischemic changes on rNCCT were comparable to those achieved with CTP. This indicates that the rNCCT could be a valuable tool in the evaluation of acute stroke patients.

Abstract TP64: Ischemic Stroke Lesion Identification in Non-Contrast CT Using Deep Learning

Stroke ◽  
2020 ◽  
Vol 51 (Suppl_1) ◽  
Author(s):  
Soren Christensen ◽  
Christian Federau ◽  
Julian Maclaren ◽  
Aditya Srivatsan ◽  
Greg Albers ◽  
...  
Keyword(s):  
Deep Learning ◽  
Acute Stroke ◽  
Hounsfield Unit ◽  
Training Data ◽  
Validation Dataset ◽  
Great Promise ◽  
Lesion Volume ◽  
Independent Validation ◽  
Stroke Lesion ◽  
Contrast Ct

Background: Automatic measurement of the acute stroke lesion volume on DWI and CT-CBF has been used in recent late window trials. Despite non-contrast CT (NCCT) being the most widely used imaging modality in the acute stroke setting, quantification of acute stroke volumes on NCCT has not been employed in trials because of the difficulty outlining territory with very mild Hounsfield unit depression. Deep learning algorithms have been effective at solving many image processing tasks and may outperform human readers given enough training data. The goal of this study was to train and test a deep learning model on NCCT scans with synthetic stroke lesions and to determine the optimal model design. Methods: Training: 20 NCCT scans without acute stroke were combined with 20 DWI lesions using co-registration producing 400 non-contrast scans with lesions. The region of the NCCT that coincided with the DWI lesion was depressed by 2 Hounsfield units to simulate an acute infarct. An independent validation dataset of 100 cases was created in the same way. Two models were used: a standard “Unet” model and a symmetry-aware Unet model. The models were compared in terms of segmentation accuracy in the independent validation dataset. Results: Both the symmetry aware U-net and the standard U-net detected some part of the true lesion in 100% of the cases. The symmetry aware U-net was more sensitive, median [iqr], (45% [27-68] vs 17% [6-54], p<0.00001) but slightly less specific (98% [93-98] vs 99% [94-99], p<0.0008) than the standard U-net. Conclusion: The symmetry aware U-net shows great promise in detection of acute strokes on NCCT; lesions with Hounsfield unit depressions that are barely visible to the eye can be automatically segmented by this model. Additional training data and architectural enhancements are likely to improve the current spatial sensitivity to above 45%.

Endovascular treatment beyond 24 hours from the onset of acute ischemic stroke: the Italian Registry of Endovascular Thrombectomy in Acute Stroke (IRETAS)

2021 ◽  
pp. neurintsurg-2021-018045
Author(s):  
Ilaria Casetta ◽  
Enrico Fainardi ◽  
Giovanni Pracucci ◽  
Valentina Saia ◽  
Stefano Vallone ◽  
...  
Keyword(s):  
Acute Stroke ◽  
Ct Perfusion ◽  
Case Fatality ◽  
Functional Independence ◽  
Primary Outcome Measure ◽  
Stroke Patients ◽  
Infarct Core ◽  
Endovascular Thrombectomy ◽  
Symptomatic Intracranial Hemorrhage ◽  
Contrast Ct

BackgroundClinical trials and observational studies have demonstrated the benefit of thrombectomy up to 16 or 24 hours after the patient was last known to be well. This study aimed to evaluate the outcome of stroke patients treated beyond 24 hours from onset.MethodsWe analyzed the outcome of 34 stroke patients (mean age 70.7±12.3 years; median National Institutes of Health Stroke Scale (NIHSS) score 13) treated with endovascular thrombectomy beyond 24 hours from onset who were recruited in the Italian Registry of Endovascular Thrombectomy in Acute Stroke. Selection criteria for patients were: pre-stroke modified Rankin scale (mRS) score of ≤2, non-contrast CT Alberta Stroke Program Early CT score of ≥6, good collaterals on single phase CT angiography (CTA) or multiphase CTA, and CT perfusion mismatch with an infarct core size ≤50% of the total hypoperfusion extent or involving less than one-third of the extent of the middle cerebral artery territory evaluated by visual inspection. The primary outcome measure was functional independence assessed by the mRS at 90 days after onset. Safety outcomes were 90 day mortality and the occurrence of symptomatic intracranial hemorrhage (sICH).ResultsSuccessful recanalization (Thrombolysis in Cerebral Infarction score of 2b or 3) was present in 76.5% of patients. Three month functional independence (mRS score 0–2) was observed in 41.1% of patients. The case fatality rate was 26.5%. and the incidence of sICH was 8.8%.ConclusionsThese findings suggest that, in a real world setting, very late endovascular therapy is feasible in appropriately selected patients.

Incorporation of relative cerebral blood flow into CT perfusion maps reduces false ’at risk' penumbra

2017 ◽  
Vol 10 (7) ◽  
pp. 657-662 ◽  
Author(s):  
Shlomi Peretz ◽  
David Orion ◽  
David Last ◽  
Yael Mardor ◽  
Yotam Kimmel ◽  
...  
Keyword(s):  
At Risk ◽  
Acute Stroke ◽  
Ct Perfusion ◽  
False Negative ◽  
Stroke Patients ◽  
True Negative ◽  
True Negative Rate ◽  
Negative Rate ◽  
Perfusion Maps

PurposeThe region defined as ‘at risk’ penumbra by current CT perfusion (CTP) maps is largely overestimated. We aimed to quantitate the portion of true ‘at risk’ tissue within CTP penumbra and to determine the parameter and threshold that would optimally distinguish it from false ‘at risk’ tissue, that is, benign oligaemia.MethodsAmong acute stroke patients evaluated by multimodal CT (NCCT/CTA/CTP) we identified those that had not undergone endovascular/thrombolytic treatment and had follow-up NCCT. Maps of absolute and relative CBF, CBV, MTT, TTP and Tmax as well as summary maps depicting infarcted and penumbral regions were generated using the Intellispace Portal (Philips Healthcare, Best, Netherlands). Follow-up CT was automatically co-registered to the CTP scan and the final infarct region was manually outlined. Perfusion parameters were systematically analysed – the parameter that resulted in the highest true-negative-rate (ie, proportion of benign oligaemia correctly identified) at a fixed, clinically relevant false-negative-rate (ie, proportion of ‘missed’ infarct) of 15%, was chosen as optimal. It was then re-applied to the CTP data to produce corrected perfusion maps.ResultsForty seven acute stroke patients met selection criteria. Average portion of infarcted tissue within CTP penumbra was 15%±2.2%. Relative CBF at a threshold of 0.65 yielded the highest average true-negative-rate (48%), enabling reduction of the false ‘at risk’ penumbral region by ~half.ConclusionsApplying a relative CBF threshold on relative MTT-based CTP maps can significantly reduce false ‘at risk’ penumbra. This step may help to avoid unnecessary endovascular interventions.

Abstract WP82: Ghost Infarct Core: Ischemic Oreoverestimation by Admission CT Perfusion on Large Vessel Occlusion Stroke Patients

Stroke ◽  
2019 ◽  
Vol 50 (Suppl_1) ◽  
Author(s):  
Gabriel M Rodrigues ◽  
Michael Frankel ◽  
Diogo C Haussen ◽  
Raul G Nogueira
Keyword(s):  
Ct Perfusion ◽  
Large Vessel ◽  
Large Vessel Occlusion ◽  
Stroke Patients ◽  
Infarct Core ◽  
Vessel Occlusion

scholarly journals CTA Source Images as a Predictor of Final Infarct Volume are Time-Dependent

2010 ◽  
Vol 37 (6) ◽  
pp. 866-867 ◽  
Author(s):  
Dylan Blacquiere ◽  
Miguel Bussière ◽  
Cheemun Lum ◽  
Dar Dowlatshahi
Keyword(s):  
Acute Stroke ◽  
Ct Angiography ◽  
Ct Perfusion ◽  
Infarct Volume ◽  
Artery Occlusion ◽  
Time Dependent ◽  
Infarct Core ◽  
Time Resolved

Avascularity on CT angiography source images (CTASI) may better predict final infarct volume in acute stroke as compared to early ischemic changes on non-contract CT. These CTASI findings may represent infarct core and help determine the extent of salvageable tissue. However, the extent of avascularity on CTASI may overestimate infarct volume if transit of contrast is prolonged due to proximal artery occlusion. We present a case where CT-perfusion (CTP) and time-resolved CT-angiography (CTA) identified salvageable tissue thought to be infarcted on CTASI.

scholarly journals Multimodal Computed Tomography in Acute Ischaemic Stroke

2011 ◽  
Vol 6 (2) ◽  
pp. 101
Author(s):  
Sachin Rastogi ◽  
David S Liebeskind ◽  
◽  
Keyword(s):  
Computed Tomography ◽  
Ischaemic Stroke ◽  
Acute Ischaemic Stroke ◽  
Ct Perfusion ◽  
Vascular Occlusion ◽  
Vascular Pathology ◽  
Stroke Patients ◽  
Infarct Core ◽  
Head Ct ◽  
Ct Angiogram

Stroke is the third leading cause of death in the US, affecting 795,000 individuals annually. Currently, only a small percentage of acute stroke patients receive thrombolytic treatment. A significant limitation is the current use of strict time criteria in the decision to treat. As there are significant inter-individual variations in response to an acute vascular occlusion, the goal of modern imaging such as multimodal computed tomography (CT) is to rapidly identify acute ischaemic stroke patients and determine which patients are likely to benefit from treatment based on tissue perfusion status rather than time of presentation alone. Multimodal CT consists of a non-contrast head CT, CT angiogram (CTA) of the head and neck, and CT perfusion (CTP). The non-contrast head CT allows rapid triage of a patient with haemorrhagic versus ischaemic stroke. The CTA allows identification of the site of vascular pathology with similar quality to digital subtraction angiography. The CTP scan allows for determination of the infarct core and surrounding ischaemic penumbra, which remains at risk for infarction if perfusion is not restored. This allows the potential to prospectively treat only those patients likely to benefit from thrombolysis while protecting those patients unlikely to benefit from the risks associated with treatment.

Abstract 38: Brain CT Perfusion is Superior to Non-contrast CT Aspects in the Evaluation of Hyperacute Infarct Volume

Stroke ◽  
2017 ◽  
Vol 48 (suppl_1) ◽  
Author(s):  
Jelle Demeestere ◽  
Carlos Garcia-Esperon ◽  
Pablo Garcia-Bermejo ◽  
Fouke Ombelet ◽  
Patrick McElduff ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Ischemic Stroke ◽  
Ct Perfusion ◽  
Infarct Volume ◽  
Lesion Volume ◽  
Infarct Core ◽  
Anterior Circulation ◽  
C Statistic ◽  
Contrast Ct ◽  
Core Volume

Objective: To compare the predictive capacity to detect established infarct in acute anterior circulation stroke between the Alberta Stroke Program Early Computed Tomography Score (ASPECTS) on non-contrast computed tomography (CT) and CT perfusion. Methods: Fifty-nine acute anterior circulation ischemic stroke patients received brain non-contrast CT, CT perfusion and hyperacute magnetic resonance imaging (MRI) within 100 minutes from CT imaging. ASPECTS scores were calculated by 4 independent vascular neurologists, blinded from CT perfusion and MRI data. CT perfusion infarct core volumes were calculated by MIStar software. The accuracy of commonly used ASPECTS cut-off scores and a CT perfusion core volume of ≥ 70 mL to detect a hyperacute MRI diffusion lesion of ≥ 70 ml was evaluated. Results: Median ASPECTS score was 9 (IQR 7-10). Median CT perfusion core volume was 22 ml (IQR 10.4-71.9). Median MRI diffusion lesion volume was 24,5 ml (IQR 10-63.9). ASPECTS score of < 6 had a sensitivity of 0.37, specificity of 0.95 and c-statistic of 0.66 to predict an acute MRI lesion ≥ 70 ml. In comparison, a CT perfusion core lesion of ≥ 70 ml had a sensitivity of 0.76, specificity of 0.98 and c-statistic of 0.92. The CT perfusion core lesion covered a median of 100% of the acute MRI lesion volume (IQR 86-100%). Conclusions: CT perfusion is superior to ASPECTS to predict hyperacute MRI lesion volume in ischemic stroke.

Abstract 2546: Correlation Between Diffusion-weighted Imaging (DWI) Lesion Volume And Alberta Stroke Program Early CT Score (ASPECTS) In Patients Undergoing Acute Stroke Intervention

Stroke ◽  
2012 ◽  
Vol 43 (suppl_1) ◽  
Author(s):  
Ashutosh P Jadhav ◽  
Mouhammad Jumaa ◽  
Sayed Zaidi ◽  
Carlos L Salinas ◽  
Guangming Zhu ◽  
...  
Keyword(s):  
Acute Stroke ◽  
Ct Scan ◽  
Endovascular Therapy ◽  
Infarct Volume ◽  
Medical Center ◽  
Lesion Volume ◽  
Infarct Core ◽  
Mri Scan ◽  
Occlusion Time ◽  
Software Analysis

Background and Purpose: Selection of patients for endovascular acute stroke therapy is evolving into imaging based paradigms that quantitatively assess infarct core thresholds beyond which reperfusion is considered futile or detrimental. We sought to determine whether a correlation exists between pre-intervention infarct volume as measured by DWI MRI and ASPECT scores on CT in patients with acute stroke treated with endovascular therapy who underwent both a pre-procedure MRI scan and a non-contrast CT scan at our institution. Methods: Retrospective review of a prospectively maintained database of acute ischemic strokes treated with endovascular therapy at the University of Pittsburgh Medical Center during 2004-2011. CT-ASPECT scores were prospectively scored by blinded observers. Infarct volume on DWI was determined by automated software analysis (RAPID, n=25 and MIPAV, n=53). The following additional factors were considered: age, NIHSS, time from last seen well (TLSW) to angiography, site of clot occlusion, time between obtaining CT scan and MRI, and parenchymal hematoma (PH) formation. Results: Of 77 patients included in the study, there was a significant negative correlation between CT-ASPECT score and DWI volume size (p<0.0001, by ANOVA). Table 1 outlines the distribution of ASPECTS scores and corresponding mean DWI volumes along with other variables of interest. The mean time between obtaining the CT and MRI scan was 207 minutes. Conclusions: A CT-ASPECT score of 7 or greater corresponds to an average DWI volume of 23 ml or less. Recent studies have shown that a pre treatment DWI volume of <25 ml is predictive of favorable outcomes. Therefore, our findings provide further support of the concept that an ASPECT score cut off of 7 or greater corresponds to core volume thresholds that are predictive of good outcomes following revascularization. Future prospective studies are needed to compare the benefit of CT ASPECTS scores alone versus DWI MRI or other advanced imaging modalities as selection tool for acute stroke endovascular therapy.

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