scholarly journals Predictive Value of the Velocity of Collateral Filling in Patients with Acute Ischemic Stroke

2014 ◽  
Vol 35 (2) ◽  
pp. 206-212 ◽  
Author(s):  
Sebastian E Beyer ◽  
Louisa von Baumgarten ◽  
Kolja M Thierfelder ◽  
Marietta Rottenkolber ◽  
Hendrik Janssen ◽  
...  
Keyword(s):  
Cerebral Blood Volume ◽  
Ct Perfusion ◽  
Mean Transit Time ◽  
Intravenous Thrombolysis ◽  
Lesion Size ◽  
Small Lesion ◽  
Time Resolved ◽  
Time To Peak ◽  
Magnetic Resonance Imaging Mri

The velocity of collateral filling can be assessed in dynamic time-resolved computed tomography (CT) angiographies and may predict initial CT perfusion (CTP) and follow-up lesion size. We included all patients with an M1± internal carotid artery (ICA) occlusion and follow-up imaging from an existing cohort of 1791 consecutive patients who underwent multimodal CT for suspected stroke. The velocity of collateral filling was quantified using the delay of time-to-peak (TTP) enhancement of the M2 segment distal to the occlusion. Cerebral blood volume (CBV) and mean transit time (MTT)-CBV mismatch were assessed in initial CTP. Follow-up lesion size was assessed by magnetic resonance imaging (MRI) or non-enhanced CT (NECT). Multivariate analyses were performed to adjust for extent of collateralization and type of treatment. Our study comprised 116 patients. Multivariate analysis showed a short collateral blood flow delay to be an independent predictor of a small CBV lesion ( P<0.001) and a large relative mismatch ( P<0.001) on initial CTP, of a small follow-up lesion ( P<0.001), and of a small difference between initial CBV and follow-up lesion size ( P=0.024). Other independent predictors of a small lesion on follow-up were a high morphologic collateral grade ( P=0.001), lack of an additional ICA occlusion ( P=0.009), and intravenous thrombolysis ( P=0.022). Fast filling of collaterals predicts initial CTP and follow-up lesion size and is independent of extent of collateralization.

Collateral Circulation Predicts the Size of the Infarct Core and the Proportion of Salvageable Penumbra in Hyperacute Ischemic Stroke Patients Treated with Intravenous Thrombolysis

2015 ◽  
Vol 40 (3-4) ◽  
pp. 182-190 ◽  
Author(s):  
Harri Rusanen ◽  
Jukka T. Saarinen ◽  
Niko Sillanpää
Keyword(s):  
Ischemic Stroke ◽  
Clinical Outcome ◽  
Collateral Circulation ◽  
Cerebral Blood Volume ◽  
Treatment Time ◽  
Ct Perfusion ◽  
Mean Transit Time ◽  
Intravenous Thrombolysis ◽  
Stroke Patients ◽  
The Impact

Background: We studied the impact of collateral circulation on CT perfusion (CTP) parametric maps and the amount of salvaged brain tissue, the imaging and clinical outcome at 24 h and at 3 months in a retrospective acute (<3 h) stroke cohort (105 patients) with anterior circulation thrombus treated with intravenous thrombolysis. Methods: Baseline clinical and imaging information were collected and groups with different collateral scores (CS) were compared. Binary logistic regression analyses using good CS (CS ≥2) as the dependent variable were calculated. Results: CTP Alberta Stroke Program Early CT Score (ASPECTS) was successfully assessed in 58 cases. Thirty patients displayed good CS. Poor CS were associated with more severe strokes according to National Institutes of Health Stroke Scale (NIHSS) at arrival (15 vs. 7, p = 0.005) and at 24 h (10 vs. 3, p = 0.003) after intravenous thrombolysis. Good CS were associated with a longer mean onset-to-treatment time (141 vs. 121 min, p = 0.009) and time to CTP (102 vs. 87 min, p = 0.047), better cerebral blood volume (CBV) ASPECTS (9 vs. 6, p < 0.001), better mean transit time (MTT) ASPECTS (6 vs. 3, p < 0.001), better noncontrast CT (NCCT) ASPECTS (10 vs. 8, p < 0.001) at arrival and with favorable clinical outcome at 3 months (modified Rankin Scale ≤2, p = 0.002). The fraction of penumbra that was salvageable at arrival and salvaged at 24 h was higher with better CS (p < 0.001 and p = 0.035, respectively). In multivariate analysis, time from the onset of symptoms to imaging (p = 0.037, OR 1.04 per minute, 95% CI 1.00-1.08) and CBV ASPECTS (p = 0.001, OR 2.11 per ASPECTS point, 95% CI 1.33-3.34) predicted good CS. In similar multivariable models, MTT ASPECTS (p = 0.04, OR 1.46 per ASPECTS point, 95% CI 1.02-2.10) and NCCT ASPECTS predicted good CS (p = 0.003, OR 4.38 per CT ASPECTS point, 95% CI 1.66-11.55) along with longer time from the onset of symptoms to imaging (p = 0.045, OR 1.03 per minute, 95% CI 1.00-1.06 and p = 0.02, OR 1.05 per minute, 95% CI 1.00-1.09, respectively). CBV ASPECTS had a larger area under the receiver operating characteristic curve for good CS (0.837) than NCCT ASPECTS (0.802) or MTT ASPECTS (0.752) at arrival. Conclusions: Favorable CBV ASPECTS, NCCT ASPECTS and MTT ASPECTS are associated with good CS along with more salvageable tissue and longer time from the onset of symptoms to imaging in ischemic stroke patients treated with intravenous thrombolysis.

scholarly journals Perfusion Changes in Acute Stroke Treated with Theophylline as an Add-on to Thrombolysis

2021 ◽  
Author(s):  
Boris Modrau ◽  
Anthony Winder ◽  
Niels Hjort ◽  
Martin Nygård Johansen ◽  
Grethe Andersen ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Cerebral Blood Volume ◽  
Neuroprotective Effect ◽  
Mean Transit Time ◽  
Control Group ◽  
Infarct Core ◽  
Treatment Groups ◽  
Stroke Models ◽  
Magnetic Resonance Imaging Mri

Abstract Purpose Theophylline has been suggested to have a neuroprotective effect in ischemic stroke; however, results from animal stroke models and clinical trials in humans are controversial. The aim of this study was to assess the effect of theophylline on the cerebral perfusion with multiparametric magnetic resonance imaging (MRI). Methods The relative cerebral blood flow (rCBF), relative cerebral blood volume (rCBV), and relative mean transit time (rMTT) in the infarct core, penumbra, and unaffected tissue were measured using multi-parametric MRI at baseline and 3‑h follow-up in patients treated with theophylline or placebo as an add-on to thrombolytic therapy. Results No significant differences in mean rCBF, rCBV, and rMTT was found in the penumbra and unaffected tissue between the theophylline group and the control group between baseline and 3‑h follow-up. In the infarct core, mean rCBV increased on average by 0.05 in the theophylline group and decreased by 0.14 in the control group (p < 0.04). Mean rCBF and mean rMTT in the infarct core were similar between the two treatment groups. Conclusion The results indicate that theophylline does not change the perfusion in potentially salvageable penumbral tissue but only affects the rCBV in the infarct core. In contrast to the penumbra, the infarct core is unlikely to be salvageable, which might explain why theophylline failed in clinical trials.

Hyperperfusion on perfusion computed tomography following revascularization for acute stroke

2005 ◽  
Vol 46 (6) ◽  
pp. 610-615 ◽  
Author(s):  
T. B. Nguyen ◽  
C. Lum ◽  
J. D. Eastwood ◽  
P. K. Stys ◽  
M. Hogan ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Acute Stroke ◽  
Cerebral Blood Volume ◽  
Ct Perfusion ◽  
Intravenous Thrombolysis ◽  
Additional Patient ◽  
Ischemic Brain ◽  
Perfusion Computed Tomography ◽  
Arterial Thrombolysis

Purpose: To describe the findings of hyperperfusion on perfusion computed tomography (CT) in four patients following revascularization for acute stroke. Material and Methods: In 2002–2003, among a series of 6 patients presenting with an acute stroke and treated with intra-arterial thrombolysis, we observed the presence of hyperperfusion in 3 patients on the follow-up CT perfusion. We included an additional patient who was treated with intravenous thrombolysis and who had hyperperfusion on the follow-up CT perfusion. We retrospectively analyzed their CT perfusion maps. Cerebral blood volume (CBV) and cerebral blood flow (CBF) maps were compared between the affected territory and the normal contralateral hemisphere. Results: In the four patients, the mean CBV and CBF were 3.6±2.0 ml/100 g and 39±25 ml/100 g/min in the affected territory compared to the normal side (mean CBV = 2.7±2.1 ml/100 g, mean CBF = 27±23 ml/100 g/min). There was no intracranial hemorrhage in the hyperperfused territories. At follow-up CT, some hyperperfused brain areas progressed to infarction, while others retained normal white to gray matter differentiation. Conclusion: CT perfusion can demonstrate hyperperfusion, which can be seen in an ischemic brain territory following recanalization.

Abstract TP152: Computed Tomography Perfusion Parameter to Predict Cerebral Hyperperfusion Phenomenon Following Carotid Artery Stenting

Stroke ◽  
2013 ◽  
Vol 44 (suppl_1) ◽  
Author(s):  
Yoichiro Takahashi ◽  
Takahisa Mori ◽  
Tomonori Iwata ◽  
Yuichi Miyazaki ◽  
Masahito Nakazaki ◽  
...  
Keyword(s):  
Carotid Artery ◽  
Carotid Artery Stenting ◽  
Cerebral Blood Volume ◽  
Ct Perfusion ◽  
Mean Transit Time ◽  
Perfusion Parameter ◽  
Unaffected Side ◽  
Time To Peak ◽  
Cerebral Hyperperfusion ◽  
Ratio Change

Background: Although SPECT is useful for predicting and finding cerebral hyperperfusion phenomenon (CHP) following carotid artery stenting (CAS), there are few institutions that could perform SPECT during peri-CAS period. The purpose of our study is to evaluate whether or not parameters derived from CT perfusion (CTP) used widely can predict CHP. Methods: Patients who underwent CTP before elective CAS and SPECT before and immediately after elective CAS in our institution from December 2010 to May 2012. We defined CHP as post-CAS increase of more than 10% of the ratio of cerebral blood flow (CBF) in the territory of the affected middle cerebral artery (MCA) divided by CBF in the ipsilateral cerebellum (MCA/CE ratio) measured by SPECT. We assessed the correlation of pre-CAS CTP’s parameters’ ratio to MCA/CE ratio change between pre-CAS and post-CAS SPECT. The CTP’s parameters’ ratio was calculated as (parameters in the affected side divided by in the unaffected side). CTP parameters we assessed are as follows: time-to-peak (TTP), mean-transit-time (MTT), cerebral blood volume (CBV) and CBF. Results: Fifty patients were analyzed. Pre-CAS TTP ratio showed a significant positive correlation with MCA/CE ratio change (r = 0.2863, p = 0.044). Other parameters (MTT, CBV and CBF) had no significant correlation. The cut-off value of pre-CAS TTP ratio was 1.08 to predict CHP (AUC = 0.77859, p = 0.032). Conclusion: Increase of pre-CAS TTP ratio is probably correlated with CHP following elective CAS.

Abstract 3268: Ct Perfusion As A Tool To Predict The Risk Of Hemorrhagic Transformation In Ischemic Stroke Treated With Tissue Plasminogen Activator: A Single Center Experience.

Stroke ◽  
2012 ◽  
Vol 43 (suppl_1) ◽  
Author(s):  
Tareq Kass-Hout ◽  
Maxim Mokin ◽  
Omar Kass-Hout ◽  
Emad Nourollahzadeh ◽  
David Wack ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Acute Stroke ◽  
Brain Tissue ◽  
Cerebral Blood Volume ◽  
Ct Perfusion ◽  
Intravenous Thrombolysis ◽  
Hemorrhagic Transformation ◽  
Stroke Therapy ◽  
Two Phase ◽  
The Mean

Objective: To use the Computed Tomography Perfusion (CTP) parameters at the time of hospital admission, including Cerebral Blood Volume (CBV) and Permeability Surface area product (PS), to identify patients with higher risk to develop hemorrhagic transformation in the setting of acute stroke therapy with intravenous thrombolysis. Methods: Retrospective study that compared admission CTP variables between patients with Hemorrhagic Transformation (HT) acute stroke and those with no hemorrhagic transformation. Both groups received standard of care intravenous thrombolysis with tPA. Twenty patients presented to our stroke center between the years 2007 - 2011 within 3 hours after stroke symptoms onset. All patients underwent two-phase 320 slice CTP which creates CBV and PS measurements. Patients were divided into two groups according to whether or not they had HT on a follow up CT head without contrast, done within 36 hours of the thrombolysis therapy. Clinical, demographic and CTP variables were compared between the HT and non-HT groups using logistic regression analyses. Results: HT developed in 8 (40%) patients. Patients with HT had lower ASPECT score ( P =.03), higher NIHSS on admission ( P= .01) and worse outcome ( P= .04) compared to patients who did not develop HT. Baseline blood flow defects were comparable between the two groups. The mean PS for the HT group was 0.53 mL/min/100g brain tissue, which was significantly higher than that for the non-HT group of 0.04 mL/min/100g brain tissue ( P <.0001). The mean area under the curve was 0.92 (95% CI). The PS threshold of 0.26 mL/min/100g brain tissue had a sensitivity of 80% and a specificity of 92% for detecting patients with high risk of hemorrhagic transformation after intravenous thrombolysis. Conclusions: Admission CTP measurements might be useful to predict patients who are at higher risk to develop hemorrhagic transformation after acute ischemic stroke therapy.

Abstract 2619: Autoregulation of Cerebral Blood Flow is Preserved in Primary Intracerebral Hemorrhage

Stroke ◽  
2012 ◽  
Vol 43 (suppl_1) ◽  
Author(s):  
E B Gould ◽  
Rebecca McCourt ◽  
Sana Vahidy ◽  
Negar Asdaghi ◽  
Michael D Hill ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Intracerebral Hemorrhage ◽  
Cerebral Autoregulation ◽  
Cerebral Blood Volume ◽  
Ct Perfusion ◽  
Mean Transit Time ◽  
Serial Ct ◽  
Acute Intracerebral Hemorrhage ◽  
Perfusion Maps

Background: Treatment of hypertension during acute intracerebral hemorrhage (ICH) is controversial. There are concerns that in the context of disrupted cerebral autoregulation, blood pressure (BP) reduction may cause decreased cerebral blood flow (CBF), particularly in the perihematoma region. CBF was assessed using serial CT perfusion (CTP) studies. We hypothesized that CBF would remain stable following BP reduction. Methods: Acute primary ICH patients were imaged pre and post BP treatment. Perfusion maps were calculated from CTP source images. Mean CBF was measured in a 1cm perihematoma region, contralateral homologous regions and in both hemispheres. Mean cerebral blood volume (CBV), mean transit time (MTT), and time to drain (TTD) were calculated in the same manner. Relative measures (i.e. rCBF) were calculated as ratios/differences between ipsilateral and contralateral regions. Results: Sixteen patients (median age 75 (54-91)) were imaged with CTP (median time from onset 19.4 (2.0-72.2) h) and re-imaged 2.0 (1.1-3.3) h later. Median NIHSS at baseline was 9 (2-24); this remained stable at the time of the second CTP (10 (2-24), P=0.14). Baseline hematoma volume was 24.8±19.9 ml and there was no change at the time of the second CTP (26.3±22.1 ml, P=0.16). Patients were recruited from an ongoing trial, in which they were randomly treated to a target systolic BP of <150mmHg (n=9) or <180mmHg (n=7). Four patients received no antihypertensives as BP was below target at the time of randomization. Mean systolic BP in treated patients (n=12) decreased significantly between the first (165±23 mmHg) and second (143±18 mmHg, P<0.0001) CTP scans. Mean perihematoma CBF in treated patients was stable with BP reduction (pre=35.1±7.1 vs. post=35.4±6.2 ml/100g/min, P=0.87). Ipsilateral hemispheric CBF was also stable (pre=47.3±7.2 vs. post=46.4±7.1 ml/100g/min, P=0.66). Although perihematoma CBF was lower than in contralateral homologous regions (rCBF=0.72±0.11), BP reduction did not decrease this further (0.74±0.14 post-treatment, P=0.58). Ipsilateral hemispheric rCBF (0.96±0.06) was also unaffected by BP treatment (0.95±0.08, P=0.64). Perihematoma rCBF decreased in 5 treated patients, but never by >12%. Linear regression showed no relationship between changes in systolic BP and perihematoma rCBF (R=-0.002, [-0.005, 0.001], P=0.18). Perihematoma rCBV (pre=0.77±0.11 vs. post=0.79±0.10, P=0.20), rMTT (pre=0.51±0.54s vs. post=0.70±0.65s, P=0.26) and rTTD (pre=0.71±1.01s vs. post=0.89±0.84s, P=0.42) also remained stable following BP treatment. Conclusions: Acute BP reduction does not appear to exacerbate perihematoma oligaemia. Stability of CBF following acute BP treatment suggests preservation of cerebral autoregulation in ICH, within the range of arterial pressures studied. These findings support the safety of early BP treatment in ICH.

scholarly journals CT Perfusion and Delayed Cerebral Ischemia in Aneurysmal Subarachnoid Hemorrhage: A Systematic Review and Meta-Analysis

2013 ◽  
Vol 34 (2) ◽  
pp. 200-207 ◽  
Author(s):  
Charlotte H P Cremers ◽  
Irene C van der Schaaf ◽  
Emerens Wensink ◽  
Jacoba P Greving ◽  
Gabriel J E Rinkel ◽  
...  
Keyword(s):  
Systematic Review ◽  
Subarachnoid Hemorrhage ◽  
Cerebral Ischemia ◽  
Blood Volume ◽  
Cerebral Blood Volume ◽  
Ct Perfusion ◽  
Aneurysmal Subarachnoid Hemorrhage ◽  
Mean Transit Time ◽  
Delayed Cerebral Ischemia ◽  
Mean Difference

Delayed cerebral ischemia (DCI) is at presentation a diagnosis per exclusionem, and can only be confirmed with follow-up imaging. For treatment of DCI a diagnostic tool is needed. We performed a systematic review to evaluate the value of CT perfusion (CTP) in the prediction and diagnosis of DCI. We searched PubMed, Embase, and Cochrane databases to identify studies on the relationship between CTP and DCI. Eleven studies totaling 570 patients were included. On admission, cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), and time-to-peak (TTP) did not differ between patients who did and did not develop DCI. In the DCI time-window (4 to 14 days after subarachnoid hemorrhage (SAH)), DCI was associated with a decreased CBF (pooled mean difference −11.9 mL/100 g per minute (95% confidence interval (CI): −15.2 to −8.6)) and an increased MTT (pooled mean difference 1.5 seconds (0.9–2.2)). Cerebral blood volume did not differ and TTP was rarely reported. Perfusion thresholds reported in studies were comparable, although the corresponding test characteristics were moderate and differed between studies. We conclude that CTP can be used in the diagnosis but not in the prediction of DCI. A need exists to standardize the method for measuring perfusion with CTP after SAH, and optimize and validate perfusion thresholds.

Optimal thresholds for ischemic penumbra predicted by computed tomography perfusion in patients with acute ischemic stroke treated with mechanical thrombectomy

2017 ◽  
Vol 10 (3) ◽  
pp. 279-284 ◽  
Author(s):  
Katsuharu Kameda ◽  
Junji Uno ◽  
Ryosuke Otsuji ◽  
Nice Ren ◽  
Shintaro Nagaoka ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Acute Ischemic Stroke ◽  
Cerebral Blood Volume ◽  
Mechanical Thrombectomy ◽  
Ct Perfusion ◽  
Characteristic Curve ◽  
Mean Transit Time ◽  
Area Under The Curve ◽  
Ischemic Penumbra ◽  
Optimal Thresholds

Background and purposeOptimal thresholds for ischemic penumbra detected by CT perfusion (CTP) in patients with acute ischemic stroke (AIS) have not been elucidated. In this study we investigated optimal thresholds for salvageable ischemic penumbra and the risk of hemorrhagic transformation (HT).MethodsA total of 156 consecutive patients with AIS treated with mechanical thrombectomy (MT) at our hospital were enrolled. Absolute (a) and relative (r) CTP parameters including cerebral blood flow (aCBF and rCBF), cerebral blood volume (aCBV and rCBV), and mean transit time (aMTT and rMTT) were evaluated for their value in detecting ischemic penumbra in each of seven arbitrary regions of interest defined by the major supplying blood vessel. Optimal thresholds were calculated by performing receiver operating characteristic curve analysis in 47 patients who achieved Thrombolysis In Cerebral Infarction (TICI) grade 3 recanalization. The risk of HT after MT was evaluated in 101 patients who achieved TICI grade 2b–3 recanalization.ResultsAbsolute CTP parameters for distinguishing ischemic penumbra from ischemic core were as follows: aCBF, 27.8 mL/100 g/min (area under the curve 0.82); aCBV, 2.1 mL/100 g (0.75); and aMTT, 7.30 s (0.70). Relative CTP parameters were as follows: rCBF, 0.62 (0.81); rCBV, 0.83 (0.87); and rMTT, 1.61 (0.73). CBF was significantly lower in areas of HT than in areas of infarction (aCBF, p<0.01; rCBF, p<0.001).ConclusionsCTP may be able to predict treatable ischemic penumbra and the risk of HT after MT in patients with AIS.

Abstract T P20: Correlation Between Whole Brain Ct Perfusion Maps And Non-contrast Ct Alberta Stroke Program Early Ct Score (aspects) In Patients Undergoing Acute Endovascular Stroke Interventions

Stroke ◽  
2014 ◽  
Vol 45 (suppl_1) ◽  
Author(s):  
Simon Morr ◽  
Maxim Mokin ◽  
Ashish Sonig ◽  
Kenneth Snyder ◽  
Adnan Siddiqui ◽  
...  
Keyword(s):  
Acute Stroke ◽  
Blood Volume ◽  
Cerebral Blood Volume ◽  
Ct Perfusion ◽  
Pearson Correlation ◽  
Volume Data ◽  
Post Intervention ◽  
Whole Brain ◽  
Brain Ct ◽  
Time To Peak

Introduction: Tools for evaluating risk of post-intervention risk hemorrhage in the setting of acute stroke include a noncontrast head CT based Alberta Stroke Program Early CT score (ASPECTS) and contrasted CT based perfusion plots. The correlation between these parameters is unknown. Methods: We performed a retrospective analysis of a prospectively collected endovascular stroke database of patients with M1 middle cerebral artery occlusion who underwent endovascular recanalization. We reviewed admission preintervention noncontrast CT for Alberta Stroke Program Early CT score (ASPECTS) and 320-detector row whole brain CT perfusion parameters (Cerebral blood volume and time to peak). Pearson correlation was determined between cerebral blood volume on the side of the stroke and ASPECTS. Results: ASPECTS and CT perfusion map were identified in 45 and 43 patients respectively. Statistically significant correlation was found between ASPECTS and cerebral blood volume data on CT perfusion MAP. (p=0.034, r=-0.28). The correlation coefficient is very weak. No correlation could be found between time to peak and ASPECTS. Conclusion: A statistically significant, but weak correlation exists between ASPECTS and CBV. Further research is needed to assess the physiological meaning of diverse imaging modalities utilized in the acute stroke setting.

Abstract 3007: What Perfusion Parameters Best Define Ischemic Penumbra in Patients with TIA and Minor Stroke; Data from the VISION study

Stroke ◽  
2012 ◽  
Vol 43 (suppl_1) ◽  
Author(s):  
Negar Asdaghi ◽  
Jonathan I Coulter ◽  
Teri S Stewart ◽  
Mayank Goyal ◽  
Andrew M Demchuk ◽  
...  
Keyword(s):  
Cerebral Blood Volume ◽  
A Priori ◽  
Intraclass Correlation ◽  
Treatment Decision ◽  
Minor Stroke ◽  
Ischemic Penumbra ◽  
Rater Reliability ◽  
Time To Peak ◽  
Infarct Expansion

Background: Patients with TIA and minor ischemic (MIS) stroke are at high risk for clinical and radiographic deterioration. Acute Perfusion-Diffusion (PWI-DWI) mismatch have been used to identify those at risk for early deterioration. However, optimal perfusion thresholds for ischemic penumbra have not been defined in TIA/MIS patients. We aimed to determine the interrater reliability of different perfusion measurements and the optimal values that predict DWI lesion expansion in patients with TIA/MIS. Methods: Patients with minor stroke (NIH Stroke Scale ≤3) and TIA were prospectively enrolled and imaged within 24 hours of symptom onset. All patients had follow-up imaging at day 30. Raw perfusion images were used to generate maps of time to peak of the impulse response (Tmax), cerebral blood flow (CBF) and cerebral blood volume (CBV). DWI and PWI volumes were measured with planimetric and thresholding techniques by two independent groups of readers (1 group with a single experienced rater and a second group with 2 inexperienced raters) and 95% confidence intervals were calculated. Infarct progression (FLAIR 30 vol-DWI Acute vol) was a priori defined as growth of at least 2.5 ml. Results: At baseline 55.2% of the 116 patients included had DWI lesions and 42.2% had PWI deficits. The inter-rater reliability for assessment of hypoperfused regions was excellent for all Tmax thresholds (Tmax+2s (Intraclass Correlation Coefficient (ICC)=0.996 [0.994, 0.997], Tmax+4s(0.99 [0.985, 0.993], Tmax+6s (0.998 [0.998, 0.999] and Tmax+8s(0.996 [0.994, 0.997]). The interrater agreement was very good for assessment of regions with reduced CBF (ICC=0.84[0.78-0.89] and moderate for evaluation of regions with low CBV (ICC=0.43 [0.27, 0.57]). 18.1% of patients had evidence of radiographic progression on follow-up. Mismatch volumes (PWI-DWI) calculated using Tmax+4s predicted infarct expansion (R=0.8, [0.21-0.28], P<0.001). In contrast, mismatch volumes calculated with CBF did not predict infarct expansion (R=0.04, [-0.31,0.50] P=0.66). A mismatch volume (Tmax+4s-DWI) of ≥10 ml predicted infarct progression with 81% sensitivity and 92% specificity (AUC =0.85, [0.74-0.97]). Conclusion: In patients with TIA/MIS, penumbral patterns are common. Application of perfusion thresholds produced Tmax maps with excellent intra-rater reliability. Mismatch volume calculated as Tmax+4s-DWI volume reliably predicted infarct expansion. Objective PWI-DWI mismatch definitions such as these may be useful for acute reperfusion treatment decision making in patients with minor ischemic symptoms

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