In patients with suspected acute stroke, CT perfusion-based cerebral blood flow maps cannot substitute for DWI in measuring the ischemic core

Background and purpose: Advanced CT perfusion (CTP) imaging can estimate the size of the ischemic core, which can be used for selection of patients for endovascular therapy. The relative cerebral blood volume (rCBV) and cerebral blood flow (rCBF) thresholds chosen to identify ischemic core influence the accuracy of prediction. The purpose of this study was to analyze the accuracy of various rCBV and rCBF thresholds for predicting 27 hour infarct volume using RAPID automated analysis software. Methods: Patients from the SWIFT PRIME study with baseline and 27 hour follow-up CT perfusion scans were included if they had complete reperfusion based on Tmax>6s perfusion maps obtained at 27 hours. Patients from both the tPA and endovascular groups were included. Infarct volume was determined on MRI (FLAIR images) or CT scans obtained 27 hours after symptom onset. The predicted ischemic core volume on rCBV and rCBF maps using thresholds ranging between 0.2 and 0.8 was compared with the actual infarct volume to determine the most accurate thresholds. Results: Among the 47 subjects, the following baseline CTP thresholds most accurately predicted the actual 27 hour infarct volume: rCBV=0.34 (Median absolute error (MAE)=11.5 ml); rCBV=0.36, MAE=9.9 ml; rCBV=0.4, MAE=12.5 ml; rCBF=0.3, MAE=8.8 ml; rCBF=0.32, MAE=7.3; and rCBF=0.34, MAE=7.8. Conclusions: Brain regions with rCBF ≤ .32 or rCBV ≤ .36 provided the most accurate prediction of infarct volume in patients who achieved complete reperfusion with median absolute errors less than 10 ml. Our data support the value of automated image analysis software as a tool for accurate prediction of ischemic core lesion volume.

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Simultaneous multimodal optical imaging of cerebral blood flow and oxygenation in focal ischemic core and penumbra in mice

Journal of Cerebral Blood Flow & Metabolism ◽

10.1038/sj.jcbfm.9591524.0488 ◽

2005 ◽

Vol 25 (1_suppl) ◽

pp. S488-S488

Author(s):

Hwa Kyoung Shin ◽

Phillip Jones ◽

Andrew K Dunn ◽

David A Boas ◽

Michael A Moskowitz ◽

...

Keyword(s):

Blood Flow ◽

Cerebral Blood Flow ◽

Optical Imaging ◽

Ischemic Core

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Abstract 96: CTP-Mismatch Maps Improve Interobserver Agreement

Stroke ◽

10.1161/str.43.suppl_1.a96 ◽

2012 ◽

Vol 43 (suppl_1) ◽

Author(s):

Waimei A Tai ◽

Archana Purushotham ◽

Matus Straka ◽

Rebecca M Sugg ◽

Naveed Akhtar ◽

...

Keyword(s):

Acute Stroke ◽

Ct Perfusion ◽

Interobserver Reliability ◽

Observer Agreement ◽

Absolute Difference ◽

Stroke Therapy ◽

Adequate Quality ◽

Ischemic Core ◽

Observer Disagreement ◽

Acute Stroke Therapy

Introduction: The use of mismatch between the ischemic core and penumbra to select patients who are likely to benefit from acute stroke therapy has gained popularity. Interpretation of the ischemic core and penumbra on standard CT-perfusion (CTP) maps is subjective. This may lead to variability among physicians in the decision if a patient is a good candidate for acute stroke therapy. A CTP-Mismatch map with outlines of the ischemic core and penumbra could limit this variability. The goal of this study was to determine if inter-observer agreement regarding a patient’s suitability for acute stroke therapy improves with the use of a CTP-Mismatch map. The figure shows a typical CTP-Mismatch map. Methods: Ninety-six consecutive patients evaluated with CTP prior to intra-arterial therapy at St. Lukes Hospital in 2008-09 were included. 79 patients had adequate quality CTP for this analysis. Standard CTP maps (CBV, CBF, MTT, and Tmax) and a CTP-Mismatch map were generated with a fully automated program for processing of CTP source images (RAPID). RAPID assessed the ischemic core using a CBF threshold <30% of the contralateral hemisphere (rCBF<30%). The ischemic penumbra was defined by a Tmax threshold of >6 sec (Tmax>6s). The standard CTP maps and the CTP-Mismatch map were independently analyzed by two vascular neurologists in a blinded fashion. The raters assessed a patient's suitability for intra-arterial therapy based on the following mismatch criteria: (1) a ratio between (Tmax>6s) and (rCBF<30%) volumes >1.8 and (2) an absolute difference between (Tmax>6s) and (CBF<30%) volumes >15ml. Interobserver reliability was assessed with Cohen’s kappa. Results: When assessment of suitability for intra-arterial therapy was based on interpretation of standard CTP maps, the two raters agreed in 58 of 79 patients (kappa=0.46; 95% CI=0.24-0.60). The agreement between observers improved when suitability was determined using CTP-Mismatch maps (agreement in 76 of 79 cases; kappa=0.92; 95% CI=0.75-0.92; p<0.001 for difference between kappa values). The 3 cases with inter-observer disagreement had artifact on the CTP-Mismatch map. Following concensus adjudication of these 3 cases, 40 of the 79 patients (51%) were deemed suitable candidates for acute stroke therapy. Conclusion: CTP-Mismatch maps with estimates of ischemic core and penumbra volumes markedly improve inter-observer agreement regarding assessment of suitability for acute stroke therapy. Such maps, which can be generated automatically, may help standardize decision making algorithms for evaluation of potential intra-arterial therapy candidates.

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Temporal Relationship Between Apparent Diffusion Coefficient and Absolute Measurements of Cerebral Blood Flow in Acute Stroke Patients

Stroke ◽

10.1161/01.str.0000048151.28173.0d ◽

2003 ◽

Vol 34 (1) ◽

pp. 64-70 ◽

Cited By ~ 44

Author(s):

Weili Lin ◽

Jin-Moo Lee ◽

Yueh Z. Lee ◽

Katie D. Vo ◽

Thomas Pilgram ◽

...

Keyword(s):

Blood Flow ◽

Diffusion Coefficient ◽

Cerebral Blood Flow ◽

Apparent Diffusion Coefficient ◽

Acute Stroke ◽

Temporal Relationship ◽

Stroke Patients ◽

Apparent Diffusion ◽

Absolute Measurements

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Regional Cerebral Blood Flow in Acute Stroke: Comparison of Two Calcium Antagonists

Cerebral Ischemia and Basic Mechanisms ◽

10.1007/978-3-642-78151-3_44 ◽

1994 ◽

pp. 430-437

Author(s):

O. B. Paulson ◽

C. Videbæk ◽

S. Vorstrup ◽

P. S. Sørensen

Keyword(s):

Blood Flow ◽

Cerebral Blood Flow ◽

Acute Stroke ◽

Calcium Antagonists ◽

Regional Cerebral Blood Flow ◽

Regional Cerebral Blood

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

Stroke ◽

10.1161/str.43.suppl_1.a2619 ◽

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.

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