Ischemic stroke
ORIGINAL RESEARCH
Correlation between cerebral blood volume values and outcomes in endovascular therapy for acute ischemic stroke Maxim Mokin,1,2 Simon Morr,1,2 Andrew A Fanous,1,2 Hussain Shallwani,1,2 Sabareesh K Natarajan,1,2 Elad I Levy,1,2,3,4 Kenneth V Snyder,1,2,3,4,5 Adnan H Siddiqui1,2,3,4,6 1
Department of Neurosurgery, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, New York, USA 2 Department of Neurosurgery, Gates Vascular Institute, Kaleida Health, Buffalo, New York, USA 3 Department of Radiology, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, New York, USA 4 Toshiba Stroke Research Center, University at Buffalo, State University of New York, Buffalo, New York, USA 5 Department of Neurology, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, New York, USA 6 Jacobs Institute, Buffalo, New York, USA Correspondence to Dr Adnan H Siddiqui, University at Buffalo Neurosurgery, 100 High Street, Suite B4, Buffalo NY 14203, USA; [email protected] Received 6 May 2014 Revised 25 July 2014 Accepted 4 August 2014 Published Online First 21 August 2014
ABSTRACT Background Neurointerventionalists do not agree about the optimal imaging protocol when evaluating patients with acute stroke for potential endovascular revascularization. Preintervention cerebrovascular blood volume (CBV) has been shown to predict outcomes in patients undergoing intra-arterial stroke therapies. Objective To determine whether CBV can predict hemorrhagic transformation and clinical outcomes in patients selected for endovascular therapy for acute ischemic middle cerebral artery (MCA) stroke using a CT perfusion (CTP)-based imaging protocol. Methods We retrospectively reviewed cases of acute ischemic stroke due to MCA M1 segment occlusion and correlated favorable clinical outcomes (modified Rankin scale (mRS) ≤2) and radiographic outcomes with preintervention CBV values. All patients underwent whole-brain (320-detector-row) CTP imaging, and absolute CBV values of the affected and contralateral MCA territories were obtained separately for the cortical and basal ganglia regions. Results Relative CBV (rCBV) of the MCA cortical regions was significantly lower in patients with poor clinical outcomes than in those with favorable clinical outcomes (0.87±0.21 vs 1.02±0.09, p=0.0003), and a negative correlation was found between rCBV values and mRS score severity. rCBV of the basal ganglia region was significantly lower in patients with hemorrhagic infarction (p=0.004) and parenchymal hematoma (p=0.04) than in those without hemorrhagic transformation. Conclusions We found that cortical CBV loss is predictive of poor clinical outcomes, whereas basal ganglia CBV loss is predictive of hemorrhagic transformation but without translation into poor clinical outcomes. Our study findings support published results of baseline preintervention CBV as a predictor of outcomes in patients undergoing intra-arterial stroke therapies.
INTRODUCTION
To cite: Mokin M, Morr S, Fanous AA, et al. J NeuroIntervent Surg 2015;7:705–708.
Preintervention cerebral blood volume (CBV) values from CT perfusion (CTP) have been shown to be predictive of hemorrhagic transformation and clinical outcomes following endovascular therapy.1–3 However, conflicting data suggest that use of advanced imaging such as CTP may only delay recanalization without correlation with improved clinical outcomes.4
Neurointerventionalists do not agree about the optimal imaging protocol for evaluating patients with acute stroke for potential endovascular revascularization. We investigated the role of CBV as a predictor of hemorrhagic transformation and clinical outcomes in patients with acute stroke from middle cerebral artery (MCA) occlusion.
METHODS This study was approved by our local institutional review board. We retrospectively reviewed the medical records of patients with acute ischemic stroke treated by endovascular intra-arterial therapy between 1 January 2010 and 1 October 2013. The acute stroke imaging protocol at our institution includes clinical evaluation, immediately followed by non-contrast brain CT and whole-brain (320-detector-row) CTP imaging in combination with craniocervical CT angiography (CTA) for all patients with suspected acute ischemic stroke. We included cases of acute ischemic stroke due to MCA M1 segment occlusion that were documented on CTA and subsequently confirmed by DSA in patients treated with endovascular therapy. Cases (n=6) of subarachnoid hemorrhage or intraparenchymal hemorrhage from catheter or wire manipulation leading to vessel perforation that were recognized during the interventional procedure were excluded from analysis to allow isolated assessment of CTP-based prediction of outcome. The following data were collected: age, sex, cerebrovascular risk factors, admission National Institutes of Health Stroke Scale score, time from symptom onset to CTP imaging, and use of intravenous recombinant tissue plasminogen activator in the emergency room. (The imaging protocol and details of imaging data collected are provided below.) Successful recanalization was defined as a Thrombolysis in Cerebral Infarction (TICI) score of 2b–3. Functional neurologic outcomes were quantified using the modified Rankin scale (mRS) at 90 days. Favorable outcome was defined as an mRS score of ≤2. Non-contrast head CT imaging obtained 24–36 h after the intervention was used to assess for hemorrhagic transformation. Intracranial hemorrhage (ICH) was classified as hemorrhagic infarction (HI) or parenchymal hematoma (PH) according to the European–Australasian Acute Stroke Study classification.5
Mokin M, et al. J NeuroIntervent Surg 2015;7:705–708. doi:10.1136/neurintsurg-2014-011279
705
Ischemic stroke Figure 1 Perfusion maps in a case of left MCA M1 segment occlusion. Numbers indicate absolute values of CBV (left) and MTT (right) maps of the affected territory (left hemisphere) and the contralateral control side (right hemisphere). Values are calculated separately for the territory of the basal ganglia and the supraganglionic (cortical) regions. CBV, cerebral blood volume; MCA, middle cerebral artery; MTT, mean transit time.
Imaging protocol All patients underwent 5 mm thick, non-contrast head CT imaging performed using the Aquilion ONE scanner (Toshiba Medical Systems, Nasu, Japan). CTP was performed using a 320-detector-row CT system (Aquilion ONE). Contrast medium infusion (50 mL, Optiray 350, Mallinckrodt, Missouri, USA) was performed at a rate of 5 mL/s via automated antecubital venous injection. CTP acquisition parameters were 80 kV tube voltage, 200 mA tube current, and 0.35 s rotation. Perfusion maps (cerebral blood flow (CBF), CBV, mean time to peak (mean transit time (MTT)), time to peak, and delay) were reconstructed using Vitrea software (V.6.4, Vital Images, Minnetonka, Minnesota, USA). On average, performing CTP and reconstructing perfusion maps takes 3–4 min. Perfusion maps are then immediately reviewed by the in-house on-call endovascular fellow, and the findings are discussed with the on-call endovascular neurosurgeon.
Table 1
Thereafter, craniocervical CTA was performed using an infusion of contrast medium (80 mL, Omnipaque 350, GE Healthcare, Waukesha, Wisconsin, USA) at a rate of 4 mL/s, with scanning starting manually once the contrast medium reached the aortic arch. CTA images were reconstructed at 0.5 mm thickness.
Image analysis Analysis of CTP maps was performed by two operators who were blinded to the final results. A freehand region of interest of increased MTT in the affected MCA territory was used to outline the total brain tissue at risk, with a mirrored region automatically generated on the CBV map, as previously described2 (figure 1). Absolute CBV values were recorded separately from two regions: (1) the MCA territory of the basal ganglia and (2) the supraganglionic territories (labeled as
Characteristics of cases with favorable and poor clinical outcomes
Characteristics Demographics Age (years), mean ±SD NIHSS score on admission, mean ±SD Female Atrial fibrillation Coronary artery disease or myocardial infarction Diabetes mellitus Hypertension Dyslipidemia Current smoker Treatment details IV rtPA Conscious sedation General anesthesia Mean time from symptom onset to CTP (min), mean±SD Mean time from CTP to groin puncture (min), mean±SD Mean time from groin puncture to recanalization (min), mean±SD Treatment outcome TICI 2b–3 recanalization CBV values CBV cortex (mL/100 g) rCBV cortex CBV basal ganglia (mL/100 g) rCBV basal ganglia
Favorable outcome (mRS=0–2, n=21),
Poor outcome (mRS=3–6, n=43),
p Value
67.5±12.6 14.4±5.5 7 (33) 3 (14) 7 (33) 5 (24) 12 (57) 7 (33) 6 (29)
71.8±11.9 17.0±4.8 18 (42) 23 (53) 10 (23) 13 (30) 31 (72) 14 (33) 11 (26)
0.21 0.078 0.59 0.003 0.55 0.77 0.27 1.0 1.0
5 (24) 15 (71) 6 (29) 291±402 103±45 55±24
11 (26) 29 (67) 14 (33) 202±246 110±67 71±28
1.0 1.0 0.33 0.68 0.064
20 (95)
25 (58)
0.003
3.04±1.13 1.02±0.09 2.61±0.87 0.95±0.16
2.53±1.03 0.87±0.21 2.53±0.96 0.92±0.11
0.095 0.0003 0.77 0.45
Results are shown as number (%) unless specified otherwise. CBV, cerebral blood volume; CTP, CT perfusion; mRS, modified Rankin scale; NIHSS, National Institutes of Health Stroke Scale; rCBV, CBV ratio; rtPA, recombinant tissue plasminogen activator; TICI, Thrombolysis in Cerebral Infarction.
706
Mokin M, et al. J NeuroIntervent Surg 2015;7:705–708. doi:10.1136/neurintsurg-2014-011279
Ischemic stroke ‘cortical regions’), using standard anatomic regions from the Alberta Stroke Program Early CT score (ASPECTS) system for CTP interpretation.6 7 Relative CBV (rCBV) was calculated as the absolute CBV value of the affected hemisphere divided by the absolute CBV value of the contralateral (control) hemisphere.
Statistical analysis Analysis of variables was performed using Fisher’s exact test for categorical data and a two-tailed t test for continuous data. Analysis of covariance was used to evaluate the association between rCBV and mRS values. For all analyses, p
ORIGINAL RESEARCH
Correlation between cerebral blood volume values and outcomes in endovascular therapy for acute ischemic stroke Maxim Mokin,1,2 Simon Morr,1,2 Andrew A Fanous,1,2 Hussain Shallwani,1,2 Sabareesh K Natarajan,1,2 Elad I Levy,1,2,3,4 Kenneth V Snyder,1,2,3,4,5 Adnan H Siddiqui1,2,3,4,6 1
Department of Neurosurgery, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, New York, USA 2 Department of Neurosurgery, Gates Vascular Institute, Kaleida Health, Buffalo, New York, USA 3 Department of Radiology, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, New York, USA 4 Toshiba Stroke Research Center, University at Buffalo, State University of New York, Buffalo, New York, USA 5 Department of Neurology, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, New York, USA 6 Jacobs Institute, Buffalo, New York, USA Correspondence to Dr Adnan H Siddiqui, University at Buffalo Neurosurgery, 100 High Street, Suite B4, Buffalo NY 14203, USA; [email protected] Received 6 May 2014 Revised 25 July 2014 Accepted 4 August 2014 Published Online First 21 August 2014
ABSTRACT Background Neurointerventionalists do not agree about the optimal imaging protocol when evaluating patients with acute stroke for potential endovascular revascularization. Preintervention cerebrovascular blood volume (CBV) has been shown to predict outcomes in patients undergoing intra-arterial stroke therapies. Objective To determine whether CBV can predict hemorrhagic transformation and clinical outcomes in patients selected for endovascular therapy for acute ischemic middle cerebral artery (MCA) stroke using a CT perfusion (CTP)-based imaging protocol. Methods We retrospectively reviewed cases of acute ischemic stroke due to MCA M1 segment occlusion and correlated favorable clinical outcomes (modified Rankin scale (mRS) ≤2) and radiographic outcomes with preintervention CBV values. All patients underwent whole-brain (320-detector-row) CTP imaging, and absolute CBV values of the affected and contralateral MCA territories were obtained separately for the cortical and basal ganglia regions. Results Relative CBV (rCBV) of the MCA cortical regions was significantly lower in patients with poor clinical outcomes than in those with favorable clinical outcomes (0.87±0.21 vs 1.02±0.09, p=0.0003), and a negative correlation was found between rCBV values and mRS score severity. rCBV of the basal ganglia region was significantly lower in patients with hemorrhagic infarction (p=0.004) and parenchymal hematoma (p=0.04) than in those without hemorrhagic transformation. Conclusions We found that cortical CBV loss is predictive of poor clinical outcomes, whereas basal ganglia CBV loss is predictive of hemorrhagic transformation but without translation into poor clinical outcomes. Our study findings support published results of baseline preintervention CBV as a predictor of outcomes in patients undergoing intra-arterial stroke therapies.
INTRODUCTION
To cite: Mokin M, Morr S, Fanous AA, et al. J NeuroIntervent Surg 2015;7:705–708.
Preintervention cerebral blood volume (CBV) values from CT perfusion (CTP) have been shown to be predictive of hemorrhagic transformation and clinical outcomes following endovascular therapy.1–3 However, conflicting data suggest that use of advanced imaging such as CTP may only delay recanalization without correlation with improved clinical outcomes.4
Neurointerventionalists do not agree about the optimal imaging protocol for evaluating patients with acute stroke for potential endovascular revascularization. We investigated the role of CBV as a predictor of hemorrhagic transformation and clinical outcomes in patients with acute stroke from middle cerebral artery (MCA) occlusion.
METHODS This study was approved by our local institutional review board. We retrospectively reviewed the medical records of patients with acute ischemic stroke treated by endovascular intra-arterial therapy between 1 January 2010 and 1 October 2013. The acute stroke imaging protocol at our institution includes clinical evaluation, immediately followed by non-contrast brain CT and whole-brain (320-detector-row) CTP imaging in combination with craniocervical CT angiography (CTA) for all patients with suspected acute ischemic stroke. We included cases of acute ischemic stroke due to MCA M1 segment occlusion that were documented on CTA and subsequently confirmed by DSA in patients treated with endovascular therapy. Cases (n=6) of subarachnoid hemorrhage or intraparenchymal hemorrhage from catheter or wire manipulation leading to vessel perforation that were recognized during the interventional procedure were excluded from analysis to allow isolated assessment of CTP-based prediction of outcome. The following data were collected: age, sex, cerebrovascular risk factors, admission National Institutes of Health Stroke Scale score, time from symptom onset to CTP imaging, and use of intravenous recombinant tissue plasminogen activator in the emergency room. (The imaging protocol and details of imaging data collected are provided below.) Successful recanalization was defined as a Thrombolysis in Cerebral Infarction (TICI) score of 2b–3. Functional neurologic outcomes were quantified using the modified Rankin scale (mRS) at 90 days. Favorable outcome was defined as an mRS score of ≤2. Non-contrast head CT imaging obtained 24–36 h after the intervention was used to assess for hemorrhagic transformation. Intracranial hemorrhage (ICH) was classified as hemorrhagic infarction (HI) or parenchymal hematoma (PH) according to the European–Australasian Acute Stroke Study classification.5
Mokin M, et al. J NeuroIntervent Surg 2015;7:705–708. doi:10.1136/neurintsurg-2014-011279
705
Ischemic stroke Figure 1 Perfusion maps in a case of left MCA M1 segment occlusion. Numbers indicate absolute values of CBV (left) and MTT (right) maps of the affected territory (left hemisphere) and the contralateral control side (right hemisphere). Values are calculated separately for the territory of the basal ganglia and the supraganglionic (cortical) regions. CBV, cerebral blood volume; MCA, middle cerebral artery; MTT, mean transit time.
Imaging protocol All patients underwent 5 mm thick, non-contrast head CT imaging performed using the Aquilion ONE scanner (Toshiba Medical Systems, Nasu, Japan). CTP was performed using a 320-detector-row CT system (Aquilion ONE). Contrast medium infusion (50 mL, Optiray 350, Mallinckrodt, Missouri, USA) was performed at a rate of 5 mL/s via automated antecubital venous injection. CTP acquisition parameters were 80 kV tube voltage, 200 mA tube current, and 0.35 s rotation. Perfusion maps (cerebral blood flow (CBF), CBV, mean time to peak (mean transit time (MTT)), time to peak, and delay) were reconstructed using Vitrea software (V.6.4, Vital Images, Minnetonka, Minnesota, USA). On average, performing CTP and reconstructing perfusion maps takes 3–4 min. Perfusion maps are then immediately reviewed by the in-house on-call endovascular fellow, and the findings are discussed with the on-call endovascular neurosurgeon.
Table 1
Thereafter, craniocervical CTA was performed using an infusion of contrast medium (80 mL, Omnipaque 350, GE Healthcare, Waukesha, Wisconsin, USA) at a rate of 4 mL/s, with scanning starting manually once the contrast medium reached the aortic arch. CTA images were reconstructed at 0.5 mm thickness.
Image analysis Analysis of CTP maps was performed by two operators who were blinded to the final results. A freehand region of interest of increased MTT in the affected MCA territory was used to outline the total brain tissue at risk, with a mirrored region automatically generated on the CBV map, as previously described2 (figure 1). Absolute CBV values were recorded separately from two regions: (1) the MCA territory of the basal ganglia and (2) the supraganglionic territories (labeled as
Characteristics of cases with favorable and poor clinical outcomes
Characteristics Demographics Age (years), mean ±SD NIHSS score on admission, mean ±SD Female Atrial fibrillation Coronary artery disease or myocardial infarction Diabetes mellitus Hypertension Dyslipidemia Current smoker Treatment details IV rtPA Conscious sedation General anesthesia Mean time from symptom onset to CTP (min), mean±SD Mean time from CTP to groin puncture (min), mean±SD Mean time from groin puncture to recanalization (min), mean±SD Treatment outcome TICI 2b–3 recanalization CBV values CBV cortex (mL/100 g) rCBV cortex CBV basal ganglia (mL/100 g) rCBV basal ganglia
Favorable outcome (mRS=0–2, n=21),
Poor outcome (mRS=3–6, n=43),
p Value
67.5±12.6 14.4±5.5 7 (33) 3 (14) 7 (33) 5 (24) 12 (57) 7 (33) 6 (29)
71.8±11.9 17.0±4.8 18 (42) 23 (53) 10 (23) 13 (30) 31 (72) 14 (33) 11 (26)
0.21 0.078 0.59 0.003 0.55 0.77 0.27 1.0 1.0
5 (24) 15 (71) 6 (29) 291±402 103±45 55±24
11 (26) 29 (67) 14 (33) 202±246 110±67 71±28
1.0 1.0 0.33 0.68 0.064
20 (95)
25 (58)
0.003
3.04±1.13 1.02±0.09 2.61±0.87 0.95±0.16
2.53±1.03 0.87±0.21 2.53±0.96 0.92±0.11
0.095 0.0003 0.77 0.45
Results are shown as number (%) unless specified otherwise. CBV, cerebral blood volume; CTP, CT perfusion; mRS, modified Rankin scale; NIHSS, National Institutes of Health Stroke Scale; rCBV, CBV ratio; rtPA, recombinant tissue plasminogen activator; TICI, Thrombolysis in Cerebral Infarction.
706
Mokin M, et al. J NeuroIntervent Surg 2015;7:705–708. doi:10.1136/neurintsurg-2014-011279
Ischemic stroke ‘cortical regions’), using standard anatomic regions from the Alberta Stroke Program Early CT score (ASPECTS) system for CTP interpretation.6 7 Relative CBV (rCBV) was calculated as the absolute CBV value of the affected hemisphere divided by the absolute CBV value of the contralateral (control) hemisphere.
Statistical analysis Analysis of variables was performed using Fisher’s exact test for categorical data and a two-tailed t test for continuous data. Analysis of covariance was used to evaluate the association between rCBV and mRS values. For all analyses, p
