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Time-dependent parameter of perfusion imaging as independent predictor of clinical outcome in symptomatic carotid artery stenosis.

Mundiyanapurath S, Ringleb PA, Diatschuk S, Eidel O, Burth S, Floca R, Möhlenbruch M, Wick W, Bendszus M, Radbruch A - BMC Neurol (2016)

Bottom Line: Thirty-two patients were included.Multivariate logistic regression showed that NIHSS score on admission (Odds Ratio (OR) 0.466, confidence interval (CI) [0.224;0.971], p = 0.041), T(max) ≥8 s (OR 0.025, CI [0.001;0.898] p = 0.043) and TTP ≥6 s (OR 0.025, CI [0.001;0.898] p = 0.043) were independent predictors of clinical outcome.Future studies should assess if perfusion weighted imaging might guide the selection of patients for recanalization procedures.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, University Hospital Heidelberg, Im Neuenheimer Feld 400, Heidelberg, 69120, Germany. sibu.mundiyanapurath@med.uni-heidelberg.de.

ABSTRACT

Background: Carotid artery stenosis is a frequent cause of ischemic stroke. While any degree of stenosis can cause embolic stroke, a higher degree of stenosis can also cause hemodynamic infarction. The hemodynamic effect of a stenosis can be assessed via perfusion weighted MRI (PWI). Our aim was to investigate the ability of PWI-derived parameters such as TTP (time-to-peak) and T(max) (time to the peak of the residue curve) to predict outcome in patients with unilateral acute symptomatic internal carotid artery (sICA) stenosis.

Methods: Patients with unilateral acute sICA stenosis (≥50% according to NASCET), without intracranial stenosis or occlusion, who underwent PWI, were included. Clinical characteristics, volume of restricted diffusion, volume of prolonged TTP and T(max) were retrospectively analyzed and correlated with outcome represented by the modified Rankin Scale (mRS) score at discharge. TTP and T(max) volumes were dichotomized using a ROC curve analysis. Multivariate analysis was performed to determine which PWI-parameter was an independent predictor of outcome.

Results: Thirty-two patients were included. Degree of stenosis, volume of visually assessed TTP and volume of TTP ≥2 s did not distinguish patients with favorable (mRS 0-2) and unfavorable (mRS 3-6) outcome. In contrast, patients with unfavorable outcome had higher volumes of TTP ≥4 s (9.12 vs. 0.87 ml; p = 0.043), TTP ≥6 s (6.70 vs. 0.20 ml; p = 0.017), T(max) ≥4 s (25.27 vs. 0.00 ml; p = 0.043), T(max) ≥6 s (9.21 vs. 0.00 ml; p = 0.017), T(max) ≥8 s (6.86 vs. 0.00 ml; p = 0.011) and T(max) ≥10s (5.94 vs. 0.00 ml; p = 0.025) in univariate analysis. Multivariate logistic regression showed that NIHSS score on admission (Odds Ratio (OR) 0.466, confidence interval (CI) [0.224;0.971], p = 0.041), T(max) ≥8 s (OR 0.025, CI [0.001;0.898] p = 0.043) and TTP ≥6 s (OR 0.025, CI [0.001;0.898] p = 0.043) were independent predictors of clinical outcome.

Conclusion: As they stood out in multivariate regression and are objective and reproducible parameters, PWI-derived volumes of T(max) ≥8 s and TTP ≥6 s might be superior to degree of stenosis and visually assessed TTP maps in predicting short term patient outcome. Future studies should assess if perfusion weighted imaging might guide the selection of patients for recanalization procedures.

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Patient with 90 % carotid artery stenosis and favorable outcome. a Large prolonged TTP volume on TTP-map provided by scanner software without thresholding. b Slight prolongation of TTP volume on TTP-map calculated by Olea-Sphere®. Maps were visualized on fluid attenuated weighted images (FLAIR). c DWI provided by scanner software showing no restrictions. d Small prolonged Tmax volume calculated by Olea-Sphere®
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Fig1: Patient with 90 % carotid artery stenosis and favorable outcome. a Large prolonged TTP volume on TTP-map provided by scanner software without thresholding. b Slight prolongation of TTP volume on TTP-map calculated by Olea-Sphere®. Maps were visualized on fluid attenuated weighted images (FLAIR). c DWI provided by scanner software showing no restrictions. d Small prolonged Tmax volume calculated by Olea-Sphere®

Mentions: Thirty-two patients were eligible for analysis. All patients suffered from acute sICA stenosis (ischemic stroke or transient ischemic attack) and were treated on our stroke unit. The patients had the following degrees of stenosis: 90 % (n = 9), 80 % (n = 9), 70 % (n = 8), 60 % (n = 1), 50 % (n = 5). None of the patients died and 23 had a favorable outcome. The median length of stay in hospital was 6.5 days (interquartile range (IQR): 4.3;8.8). Among patients with high grade stenosis and large prolonged visually assessed TTP volume, some had a small pathological perfusion volume on Tmax maps, only a slight prolongation of the TTP in the TTP maps with thresholds (≥2 s) and favorable outcome (Fig. 1). On the other hand, some of these patients had a large pathological perfusion volume with higher values of TTP/Tmax and unfavorable outcome (Fig. 2). Additional middle cerebral artery stenosis or occlusion was ruled out by CT angiography for this patient (Additional file 1: Figure S1). We therefore investigated whether and at what threshold pathological TTP and Tmax volume can predict outcome using a ROC analysis. The visually assessed TTP volume and the volume with a TTP ≥2 s failed to differentiate between favorable and unfavorable outcome (AUC = 0.560; p = 0.600 and AUC = 0.686; p = 0.107, respectively). All other PWI-derived parameters were significantly different in patients with favorable and unfavorable outcome in the ROC-analysis (Additional file 2: Table S1) and in univariate analysis that included other clinical parameters (age, side and degree of stenosis, risk factors, treatment, time from symptom onset to MRI, NIHSS score, mRS score and TCD parameters) as well (Table. 1). For additional multivariate analysis, a threshold for Tmax and TTP maps was chosen from the ROC curve, which resulted in a sensitivity of 0.778 for all parameters (Additional file 2: Table S1). The Tmax and TTP parameter with the highest area under the curve (Tmax ≥8 s and TTP ≥6 s) were used in multivariate logistic regression analysis that included all significant (p <0.05) parameters from the univariate analysis as well. As a significant collinearity of the TTP and Tmax parameter was evident, we performed two separate regression analyses using only one of the perfusion parameters in each of them. The dichotomized volume of Tmax ≥8 s (threshold >0.94 ml, odds ratio 0.026; 95 % confidence interval [0.001;0.925]; p = 0.045) and TTP ≥6 s (threshold 1.42 ml, odds ratio 0.026; 95 % confidence interval [0.001;0.925]; p = 0.045) were independent predictors of outcome even though NIHSS score on admission and DWI lesion volume were included (Table 2).Fig. 1


Time-dependent parameter of perfusion imaging as independent predictor of clinical outcome in symptomatic carotid artery stenosis.

Mundiyanapurath S, Ringleb PA, Diatschuk S, Eidel O, Burth S, Floca R, Möhlenbruch M, Wick W, Bendszus M, Radbruch A - BMC Neurol (2016)

Patient with 90 % carotid artery stenosis and favorable outcome. a Large prolonged TTP volume on TTP-map provided by scanner software without thresholding. b Slight prolongation of TTP volume on TTP-map calculated by Olea-Sphere®. Maps were visualized on fluid attenuated weighted images (FLAIR). c DWI provided by scanner software showing no restrictions. d Small prolonged Tmax volume calculated by Olea-Sphere®
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Fig1: Patient with 90 % carotid artery stenosis and favorable outcome. a Large prolonged TTP volume on TTP-map provided by scanner software without thresholding. b Slight prolongation of TTP volume on TTP-map calculated by Olea-Sphere®. Maps were visualized on fluid attenuated weighted images (FLAIR). c DWI provided by scanner software showing no restrictions. d Small prolonged Tmax volume calculated by Olea-Sphere®
Mentions: Thirty-two patients were eligible for analysis. All patients suffered from acute sICA stenosis (ischemic stroke or transient ischemic attack) and were treated on our stroke unit. The patients had the following degrees of stenosis: 90 % (n = 9), 80 % (n = 9), 70 % (n = 8), 60 % (n = 1), 50 % (n = 5). None of the patients died and 23 had a favorable outcome. The median length of stay in hospital was 6.5 days (interquartile range (IQR): 4.3;8.8). Among patients with high grade stenosis and large prolonged visually assessed TTP volume, some had a small pathological perfusion volume on Tmax maps, only a slight prolongation of the TTP in the TTP maps with thresholds (≥2 s) and favorable outcome (Fig. 1). On the other hand, some of these patients had a large pathological perfusion volume with higher values of TTP/Tmax and unfavorable outcome (Fig. 2). Additional middle cerebral artery stenosis or occlusion was ruled out by CT angiography for this patient (Additional file 1: Figure S1). We therefore investigated whether and at what threshold pathological TTP and Tmax volume can predict outcome using a ROC analysis. The visually assessed TTP volume and the volume with a TTP ≥2 s failed to differentiate between favorable and unfavorable outcome (AUC = 0.560; p = 0.600 and AUC = 0.686; p = 0.107, respectively). All other PWI-derived parameters were significantly different in patients with favorable and unfavorable outcome in the ROC-analysis (Additional file 2: Table S1) and in univariate analysis that included other clinical parameters (age, side and degree of stenosis, risk factors, treatment, time from symptom onset to MRI, NIHSS score, mRS score and TCD parameters) as well (Table. 1). For additional multivariate analysis, a threshold for Tmax and TTP maps was chosen from the ROC curve, which resulted in a sensitivity of 0.778 for all parameters (Additional file 2: Table S1). The Tmax and TTP parameter with the highest area under the curve (Tmax ≥8 s and TTP ≥6 s) were used in multivariate logistic regression analysis that included all significant (p <0.05) parameters from the univariate analysis as well. As a significant collinearity of the TTP and Tmax parameter was evident, we performed two separate regression analyses using only one of the perfusion parameters in each of them. The dichotomized volume of Tmax ≥8 s (threshold >0.94 ml, odds ratio 0.026; 95 % confidence interval [0.001;0.925]; p = 0.045) and TTP ≥6 s (threshold 1.42 ml, odds ratio 0.026; 95 % confidence interval [0.001;0.925]; p = 0.045) were independent predictors of outcome even though NIHSS score on admission and DWI lesion volume were included (Table 2).Fig. 1

Bottom Line: Thirty-two patients were included.Multivariate logistic regression showed that NIHSS score on admission (Odds Ratio (OR) 0.466, confidence interval (CI) [0.224;0.971], p = 0.041), T(max) ≥8 s (OR 0.025, CI [0.001;0.898] p = 0.043) and TTP ≥6 s (OR 0.025, CI [0.001;0.898] p = 0.043) were independent predictors of clinical outcome.Future studies should assess if perfusion weighted imaging might guide the selection of patients for recanalization procedures.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, University Hospital Heidelberg, Im Neuenheimer Feld 400, Heidelberg, 69120, Germany. sibu.mundiyanapurath@med.uni-heidelberg.de.

ABSTRACT

Background: Carotid artery stenosis is a frequent cause of ischemic stroke. While any degree of stenosis can cause embolic stroke, a higher degree of stenosis can also cause hemodynamic infarction. The hemodynamic effect of a stenosis can be assessed via perfusion weighted MRI (PWI). Our aim was to investigate the ability of PWI-derived parameters such as TTP (time-to-peak) and T(max) (time to the peak of the residue curve) to predict outcome in patients with unilateral acute symptomatic internal carotid artery (sICA) stenosis.

Methods: Patients with unilateral acute sICA stenosis (≥50% according to NASCET), without intracranial stenosis or occlusion, who underwent PWI, were included. Clinical characteristics, volume of restricted diffusion, volume of prolonged TTP and T(max) were retrospectively analyzed and correlated with outcome represented by the modified Rankin Scale (mRS) score at discharge. TTP and T(max) volumes were dichotomized using a ROC curve analysis. Multivariate analysis was performed to determine which PWI-parameter was an independent predictor of outcome.

Results: Thirty-two patients were included. Degree of stenosis, volume of visually assessed TTP and volume of TTP ≥2 s did not distinguish patients with favorable (mRS 0-2) and unfavorable (mRS 3-6) outcome. In contrast, patients with unfavorable outcome had higher volumes of TTP ≥4 s (9.12 vs. 0.87 ml; p = 0.043), TTP ≥6 s (6.70 vs. 0.20 ml; p = 0.017), T(max) ≥4 s (25.27 vs. 0.00 ml; p = 0.043), T(max) ≥6 s (9.21 vs. 0.00 ml; p = 0.017), T(max) ≥8 s (6.86 vs. 0.00 ml; p = 0.011) and T(max) ≥10s (5.94 vs. 0.00 ml; p = 0.025) in univariate analysis. Multivariate logistic regression showed that NIHSS score on admission (Odds Ratio (OR) 0.466, confidence interval (CI) [0.224;0.971], p = 0.041), T(max) ≥8 s (OR 0.025, CI [0.001;0.898] p = 0.043) and TTP ≥6 s (OR 0.025, CI [0.001;0.898] p = 0.043) were independent predictors of clinical outcome.

Conclusion: As they stood out in multivariate regression and are objective and reproducible parameters, PWI-derived volumes of T(max) ≥8 s and TTP ≥6 s might be superior to degree of stenosis and visually assessed TTP maps in predicting short term patient outcome. Future studies should assess if perfusion weighted imaging might guide the selection of patients for recanalization procedures.

Show MeSH
Related in: MedlinePlus