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


CONCLUSIONS
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.
Department of Neurology, University Hospital Heidelberg, Im Neuenheimer Feld 400, Heidelberg, 69120, Germany. sibu.mundiyanapurath@med.uni-heidelberg.de.
Sibu
S
Mundiyanapurath
Department of Neurology, University Hospital Heidelberg, Im Neuenheimer Feld 400, Heidelberg, 69120, Germany.
Peter Arthur
PA
Ringleb
Department of Neuroradiology, University Hospital Heidelberg, Im Neuenheimer Feld 400, Heidelberg, 69120, Germany.|German Cancer Research Center, Department of Radiology, INF 280, Heidelberg, 69120, Germany.
Sascha
S
Diatschuk
Department of Neuroradiology, University Hospital Heidelberg, Im Neuenheimer Feld 400, Heidelberg, 69120, Germany.
Oliver
O
Eidel
Department of Neuroradiology, University Hospital Heidelberg, Im Neuenheimer Feld 400, Heidelberg, 69120, Germany.
Sina
S
Burth
German Cancer Research Center, Department of Radiology, INF 280, Heidelberg, 69120, Germany.
Ralf
R
Floca
Department of Neuroradiology, University Hospital Heidelberg, Im Neuenheimer Feld 400, Heidelberg, 69120, Germany.
Markus
M
Möhlenbruch
Department of Neurology, University Hospital Heidelberg, Im Neuenheimer Feld 400, Heidelberg, 69120, Germany.|CCU Neurooncology, German cancer Consortium (DKTK) & German Cancer Research Center (DKFZ), INF 280, Heidelberg, 69120, Germany.
Wolfgang
W
Wick
Department of Neuroradiology, University Hospital Heidelberg, Im Neuenheimer Feld 400, Heidelberg, 69120, Germany.
Martin
M
Bendszus
Department of Neuroradiology, University Hospital Heidelberg, Im Neuenheimer Feld 400, Heidelberg, 69120, Germany.|German Cancer Research Center, Department of Radiology, INF 280, Heidelberg, 69120, Germany.
Alexander
A
Radbruch
D000368:Aged; D000369:Aged, 80 and over; D016893:Carotid Stenosis / Q000150:complications*; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D055420:Perfusion Imaging / Q000379:methods*; D012372:ROC Curve; D012189:Retrospective Studies; D020521:Stroke / Q000209:etiology*; D013997:Time Factors
Carotid stenosis; Ischemic stroke; Magnetic resonance perfusion; TTP; Tmax