Max Wintermark MD, Abstract Co-Author: Nothing to Disclose

Adam Eugene Flanders MD, Abstract Co-Author: Nothing to Disclose

Maarten Simon Van Leeuwen PhD, Presenter: Nothing to Disclose

Carissa Pineda MD, Abstract Co-Author: Nothing to Disclose

James Anderson MD, Abstract Co-Author: Nothing to Disclose

Gary Nesbit MD, Abstract Co-Author: Nothing to Disclose

Salvador Pedraza MD, Abstract Co-Author: Nothing to Disclose

Jay Cinnamon MD, Abstract Co-Author: Nothing to Disclose

Reto Meuli MD, Abstract Co-Author: Nothing to Disclose

Scott K. Pohlman MS, Abstract Co-Author: Nothing to Disclose

Marcel Quist MS, Abstract Co-Author: Nothing to Disclose

Pierre Schnyder MD, Abstract Co-Author: Nothing to Disclose

Birgitta Velthuis MD, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

Cerebral vascular autoregulation in acute stroke patients is meant to compensate for reduced local blood flow secondary to vascular occlusion. It involves vasodilatation and recruitment of collaterals. It is the hallmark of penumbra or tissue at risk. Perfusion-CT (PCT) has been suggested in pilot studies as a tool able to characterize cerebral vascular autoregulation in acute stroke patients. The purpose of this study was to evaluate this hypothesis in a large series of patients.

A prospective international multicenter trial was designed to enroll 130 acute stroke patients. Patients were enrolled if they presented to the emergency room with symptoms suggesting hemispheric stroke lasting = 12 hours, and if there was no evidence of intracerebral hemorrhage. An acute and/or follow-up MR scan confirming the final diagnosis of ischemic hemispheric stroke was performed. CT- and MR-angiography were used to assess vessel patency and possible arterial recanalization. DWI, and PWI when available, were used to delineate the acute and final infarct core, and the tissue at risk. PCT maps were assessed for areas with reduced regional cerebral blood volume (CBV), low regional cerebral blood flow (rCBF), and increased mean transit time (MTT), both in an absolute quantitative and in a relative way (comparison of the ischemic hemisphere to the healthy one). ROC analysis was performed to determine the best PCT parameter, and the best threshold for each parameter.

Currently, 75 patients have been enrolled in the study. The PCT paramater that best correlated with the identification of ischemic tissue with preserved autoregulation is increased relative MTT (area under the curve = 0.94). The optimal threshold is a MTT value increased to 140% of the contralateral value. The PCT parameter that best correlated with the identification of ischemic tissue with altered autoregulation is decreased absolute rCBV (area under the curve = 0.88), with an optimal threshold at 1.9 [ccx100g-1].

PCT provides insight into cerebral vascular autoregulation in acute stroke patients. It shows distinct patterns possibly correlated with tissue at risk or penumbra.

S.P.,M.Q.: Scott Pohlman and Marcel Quist are employees or Philips Medical SystemsM.W.,A.E.F.,M.v.,C.P.,J.A.,G.N.,J.C.,S.P.,R.M.,P.S.,B.V.: The present study is an international multicenter trial supported by a grant from Philips medical Systems

Wintermark, M, Flanders, A, Van Leeuwen, M, Pineda, C, Anderson, J, Nesbit, G, Pedraza, S, Cinnamon, J, Meuli, R, Pohlman, S, Quist, M, Schnyder, P, Velthuis, B, et al, , Cerebral Vascular Autoregulation Assessed by Perfusion-CT in a Large Series of Acute Stroke Patients.  Radiological Society of North America 2004 Scientific Assembly and Annual Meeting, November 28 - December 3, 2004 ,Chicago IL. http://archive.rsna.org/2004/4403794.html