HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) Correspondence: Submit a response Alert me when this article is cited Alert me when Correspondence are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Olivot, J-M Articles by Albers, G. W. Search for Related Content PubMed PubMed Citation Articles by Olivot, J-M Articles by Albers, G. W. Related Collections MRI Infarction

Perfusion MRI (Tmax and MTT) correlation with xenon CT cerebral blood flow in stroke patients

From the Department of Neurology and Neurological Sciences and the Stanford Stroke Center (J.-M.O., M.M., N.S., M.G.L., G.W.A.) and Department of Radiology and the Stanford Stroke Center (G.Z., M.S., R.B., M.E.M.), Stanford University Medical Center, CA.

Address correspondence and reprint requests to Dr. Jean-Marc Olivot, Department of Neurology and Neurological Sciences and the Stanford Stroke Center, Stanford University Medical Center, 701 Welch Rd., Suite 325, Palo Alto, CA 94304 jmolivot{at}stanford.edu

Background: While stable xenon CT (Xe-CT) cerebral blood flow (CBF) is an accepted standard for quantitative assessment of cerebral hemodynamics, the accuracy of magnetic resonance perfusion-weighted imaging (PWI-MRI) is unclear. The Improved PWI Methodology in Acute Clinical Stroke Study compares PWI findings with Xe-CT CBF values in patients experiencing symptomatic severe cerebral hypoperfusion.

Methods: We compared mean transit time (MTT) and Tmax PWI-MRI with the corresponding Xe-CT CBF values in 25 coregistered regions of interest (ROIs) of multiple sizes and locations in nine subacute stroke patients. Comparisons were performed with Pearson correlation coefficients (R). We performed receiver operating characteristic (ROC) curve analyses to define the threshold of Tmax and absolute MTT that could best predict a Xe-CT CBF <20 mL/100 g/minute.

Results: The subjects’ mean (SD) age was 50 (15) years, the median (interquartile range [IQR]) NIH Stroke Scale score was 2 (2–6), and the median (IQR) time between MRI and Xe-CT was 12 (–7–19) hours. The total number of ROIs was 225, and the median (IQR) ROI size was 550 (360–960) pixels. Tmax correlation with Xe-CT CBF (R = 0.63, p < 0.001) was stronger than absolute MTT (R = 0.55, p < 0.001), p = 0.049. ROC curve analysis found that Tmax >4 seconds had 68% sensitivity, 80% specificity, and 77% accuracy and MTT >10 seconds had 68% sensitivity, 77% specificity, and 75% accuracy for predicting ROIs with Xe-CT CBF <20 mL/100 g/minute.

Conclusion: Our results suggest that in subacute ischemic stroke patients, Tmax correlates better than absolute mean transit time (MTT) with xenon CT cerebral blood flow (Xe-CT CBF) and that both Tmax >4 seconds and MTT >10 seconds are strongly associated with Xe-CT CBF <20 mL/100 g/minute.

CBF = cerebral blood flow; DBP = diastolic blood pressure; DEFUSE = Diffusion and Perfusion Imaging Evaluation for Understanding Stroke Evolution; DWI = diffusion-weighted imaging; EPITHET = Echoplanar Imaging Thrombolytic Evaluation Trial; FOV = field of view; ICA = internal carotid artery; IQR = interquartile range; MCA = middle cerebral artery; MTT = mean transit time; NIHSS = NIH Stroke Scale; PWI = perfusion-weighted imaging; PWI-MRI = magnetic resonance perfusion-weighted imaging; ROC = receiver operating characteristic; ROI = region of interest; SBP = systolic blood pressure; SVD = singular value decomposition; Xe-CT = xenon CT.

Supported in part by NIH grants (5 R01 NS047607-04, 2R01EB002711, 1R21EB006860, P41RR09784, K23 NS051372).

Disclosure: The authors report no disclosures.

Received August 27, 2008. Accepted in final form December 16, 2008.

This article has been cited by other articles:

				J.-M. Olivot, M. Mlynash, V. N. Thijs, A. Purushotham, S. Kemp, M. G. Lansberg, L. Wechsler, G. E. Gold, R. Bammer, M. P. Marks, et al. Geography, Structure, and Evolution of Diffusion and Perfusion Lesions in Diffusion and Perfusion Imaging Evaluation For Understanding Stroke Evolution (DEFUSE) Stroke, October 1, 2009; 40(10): 3245 - 3251. [Abstract] [Full Text] [PDF]

				G. Zaharchuk, R. Bammer, M. Straka, A. Shankaranarayan, D. C. Alsop, N. J. Fischbein, S. W. Atlas, and M. E. Moseley Arterial Spin-Label Imaging in Patients with Normal Bolus Perfusion-weighted MR Imaging Findings: Pilot Identification of the Borderzone Sign Radiology, September 1, 2009; 252(3): 797 - 807. [Abstract] [Full Text] [PDF]