gms | German Medical Science

58. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie e. V. (DGNC)

Deutsche Gesellschaft für Neurochirurgie (DGNC) e. V.

26. bis 29.04.2007, Leipzig

Confirmation of cerebrovascular insufficiency as part of the preoperative work-up for cerebral revascularization: A correlation study of TTP and MTT with stable Xenon contrast enhanced CT

Verifizierung der cerebrovaskulären Insuffizienz im Rahmen der präoperativen Abklärung zur zerebralen Revaskularisierung: Eine Studie zur Korrelation von TTP und MTT mit der Xenon-verstärkten CT

Meeting Abstract

  • corresponding author G.A. Schubert - Neurochirurgische Klinik, Universitätsklinikum Mannheim, Universität Heidelberg
  • C. Weinmann - Abteilung für Neuroradiologie, Universitätsklinikum Mannheim, Universität Heidelberg
  • L. Gerigk - Abteilung für Neuroradiologie, Universitätsklinikum Mannheim, Universität Heidelberg
  • C. Weiss - Institut für Biomedizinische Statistik, Universitätsklinikum Mannheim, Universität Heidelberg
  • P. Horn - Neurochirurgische Klinik, Universitätsklinikum Hamburg-Eppendorf
  • C. Thomé - Neurochirurgische Klinik, Universitätsklinikum Mannheim, Universität Heidelberg

Deutsche Gesellschaft für Neurochirurgie. 58. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie e.V. (DGNC). Leipzig, 26.-29.04.2007. Düsseldorf: German Medical Science GMS Publishing House; 2007. DocSO.03.07

The electronic version of this article is the complete one and can be found online at:

Published: April 11, 2007

© 2007 Schubert et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.



Objective: Patients suffering from hemodynamic ischemia can benefit from cerebral revascularization procedures such as EC/IC-bypass, and Xenon-CT scanning has been established to reliably measure the critical cerebrovascular reserve capacity (CVRC). This technique is not ubiquitously available and also is not tolerated by every patient, so a need for alternative quantification methods arises. This study aims to characterize both time-to-peak (TTP) and mean-transit-time (MTT) in perfusion weighted imaging (PWI) in this particular subset of patients.

Methods: We prospectively enrolled ten patients who underwent both XeCT scanning and PWI as part of the regular preoperative work-up. Cerebrovascular reserve capacity (CVRC) was calculated for each region of interest (ROI, n=504), an increase of less than 30% after administration of a vasoactive stimulus (acetazolamide) was considered pathological. ROIs were anatomically matched with those of PWI after TTP and MTT were calculated. All patients demonstrated areas of both intact and compromised CVRC.

Results: Strongly significant negative correlation was found for TTP and CVRC (r=–0.4, p<0.001), while MTT did not correlate significantly. The optimum threshold for TTP to distinguish normal from pathological cerebrovascular reactivity was found at 4sec (specificity 90.8%, sensitivity 44.4%, McNemar test: p<0.0001), and an approximative equation to calculate the probability of pathological findings could be derived from the data. Positive predictive value (PPV) was 0.77 with a negative predictive value (NPV) of 0.71 at the given specificity and sensitivity with an estimated prevalence of 40%, but decreases accordingly with the expected low prevalence found in a more generalized population.

Conclusions: While PWI with MTT and TTP is not able to replace XeCT in the direct quantification of CVRC, a TTP threshold of 4sec may help to confirm a compromise within the cerebral vasculature in a selected high-risk subgroup of patients where XeCT is not applicable.