gms | German Medical Science

60th Annual Meeting of the German Society of Neurosurgery (DGNC)
Joint Meeting with the Benelux countries and Bulgaria

German Society of Neurosurgery (DGNC)

24 - 27 May 2009, Münster

OEF-MRI studies selecting patients for extra-intracranial bypass-surgery

Meeting Abstract

  • S. Siemonsen - Neuroradiologische Abteilung, Universitätsklinikum Hamburg-Eppendorf, Hamburg
  • K. Mouridsen - Science Institute Neuroimaging, Carlsberg, Denmark
  • J. Fiehler - Neuroradiologische Abteilung, Universitätsklinikum Hamburg-Eppendorf, Hamburg
  • R. Hahn - Neurochirurgische Klinik, Universitätsklinikum Hamburg-Eppendorf, Hamburg
  • J. Regelsberger - Neurochirurgische Klinik, Universitätsklinikum Hamburg-Eppendorf, Hamburg

Deutsche Gesellschaft für Neurochirurgie. 60. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit den Benelux-Ländern und Bulgarien. Münster, 24.-27.05.2009. Düsseldorf: German Medical Science GMS Publishing House; 2009. DocP13-01

doi: 10.3205/09dgnc387, urn:nbn:de:0183-09dgnc3871

Published: May 20, 2009

© 2009 Siemonsen 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: Severe hemodynamic compromise together with an abolished cerebral autoregulation characterizes patients which are believed to profit by an extra-intracranial bypass procedure. While numerous imaging modalities contain methodological errors under these circumstances, and quantitative PET or Xenon-CT are not available in most institutions, CBF rates and oxygen extraction fraction (OEF) remain less expressive for patient selection.

Methods: Four patients underwent MR imaging including perfusion weighted imaging (PWI) prior to and after EC-IC bypass surgery. After calculation of perfusion parameter maps (CBV, CBF) including OEF, regions of maximally prolonged Time To Peak (TTP) were defined and superimposed onto the corresponding perfusion and OEF maps. Differences of OEF values before and after bypass surgery were calculated (OEFdif) and correlated to the clinical course (NIHSS and MRS).

Results: Postoperatively, three patients showed stable or improved neurological condition (NIHSS 0 to –2; MRS 0 to +1) correlating with a decrease in OEF-rates (mean 32%). OEFdif (range of 0.1143 to 0.2765) were greatest for the patient with the most evident clinical postoperative improvement (NIHSS –2; MRS +1). TTP and MTT were accelerated in these patients (mean 3s). No neurological worsening was notified in one patient with OEFdif of -0.1304 and decelerating transit times.

Conclusions: Clinical improvement following standard EC-IC bypass surgery goes along with a decrease of OEF-PWI values and an increase in OEFdif rates, thus suggesting MRI to be a reliable method in controlling surgical outcome. Moreover, it seems to be a promising tool to detect patients who are at higher risk for stroke and therefore good candidates for bypass surgery.