Joint Annual Meeting ISMRM-ESMRMB 2014 10-16 May 2014 Milan, Italy

Cerebrovascular Reserve
SKILL LEVEL: Basic to Advanced
ORGANIZERS: David B. Hackney, M.D. & Greg Zaharchuk, M.D., Ph.D.
Tuesday, 13 May 2014

This session will combine invited expert speakers and scientific papers focused on brain ischemia and cerebrovascular reserve. Physiology of blood flow in the blood as well as autoregulation, current assessment, and emerging techniques will be discussed in an interactive session.

Physiologists, neuroscientists, physicists, and clinicians who wish to learn more about cerebrovascular reserve and MRI assessment.

As a result of attending this course, participants should be able to:

  • Employ concepts of the neurovascular unit to understand cerebral blood flow regulation; and
  • Select MRI methods for use in cerebrovascular reserve assessment.


Moderators: David B. Hackney, M.D. & Greg Zaharchuk, M.D., Ph.D.

13:30 Physiology & Relevance of Cerebrovascular Reserve Jeroen Hendrikse, M.D., Ph.D.
14:00 Techniques in Cerebrovascular Reserve David J. Mikulis, M.D.
14:30 0345.   BOLD-based characterization of relative oxygen extraction fraction in patients with ischemia
Christine Preibisch1,2, Monika Ankenbrank1, Alexandra Gersing1, Vivien Toth1, Nuria Hirsch1, Hendrik Kooijman3, Silke Wunderlich2, and Claus Zimmer1
1Neuroradiologie, Klinikum rechts der Isar, Technische Universität München, Munich, Germany, 2Neurologische Klinik und Poliklinik, Klinikum rechts der Isar, Technische Universität München, Munich, Germany, 3Philips Healthcare, Hamburg, Germany

Purpose of this study was to evaluate a protocol for measurement of a relative oxygen extraction fraction (rOEF) with separate quantification of T2, T2* and CBV for improved penumbra estimation in patients with ischemia. Compared to rOEF in healthy appearing tissue (0.59 ± 0.19), rOEF presented a stronger increase in areas with prolonged TTP without diffusion restriction (1.44 ± 0.85) than in regions with diffusion restriction (1.03 ± 0.62). rOEF measurement allows to identify ischemic areas and detects differences in rOEF between ischemic core and surrounding tissue. Further work is needed to delineate utility of rOEF for the penumbra concept.

14:40 0346.   
Evaluation of Lesion Severity in Transient MCAO Rat Brain During Early Reperfusion Using Combined Cerebral Vascular Reactivity and Diffusion Imaging - permission withheld
Xiao Wang1, Xiao-Hong Zhu1, Afshin A Divani2, Yi Zhang1, and Wei Chen1
1Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota Medical School, Minneapolis, Minnesota, United States,2Neurology, University of Minnesota, Minnesota, United States

Ischemic stroke is a leading cause of death and long-term disability in the United States. Tremendous effort has been taken and great progress has been made to detect and treat the ischemic lesion at an early stage. The use of thrombolytic agent such as tissue plasminogen activator (tPA) can be helpful to restore the function of salvageable tissues, however, reperfusion paradoxically may also lead to the secondary cell death concurrently. The severity of the reperfusion lesion was evaluated with the ADC, CVR images at a relatively early stage (24 hours after a 1-hour MCA occlusion) of rat brain and the corresponding histology images were obtained on day 7 of the post-occlusion. The results show that the spatial pattern of declined ADC correlates well with the actual lesion region determined by the histology images, while the compromised CVR with normal ADC turns out to be histologically intact. Therefore, three regions regarding the lesion severity can be identified with combined ADC and CVR images: severe lesion region with both ADC and CVR decreased; mild lesion region with impaired CVR but normal ADC and the normal brain region with intact CVR and ADC. The mismatched areas with compromised CVR but intact ADC at the early stage of reperfusion potentially could serve as the treatment target to improve the clinical outcomes.

14:50 0347.   
Activation induced BOLD and CBF responses upon acetazolamide administration: implications for inferring neurovascular and metabolic coupling in patients with impaired cerebrovascular reactivity
Jeroen C.W. Siero1, Nolan Hartkamp1, Anita A. Harteveld1, Annette Compter1, Bart van der Worp1, Manus J. Donahue2, Esben T. Petersen1, and Jeroen Hendrikse1
1University Medical Center Utrecht, Utrecht, Utrecht, Netherlands, 2Radiology and Radiological Sciences, Vanderbilt University, TN, United States

We acquired CBF and BOLD data in patients with cerebrovascular disease (stenosis/occlusion of vertebral basilar artery) during visual stimulation before and after acetazolamide (ACZ) administration. One third of the patients showed negative BOLD responses post-ACZ while CBF remained positive. As the conventionally assumed one-to-one relationship between BOLD and CBF responses seems compromised, caution is warranted when inferring cortical activation and neurovascular coupling in these patients when solely using BOLD fMRI. Our findings indicate altered neurovascular and/or metabolic coupling in these patients and could potentially be valuable marker for clinical outcome.

15:00 0348.   
Quantifying cerebral haemodynamics and maximum potential oxygen delivery in patients with chronic ischemia using DSC perfusion MRI
Amit Mehndiratta1, Chang Sub Park1, David E Crane2, Bradley J MacIntosh2, Stephen J Payne1, and Michael A Chappell1
1Institute of Biomedical Engineering, University of Oxford, Oxford, Oxfordshire, United Kingdom, 2Medical Biophysics, Sunnybrook Research Institute, University of Toronto, Toronto, ON, Canada

Estimation of capillary haemodynamics has historically been a challenge in DSC-MRI analysis. With the Control Point Interpolation method it is now possible to study variation in residue function and haemodynamics in-vivo. This study examined the changes in tissue haemodynamics, maximum potential oxygen delivery corresponding maximum potential tissue metabolic activity in a cohort of seventeen patients with atherosclerotic diseases both pre- and post-carotid endarterectomy. It was found that capillary heterogeneity increased in ischemic tissue, which would be associated with an increase in maximum tissue oxygen extraction fraction that could assist the tissue to maintain normal metabolic activity.

15:10 0349.   Changes over time of brain perfusion and cerebral vasoreactivity after stroke: preliminary results
Olivier Heck1,2, Johan Pietras3, Thomas Perret4, Agnès Aghetti1,3, Marie-Charlotte Plichta1,3, Irène Troprès4,5, Sylvie Grand1, Olivier Detante5,6, Assia Jaillard3,7, and Alexandre Krainik1,5
1Department of Neuroradiology and MRI, University Hospital of Grenoble, Grenoble, France, 2Department of Neuroradiology, University Hospital of Nancy, Nancy, France, 3UMS IRMaGe, Grenoble, France, 4Inserm U836, Grenoble Institute of Neurosciences, Grenoble, France, 5University Joseph Fourier, Grenoble, France, 6Stroke Unit, University Hospital of Grenoble, Grenoble, France, 7Research Department, University Hospital of Grenoble, Grenoble, France

Purpose: To investigate changes over time of cerebral perfusion and CO2 vasoreactivity (CVR) after anterior stroke using MRI. Methods: Basal perfusion with dynamic susceptibility contrast, and CVR with BOLD contrast measured in 16 stroke subjects at 35, 50, and 180 days after stroke onset. Results: Basal perfusion decreased in both necrotic and perinecrotic rim. In the undamaged MCA territory, perfusion remained stable over time. CVR increased in the perinecrotic rim, but remained stable in the necrosis and the undamaged MCA territory. Conclusion: These preliminary results suggest functional improvement of the perilesional vasculature during the first 180 days after stroke.

15:20 0350.   
Alterations in Cerebrovascular Reactivity across the Adult Lifespan: a 4-year Follow-up
Yang Li1, Denise C. Park2, Karen M. Rodrigue2, Yamei Cheng1, and Hanzhang Lu1
1Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, United States, 2Center for Vital Longevity, School of Behavioral and Brain Sciences, Uiversity of Texas at Dallas, Dallas, Texas, United States

Age is the single most important risk factor for stroke and associated cerebrovascular diseases. To date, the most direct vascular marker in vivo has been shown to be cerebrovascular reactivity (CVR), which reflects the ability of the vessel to dilate when challenged. In this work, we present four-year longitudinal follow-up CVR data in 80 healthy individuals ranging from 20 to 85 years old. The findings from the longitudinal data were compared to those from the cross-sectional data. Regional differences were also investigated.

      Q & A / Panel Discussion  
15:30     Adjournment