ISMRM 24th Annual Meeting & Exhibition 07-13 May 2016 Singapore

Weekend Educational Course: Quantitative Physiology: Imaging Oxygenation

Skill Level: Basic to Intermediate

Organizers: Steven Sourbron Ph.D., Jonathan R. Polimeni, Ph.D. & Eric C. Wong, M.D., Ph.D.

Sunday 08 May 2016

This course will review the physiology of oxygen delivery and metabolism, describe the mechanisms by which oxygenation can be probed using MRI, and survey applications of oxygenation imaging in several organ systems.

Target Audience
Clinicians and basic scientists who are interested in using MRI to map oxygenation and metabolism; MR physicists and engineers developing methods for quantitative physiological imaging.

Educational Objectives
Upon completion of this course, participants should be able to:

  • Describe the role of oxygen in tissue metabolism;
  • Differentiate between methodological approaches for obtaining sensitivity to oxygenation using MR imaging;
  • Describe and apply organ specific MR methods for imaging of oxygenation; and
  • Select oxygenation imaging methods that are best suited for particular organ systems and applications.

Moderator: Audrey Fan, Andreas Pohlmann
The Role of Oxygen in Brain Tissue Function
Weili Lin1 and William J Powers2
1Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States, 2Neurology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
While our brains utilize oxygen and glucose at rapid rates, they have little energy reserves and require constant supplies of glucose and oxygen to maintain normal brain function.  Cerebral blood flow serves as the means through which these energy sources are delivered to the brain.  This presentation will introduce the concepts of cerebral oxygen metabolism, the approaches to measure it, and the applications of these approaches to discern the interplay between CBF, OEF, and CMRO2 in both normal and pathophysiological conditions.  Emphases will be made, when possible, to compare PET and MR approaches that provide similar physiological measures and their in vivo results.    

Imaging of Oxygenation Using MR
Dmitriy Yablonskiy1
1Mallinckrodt Institute of Radiology
Quantitative evaluation of brain hemodynamics and metabolism, particularly the relationship between brain function and oxygen utilization, is important for understanding normal human brain operation as well as pathophysiology of neurological disorders. It can also be of great importance for evaluation of hypoxia within tumors of the brain and other organs. Most of the currently used methods are based on measuring blood oxygenation level and directly related to it oxygen extraction fraction, OEF. Combining measurement of OEF with measurement of CBF allows evaluation of oxygen consumption, CMRO2.

Imaging of Oxygenation in the Brain
Audrey P. Fan1, Nicholas P. Blockley2, Divya S. Bolar3, Claudine J. Gauthier4, Peiying Liu5, Wendy W. Ni1, Zachary Rodgers6, and Greg Zaharchuk1
1Stanford University, 2University of Oxford, 3Massachusetts General Hospital, 4Concordia University, 5Johns Hopkins University, 6University of Pennsylvania
       The brain has a uniquely high oxygen metabolic demand, and the ability to noninvasively image brain oxygenation is critical to understand normal brain function and many cerebrovascular and neurological disorders.

       Three classes of MRI contrast mechanisms to image oxygenation have been explored, including (1) extravascular blood oxygenation level dependent (BOLD); (2) intravascular T2-relaxation; and (3) magnetic susceptibility in cerebral veins. These methods have different abilities to localize regional oxygenation and different strengths and weaknesses.

       Because MRI methods to image oxygenation are fairly new, additional studies are needed to validate oxygenation measurements with each other, and with the PET reference standard. Promising clinical studies in patients highlight the promise of MRI oxygenation imaging and will benefit from optimized and robust protocols to quantify oxygen metabolism.

Break & Meet the Teachers
Imaging of Oxygenation in the Kidney
Pottumarthi Prasad
Unlike most organs, in the kidneys, oxygen consumption changes with blood flow and increased blood flow doesn't necessary lead to increased oxygen delivery. This leads to a need for independent measures of perfusion and oxygentation  BOLD MRI is the only non-invasive method to evaluate renal oxygenation.  It is most useful for detecting acute changes following pharmacologic/physiologic maneuvers.  Based on evidence from pre-clinical models, translation to the clinic is being pursued.  Limitations in conventional ROI analysis have been identified, creating an interest in alternative methods, including whole kidney analysis.  Alternate methods to measure oxygenation include electron paramagnetic resonance and fluorine-19 MRI, both involving exogenous materials to be used.

Imaging of Oxygenation in the Lung
David Dubowitz1
1Center for fMRI, Pulmonary Imaging Lab, Department of Radiology, University of California San Diego
The lung is a gas exchange organ, so its primary function is transfer of oxygen from the atmosphere to the blood and CO2 from the blood back to the atmosphere. To quantify this we need more than just measurements of alveolar ventilation (V). We also need to know the capillary perfusion (Q), and most importantly, how well these are matched (the V/Q ratio). In this talk I will focus on some novel methods to image pulmonary ventilation and perfusion with conventional proton MRI, and discuss the technical challenges that need to be overcome to make physiological measurements of lung function.

Imaging of Oxygenation in Tumors
Ralph Peter Mason1
1Radiology, University of Texas Southwestern Medical Center, Dallas, TX, United States
Tumor hypoxia is associated with aggressive phenotypes and resistance to therapy. Several MRI approaches are being developed and evaluated to measure tumor oxygenation. Many use exogenous reporter molecules, whilst some exploit endogenous signal. This review will present strengths and weaknesses in terms of temporal and spatial resolution, precision and accuracy, ease of implementation and robustness of observations. Methods may provide qualitative or quantitative insights including dynamic response to interventions. Some are limited to pre-clinical studies, while others offer ready translation to human patients.

Adjournment & Meet the Teachers

The International Society for Magnetic Resonance in Medicine is accredited by the Accreditation Council for
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