from Section 1 - Techniques
Published online by Cambridge University Press: 05 May 2013
Introduction
Tissue oxygenation is a critical physiological parameter in most organ systems. In the brain, oxygenation status plays an important role in hypoxic and ischemic injuries, carotid artery disease, and tumor growth and response to therapy. Traditionally, positron emission tomography (PET) has been used to measure brain oxygen metabolism, but more recently the feasibility of measuring brain oxygenation with MRI has been explored [1–6]. This chapter discusses the theory and methodology of several approaches for measuring brain tissue oxygenation using MRI, including quantitative blood oxygenation level-dependent (qBOLD), quantitative susceptibility mapping (QSM), and T2 relaxation under spin tagging (TRUST). Additional detail, particularly more technical aspects, can be found in a recent review article [7]. Before delving into these methods, we will present a brief review of cerebral autoregulation as it affects oxygenation measurements.
Theory
Cerebrovascular autoregulation and oxygenation measurements
When an artery becomes narrowed or completely occluded, the mean arterial pressure (MAP) in the distal circulation may fall, depending on both the degree of stenosis and the adequacy of collateral sources of blood flow [8]. If collateral flow is inadequate, MAP will fall, leading to a reduction in cerebral perfusion pressure (CPP), which is defined as the difference between MAP and venous backpressure.
To save this book to your Kindle, first ensure [email protected] is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Find out more about the Kindle Personal Document Service.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.