Correlation between Absolute Deoxyhaemoglobin [dHb] Measured by Near Infrared Spectroscopy (NIRS) and Absolute R2′ as Determined by Magnetic Resonance Imaging (MRI)
Magnetic Resonance Imaging (MRI) is a technique which provides high spatial resolution combined with a wide range of image contrast mechanisms. Standard MR image contrast relies upon tissue differences in MR visible hydrogen spin density, spin-lattice (T1) relaxation and spin-spin (T2) relaxation. In soft tissue, the variation of MR visible hydrogen spin density between tissues types is small (up to 30%) whereas T1 and T2 relaxation times can vary considerably (>100%). However, despite this sensitivity, these standard forms of contrast mainly reflect the longer term disruption of tissue structure. Since alterations in tissue function normally precede structural damage, MR image contrast which accurately reflects this tissue function holds the promise of earlier detection of pathophysiology.
KeywordsCerebral Blood Volume Blood Oxygenation Level Dependant Blood Volume Change United Kingdom Introduction Image Matrix Size
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