Refinement of optical imaging spectroscopy algorithms using concurrent BOLD and CBV fMRI

• Published in: NeuroImage (Orlando, Fla.) Vol. 47; no. 4; pp. 1608 - 1619
• Main Authors: Kennerley, Aneurin J., Berwick, Jason, Martindale, John, Johnston, David, Zheng, Ying, Mayhew, John E.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-10-2009; Elsevier Limited
• Subjects: Algorithms; Animals; Biophysical model; Brain; Brain - blood supply; Brain - physiology; Brain Mapping - methods; Cerebrovascular Circulation - physiology; Female; fMRI; Haemodynamics; Light; Magnetic Resonance Imaging - methods; NMR; Nuclear magnetic resonance; Optical imaging spectroscopy; Oxygen - blood; Oxygen Consumption - physiology; Rats; Spectrum analysis; Spectrum Analysis - methods; Studies; Time series; fMRI; Biophysical model; Haemodynamics; Optical imaging spectroscopy
• ISSN: 1053-8119; 1095-9572
• DOI: 10.1016/j.neuroimage.2009.05.092

We describe the use of the three dimensional characteristics of the functional magnetic resonance imaging (fMRI) blood oxygenation level dependent (BOLD) and cerebral blood volume (CBV) MRI signal changes to refine a two dimensional optical imaging spectroscopy (OIS) algorithm. The cortical depth profiles of the BOLD and CBV changes following neural activation were used to parameterise a 5-layer heterogeneous tissue model used in the Monte Carlo simulations (MCS) of light transport through tissue in the OIS analysis algorithm. To transform the fMRI BOLD and CBV measurements into deoxy-haemoglobin (Hbr) profiles we inverted an MCS of extra-vascular MR signal attenuation under the assumption that the extra-/intravascular ratio is 2:1 at a magnetic field strength of 3 T. The significant improvement in the quantitative accuracy of haemodynamic measurements using the new heterogeneous tissue model over the original homogeneous tissue model OIS algorithm was demonstrated on new concurrent OIS and fMRI data covering a range of stimulus durations.