Functional changes in CSF volume estimated using measurement of water T₂ relaxation

Abstract

Cerebrospinal fluid (CSF) provides hydraulic suspension for the brain. The general concept of bulk CSF production, circulation, and reabsorption is well established, but the mechanisms of momentary CSF volume variation corresponding to vasoreactive changes are far less understood. Nine individuals were studied in a 3T MR scanner with a protocol that included visual stimulation using a 10-Hz reversing checkerboard and administration of a 5% CO 2 mix in air. We acquired PRESS-localized spin-echoes (TR ‫؍‬ 12 sec, TE ‫؍‬ 26 ms to 1.5 sec) from an 8-mL voxel located in the visual cortex. Echo amplitudes were fitted to a two-compartmental model of relaxation to estimate the partial volume of CSF and the T 2 relaxation times of the tissues.

IVIM analysis of brain tumors: an investigation of the relaxation effects of CSF, blood, and tumor tissue on the estimated perfusion fraction

“…The f values in white matter did not undergo any significant change with increasing TE, which may be explained in consideration of a lower (or negligible) CSF fraction compared to cortical structures [20] and an insufficient difference in T2 values between blood and white matter. In our work, blood was assumed to predominantly represent the arterial (or normoxic) fraction, which is significantly more attenuated by diffusion gradients as a result of its pulsatile and more turbulent nature compared to the venous (less oxygenated) fraction [21].…”

In vivo detection of acute pain-induced changes of GABA+ and Glx in the human brain by using functional 1H MEGA-PRESS MR spectroscopy

“…In case of GABA+, the same T 1 and T 2 constants were used for GM and WM (Puts et al, 2013;Edden et al, 2012). Water relaxation times were taken from Deistung et al (Deistung et al, 2008), Piechnik et al (Piechnik et al, 2009), and Rooney et al (Rooney et al, 2007).…”

Dual-echo EPI for non-equilibrium fMRI — Implications of different echo combinations and masking procedures

“…If this procedure is performed individually for each single volume it will be referred to as "volume-wise mask" throughout the manuscript. As a conservative threshold, the T 2 -value of CSF at 3 T (503 ms) was chosen as upper threshold for the T 2 * -maps (Piechnik et al, 2009), yielding the threshold values of 1.0447 (lower threshold) and 0.9572 (upper threshold) for Q 1/2 and Q 2/1 , respectively, if an echo time difference TE 2 − TE 1 = 22 ms is chosen. The problem with volume-wise masking is the fact that each voxel where the derived parameter is close to the threshold will be frequently set to zero, thus resulting in a high signal variation across the time series.…”