Three‐dimensional whole‐brain mapping of cerebral blood volume and venous cerebral blood volume using Fourier transform–based velocity‐selective pulse trains

Abstract

Purpose To develop 3D MRI methods for cerebral blood volume (CBV) and venous cerebral blood volume (vCBV) estimation with whole‐brain coverage using Fourier transform–based velocity‐selective (FT‐VS) pulse trains. Methods For CBV measurement, FT‐VS saturation pulse trains were used to suppress static tissue, whereas CSF contamination was corrected voxel‐by‐voxel using a multi‐readout acquisition and a fast CSF T2 scan. The vCBV mapping was achieved by inserting an arterial‐nulling module that included a FT‐VS inversion pulse train. Using these methods, CBV and vCBV maps were obtained on 6 healthy volunteers at 3 T. Results The mean CBV and vCBV values in gray matter and white matter in different areas of the brain showed high correlation (r = 0.95 and P < .0001). The averaged CBV and vCBV values of the whole brain were 5.4 ± 0.6 mL/100 g and 2.5 ± 0.3 mL/100 g in gray matter, and 2.6 ± 0.5 mL/100 g and 1.5 ± 0.2 mL/100 g in white matter, respectively, comparable to the literature. Conclusion The feasibility of FT‐VS‐based CBV and vCBV estimation was demonstrated for 3D acquisition with large spatial coverage.

Velocity‐selective arterial spin labeling perfusion MRI: A review of the state of the art and recommendations for clinical implementation

“…Recently, the feasibility of FT-VS-based CBV and venous CBV estimation was demonstrated for 3D acquisition with large spatial coverage. 97 To label most microvessels, the cutoff velocity required for CBV quantification is considerably lower than typically used in CBF mapping (e.g., 0.35 vs 2.0 cm/s). Care should be taken to mitigate CSF contamination as well as unbalanced diffusion weighting.…”

T2‐oximetry–based cerebral venous oxygenation mapping using Fourier‐transform–based velocity‐selective pulse trains

“…This condition is supported by the close resemblance between the DIR GM images and the venous blood signal obtained at the second echo in this study (Figures 2, 3) or the vCBV maps derived from the same preparation modules in a prior study. 53 Meanwhile, FT-VS experiments using V cut of 0.5 cm/s had 23% higher venous blood signal (5.9 vs. 4.8) (Table 1) than using V cut of 1.4 cm/s, indicating that lower V cut could increase the venous blood signal being detected. As discussed before, 21 the chosen V cut determines the trailing edge of the venous bolus and ideally should be just above capillary blood velocities (close to 0.1 cm/s 36 ) to achieve the maximum available venous signal.…”

“…It has the same preparation modules and timing as the sequence for vCBV mapping 53 . A slab‐selective presaturation pulse train 55 is used at the start for resetting any magnetization from the previous history, followed by a postsaturation delay of 2500 ms. A spatially nonselective arterial‐nulling module, which consists of an FT‐VSI pulse train plus an NSI pulse, is followed by an outflow time of 1050 ms based on the arterial T 1 at 3 Tesla (T) of 1.89 s for a hematocrit (Hct) of 0.42 56,57 and an FT‐VSI + NSI inversion efficiency of 0.86 53 . Interleaved scans with FT‐VSS label and control pulse trains applied at the end of TO and before imaging are acquired to effectively subtract out the signal of static tissue.…”

“…3 Tesla (T) of 1.89 s for a hematocrit (Hct) of 0.42 56,57 and an FT-VSI + NSI inversion efficiency of 0.86. 53 Interleaved scans with FT-VSS label and control pulse trains applied at the end of TO and before imaging are acquired to effectively subtract out the signal of static tissue. Two sets of FT-VS pulse train parameters were compared.…”

“…Unlike previous studies, 21,23 the T 2 attenuation effects of both the capillary and venous blood during the first and second VS pulse trains were taken into account in the present simulation as done for vCBV mapping 53 : assuming Hct of 0.42; Y v of 0.6 for venous blood; and a modeled capillary oxygen distribution, T 2,v = 71 ms, T 2,c = 118 ms, for FT-VS and VSS pulse trains with 6 ms and 12.5 ms interecho spacing, respectively. The corresponding T 2 attenuation effects were calculated as −0.62 (0.62 after NSI) for capillary blood and 0.61 for venous blood during the FT-VSI and FT-VSS 53 (Figure 1A), and as 0.79 for capillary blood and 0.70 for venous blood during the first and second VSS pulse trains (Figure 1B), respectively. Hence the estimated magnetization of venous blood after the second VS pulse trains for FT-VS and VSS-based preparations were 0.42 and − 0.27, respectively.…”