Non‐contrast‐enhanced abdominal MRA at 3 T using velocity‐selective pulse trains

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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.

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confidence: 99%

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

Liu

Zijl

et al. 2021

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“…For abdominal VSMRA, O45° encoding was chosen to cover both the descending aorta and renal arteries. 19 The direction dependence of conventional VS pulse trains has also been demonstrated for a phantom and the hand MRA, 5 as well as the brain VSASL for larger values of Vc. 8 When Vc is below 4 cm/s, previous work on cerebral VSMRA and VSASL showed much improved isotropy with respect to velocity-encoding directions.…”

Section: Discussionmentioning

confidence: 87%

“…The special configuration of QASPER phantom amplifies this issue. For abdominal VSMRA, O45° encoding was chosen to cover both the descending aorta and renal arteries 19 . The direction dependence of conventional VS pulse trains has also been demonstrated for a phantom and the hand MRA, 5 as well as the brain VSASL for larger values of Vc 8 .…”

Section: Discussionmentioning

confidence: 97%

“…Alternatively, the emerging techniques of Fourier transform (FT)–based VS pulse trains are able to saturate (FT‐VSS) or invert (FT‐VSI) static tissue while preserving spins flowing above V C . The FT‐VS pulse trains have been applied to non‐subtraction‐based VSMRA 13‐19 and VSASL‐derived quantitative mapping of cerebral blood flow 20‐26 as well as cerebral blood volume 27 …”

Section: Introductionmentioning

confidence: 99%

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Magnetic resonance angiography and perfusion mapping by arterial spin labeling using Fourier transform–based velocity‐selective pulse trains: Examination on a commercial perfusion phantom

Zhu

Fan

et al. 2021

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Purpose Benchmarking of flow and perfusion MR techniques on standardized phantoms can facilitate the use of advanced angiography and perfusion‐mapping techniques across multiple sites, field strength, and vendors. Here, MRA and perfusion mapping by arterial spin labeling (ASL) using Fourier transform (FT)–based velocity‐selective saturation and inversion pulse trains were evaluated on a commercial perfusion phantom. Methods The FT velocity‐selective saturation–based MRA and FT velocity‐selective inversion–based ASL perfusion imaging were compared with time‐of‐flight and pseudo‐continuous ASL at 3 T on the perfusion phantom at two controlled flow rates, 175 mL/min and 350 mL/min. Velocity‐selective MRA (VSMRA) and velocity‐selective ASL (VSASL) were each performed with three velocity‐encoding directions: foot–head, left–right, and oblique 45°. The contrast‐to‐noise ratio for MRA scans and perfusion‐weighted signal, as well as labeling efficiency for ASL methods, were quantified. Results On this phantom with feeding tubes having only vertical and transverse flow directions, VSMRA and VSASL exhibited the dependence of velocity‐encoding directions. The foot–head‐encoded VSMRA and VSASL generated similar signal contrasts as time of flight and pseudo‐continuous ASL for the two flow rates, respectively. The oblique 45°–encoded VSMRA yielded more uniform contrast‐to‐noise ratio across slices than foot–head and left–right‐encoded VSMRA scans. The oblique 45°–encoded VSASL elevated labeling efficiency from 0.22‐0.68 to 0.82‐0.90 through more uniform labeling of the entire feeding tubes. Conclusion Both FT velocity‐selective saturation–based VSMRA and FT velocity‐selective inversion–based VSASL were characterized on a commercial perfusion phantom. Careful selection of velocity‐encoding directions along the major vessels is recommended for their applications in various organs.

“…Although cardiac‐gated 3D FSE typically has a longer acquisition time because of the need for two acquisitions to perform a subtraction, this increased acquisition time might now be compensated for by the high acceleration factors offered by KSPIC. The averaged acquisition times were 3.2 (15×) or 2.3 (20×) minutes for data sets with the matrix size of 320 × 320 × 80, which is even shorter than some other nonsubtractive peripheral NCE‐MRA approaches, such as velocity‐selective magnetization‐prepared MRA 41,42 (5.3 minutes for acquisitions with a similar matrix size 42 and 3‐4 minutes for 8× CS‐accelerated acquisitions with a smaller size 43 ).…”

Section: Discussionmentioning

confidence: 96%

Highly accelerated subtractive femoral non‐contrast‐enhanced MRA using compressed sensing with k‐space subtraction, phase and intensity correction

Graves

Shaida

et al. 2021