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Investigation of inter-slice magnetization transfer effects as a new method for MTR imaging of the human brain.

Barker JW, Han PK, Choi SH, Bae KT, Park SH - PLoS ONE (2015)

Bottom Line: The effects of varying flip angle and phase encoding (PE) order were investigated experimentally in normal, healthy subjects.Simulations were also used to investigate the effects of varying acquisition parameters, and the effects of varying flip angle, PE steps, and interslice delay are discussed.Lastly, we demonstrated reduced banding with a non-balanced SSFP-FID sequence and showed preliminary results of interslice MTR imaging of meningioma.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America; Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.

ABSTRACT
We present a new method for magnetization transfer (MT) ratio imaging in the brain that requires no separate saturation pulse. Interslice MT effects that are inherent to multi-slice balanced steady-state free precession (bSSFP) imaging were controlled via an interslice delay time to generate MT-weighted (0 s delay) and reference images (5-8 s delay) for MT ratio (MTR) imaging of the brain. The effects of varying flip angle and phase encoding (PE) order were investigated experimentally in normal, healthy subjects. Values of up to ∼50% and ∼40% were observed for white and gray matter MTR. Centric PE showed larger MTR, higher SNR, and better contrast between white and gray matter than linear PE. Simulations of a two-pool model of MT agreed well with in vivo MTR values. Simulations were also used to investigate the effects of varying acquisition parameters, and the effects of varying flip angle, PE steps, and interslice delay are discussed. Lastly, we demonstrated reduced banding with a non-balanced SSFP-FID sequence and showed preliminary results of interslice MTR imaging of meningioma.

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MTR images of a 10% agar phantom (left) and saline phantom (right).
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pone.0117101.g002: MTR images of a 10% agar phantom (left) and saline phantom (right).

Mentions: Fig. 2 shows the resulting MTR images of the 10% agar phantom and saline phantom. The MTR images of the agar phantom (left) showed relatively homogeneous MTR values with the exception of dark spots caused by air bubbles trapped in the phantom. The saline phantom (right), which was expected to have no MT effects, was free from extraneous signals (note the scale difference between the two images). Together, the agar and control phantom images strongly support MT effects as the source of image contrast.


Investigation of inter-slice magnetization transfer effects as a new method for MTR imaging of the human brain.

Barker JW, Han PK, Choi SH, Bae KT, Park SH - PLoS ONE (2015)

MTR images of a 10% agar phantom (left) and saline phantom (right).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4321840&req=5

pone.0117101.g002: MTR images of a 10% agar phantom (left) and saline phantom (right).
Mentions: Fig. 2 shows the resulting MTR images of the 10% agar phantom and saline phantom. The MTR images of the agar phantom (left) showed relatively homogeneous MTR values with the exception of dark spots caused by air bubbles trapped in the phantom. The saline phantom (right), which was expected to have no MT effects, was free from extraneous signals (note the scale difference between the two images). Together, the agar and control phantom images strongly support MT effects as the source of image contrast.

Bottom Line: The effects of varying flip angle and phase encoding (PE) order were investigated experimentally in normal, healthy subjects.Simulations were also used to investigate the effects of varying acquisition parameters, and the effects of varying flip angle, PE steps, and interslice delay are discussed.Lastly, we demonstrated reduced banding with a non-balanced SSFP-FID sequence and showed preliminary results of interslice MTR imaging of meningioma.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America; Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.

ABSTRACT
We present a new method for magnetization transfer (MT) ratio imaging in the brain that requires no separate saturation pulse. Interslice MT effects that are inherent to multi-slice balanced steady-state free precession (bSSFP) imaging were controlled via an interslice delay time to generate MT-weighted (0 s delay) and reference images (5-8 s delay) for MT ratio (MTR) imaging of the brain. The effects of varying flip angle and phase encoding (PE) order were investigated experimentally in normal, healthy subjects. Values of up to ∼50% and ∼40% were observed for white and gray matter MTR. Centric PE showed larger MTR, higher SNR, and better contrast between white and gray matter than linear PE. Simulations of a two-pool model of MT agreed well with in vivo MTR values. Simulations were also used to investigate the effects of varying acquisition parameters, and the effects of varying flip angle, PE steps, and interslice delay are discussed. Lastly, we demonstrated reduced banding with a non-balanced SSFP-FID sequence and showed preliminary results of interslice MTR imaging of meningioma.

Show MeSH
Related in: MedlinePlus