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Fetal MRI

T2-weighted Fourier Velocity Encoding (FVE)

T2-weighted Fourier velocity encoding: in vivo vascular MR oximetry

MR oximetry based on conventional quantitative T2 measurement is a technique for measuring vascular oxygen saturation noninvasively. The addition of Fourier velocity encoding overcomes these limitations by separating moving blood from static tissue based on velocity.

Summary

Conventional quantitative T2 measurement can measure vascular oxygen saturation noninvasively. However, partial volume effects can limit T2 accuracy or impose increased spatial resolution, requiring long scan times at reduced SNR. The addition of Fourier velocity encoding in a technique called Magnetic resonance Oximetry with Velocity Encoding (MOVE), overcomes these limitations by separating moving blood from static tissue based on velocity.

Conventional MR oximetry consists of a T2 preparation stage, followed by a fast imaging sequence. MOVE augments the conventional technique with flow-encoding and employs a spiral trajectory for fast imaging and is able to scan at low spatial resolution while maintaining T2 accuracy, permitting potential reductions in scan time. Consequently, MOVE may be able to measure blood oxygen saturation in narrow vessels in less time than conventional oximetry, and has a lower sensitivity to vessel motion.

T2-Weighted Fourier Velocity Encoding image
Conventional oximetry image (TE = 3 ms)
T2-Weighted Fourier Velocity Encoding image
Corresponding MOVE image for v=-17cm/s showing separation of right and left internal jugular veins (RIJV,LIJV) from static tissue based on velocity. Non-zero velocity planes are independently scaled.
T2-Weighted Fourier Velocity Encoding image
Corresponding MOVE image for v=0cm/s showing static tissue.
T2-Weighted Fourier Velocity Encoding image
Corresponding MOVE image for v=+17cm/s showing separation of right and left common carotid arteries (RCCA,LCCA) from static tissue based on velocity. Non-zero velocity planes are independently scaled.