Analysis and correction of background velocity offsets in phase-contrast flow measurements using magnetic field monitoring
نویسندگان
چکیده
منابع مشابه
Image based magnetic field background correction for aortic and pulmonary artery flow measurement using phase contrast
Methods A large gel phantom was used to assess phase offset in through-plane phase contrast images in x (left to right), y (anterior to posterior) and z directions at the isocenter and in positions ±40 mm and ±80 mm away from the isocenter. Repeated measures were averaged and fit to linear regressions. Phase correction was validated in human study for the assessment of aorta and pulmonary arter...
متن کاملImage based background magnetic field correction for aortic and pulmonary artery flow measurement using phase contrast
Methods Twelve volunteers underwent breath-hold through-plane phase contrast (PC) imaging of cross sectional view of the ascending aorta and PA. PC imaging was immediately repeated on a static fluid-filled phantom. Phase images were analyzed using QFlow (Medis, Leiden, Netherlands.). Phase shift was also analyzed in static background and in surrounding tissues including chest wall fat and muscl...
متن کاملBackground phase correction using k-space filters in phase contrast velocity encoded MRI
Figure 5: In-vivo background phase correction. (a) Magnitude image, (b) the original phase image, with the dashed blue line defining the area and (c) the red contour of stationary tissue for polynomial surface subtraction, (d) is ground truth, (e) 5th order polynomial subtraction, and (f) k-space filtering with a 64×64 pixel Gaussian kernel. Figure 1: phantom with steady-state flow. Red lines s...
متن کاملEffects from RF spoiling disequilibrium in the background offsets of phase-contrast velocity imaging
Background Phase-contrast imaging normally uses gradient-echoes with RF spoiling and phase-encode rewinding with a fixed dephasing by gradient “spoiler” pulses in each TR (time between RF pulses) studied in detail (1) where effective artifact suppression in magnitude images required >≈ 8PI dephasing over the slice thickness, with >≈ 2PI dephasing over an FE pixel. However, the effectiveness of ...
متن کاملAnalysis and Correction of the Effect of Spatial Gradient Field Distortions on Velocity Measurements with Phase Contrast MRI
An analysis of the effect of spatially inhomogeneous gradient fields on quantitative phase contrast MRI measurements is presented. A local error in the gradient strength leads to incorrect velocity encoding. Here the error in the measured velocities is compared to a theoretical model of gradient field imperfection. Depending on the spatial location of the region of interest for velocity measure...
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ژورنال
عنوان ژورنال: Magnetic Resonance in Medicine
سال: 2011
ISSN: 0740-3194
DOI: 10.1002/mrm.23111