M. Hedley and D. Rosenfeld, "A new two-dimensional phase unwrapping algorithm for MRI images," Magnet. Reson. Med., vol. 24, pp. 177--181, 1992.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....Many of the existing unwrapping techniques proposed for MR applications were only written to deal with 2D slices. These methods are based on various approaches including region growing [16, 18, 1] cost function optimisation [17] neighbourhood voting filtering [2] and phase path integration [8]. Although these approaches all generalise straightforwardly to 3D images they are generally inefficient and consequently unacceptably slow for many applications, especially rapid, automated shimming. This report presents a fast, robust method for unwrapping phase maps that is general and can be ....

Mark Hedley and Dov Rosenfeld. A new two-dimensional phase unwrapping algorithm for mri images. Magnetic Resonance in Medicine, 24(1):177--181, 1992.

....signal ( 100 cm s) In this example the dynamic range is reduced from 100cm s to 75cm s, so that for example a speed of 85cm s maps to 65cm s after wrapping. If w (x) is the wrapped phase and (x) the actual phase then w (x) x) 2n(x) 1) where n(x) is an integer and Gamma w (x) [3]. The unwrapping problem is that of determining the integer n(x) for each point x in the image. Once n(x) is know it is trivial to unwrap the phase using (1) The problem is made more difficult by signal noise, but if we assume that Gamma1 n 1, i.e. that the phase is wrapped no more than one ....

....are all very well if the output is used only to guide the unwrapping, not to replace the signal. Many of the algorithms used for unwrapping in both flow imaging, and determining magnetic field inhomogeneity and magnetic susceptibility variation, employ path following or region growing methods [3] [9] 10] 11] They are necessarily causal using a toppling domino effect to sequentially correct a series of phase wrapped points. Region growing approaches suffer from the problem that different starting points may give different outputs. Furthermore, path following strategies become much more ....

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M. Hedley and D. Rosenfeld. A New Two Dimensional Phase Unwrapping Algorithm for MRI Image. Magnetic Resonance in Medicine, 24:177--181, 1992.

.... phase perturbations [11] coherent imaging [13] phase retrieval from intensity data in optics [14, 15] digital image reconstruction from Fourier transform phase or magnitude [16] speckle interferometry [17] measurement of magnetic field inhomogeneities in magnetic resonance imaging [18, 19, 20, 21], geophysics [22] and generation of high precision digital elevation models (DEM) of a remotely sensed terrain in synthetic aperture radar (SAR) interferometry [23] 3 In this paper, we investigate the properties of a solution given by GHF developed in Ref. 8] We show that the phase unwrapped ....

M. Hedley and D. Rosenfeld. A new two-dimensional phase unwrapping algorithm for MRI images. Magnetic Resonance in Medicine, 24:177--181, 1992.

....Phase information has fundamental importance in many one and two dimensional signal processing problems. When dealing with two dimensional signals, estimates of the phase are required in different applications such as 2 D homomorphic signal processing, magnetic resonance imaging (MRI) 1] [3], optical imaging, 4] and interferometric synthetic aperture radar (INSAR) 5] 6] In processing nonstationary one dimensional signals, as well as in the case of nonhomogeneous multidimensional signals, the phase contains useful information. In one dimensional signals the first derivative of ....

M. Hedley and D. Rosenfeld, " A New Two-Dimensional Phase Unwrapping Algorithm for MRI Images," Magn. Reson. Med., vol. 24, pp. 177-181, 1992.

No context found.

M. Hedley and D. Rosenfeld, "A new two-dimensional phase unwrapping algorithm for MRI images," Magnet. Reson. Med., vol. 24, pp. 177--181, 1992.

No context found.

M. Hedley and D. Rosenfeld, " A New Two-Dimensional Phase Unwrapping Algorithm for MRI Images," Magn. Reson. Med., vol. 24, pp. 177-181, 1992.

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