Artifact reduction of susceptibility-weighted imaging using a short-echo phase mask

Susceptibility-weighted imaging (SWI) is utilized in magnetic resonance (MR) venography and other applications, but can include artifacts caused by the phase-masking process.

To demonstrate risks of filter processes used in making phase masks for SWI, and to propose a simple method for reducing artifacts.

Phase linearity related to echo time (TE) was evaluated for the original phase and high-pass-filtered phase using a CuSO(4)-doped water phantom. Effect of filter size of the Hanning window and background homogeneity were also evaluated in a phantom study. Use of a phase mask generated by data with differing magnitudes of TE was attempted in a human study. Shorter TE was used for making the phase mask, and the number of multiplications was increased. As short and long TEs were necessary simultaneously for phase mask and T2* contrast, a dual-echo technique was used.

Linearity of TE and phase value collapsed, and an unexpected negative phase appeared in the high-pass-filtered phase. Using a short-TE phase mask, phase-aliasing artifacts were reduced and visibility of deep veins was equivalent to that under conventional methods with an increased number of multiplications.

Use of a short-echo phase mask in SWI is useful for reducing artifacts.