Comparison of Multiecho Postprocessing Schemes for SWI with Use of Linear and Nonlinear Mask Functions

Abstract

BACKGROUND AND PURPOSE:SWI is an MR technique conventionally implemented with single-echo gradient-echo data. The purpose of this study was to compare single-echo SWI processing and 2 multiecho SWI processing schemes: postaverage, where an SWI image is created for each echo and then averaged to create a single volume; and frequency-based, where a SWI image is generated from an average frequency image. Linear and nonlinear mask functions were investigated for all 3 processing schemes.

Quantitative susceptibility mapping of the head‐and‐neck using SMURF fat‐water imaging with chemical shift and relaxation rate corrections

“…This shows that, to achieve susceptibility maps with high CNR in the cerebrum, cerebellum, brainstem, as well as in the non-brain regions of the neck, both earlier and later echoes have to be acquired and combined with an effective echo combination approach, such as inverse variance weighting. 29,62,63 A similar fat-water separation quality was expected to be achieved at 3 and 7 Tesla as both the field inhomogeneity and the chemical shift scale with field strength. In fact, while at 3 T correct fat-water separation was achieved in all cases over the entire head-and-neck (in addition to the subcutaneous region of the caudal neck area of two volunteers), at 7 T, some fat-water swaps occurred in the very inferior or caudal area of the neck for all volunteers.…”

A Comparison Study of Single-Echo Susceptibility Weighted Imaging and Combined Multi-Echo Susceptibility Weighted Imaging in Visualizing Asymmetric Medullary Veins in Stroke Patients

“…The main reason is that it is difficult to segment DMV because of low local contrasts and high noise levels of DMV in current MR technique. Venous contrast could be improved by using complex post-processing techniques, which has been reported in recent studies [ 23 , 35 ]. The small DMV may be successfully segmented by using post-processing methods, which requires further investigation.…”

Apparent transverse relaxation () on MRI as a method to differentiate treatment effect (pseudoprogression) versus progressive disease in chemoradiation for malignant glioma

“…SWIs were created using in‐house software using a frequency based approached initially described by Brainovich et al . The background phase was removed using an 11 mm Gaussian filter and a linear frequency mask with a 15 Hz cut‐off described by Quinn et al . was used to preserve the venous vasculature.…”