Restoration of Whole-Body MRI for Intensity Nonuniformities with Discontinuities

Stathis Hadjidemetriou

Keywords: Whole-body MRI, intensity homogenization, cooccurrence statistics, Bayesian coring, anisotropic smoothing

TL;DR: Whole-body MRI uses multiple coils that produce images with spatially discontinuous intensity (shadows). We remove piecewise-smooth shadowing by deconvolving their effects from image statistics, back-projecting, and smoothing anisotropically.

Abstract:

MRI assumes a uniform Radio-Frequency (RF) field.
However, in Whole-Body (WB) MRI this is violated since the
smooth coils’ sensitivities differ, which results in discontinuities
of the intensity nonuniformities at the junctions between them
as well as in overall nonuniformity differences. A method is
presented for the joint intensity homogenization of two WB
anatomic images. The effect of the spatial intensity nonuniformity
on the co-occurrence statistics of the two images is modeled with
non-stationary Point Spread Functions (PSFs) and is deconvolved.
These statistics provide with Bayesian coring estimates of the
posterior Bayesian expectations of the nonuniformity fields. These
are processed with anisotropic filtering that enables piecewise
smooth restorations. The implementation is iterative. The method
has been validated with MRI datasets of forty-nine cancer
patients compared to isotropic filtering.

Submission Number: 174