Optimization of Spiral MRI Using a Perceptual Difference Model

Donglai Huo,David L Wilson,Yuhao Jiang,Kyle A Salem

doi:10.1155/ijbi/2006/35290

Abstract

We systematically evaluated a variety of MR spiral imaging acquisition and reconstruction schemes using a computational perceptual difference model (PDM) that models the ability of humans to perceive a visual difference between a degraded “fast” MRI image with subsampling of k-space and a “gold standard” image mimicking full acquisition. Human subject experiments performed using a modified double-stimulus continuous-quality scale (DSCQS) correlated well with PDM, over a variety of images. In a smaller set of conditions, PDM scores agreed very well with human detectability measurements of image quality. Having validated the technique, PDM was used to systematically evaluate 2016 spiral image conditions (six interleave patterns, seven sampling densities, three density compensation schemes, four reconstruction methods, and four noise levels). Voronoi (VOR) with conventional regridding gave the best reconstructions. At a fixed sampling density, more interleaves gave better results. With noise present more interleaves and samples were desirable. With PDM, conditions were determined where equivalent image quality was obtained with 50% sampling in noise-free conditions. We conclude that PDM scoring provides an objective, useful tool for the assessment of fast MR image quality that can greatly aid the design of MR acquisition and signal processing strategies.

Highlights

There is significant effort to speed MR imaging with techniques such as keyhole imaging [1,2,3], wavelet imaging [4, 5], radial [6, 7] and spiral acquisitions [8,9,10], and parallel imaging [11, 12]
Human observer scoring of image quality was highly correlated with perceptual difference model (PDM) scores (R = 0.97, p < 0.001)
The evaluation of image quality in MR spiral imaging presents a unique challenge for existing methods since images are degraded by several factors and since so many different imaging techniques are possible

Summary

Introduction

There is significant effort to speed MR imaging with techniques such as keyhole imaging [1,2,3], wavelet imaging [4, 5], radial [6, 7] and spiral acquisitions [8,9,10], and parallel imaging [11, 12]. Spiral imaging is an effective and widely used fast MRI technique with a number of advantages It traverses the k-space very efficiently; it has superior flow and motion characteristics due to the fact that the trajectory starts from the k-space center, providing gradient moment compensation to all orders. The first and most commonly cited method described by Meyer et al [8] and Jackson et al [15] is often referred to as conventional regridding This method interpolates the nonuniform data to a rectilinear grid before Fourier reconstruction. Another method is matrix resampling (MXR), proposed by Oesterle et al [16]. We do not compare these latter methods in this paper

Methods

Results

Conclusion