Hexagonal Undersampling for Faster MRI Near Metallic Implants

Abstract

Slice encoding for metal artifact correction acquires a three-dimensional image of each excited slice with view-angle tilting to reduce slice and readout direction artifacts respectively, but requires additional imaging time. The purpose of this study was to provide a technique for faster imaging around metallic implants by undersampling k-space.Assuming that areas of slice distortion are localized, hexagonal sampling can reduce imaging time by 50% compared with conventional scans. This work demonstrates this technique by comparisons of fully sampled images with undersampled images, either from simulations from fully acquired data or from data actually undersampled during acquisition, in patients and phantoms. Hexagonal sampling is also shown to be compatible with parallel imaging and partial Fourier acquisitions. Image quality was evaluated using a structural similarity (SSIM) index.Images acquired with hexagonal undersampling had no visible difference in artifact suppression from fully sampled images. The SSIM index indicated high similarity to fully sampled images in all cases.The study demonstrates the ability to reduce scan time by undersampling without compromising image quality. Magn Reson Med 73:662-668, 2015. © 2014 Wiley Periodicals, Inc.

View details for DOI 10.1002/mrm.25132

View details for Web of Science ID 000348139500023

View details for PubMedID 24549782

View details for PubMedCentralID PMC4156560