Research Paper

Study of MRI Susceptibility Artifacts for Nanomedical Applications

[+] Author and Article Information
Tim Wortmann1

Department of Computing Science, Division Microrobotics and Control Engineering, University of Oldenburg–KISUM, D-26129 Oldenburg, Germanywortmann@informatik.uni-oldenburg.de

Christian Dahmen, Sergej Fatikow

Department of Computing Science, Division Microrobotics and Control Engineering, University of Oldenburg–KISUM, D-26129 Oldenburg, Germany


Corresponding author.

J. Nanotechnol. Eng. Med 1(4), 041002 (Oct 21, 2010) (5 pages) doi:10.1115/1.4002501 History: Received July 30, 2010; Revised August 26, 2010; Published October 21, 2010; Online October 21, 2010

This article deals with the exploitation of magnetic susceptibility artifacts in magnetic resonance imaging (MRI) for the recognition of metallic delivery capsules. The targeted application is a closed-loop position control of magnetic objects implemented using the components of a clinical MRI scanner. Actuation can be performed by switching the magnetic gradient fields, whereas object locations are detected by an analysis of the MRI scans. A comprehensive investigation of susceptibility artifacts with a total number of 108 experimental setups has been performed in order to study scaling laws and the impact of object properties and imaging parameters. In addition to solid metal objects, a suspension of superparamagnetic nanoparticles has been examined. All 3D scans have been segmented automatically for artifact quantification and location determination. Analysis showed a characteristic shape for all three base types of sequences, which is invariant to the magnetic object shape and material. Imaging parameters such as echo time and flip angle have a moderate impact on the artifact volume but do not modify the characteristic artifact shape. The nanoparticle agglomerates produce imaging artifacts similar to the solid samples. Based on the results, a two-stage recognition/tracking procedure is proposed.

Copyright © 2010 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.



Grahic Jump Location
Figure 1

System overview for MRI-guided drug delivery, two signal paths are shown: case 1 (upper path) is executed one time using a full 3D scan and case 2 is subsequently executed using single slice scans

Grahic Jump Location
Figure 2

Heavy distortions caused by ferrofluid embedded into a 0.5 l container of agar in gradient echo (left) and spin echo (middle), spin-echo scan of agar phantom without ferrofluid (right)

Grahic Jump Location
Figure 3

Agar-filled containers (left) and air channels in an agar container scanned with gradient-echo sequence (right)

Grahic Jump Location
Figure 4

Typical artifacts in sagittal plane for gradient echo (left), spin echo (middle), and single-shot spin echo (right) resulting from a 3 mm steel sphere (upper row) and ferrofluid (lower row); the vertical lines result from the ferrofluid sample preparation and are not an imaging artifact

Grahic Jump Location
Figure 5

Resulting segmentation zones for SSFSE sequence scan

Grahic Jump Location
Figure 6

EM segmentation results for single-shot fast spin echo (top), gradient echo (middle), and spin echo (bottom) for steel spheres; diameter: 3 mm, 2.5 mm, 2.0 mm, 1.5 mm, 1.2 mm, and 1mm (left-right)

Grahic Jump Location
Figure 7

Artifact volume comparison of all sequences used for the 2 mm steel sphere with varying echo time (TE), flip angle (FA), and voxel size in frequency encoding direction (FM)

Grahic Jump Location
Figure 8

Artifact volume comparison for different sequences; the volume is derived by a fixed threshold 3D segmentation




Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In