Method for automatic localization of MR-visible markers using morphological image processing and conventional pulse sequences: Feasibility for image-guided procedures
✍ Scribed by Harald Busse; Robert Trampel; Wilfried Gründer; Michael Moche; Thomas Kahn
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 894 KB
- Volume
- 26
- Category
- Article
- ISSN
- 1053-1807
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✦ Synopsis
Abstract
Purpose
To evaluate the feasibility and accuracy of an automated method to determine the 3D position of MR‐visible markers.
Materials and Methods
Inductively coupled RF coils were imaged in a whole‐body 1.5T scanner using the body coil and two conventional gradient echo sequences (FLASH and TrueFISP) and large imaging volumes up to (300 mm^3^). To minimize background signals, a flip angle of ≈1° was used. Morphological 2D image processing in orthogonal scan planes was used to determine the 3D positions of a configuration of three fiducial markers (FMC). The accuracies of the marker positions and of the orientation of the plane defined by the FMC were evaluated at various distances r~M~ from the isocenter.
Results
Fiducial marker detection with conventional equipment (pulse sequences, imaging coils) was very reliable and highly reproducible over a wide range of experimental conditions. For r~M~ ≤ 100 mm, the estimated maximum errors in 3D position and angular orientation were 1.7 mm and 0.33°, respectively. For r~M~ ≤ 175 mm, the respective values were 2.9 mm and 0.44°.
Conclusions
Detection and localization of MR‐visible markers by morphological image processing is feasible, simple, and very accurate. In combination with safe wireless markers, the method is found to be useful for image‐guided procedures. J. Magn. Reson. Imaging 2007;26:1087–1096. © 2007 Wiley‐Liss, Inc.