Visualisierung von Instrumenten in der interventionellen Kernspintomographie

The term interventional MRI (magnetic resonance imaging) identifies a methodology where MR imaging is used to guide therapeutic procedures. A basic prerequisite for such interventions is the visualization of the applied instruments (i.e. catheters and needles) in the acquired MR images. This dissertation presents a completely new concept for visualizing instruments incorporating properties of other known methods and enhancing these for example by offering the visualization of the entire instrument rather than only a single point of it. The method is based on the formation of local inhomogeneities of the MR scanner’s main field which are spatially bound to the instrument. These inhomogeneities are generated by a current which is lead through an electrical conductor along the instrument. First, the impact of such main field inhomogeneities on the imaging process is studied by simulations and experiments. Because of a change in proton resonance frequency and due to the finite spatial resolution in the MR images the inhomogeneities lead to geometry distortion and intra voxel dephasing. Both phenomenons can be exploited for visualizing instruments. Based on this, dedicated MR imaging sequences are developed which provide a time-optimized, simultaneous visualization of the instrument and the anatomy. Subtraction methods are presented which allow a computed extraction of the instrument’s position from the acquired MRI data. Another method uses temporal modulated inhomogeneity fields during data acquisition enabling the separation of instrument and anatomy without the need to sample extra echoes. Finally, the feasibility of the proposed concept and the developed MR imaging sequences are demonstrated in in-vivo studies, which were performed at the department of radiology of the RWTH Aachen.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2000

Author dc:creator

• Glowinski, Arndt

Contributors dc:contributor

• Noll, Tobias G.

• info:eu-repo/classification/ddc/610
• Medizin

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

ger

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-121107%22

OAI identifier oai:identifier

oai:publications.rwth-aachen.de:59310