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Interventional and intravascular MR angiography
1Zentralinstitut für Röntgendiagnostik, Universitätsklinikum Essen, Germany. mark.ladd@uni-essen.de
Abstract:
Magnetic resonance imaging (MRI) has a number of characteristics which make it attractive for guidance of intravascular therapeutic procedures, including high soft tissue contrast, imaging in any arbitrary oblique plane, lack of ionizing radiation, and the ability to provide functional information, such as flow velocity and volume per unit time. For MR guidance of vascular interventions to be safe, catheters and guidewires must be visualized relative to the vascular system and surrounding tissues. A number of approaches for making instruments visible in an MR environment are presented, including both passive and active techniques. Passive techniques depend on contrast agents or susceptibility artifacts, whereas active techniques, including MR tracking, MR profiling, and active field inhomogeneity, use some form of electrical coil built into the instrument. The potential for obtaining high-resolution images of the vessel wall using coils built into a catheter is also discussed. These images provide the capability to distinguish and identify various plaque components. The additional capabilities of MRI could potentially open up new applications beyond those currently performed under X-ray fluoroscopic guidance.
Insights
Magnetic resonance imaging (MRI) offers safe guidance for intravascular procedures by visualizing catheters and guidewires. New techniques enhance instrument visibility and enable detailed vessel wall imaging, expanding MRI applications in vascular interventions.
Area of Science:
- Medical Imaging
- Biomedical Engineering
- Interventional Radiology
Background:
- Magnetic resonance imaging (MRI) presents unique advantages for guiding intravascular procedures, including superior soft tissue contrast, multiplanar imaging capabilities, and the absence of ionizing radiation.
- Functional information, such as blood flow velocity and volume, can be acquired using MRI, enhancing its utility in vascular interventions.
- Safe guidance necessitates accurate visualization of interventional tools like catheters and guidewires within the vascular system and surrounding tissues.
Purpose of the Study:
- To review and present various techniques for visualizing interventional instruments during MRI-guided vascular procedures.
- To explore the potential of MRI for high-resolution imaging of vessel walls and plaque characterization.
- To discuss the expanded applications of MRI in vascular interventions beyond current X-ray fluoroscopy guidance.
Main Methods:
- Presentation of passive visualization techniques, including contrast agents and susceptibility artifacts.
- Description of active visualization techniques, such as MR tracking, MR profiling, and active field inhomogeneity using built-in electrical coils.
- Discussion of high-resolution imaging of the vessel wall using catheter-based coils for plaque component identification.
Main Results:
- Various passive and active methods are available for visualizing instruments in the MR environment.
- Active techniques incorporate electrical coils into instruments for enhanced MR tracking and profiling.
- Catheter-based coils show potential for high-resolution vessel wall imaging, aiding in plaque component differentiation.
Conclusions:
- MRI offers a radiation-free modality with excellent soft tissue contrast and functional imaging capabilities for vascular interventions.
- Both passive and active techniques can ensure safe visualization of instruments during MRI-guided procedures.
- Advanced MRI techniques, particularly high-resolution vessel wall imaging, promise to expand the scope of minimally invasive vascular treatments.