Interventional and Intravascular MR Angiography

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.

Stenosis Detection with MR Angiography and Digital Subtraction Angiography in Dysfunctional Hemodialysis Access Fistulas and Grafts

“…A clear advantage of DSA over contrast-enhanced MR angiography is the possibility of performing the corrective intervention immediately, should a hemodynamically significant stenosis be detected. Techniques for MR-guided endovascular interventions still have to be developed further to provide a clinically attractive alternative (28). The presence of vascular metallic stents, especially those made of stainless steel, may be another limitation of contrast-enhanced MR angiography, as it is well known that these objects can hamper postinterventional MR imaging (29).…”

Postangioplasty Restenosis Followed with Magnetic Resonance Imaging in an Atherosclerotic Rabbit Model

“…Percutaneous ultrasound can be applied in animal models [33], but because of the inter-observer variability it is not commonly used in animal studies. Intravascular MRI can be used for measuring and diagnosing vessel wall morphology [18, 19]. Although the modality is less operator dependent, its invasive approach limits its use.…”

Atherosclerosis Imaging Using MR Imaging: Current and Emerging Applications

“…The ability of MR imaging to generate highresolution images of the vessel wall, delineate perivascular soft tissue structures, and generate multiplanar images in real time have generated interest in MR imaging as a replacement for X-ray angiography [66]. In a recent study on swine, an intravascular MR coil/guide wire (Surgi-Vision, Gaithersburg, Maryland), introduced through the external iliac vein into the inferior vena cava generated excellent images in vivo that correlated well with histologic findings (Fig.…”