Background: Intravascular magnetic resonance (MR) imaging to guide interventional procedures is a rapidly growing field. A primary concern with these new techniques is their thermal safety. The purpose of this study was to evaluate, in vivo, the thermal effect of an MR imaging-guidewire (MRIG) for intravascular MR imaging (IVMRI).
Material/Methods: Two indications of potentially adverse local heating were investigated: blood coagulation disorders and pathologic changes in target vessels. Experiments were performed on ten rabbits with a 1.5 T MR scanner. Using a 0.64-mm MRIG as the RF receiver, we imaged the target aorta using a fast spin-echo pulse sequence with an average specific absorption rate (SAR) of 0.6 W/kg. The total MR imaging time was approximately 70 minutes.
Results: There were no abnormal value changes of the coagulation factors between pre- and post-IVMRI, no clinical manifestations of blood coagulation disorders, and, histopathologically, no thermal damage in target vessels.
Conclusions: This study demonstrates, from a pathophysiological point of view, the potential safe use of the MR imaging-guidewire for intravascular MR imaging. Further study is required to precisely define the boundaries of these safe operating parameters.

Keywords: MR safety, intravascular MR imaging, interventional MR