Thermal effect of intravascular MR imaging using an MR imaging-guidewire: an in vivo laboratory and histopathological evaluation.
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).


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.
Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287-0845, USA. xyang@mri.jhu.edu
Xiaoming
X
Yang
Christopher J
CJ
Yeung
Hongxiu
H
Ji
Jean-Michel
JM
Serfaty
Ergin
E
Atalar
D000818:Animals; D001012:Aorta, Abdominal / Q000473:pathology*; D001778:Blood Coagulation Disorders / Q000378:metabolism / Q000473:pathology; D006358:Hot Temperature / Q000009:adverse effects; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000009:adverse effects / Q000379:methods; D011817:Rabbits; D011846:Radio Waves / Q000009:adverse effects; D025321:Surgery, Computer-Assisted / Q000379:methods*