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Gadolinium‐enhanced off‐resonance contrast angiography
Author(s) -
Edelman Robert R.,
Storey Pippa,
Dunkle Eugene,
Li Wei,
Carrillo Andres,
Vu Anthony,
Carroll Timothy J.
Publication year - 2007
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.21175
Subject(s) - gadolinium , contrast (vision) , nuclear magnetic resonance , angiography , magnetic resonance angiography , magnetic resonance imaging , radiology , nuclear medicine , medicine , chemistry , physics , optics , organic chemistry
We describe a novel physical basis and methodology for gadolinium (Gd)‐enhanced MRA, which we call “off‐resonance contrast angiography” (ORCA). Unlike standard contrast‐enhanced (CE) MR angiography (MRA), ORCA contrast depends not on T 1 but on Gd‐induced shifts in intravascular resonance frequency due to the bulk magnetic susceptibility (BMS) effects of Gd. The method was tested at 3 Tesla in phantoms with a range of dilutions of Gd‐DTPA and ultrasmall iron oxide contrast agent (CA). With the use of ORCA, complete background suppression was obtained without image subtraction. As a result, catheters filled with various Gd dilutions proved to be highly conspicuous in ORCA projection images. This feature may make ORCA particularly attractive for passive catheter tracking during MR‐guided endovascular procedures. Gd‐induced intravascular frequency shifts were measured in human subjects and found to be in the expected range. ORCA was used to create angiograms of forearm veins that were comparable in quality to standard CE‐MRA. In addition, ORCA images of the extracranial carotid bifurcation were successfully acquired during intravenous contrast administration. However, significant technical restrictions also exist, including a dependence on vessel orientation with respect to B 0 , and sensitivity to static field inhomogeneities. Further study is needed to determine the practicality and potential clinical utility of this method. Magn Reson Med 57:475–484, 2007. © 2007 Wiley‐Liss, Inc.