Abstract 11217: Non-contrast Enhanced Magnetic Resonance Angiography is Superior to Contrast-enhanced Magnetic Resonance Angiography for Correct Aortic Sizing Before Transcatheter Aortic Valve Replacement: A Comparison to Multislice Computed Tomography

Abstract

Background: Correct sizing of the aortic annulus and root in aortic valve stenosis is crucial for successful transcatheter implantation of aortic bioprosthesis. Until now the ultimate imaging method for correct sizing is under debate. Multislice computed tomography (MSCT) seems to be most promising, but has the disadvantage of exposing mostly co-morbid patients to iodine and nephrotoxic contrast agents. To establish a useful method for aortic root sizing without the use of contrast media, we compared measurements of a non-contrast 3D steady-state free-precession (SSFP) magnetic resonance (MRI) and a contrast-enhanced magnetic resonance angiography (MRA) with MSCT serving as the reference standard.

Methods: 19 patients who underwent transcatheter aortic valve replacement underwent previously MSCT and MRI examination, respectively. MRI examination included a 3D SSFP sequence covering the entire ascending aorta and contrast-enhanced MRA. Minimal and maximal aortic root diameters of all three imaging modalities were analyzed by two blinded readers in consensus. Decision for the valve size was based on the median of these diameters

Results: Mean age of our patients was 83.9±4.5 years. 11 (57.9%) were female. Mean aortic root diameter as measured by MSCT was 24.3±2.0 mm. MRA yielded a mean diameter of 25.8±3.3 mm with a correlation coefficient to MSCT r=0.72 (p=0.001). Mean aortic root diameter on SSFP images was 24.5±2.2 with good correlation to MSCT (r=0.94, p<0.0001). Decision for valve size showed good correlation between MSCT and MRA (ρ=0.76, p=0.0005) and better correlation between MSCT and SSFP (ρ=0.88, p<0.0001).

Conclusion: In conclusion, both MRI techniques, MRA and SSFP show good correlation to MSCT in the assessment of the aortic root and valve sizing. The SSFP MRI sequence yielded better correlation to MSCT and might offer an alternative without necessity of nephrotoxic exogenous contrast agent for the evaluation before transcatheter aortic valve replacement.