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4D FLOW MRI AND LUMPED-PARAMETER MODELING TO ASSESS OF AORTIC VALVE HEMODYNAMICS
2206 JACC April 5, 2016 Volume 67, Issue 13
Valvular Heart Disease 4D FLOW MRI AND LUMPED-PARAMETER MODELING TO ASSESS OF AORTIC VALVE HEMODYNAMICS Poster Contributions Poster Area, South Hall A1 Saturday, April 02, 2016, 3:45 p.m.-4:30 p.m. Session Title: Novel Quantitative Imaging Techniques for Valvular Heart Disease Abstract Category: 40. Valvular Heart Disease: Clinical Presentation Number: 1134-039 Authors: Julio Garcia Flores, Alex Barker, Michael Markl, James Thomas, Northwestern University, Chicago, IL, USA
Background: Three-dimensional, time-resolved phase contrast MRI (4D flow) can be used to assess aortic valve hemodynamics (i.e. effective orifice area [EOA] and peak velocity [PV]). Lumped-parameter modeling (LPM) may help to confirm valve findings by imaging. Thus this study aims to investigate the value of LPM to assess aortic valve hemodynamics using MRI inputs.
Methods: 66 subjects (age=56±15 yrs, 17 females, 29 bicuspid valve) underwent aortic 4D flow MRI. Stroke volume (SV) was measured at the LV outflow tract, PV was obtained at peak systole, and EOA was calculated using the jet shear-layer detection. LPM inputs were set to normal and used to generate PV reference values for EOA (0.5 - 3 cm2). MRI measured EOA was used as input to the LPM, so the modelestimated SV (SVe) approximated SV. Model-estimated PV (PVe) was compared to PV by linear regression and Bland-Altman, as well as categorical grading among normal (4 m/s), mild (2-2.9 m/s), moderate (3-3.9 m/s) and severe (>4 m/s). Results: SVe and PVe obtained from the LPM matched values measured by 4D flow MRI (Fig. 1): SVe = 82±16 mL vs. SV= 84±19 mL (p=0.42); r=0.94 (p<0.001), dSV = -2±13 mL; PVe= 2.2±0.6 m/s vs. PV=2.1±0.7 m/s (p=0.56), r=0.77 (p<0.001), dPV = 0.07±0.89 m/s. Valve severity grading by measured PV and PVe led to normal (29 vs. 34), mild (28 vs. 23), moderate (8 vs. 9), and severe (1 vs. 0), for a total of n=28 (42%) cases with inconsistent grading. Conclusions: LPM may be useful to unmask inconsistencies in aortic valve hemodynamics.
Valvular Heart Disease 4D FLOW MRI AND LUMPED-PARAMETER MODELING TO ASSESS OF AORTIC VALVE HEMODYNAMICS Poster Contributions Poster Area, South Hall A1 Saturday, April 02, 2016, 3:45 p.m.-4:30 p.m. Session Title: Novel Quantitative Imaging Techniques for Valvular Heart Disease Abstract Category: 40. Valvular Heart Disease: Clinical Presentation Number: 1134-039 Authors: Julio Garcia Flores, Alex Barker, Michael Markl, James Thomas, Northwestern University, Chicago, IL, USA
Background: Three-dimensional, time-resolved phase contrast MRI (4D flow) can be used to assess aortic valve hemodynamics (i.e. effective orifice area [EOA] and peak velocity [PV]). Lumped-parameter modeling (LPM) may help to confirm valve findings by imaging. Thus this study aims to investigate the value of LPM to assess aortic valve hemodynamics using MRI inputs.
Methods: 66 subjects (age=56±15 yrs, 17 females, 29 bicuspid valve) underwent aortic 4D flow MRI. Stroke volume (SV) was measured at the LV outflow tract, PV was obtained at peak systole, and EOA was calculated using the jet shear-layer detection. LPM inputs were set to normal and used to generate PV reference values for EOA (0.5 - 3 cm2). MRI measured EOA was used as input to the LPM, so the modelestimated SV (SVe) approximated SV. Model-estimated PV (PVe) was compared to PV by linear regression and Bland-Altman, as well as categorical grading among normal (4 m/s), mild (2-2.9 m/s), moderate (3-3.9 m/s) and severe (>4 m/s). Results: SVe and PVe obtained from the LPM matched values measured by 4D flow MRI (Fig. 1): SVe = 82±16 mL vs. SV= 84±19 mL (p=0.42); r=0.94 (p<0.001), dSV = -2±13 mL; PVe= 2.2±0.6 m/s vs. PV=2.1±0.7 m/s (p=0.56), r=0.77 (p<0.001), dPV = 0.07±0.89 m/s. Valve severity grading by measured PV and PVe led to normal (29 vs. 34), mild (28 vs. 23), moderate (8 vs. 9), and severe (1 vs. 0), for a total of n=28 (42%) cases with inconsistent grading. Conclusions: LPM may be useful to unmask inconsistencies in aortic valve hemodynamics.