Purpose: In aortic stenosis (AS), the discrepancy between moderately accelerated flow and effective
orifice area (EOA) continues to pose a challenge. We developed a method of measuring the vena contracta
area as hemodynamic EOA using cardiac MRI focusing on AS patients with a moderately accelerated
flow to solve the problem that AS severity can currently be determined only by echocardiography.
Methods: We investigated 40 patients with a peak transvalvular velocity > 3.0 m/s on transthoracic
echocardiography (TTE). The patients were divided into highly accelerated and moderately
accelerated AS groups according to whether or not the peak transvalvular velocity was ≥ 4.0 m/s. From
the multislice 2D cine phase-contrast MRI data, the cross-sectional area of the vena contracta of the
reconstructed streamline in the Valsalva sinus was defined as MRI-EOAs. Patient symptoms and echocardiography data, including EOA (defined as TTE-EOA), were derived from the continuity equation
using TTE.
Results: All participants in the highly accelerated AS group (n = 19) showed a peak velocity ≥ 4.0 m/s in
MRI. Eleven patients in the moderately accelerated AS group (n = 21) had a TTE-EOA < 1.00 cm2
. In the
moderately accelerated AS group, MRI-EOAs demonstrated a strong correlation with TTE-EOAs (r = 0.76,
P < 0.01). Meanwhile, in the highly accelerated AS group, MRI-EOAs demonstrated positivity but a
moderate correlation with TTE-EOAs (r = 0.63, P = 0.004). MRI-EOAs were overestimated compared
to TTE-EOAs. In terms of the moderately accelerated AS group, the best cut-off value for MRI-EOAs was
< 1.23 cm2
, compatible with TTE-EOAs < 1.00 cm2
, with an excellent prediction of the New York Heart
Association classification ≥ III (sensitivity 87.5%, specificity 76.9%).
Conclusion: MRI-EOAs may be an alternative to conventional echocardiography for patients with
moderately accelerated AS, especially those with discordant echocardiographic parameters.
Keywords: aortic stenosis, cardiovascular magnetic resonance imaging, blood flow, diagnosis

Yu Hohri , Keiichi Itatani , Akiko Matsuo, Yoshiaki Komori , Takeshi Okamoto , Tomoyuki Goto , Takuma Kobayashi , Takeshi Hiramatsu , Shohei Miyazaki , Teruyasu Nishino , and Hitoshi Yaku, "Estimating the Haemodynamic Streamline Vena Contracta as the Effective Orifice Area Measured from Reconstructed Multislice Phase-contrast MR Images for Patients with Moderately Accelerated Aortic Stenosis", Estimating the Haemodynamic Streamline Vena Contracta as the Effective Orifice Area Measured from Reconstructed Multislice Phase-contrast MR Images for Patients with Moderately Accelerated Aortic Stenosis, Published Online (2021) .