Combining Automatic Angle Correction and 3-D Tracking Doppler for Aortic Stenosis Severity Assessment

摘要

Aortic valve stenosis (AS)is a narrowing of the aortic valve opening, which causes increased load on the left ventricle. If not treated properly, this condition can eventually lead to heart failure and death. Maximum velocity estimation using continuous wave (CW)Doppler is an important index for the clinical evaluation of AS, with velocities above 4 m/s indicating a severe stenosis. In the attempt to align the aortic jet with the ultrasound beam, it is recommended to perform CW Doppler from multiple views. The procedure is cumbersome, but failing to comply can lead to substantial underestimation of AS severity. In this work we perform non-compounded 3-D plane wave imaging for retrospective estimation of maximum velocities in aortic jets. This is achieved by combining an hybrid 3-D speckle tracking method for flow direction estimation and 3-D tracking Doppler for spectral estimation, using the direction from speckle tracking as input. Results from simulations of jet flow through an orifice show that the 3-D speckle tracking can estimate the beam-to-flow angle with good accuracy for angles below 60° and 20 dB SNR. In vivo results show that maximum velocity estimates from the combination of 3-D tracking Doppler and 3-D speckle tracking can match CW Doppler with less effort from the clinician, motivating further feasibility investigation.