Shear rate estimation using a clinical ultrasound scanner.
Wall shear stress is a factor in the development of atherogenesis, thrombus formation, and embolization, but its existence is very difficult to determine with ultrasonography. Instead, we estimated shear rates using a clinical ultrasound scanner and compared results from vessels with and without stenoses. Velocity profiles were obtained from color M-mode images on a P700 scanner. Maximum shear rates were calculated off-line as the maximum velocity gradients. In vitro, studies were performed on a flow phantom with a vessel containing a 50% stenosis. Shear rates within the stenosis were significantly higher than those obtained outside the stenosis (P < 0.00001) and varied more than the peak velocities. In vivo, the internal carotid artery of 10 volunteers and 13 patients (with stenoses) was studied. The mean shear rate was 414 s(-1) +/- 154.5 s(-1) in normal vessels and 687 s(-1) +/- 263.5 s(-1) in stenotic vessels (P = 0.00017). In conclusion, shear rate estimates can be obtained with a clinical ultrasound scanner from color M-mode images. Shear rates estimated in vessels with stenoses are significantly higher than those obtained in normal vessels in vitro as well as in vivo.
Forsberg
F
F
Department of Radiology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
Morvay
Z
Z
Rawool
N M
NM
Deane
C R
CR
Needleman
L
L
D001783:Blood Flow Velocity; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging*; D016893:Carotid Stenosis / Q000000981:diagnostic imaging / Q000503:physiopathology*; D005240:Feasibility Studies; D006801:Humans; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D018615:Ultrasonography, Doppler, Color