title: Vector Flow Imaging Compared with Conventional Doppler Ultrasound and Thermodilution for Estimation of Blood Flow in the Ascending Aorta.
abstract: Transverse oscillation (TO) is a real-time ultrasound vector flow method implemented on a commercial scanner. The TO setup was examined on a flowrig with constant and pulsatile flow. Subsequently, 25 patients undergoing cardiac bypass surgery were scanned intraoperatively with TO on the ascending aorta and compared to transesophageal echocardiography (TEE) and pulmonary artery catheter thermodilution (PACTD). On the flowrig, TO had a precision of 5.5%, 9.4% and 14.7%, a percentage error of 18.2%, 14.6% and 40.7%, and a mean bias of 0.4 cm/s, 36.8 ml/min and 32.4 ml/min for velocity and flow rate (constant and pulsatile) estimation. The correlation coefficients for all flowrig evaluations were 0.99 indicating systematic bias. After bias correction, the percentage error was reduced to 11.5%, 12.6% and 15.9% for velocity and flow rate (constant and pulsatile) estimation. In the in vivo setup, TO, TEE, and PACTD had a precision of 21.9%, 13.7%, and 12.0%. TO compared with TEE and PACTD had a mean bias of 12.6 cm/s and -0.08 l/min, and a percentage error of 23.4%, and 36.7%, respectively. The percentage error was reduced to 22.9% for the TEE comparison, but increased to 43.8% for the PACTD comparison, after correction for the systematic bias found in the flowrig. TO is a reliable and precise method for velocity and flow rate estimation on a flowrig. However, TO with the present setup, is not interchangeable with PACTD for cardiac volume flow estimation, but is a reliable and precise angle-independent ultrasound alternative for velocity estimation of cardiac flow.
authors.affiliation: 1 Department of Radiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark.
authors.forename: Kristoffer Lindskov
authors.initials: KL
authors.lastname: Hansen
authors.affiliation: 2 Department of Cardiothoracic Anesthesiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark.
authors.forename: Hasse
authors.initials: H
authors.lastname: Møller-Sørensen
authors.affiliation: 3 Department of Cardiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark.
authors.forename: Jesper
authors.initials: J
authors.lastname: Kjaergaard
authors.affiliation: 2 Department of Cardiothoracic Anesthesiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark.
authors.forename: Maiken Brit
authors.initials: MB
authors.lastname: Jensen
authors.affiliation: 4 Department of Cardiothoracic Surgery, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark.
authors.forename: Jens Teglgaard
authors.initials: JT
authors.lastname: Lund
authors.affiliation: 1 Department of Radiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark.
authors.forename: Mads Møller
authors.initials: MM
authors.lastname: Pedersen
authors.affiliation: 5 Center for Fast Ultrasound Imaging, DTU Elektro, Technical University of Denmark, Kongens Lyngby, Denmark.
authors.forename: Jacob Bjerring
authors.initials: JB
authors.lastname: Olesen
authors.affiliation: 5 Center for Fast Ultrasound Imaging, DTU Elektro, Technical University of Denmark, Kongens Lyngby, Denmark.
authors.forename: Jørgen Arendt
authors.initials: JA
authors.lastname: Jensen
authors.affiliation: 1 Department of Radiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark.
authors.forename: Michael Bachmann
authors.initials: MB
authors.lastname: Nielsen
keywords: ascending aorta; flowrig; intraoperative cardiac ultrasound; transverse oscillation; vector flow imaging