title: Shunt flow evaluation in congenital heart disease based on two-dimensional speckle tracking.
abstract: High-frame-rate ultrasound speckle tracking was used for quantification of peak velocity in shunt flows resulting from septal defects in congenital heart disease. In a duplex acquisition scheme implemented on a research scanner, unfocused transmit beams and full parallel receive beamforming were used to achieve a frame rate of 107 frames/s for full field-of-view flow images with high accuracy, while also ensuring high-quality focused B-mode tissue imaging. The setup was evaluated in vivo for neonates with atrial and ventricular septal defects. The shunt position was automatically tracked in B-mode images and further used in blood speckle tracking to obtain calibrated shunt flow velocities throughout the cardiac cycle. Validation toward color flow imaging and pulsed wave Doppler with manual angle correction indicated that blood speckle tracking could provide accurate estimates of shunt flow velocities. The approach was less biased by clutter filtering compared with color flow imaging and was able to provide velocity estimates beyond the Nyquist range. Possible placements of sample volumes (and angle corrections) for conventional Doppler resulted in a peak shunt velocity variations of 0.49-0.56 m/s for the ventricular septal defect of patient 1 and 0.38-0.58 m/s for the atrial septal defect of patient 2. In comparison, the peak velocities found from speckle tracking were 0.77 and 0.33 m/s for patients 1 and 2, respectively. Results indicated that complex intraventricular flow velocity patterns could be quantified using high-frame-rate speckle tracking of both blood and tissue movement. This could potentially help increase diagnostic accuracy and decrease inter-observer variability when measuring peak velocity in shunt flows.
authors.affiliation: MI Lab and the Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway. Electronic address: solveig.fadnes@ntnu.no.
authors.forename: Solveig
authors.initials: S
authors.lastname: Fadnes
authors.affiliation: MI Lab and the Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway; Department of Pediatrics, St. Olav's University Hospital, Trondheim, Norway.
authors.forename: Siri Ann
authors.initials: SA
authors.lastname: Nyrnes
authors.affiliation: MI Lab and the Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Hans
authors.initials: H
authors.lastname: Torp
authors.affiliation: MI Lab and the Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Lasse
authors.initials: L
authors.lastname: Lovstakken
mesh_terms: D000465:Algorithms; D001783:Blood Flow Velocity; D003326:Coronary Circulation; D015150:Echocardiography, Doppler / Q000295:instrumentation / Q000379:methods*; D005240:Feasibility Studies; D006344:Heart Septal Defects, Atrial / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006345:Heart Septal Defects, Ventricular / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D007231:Infant, Newborn; D008297:Male; D019047:Phantoms, Imaging
keywords: 2-D blood flow imaging; Atrial septal defect; In vivo; Speckle tracking; Ventricular septal defect