Model-Based Correction of Velocity Measurements in Navigated 3-D Ultrasound Imaging During Neurosurgical Interventions

Abstract—In neurosurgery, information of blood flow is important
to identify and avoid damage to important vessels. Threedimensional
intraoperative ultrasound color flow imaging has
proven useful in this respect. However, due to Doppler angledependencies
and the complexity of the vascular architecture,
clinical valuable 3-D information of flow direction and velocity is
currently not available. In this work we aim to utilize navigated
ultrasound imaging to correct for angle-dependencies in 3-D
using a model-based approach. By using a navigation system to
register the position and the orientation of 2-D ultrasound images,
we can construct a 3-D model of the neurovascular tree. The
position data is used to angle correct Doppler measurements. The
information about the position is also used to estimate the flow
direction of the blood. Based on the flow direction are we able to
do aliasing correction of velocities up to 2 times the Nyquist limit.
In vitro experiments revealed a good accuracy for estimating the
true direction of flow. Angle correction velocities further resulted
in a bias of 0.19-0.42 cm/s. The method also showed promising
results in vivo, improving the visualization of the distal branches
of intracranial aneurysms and an arteriovenous malformation.
In all in vivo cases the correct flow direction was estimated.