Procedures such as Radiofrequency Ablation (RFA) and Transjugular Intrahepatic Portosystemic Shunt (TIPS) placement are minimally invasive image-guided alternatives to surgical procedures.
4D ultrasound (US) has great potential for these interventions,
as it provides real-time 3D imaging.
respiratory liver motion hampers adequate visualization of the target region.
Therefore we propose a method to compensate breathing motion using real-time 3D US registration.
Additionally the approach would help in keeping the registration up to date in US fusion imaging.
Methods and materials
Our registration method consists of four basic steps: a) Point Selection,
c) Outliers Rejection,
and d) Computation of a rigid transformation using the inliers.
The block-matching uses a similarity metric to establish point correspondences between volumes.
The outlier rejection uses geometric consistency to remove erroneous matchings from the block-matching.
The rigid transformation is computed using singular value decomposition method.
Thirteen 4D US volume sequences were acquired from six healthy volunteers at 6 Hz from an iU22 Philips machine.
From the 4D US sequences,
seven pairs of frames were selected in a systematic way such that they are representative of the whole breathing cycle.
Reference standard (ground truth) registration was established using the standard Elastix registration toolkit .
The Elastix toolbox is intensity based medical image registration application.
The Elastix results were visually inspected,
and as a result 6 pairs of images of the 91...
We proposed and evaluated 3D US to US registration approach for motion compensation of liver.
A mean error of 1.3 mm is achieved for 85 non-consecutive pairs of 3D ultrasound volumes acquired from 4D ultrasound sequences.
Additionally we demonstrate that,
a GPU implementation of our registration approach can be used in real-time.
Jyotirmoy Banerjee is working in Erasmus MC as a PhD Student in the STW-funded project (OTP 10482): of "4D ultrasound for improved image guidance in minimally invasive needle interventions: the interventional cockpit".
His works aims at replacing classical surgical interventions by minimally invasive alternatives and help improve patient care.
elastix: A toolbox for intensity-based medical image registration.