W presentent a new system to acquire and reconstruct 3D freehand ultrasound volumes from arbitrary 2D image acquisitions over time. Motion artifacts are significantly reduced with a novel gating approach which correlates pulse oximetry data with Doppler ultrasound. The reconstruction problem is split into a ray-based sample selection on a per-scanline basis and a backward algorithm which is based on the concept of normalized convolution. We introduce an adaptive derivation of time-domain interpolation from the correlated pulse-oximetry and Doppler signals as well as an ellipsoid kernel size for spatial interpolation based on the physical resolution of the ultrasound data. We compare pulse-oximetry to classical ECG gating and further show the suitability of our normalized pulse signal for 3D+T reconstructions. The ease of use of the setup without the need of uncomfortable triggering via ECG provides the ability to use 3D+T ultrasound in every day clinical practice.
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