Multi-resolution parallel integral projection for fast localization of a straight electrode in 3D ultrasound images

We address the problem of fast and accurate localization of miniature surgical instruments like needles or electrodes using 3D ultrasound (US). An algorithm based on maximizing a parallel integral transform (PIP) can automatically localize line-shaped objects in 3D US images with accuracy on the order of hundreds of micrometers. Here we propose to use a multi-resolution to accelerate the algorithm significantly. We use a maximum function for downsampling to preserve the high intensity voxels of a thin electrode. We integrate the multi-resolution pyramid into a hierarchical mesh-grid search of PIP. The experiments with a tissue mimicking phantom and breast biopsy data show that proposed method works well on real US images. The speed-up is threefold compared to original PIP method with the same accuracy 0.4 mm. A further speed-up up to 16 times is reached by an early stopping of the optimization, at the expense of some loss of accuracy.