Focal Liver Lesion Tracking in CEUS for Characterisation Based on Dynamic Behaviour

This paper presents a methodology for tracking a hypo- or hyper-enhanced focal liver lesion (FLL) and a healthy liver region in a video sequence of a Contrast-Enhanced Ultrasound (CEUS) examination. The outcome allows the differentiation between benign and malignant cases, by characterising FLLs of typical behaviour, according to their Time-Intensity curves. The task is challenging mainly due to intensity changes caused by contrast agents. Initially the ultrasound mask is automatically localised and then the FLL and parenchyma regions are tracked, assuming affine transformations on the image plane, employing the point-based registration technique of Lowe’s scale-invariant feature transform (SIFT) keypoints detector. Finally, a quantitative evaluation of the tracking process provides a confidence measure for the characterisation decision.