Automatic lesions segmentation in ultrasound nonlinear imaging

Doppler has been used for many years for cardiovascular exploration in order to visualize the vessels walls and anatomical or functional diseases. The use of ultrasound contrast agents makes it possible to improve ultrasonic information. Nonlinear ultrasound imaging highlights the detection of these agents within an organ and hence is a powerful technique to image perfusion of an organ in real-time. The visualization of flow and perfusion provides important information for the diagnosis of various diseases as well as for the detection of tumors. We present a new method to automatically segment hepatic tumors, during a perfusion phase, in ultrasound hepatic nonlinear imaging. It is based on a coherence enhancing diffusion process, which removes noise and raises the structural characteristics. The segmentation procedure is a fuzzy competitive agglomerative clustering which takes into account of the perfusion phenomenon. We have tested our method on clinical sequences and obtained excellent results.