Contrast enhancement of invasive ultrasound transducers using denoising wavelets to establish dynamic threshold and gain

Next generation in-vivo ultrasound probes will in all likelihood be multiple frequency and may be capable eventually of volume acquisition. Recent advances in gas bubble contrast agents such as Albunex now make possible capillary imaging of the heart. Although previous gas bubble contrast agents could not pass through the lungs, and only allowed for right heart imaging, with recent instability problems improved it is now possible to image the left heart which is clinically more significant [1]. At present small invasive catheter based ultrasound probes are beginning to be developed [2]. This paper presents initial discussion on the issue and examines some practical considerations to perhaps exploiting the reduction in the dynamic gain requirements of such devices as a means to enhance dynamic contrast by dynamic thesholding. Using denoising wavelets we examine the change in specular information before and after threshold change and examine the contrast advantages of such a simple technique. We conclude that it may be possible to develop a dynamic threshold and gain control for the purposes of feature extraction.