7A-4 A New Method for Enhancing Dynamic Vascular Patterns of Focal Liver Lesions in Contrast Ultrasound

The differential diagnosis of focal liver lesions (FLL) frequently presents a dilemma, as FLL cannot be reliably characterized with conventional ultrasound. Recently, ultrasound contrast agents (UCA) and contrast-specific imaging methods have substantially improved the characterization of FLL. This was made possible by the known differences in dynamic vascular patterns (DVP) between healthy parenchyma and various FLL types, revealed by UCA. The purpose of this work was to develop a new method, called DVP processing, which provides a DVP-enhanced imaging mode of FLL using contrast ultrasound; this mode allows an improved differentiation of benign from malignant lesions. DVP processing consists in generating a sequence of images, where hyper-echoic and hypo- echoic pixels, compared to reference levels taken in healthy parenchyma, are coded over time in warm and cold colors, respectively. For example, a benign lesion remains hyper-echoic over time, while a malignant lesion is hyper-echoic in the arterial phase and turns into hypo-echoic in the portal phase. This method was implemented as an image-processing software program, which was the object of clinical evaluation. Sequences of 111 FLL were acquired with real-time low-MI contrast- specific ultrasound after a 2.5-mL bolus injection of SonoVuetrade, and subsequently analyzed off-fine with DVP processing. The sensitivity and specificity achieved by two clinical observers in this way were 92%, and 86%, respectively. These results reflect a significant improvement over accuracy scores achieved with contrast-enhanced ultrasound alone, having resulted in 93% and 82% in sensitivity and specificity, respectively.