Figure 1. Gray-scale coronal US images (upper right and left and lower left images) of four retroperitoneally implanted VX2 tumors clearly show the outer borders (arrows) of the tumors. Necrotic areas (N) are seen in a larger tumor. Contrast-enhanced harmonic power Doppler US image (lower right image) obtained before ablation shows central (arrowhead) and peripheral (arrows) vascularity. Inset diagrams show plane and direction of view of each image.