Figure 4c. (a) Precontrast radial color power Doppler US image of a malignant axillary node shows central (open arrow) and peripheral (solid arrow) vessels. (b) Postcontrast radial color power Doppler US image of the same lesion as in a shows a florid increase in central (arrows) and peripheral (arrowheads) vessels. (c) Precontrast radial color power Doppler US of the corresponding breast cancer in the same patient as in a shows a solitary tiny vessel (arrow) outside of the lesion. (d) Postcontrast radial color power Doppler US image of the same lesion as in c shows a moderate increase in the number of peripheral vessels (arrows). This increase is markedly lower than the increase in peripheral vessel number in the axillary node seen in b.