Image from one of the slices obtained by dynamic computed tomography centered on the palpable axillary node in patient AF with right breast carcinoma. A region of interest (ROI) was manually drawn along the margins of the target node (3). ROIs 1 and 2 were positioned in the axillary artery and vein. They were chosen with a very small area, as suggested by the software designer, to avoid partial volume effects. ROI 4 was drawn in the Teres major muscle for control.