Figure 3: Unsuccessful use of the CrossBoss and Stingray catheter. (a) Angiography showing occlusion of the left superficial femoral artery (SFA) at its ostium (arrow). The course of the occluded vessel is outlined by areas of calcification (arrowheads). (b) Wire inside the CrossBoss catheter (arrow) crossing an occluded, calcified segment. (c) Wire advanced through the StingRay balloon catheter (arrow) trying to gain entry into the true lumen of the distal SFA. (d) Wire back into the StingRay balloon catheter with final angiography showing retrograde filling of the distal SFA and some contrast extravasation (arrowhead).