An apparatus is described for treating arterial occlusions combining an intraluminally operable catheter having an occlusion-crossing working element, with an extraluminally operable locator for imaging the progress of the working element through the occlusion. Suction coupling means are described for removably anchoring the locator to a surface proximate the heart. A method for treating arterial occlusions is described in which the distal end of the catheter shaft exits a lumen of the locator, penetrates the arterial wall distal to the occlusion, crosses the occlusion retrograde and passes into a separately introduced standard intravascular catheter, whereupon the distal end of the shaft may be manipulated from the proximal end of the standard catheter. The proximal end of the shaft is then released from external attachments and drawn into the artery to perform treatment or guiding functions. Spatial interrelationships are observed real-time via the locator. Conical, abrasive, blunt-dissecting, sharp-pointed and guide-wire type working elements, steerable and non-steering, are described. Acoustic transducers and a flexible imaging tube are described for the locator. A signal-emitting working element and cooperating signal-receiving locator are described.