A method for advancing a medical instrument along a desired trajectory or path in one dimension while remaining within a particular area defined in an orthogonal dimension. For example, a method of traversing an occlusion within a body vessel using a medical instrument, the method comprising steps of positioning a target object at a first side of the occlusion, imaging the target object along an imaging plane substantially parallel to a longitudinal axis of the occlusion and advancing the medical instrument within the body vessel through an opposite side of the occlusion, thereby traversing the occlusion.
