A vessel occlusion apparatus includes an elongate shaft having a fluid delivery lumen and an expandable member carried on a distal end portion of the shaft, the expandable member comprising a body defining an interior region, the interior region in communication with the fluid delivery lumen, the body comprising a wall having one or more embedded fluid pockets therein, each of the one or more pockets containing a fluid capable of being imaged, e.g., having echogenic qualities for detection using ultrasound imaging.
