Abstract: Apparatus (220/20) and methods are described including a transluminal ablation catheter (40) that includes at least one ultrasound transducer (50/52/150). The at least one ultrasound transducer is inserted into a chamber (190) of a subject's heart and is configured (a) to ablate tissue of the subject by applying ultrasound energy to the tissue, and (b) to image tissue of the subject by applying non-ablating ultrasound energy to the tissue. An expandable cage (30/301) is disposed around the at least one ultrasound transducer. The at least one ultrasound transducer is configured to rotate and axially translate back and forth within the expandable cage, such as to generate a three-dimensional image of the tissue. Other applications are also described.