Catheter ultrasound ablation

A method for ablating an ostium of a blood vessel of a subject that extends from a chamber of a heart of the subject, the method comprising:

• positioning an ultrasound transducer at the blood vessel ostium;
• rotating the transducer about its axis and scanning tissue of the blood vessel ostium;
• recording one or more baseline returned signals from the tissue and creating a baseline image of the blood vessel ostium based on at least one of the returned signals;
• ablating tissue of the blood vessel ostium in consecutive segments by rotating the transducer segmentally until full rotation is completed;
• recording the returned signals of the ablated segments in real-time with respect to the ablation of the ablated segments, and creating a real-time image based on the one or more returned signals;
• comparing the real-time returned signals and/or the real-time image to the baseline returned signals and/or image;
• identifying changes in the real-time returned signals and/or real-time image with respect to the baseline returned signals and/or baseline image that represent changes in the tissue that correspond to ablation lesion formation;
• and
• terminating ablation after the identified changes indicate an achieved predetermined level of ablation lesion formation.