The invention relates to a catheter-based acoustic radiation force impulse system. A probe, includes an ablation element which is configured to perform ablation of tissue. The probe also includes an ultrasonic transducer, located in proximity to the ablation element, which is configured to transmit acoustic radiation force impulses (ARFIs) to the tissue, and to measure a displacement of the tissue in response to the ARFIs so as to monitor the ablation of the tissue.