A medical system, comprising an ablation catheter is disclosed. The ablation catheter includes an elongate shaft with a proximal end, a distal end and a lumen disposed between the proximal end and the distal end. The ablation catheter also includes an expandable element in fluid communication with the lumen, a first temperature sensor operable to measure a first temperature and a second temperature sensor operable to measure a second temperature. The first temperature sensor and the second temperature sensor are longitudinally separated from each other by at least a portion of the expandable element.
