A system for predicting lesion quality, the system comprising: a treatment device , the treatment device including at least one temperature sensor and a shaft , the shaft including an occlusion element, a central lumen and at least one opening in fluid communication with the central lumen ; and a console including: a source of cooled saline in fluid communication with the central lumen and the at least one opening , the cooled saline being injected from the treatment device ; an energy generator in electrical communication with the treatment device ; and a processor , the at least one temperature sensor being configured to send temperature data to the processor , the processor being programmed to receive temperature data recorded by the at least one temperature sensor and to calculate a rate of temperature increase in the cooled saline after injection from the treatment device over a time period of between approximately 2 seconds and approximately 15 seconds, the processor being further programmed to determine a pulmonary vein occlusion status based at least in part on the rate of temperature increase and to predict a lesion quality, the lesion quality being based at least in part on the pulmonary vein occlusion status. a treatment device , the treatment device including at least one temperature sensor and a shaft , the shaft including an occlusion element, a central lumen and at least one opening in fluid communication with the central lumen ; and a console including: a source of cooled saline in fluid communication with the central lumen and the at least one opening , the cooled saline being injected from the treatment device ; an energy generator in electrical communication with the treatment device ; and a processor , the at least one temperature sensor being configured to send temperature data to the processor , the processor being programmed to receive temperature data recorded by the at least one temperature sensor and to calculate a rate of temperature increase in the cooled saline after injection from the treatment device over a time period of between approximately 2 seconds and approximately 15 seconds, the processor being further programmed to determine a pulmonary vein occlusion status based at least in part on the rate of temperature increase and to predict a lesion quality, the lesion quality being based at least in part on the pulmonary vein occlusion status. a source of cooled saline in fluid communication with the central lumen and the at least one opening , the cooled saline being injected from the treatment device ; an energy generator in electrical communication with the treatment device ; and a processor , the at least one temperature sensor being configured to send temperature data to the processor , the processor being programmed to receive temperature data recorded by the at least one temperature sensor and to calculate a rate of temperature increase in the cooled saline after injection from the treatment device over a time period of between approximately 2 seconds and approximately 15 seconds, the processor being further programmed to determine a pulmonary vein occlusion status based at least in part on the rate of temperature increase and to predict a lesion quality, the lesion quality being based at least in part on the pulmonary vein occlusion status. <EOS>