A medical catheter has an inflatable balloon assembly on its distal portionand a plurality of ablation electrodes disposed on the surface of the balloonassembly. Conductors extending through the shaft supply the ablationelectrodeswith electrical power when connected to a power source. A plurality ofthermistorson the balloon assembly are connected to the conductors to form a resistivenetwork, and a plurality of access points on the conductors are provided forobtaining electrical measurements and analyzing the measurements to determinerespective resistances of the thermistors.
