A device for measuring a spatial location of a tissue surface, such as the interface between different types of tissues or between tissue and body fluids, generally includes an elongate catheter body having a distal end portion, a plurality of localization elements carried by the distal end portion, and at least one pulse-echo acoustic element carried by the distal end portion. The localization elements allow the catheter to be localized (e.g., position and/or orientation) within a localization field, while the acoustic element allows for the detection of tissue surfaces where incoming acoustic energy will reflect towards the acoustic element. A suitable controller can determine the location of the detected tissue surface from the localization of the distal end portion of the catheter body. Tissue thicknesses can be derived from the detected locations of multiple (e.g., near and far) tissue surfaces. Maps and models of tissue thickness can also be generated.
