PROBLEM TO BE SOLVED: To measure the tissue thickness.SOLUTION: Wall thickness of a cavity is determined by inserting a catheter into contact with a wall of a cavity in the body of a subject. A distal segment of the catheter is provided with a contact force sensor and an ultrasound transducer. The transducer is actuated to acquire ultrasound reflection data from the wall of the cavity and, while the transducer is actuated, the catheter is reciprocated against the wall of the cavity and the contact force is measured between the catheter and the wall of the cavity. The reflection data is correlated with the contact force. A set of the correlated reflection data having the highest correlation with the contact force is identified. The tissue thickness between the inner surface and the identified set of the reflection data is calculated according to the time-of-flight therebetween.SELECTED DRAWING: Figure 1
