An imaging probe adapter for measuring the properties of a lumen like the vaginal canal, the rectum, or anal sphincter. The device has an adapter body with a proximal end and a distal end. The distal end of the adapter body may be formed into an insertion tip capable of easy insertion into the appropriate lumenal structure. An inflatable pressure chamber covers the distal end of the adapter body. A baseplate formed on the proximal end of the adapter body incorporates fluid channels for inflating the pressure chamber and a probe channel that receives an ultrasound probe or other suitable imaging probe. The device is used to measure and model lumenal biomechanical properties such as stiffness, compliance, elastic versus viscous contributions to overall stiffness, and total displacement.