Proof of Principle In Vitro Study of a Prototype Ultrasound Technology to Size Stone Fragments During Ureteroscopy

Abstract

Purpose:

Proof-of-principle in vitro experiments evaluated a prototype ultrasound technology to size kidney stone fragments.

Materials and Methods:

Nineteen human stones were measured using manual calipers. A 10-MHz, 1/8″ (10F) ultrasound transducer probe pinged each stone on a kidney tissue phantom submerged in water using two methods. In Method 1, the instrument was aligned such that the ultrasound pulse traveled through the stone. In Method 2, the instrument was aligned partially over the stone such that the ultrasound pulse traveled through water.

Results:

For Method 1, the correlation between caliper- and ultrasound-determined stone size was r² = 0.71 (P < 0.0001). All but two stone measurements were accurate and precise to within 1 mm. For Method 2, the correlation was r² = 0.99 (P < 0.0001), and measurements were accurate and precise to within 0.25 mm.

Conclusions:

The prototype technology and either method measured stone size with good accuracy and precision. This technology may be possible to incorporate into ureteroscopy.