Stone-tissue differentiation in urology

The disintegration of hard concrements such as stones in the urinary and bile duct can be performed very well by means of pulsed laser radiation minimally invasive via multimode optical fibers, guided through the working channel of uretheroscopes. In particular, pulsed IR lasers in the spectral range of 2 µm wavelength have recently gained acceptance, mainly flashlamp-excited holmium-YAG lasers and thulium-doped fiber lasers.

 

In a current project at the Medical Laser Center Lübeck, we are investigating whether automatic stone tissue recognition using laser-induced fluorescence is possible to increase the safety of the application and to automatically control the therapy laser. The green radiation of the target (pilot) laser is used for fluorescence excitation. First experimental and clinical results show that stone fluorescence can be achieved with low power of only 0.5 mW for almost all common types of urinary stones and that the fluorescence is 7-100 times greater than that of the bladder or ureter wall.

Own publications, peer reviewed:
1.  Lange B, Cordes J, Brinkmann R. Exploiting the Aiming Beam to Increase the Safety of Laser Lithotripsy: Experimental Evaluation of Light Reflection and Fluorescence. Las Surg Med 2019.
2.  Lange B, Jocham D, Brinkmann R, Cordes J. Stone/Tissue Differentiation for Holmium Laser Lithotripsy using Autofluorescence: Clinical proof of concept study. Las Surg Med 2017; 49(4):361-365.
3.  Lange B, Cordes J, Brinkmann R. Stone/Tissue Differentiation for Holmium Laser Lithotripsy using Autofluorescence. Las Surg Med 2015; 47(9):737-744.
4.  Lange B, Jocham D, Brinkmann R, Cordes J. Stone/Tissue Differentiation During Intracorporeal Lithotripsy Using Diffuse White Light Reflectance Spectroscopy: In Vitro and Clinical Measurements. Las Surg Med 2014; 46(8):614-619.
5.  Cordes J, Nguyen F, Lange B, Brinkmann R, Jocham D. Damage of stone baskets by endourologic lithotripters: a laboratory study of 5 lithotripters and 4 basket types. Adv Urol 2013; 2013:632790.