Gallstone fragmentation during biliary lithotripsy: effect of stone composition and structure

Area of Science:

• Biomedical Engineering
• Gastroenterology
• Materials Science

Background:

• Biliary lithotripsy is a common procedure for gallstone treatment.
• Gallstone composition varies, potentially affecting fragmentation efficiency.
• Understanding fragmentation mechanisms is crucial for optimizing lithotripsy.

Purpose of the Study:

• To investigate the correlation between gallstone composition and fragmentation patterns during in vitro lithotripsy.
• To determine if global and regional composition influence the number of shock waves required for effective gallstone pulverization.

Main Methods:

• In vitro lithotripsy performed on 36 gallstones using the Siemens Lithostar in an anthropomorphic phantom.
• Gallstone composition analyzed using Fourier-transform infrared spectroscopy (FTIR) for regional/microcomposition and scanning electron microscopy (SEM) for microstructure.
• Fragmentation ease and pattern correlated with stone composition.

Main Results:

• Gallstones with >62% cholesterol required 50% more shock waves for fragmentation compared to those with <62% cholesterol (p<0.01).
• An inverse relationship (r=-0.77) was observed between shock wave number and cholesterol content.
• Peripheral pigment rims and specific microstructures influenced fragmentation patterns and efficiency.

Conclusions:

• Gallstone cholesterol content is a key factor predicting fragmentation efficiency in biliary lithotripsy.
• Stone architecture, including regional composition and microstructure, partially explains fragmentation mechanisms.
• These findings may aid in refining patient selection and understanding gallstone fragmentation.