Prediction of the energy required for extracorporeal shock wave lithotripsy of certain stones composition using simple radiology and computerized axial tomography

Abstract

ObjectiveTo demonstrate that urinary lithiasis have a specific susceptibility to fracture through extracorporeal shock wave lithotripsy (ESWL), which is common for all calculi with the same composition and which can be estimated before treatment using CT or plain X-ray. Material and methodWe present an in vitro, prospective, randomized, blind and multi-center study involving 308urinary calculi. 193 of these met the inclusion criteria: whole calculi composed purely of calcium oxalate monohydrate (COM), uric acid (UA) or carbonate apatite (CA), or a mix of oxalate (COMix) and of a size greater than 0.5cm. The samples were broken using lithotripsy until reaching a pre-established level of comminution. The variables employed were energy dose (Edose) per cm3 of lithiasis and Edose adjusted to lithiasic surface (EdAJ) per cm3. ResultsCOM was the hardest, requiring an Edose of 119,624mJ/cm3 and an EdAJ of 36,983mJ/cm3, followed by COMix (75,501/36,983), CA (22,734/21,186) and UA (22,580/6837) (p<0.05). Gmax and Gmda were correlated with Edose (r=0.434/r=0.420) and EdAJ (r=0.599/r=0.545) (p<0.01). UH were correlated, in bone window and soft tissue window, with Edose/cm3 (r=0.478/r=0.539) y EdAJ/cm3 (r=0.745/r=0.758) (p<0.01). ConclusionsIn our in vitro research lithiasis require, due to the specific nature of their composition, a given amount of energy in order to be broken by ESWL, which is inherent to all those sharing the same composition, and can be predicted using CT or plain X-ray.