Possibilities of multislice computed tomography in assessing the structural and compositional features of calcium-containing urinary stones

The aim: to study the X-ray density index (HU) in calcium-containing urinary stones with different structural and compositional features. The structural and compositional features of 118 samples of calcium-containing urinary stones, which were obtained as a result of extracorporeal shock wave lithotripsy, percutaneous nephrolithotripsy and ureteroscopic lithotripsy in patients with kidney and ureteral stones were studied. The structural features of the stones were evaluated by conducting a crystal-optical analysis, during which the linear dimensions, shape, color and degree of transparency of crystalline elements were estimated, and the volume fractions of the amorphous and crystalline phases in the sample structure were calculated. The compositional features of kidney stones were studied on the basis of a qualitative and quantitative assessment of their mineral composition by infrared spectroscopy. X-ray density of calcium-containing kidney stones was assessed based on the data of computed tomography without contrast, which was performed in all patients in the preoperative period. Structural and compositional features of calcium-containing urinary stones are characterized by the presence in their composition of calcium oxalate compounds in the form of vewellite and weddelite, as well as calcium phosphate in the form of apatite, hydroxylapatite, fluorapatite, carbonate apatite, which, depending on the stage of crystallization, can be in amorphous, amorphous-crystalline or crystalline state. The X-ray density of this type of urinary stones, according to multislice computed tomography, corresponds to the range of 1090-1785 HU. There is a direct correlation between the level of X-ray density of the stone and the volume fraction of the crystalline phase in its structure.