Effect of Stone Hounsfield Units Measured By Multidetector Computed Tomography on The Stone Disintegration After Extra Corporeal Shock Waves Lithotripsy For Renal Stones

Abstract

Attenuation value of renal stones was measured by CT in terms of Hounsfield units. The relation between Hounsfield units and stone disintegration (measured by number of ESWL sessions) as follows. Up to 970 HU(16 patients),most stones disintegrated after 2 sessions. P value 0.002 and correlation coefficient 0.532 which means statistically significant correlation between HU and stone disintegration (no. Of ESWL sessions).As Hounsfield units increase, the number of ESWL sessions increase and consequently stone disintegration. Taking into consideration that stone free rate is related to other factors including skin to stone distance, site and size of stone. ESWL results were affected by stone site. The clearance rate of stones located in the pelvis is higher than those located in the calyces. The clearance rate for upper pole stones is faster than for stones in the lower pole. Key words: Computed Tomography- Hounsfield Units- Stone free rate- Percutaneous nephrolithotripsy Multidetector computed Tomography