Relationship between skin to stone distance on computed tomography (CT) and clearance rate after ESWL

Abstract

he aim of this work is to determine whether the distance from skin to stone, as measured by computed tomography (CT) scans, could affect the stone – free rate achieved via extracorporeal shock wave lithotripsy (ESWL) in renal stone patients. The work is a prospective study which include twenty five patients complaining from renal stones measuring between 5 to 20 mm, presented to the urology department in Ain shams university Hospitals To all the patients history were taken, BMI were measured, Full laboratory evaluation and radiological examination were done All the patient were scanned with a multidetector row helical CT scanner (HiSpeed Dual, GE medical systems, Milwaukee, USA), and the images were obtained using high quality mode at 200 mA, 120 KV and 5mm collimation reconstructed at 3mm. to measure Stone density in Hounsfield Unit (HU), stone site and stone size, SSD. All the patients were treated by extracorporeal shock wave lithotripsy (ESWL) using a siemnes modularis lithotripter. Where the stone were fragmented under fluoroscopic guidance by a single operator, during each session T Summary  120 a constant number of shocks (3000 Shocks) were delivered to a maximal power of 22-24 KV at 120 shocks/min. Then all the patients were evaluated after one to six weeks from the last ESWL session with a plain KUB film and non-enhanced spiral computed tomography to assess stone fragmentation. And the patients were classified according to ESWL result into two groups, Successful group (stone free or clinically insignificant stone fragments) and Failure group (With residual fragments more than 3mm in size). In our study, we found that, age, sex, laterality and location of stones does not have any significance in predicting the outcome of ESWL on upper urinary tract stones. While SSD as measured by non contrast spiral computed tomography (NCSCT) is a good predictor of stone disintegration by ESWL. Where it showed that SSD >11.5cm is a predictor of ESWL failure while stones with SSD <11.5cm