Evaluation of renal stone hounsfield unit (hu) value with multidetector computed tomography (32 slice thickness) and comparision with renal stone biochemistry and urinary ph

Abstract

ABSTRACT INTRODUCTION The Hounsfield unit (HU) is a unit of radio density used universally to interpret computed tomography (CT) images. Nephrolithiasis is an extremely common and very often painful urological disorder, with the lifetime risk estimated to be as high as 10–15%. Extracorporeal shock wave lithotripsy (ESWL) is the most commonly employed technique that is used in the management of renal stones; however, the success of this technique depends heavily on the chemical composition of the calculus and its fragility. Hence, the pre-treatment identification of the composition of calculi becomes extremely important. Even though there is currently insufficient data available regarding the usefulness of knowing the chemical composition pre-operatively for assessing the efficacy of percutaneous nephrolithotomy, ureterorenoscopic ureterolithotripsy and medical expulsive treatment, it might assist urologists to decide which of these treatments should be used to treat a patient. Given the lack of a standard non-invasive investigative modality to achieve this composition identification pre-operatively and given that various reports in the past that have had varying success when using CT and HU values to determine the composition of urinary calculi, the aim of our study was to determine HU values and the chemical composition of renal stones in a cohort of our patients and to then correlate HU value with urine pH and also to compare the results with stone analysis done in biochemistry lab.