ROLE OF MULTI-DETECTOR COMPUTED TOMOGRAPHY INDICES IN PREDICTING EXTRACORPOREAL SHOCKWAVE LITHOTRIPSY OUTCOME IN PATIENTS WITH NEPHROLITHIASIS

Abstract

BACKGROUND: Nephrolithiasis is a common renal pathology in which calculi are formed within the kidneys. Non-contrast Computed Tomography is gold standard imaging investigation to diagnose nephrolithiasis. We evaluated nephrolithiasis on Multidetector Computed Tomography to prognosticate the outcome of Extracorporeal Shockwave Lithotripsy. AIMS & OBJECTIVES: To perform NCCT-KUB (non-contrast Computed Tomography of Kidneys, Ureter & Bladder) and evaluate following indices: Hounsfield unit, Hounsfield density, calculus size, location and skin-stone distance. To derive cut-off values for the above indices in predicting successful extracorporeal shockwave lithotripsy results. MATERIALS & METHODS: In this prospective cross-sectional study, we analyzed 45 patients suffering from nephrolithiasis and referred to R.L. Jalappa Hospital & Research Centre, attached to Sri Devaraj Urs Medical College, Kolar, Karnataka for CT-KUB (kidneys, ureter, bladder). The duration of the study is 18 months. RESULTS: Hounsfield units of 1179 and below had sensitivity of 97.62% and specificity of 100% with a total diagnostic accuracy of 97.78%. Hence, a mean HU value of ≤1179 has a favorable ESWL outcome (p<0.05). Based on location of calculus, there was 100% clearance (n=14) in renal pelvis while 1 failure case was observed each in upper, inter and lower pole; therefore, renal pelvis has better ESWL outcomes as compared to other locations. XV Out of 3 cases having failed ESWL, the calculus size was <13.30 mm for 1 (33.33%) and >=13.30 mm for 2 (66.67%) participants. Skin-stone distance was >=7.55 cm for 1 (33.33%) and <7.55 cm for 2 (66.67%) cases in the failure group. Out of 3 cases with failed ESWL, the Hounsfield density was <89.65 for 1 (33.33%) and >=89.65 for 2 (66.67%) cases. Hounsfield density, calculus size and skin-stone distance did not demonstrate statistical significance to prognosticate ESWL outcome (p>0.05), hence cut-off values could not be derived for these parameters. CONCLUSION: MDCT (multidetector Computed Tomography) evaluation of nephrolithiasis can predict the ESWL success and can help in selection of patients with good prognosis