Role of Multidetector Non-Contrast CT Scan in Estimation of Attenuation Value of Urinary Calculi and Predicting the Outcome of ESWL

Abstract

Introduction: Urolithiasis is a common disease with an increasing incidence worldwide. Non- contrast computed tomography (NCCT) is the gold standard imaging modality for the patients presenting with acute renal colic. Extracorporeal shock wave lithotripsy (ESWL) has emerged as the treatment of choice for urolithiasis. The attenuation value in Hounsfield units evaluated by NCCT is reported to be a strong predictive factor for the successful outcome of ESWL.

Aim: To determine the attenuation value of urinary calculi by NCCT and to correlate it with the outcome of ESWL.

Materials & Method: This study is a prospective analytical study of 75 patients with urolithiasis who have undergone NCCT and ESWL at Ramaiah Medical college and hospitals, Bengaluru, Karnataka. The study period was from November 2013 to June 2015.

Results: The successful outcome post ESWL in different groups of attenuation value are 100% in group 1(<500HU), 92.6% in group 2(500-1000HU) and 33.3% in group 3(>1000HU). The failure rate was 7.3% in group 1 and 66.6% in group 3.   The calculus density above 1000 HU decreases the rate of successful outcome post ESWL.

Conclusion: The attenuation value (HU) of the urinary calculi estimated by NCCT predicts the ESWL outcome thus identifying patients suitable to undergo ESWL.