DIAGNOSTIC ACCURACY OF CT HOUNSFIELD UNIT FOR DETECTION OF CALCIUM STONES IN PATIENTS WITH RENAL STONE DISEASE

*Dr. Mudassar Saeed Pansota (MS Urology), Dr. Fariha Mumtaz (FCPS Radiology), Dr. Mubasher Saeed Pansota, Dr. Muhammad Burhan Barkar (MS Urology), Dr. Muhammad Shahzad Saleem (FCPS)., Dr. Mumtaz Rasool (FCPS).

ABSTRACT

Introduction: Different radiological investigations are used to evaluate renal stones and among all, non-contrast-enhanced computer tomography (CT) provides the highest level of diagnostic accuracy with low radiation exposure for urinary stones. Hounsfield unit is linear transformation of original linear attenuation coefficient measurement into one in which the radio-density of distilled water at standard pressure and temperature is defined as zero Hounsfield unit. Materials & Methods: A total of 201 patients of both genders (Male and Female) with age 15-60 years presenting with renal stones of any size undergoing percutaneous nephrolithotomy were included. Pregnant females, claustrophobia, young age and morbid obese were excluded. Non-contrast Computerized Tomographic scan (CT scan) was performed. Using GE-128 Slice and Hounsfield Unit was determined. Patient were undergone percutaneous nephrolithotomy and extracted stone was subjected to chemical analysis. Results: In CT positive cases, 95 were true positive and 08 were false positive. While in CT negative patients, 91 were true negative and 07 were false negative. Overall sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of CT Hounsfield unit for detection of calcium stones in patients with renal stone disease taking stone chemical composition as gold standard is 93.14%, 91.92%, 92.23%, 92.86% and 92.54% respectively. Conclusion: This study concluded that the diagnostic accuracy of CT Hounsfield unit for detection of calcium stones in patients with renal stone disease is very high.

Keywords: Urolithiasis, calcium oxalate, computed tomography.