Role of Computed Tomography in Differentiation of Radio-Lucent Stones from Radio-Opaque Stones in The Renal System Depending on Attenuation Measurements (Hounsfield Unit)

Abstract

Renal calculus remains to be a common problem in the hospital. It is the third most common urological problem after urinary tract infection and prostate disease
 Computed tomography (CT) has a superior sensitivity and specificity over all other modalities in
 Diagnosis of renal stones in determining the size and number of kidney stones, no matter how small it is, also it helps in the identification of Hounsfield unit (HU) and thus determines the composition of gravel.
 Aim:
 The aim of this study is to differentiate between radio-opaque from radio lucent stones depending on attenuation measurements of the Hounsfield unit (HU) and to find the cutoff value depending on the Hounsfield unit in computed tomography (CT).
 PATIENT AND METHOD:
 This was a cross-sectional study of 100 patients (65 male and 35 female) aged between 18 and 80, having kidney stones of size more than or equal (l0 mm). The study was done between September 2014 and June 2015 in Al-Emammain Al-Kadhymain Medical City, Baghdad, Iraq. In all patients, an X-ray of the Kidney, ureter, and bladder (KUB) was done after preparation, and then nou contrast Computed Tomography (CT) was performed to all patients. Two parameters were studied, which are the appearance of stone on KUB and Hounsfield unit for each stone was measured in Computed Tomography (CT).
 RESULTS:
 We classified the stones according to their appearance on KUB to Radio-Opaque stone (71 stones) and Radio-Lucent stone (29 stones).
 By statistical analysis, we found that the cut-off value of HU was 573, with a sensitivity of 97.2% and specificity of 93.1%.
 CONCLUSION
 Find the cut-off value of the Hounsfield unit (HU), which is a value in the classification of gravel according to their appearance.