Implementation of a Technique Based on Hounsfield Units and Hounsfield Density to Determine Kidney Stone Composition.

Irvin Tadeo Rodríguez-Plata,Nina Méndez-Domínguez,Azalia Avila-Nava,Ana Ligia Gutiérrez-Solis,Martha Medina-Escobedo,Roberto Lugo,Mario Basulto-Martínez

doi:10.3390/tomography7040051

Irvin Tadeo Rodríguez-Plata, Nina Méndez-Domínguez + Show 5 more

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https://doi.org/10.3390/tomography7040051

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Abstract

Hounsfield units (HU) are a measure of radiodensity, related to the density of a tissue and the composition of kidney stones. Hounsfield density is what is related to the composition of kidney stones. In the standard acquisition method, these measures are arbitrary and dependent on the operator. This study describes the implementation of a technique based on the HU and Hounsfield density to predict the stone compositions of patients with nephrolithiasis. By conventional percutaneous nephrolithotomy, thirty kidney stone samples corresponding to the cortex, middle, and nucleus were obtained. The HU were obtained by CT scanning with a systematic grid. Hounsfield density was calculated as the HU value divided by the stone’s greatest diameter (HU/mm). With that method and after analyzing the samples by IR-spectroscopy, anhydrous uric acid and ammonium magnesium phosphate were identified as the compounds of kidney stones. Additionally, anhydrous uric acid, magnesium ammonium phosphate, and calcium oxalate monohydrate were identified via Hounsfield density calculation. The study identified HU ranges for stone compounds using a systematic technique that avoids bias in its analysis. In addition, this work could contribute to the timely diagnosis and development of personalized therapies for patients with this pathology.

Highlights

Nephrolithiasis is a multifactorial disease characterized by the accumulation of crystals that generate stones in the kidney [1]
The samples were analyzed by IR-spectroscopy, and the results indicated that none of the stones observed were ”pure” in their composition; they were all calculi with two or three components
The IR-spectroscopy identified the stones as calcium oxalate monohydrate, calcium oxalate dihydrate, apatite carbonate, magnesium ammonium phosphate, and anhydrous uric acid

Summary

Introduction

Nephrolithiasis is a multifactorial disease characterized by the accumulation of crystals that generate stones in the kidney [1]. Identification of stone composition has become a task for many researchers and clinicians, so that they might develop optimal approaches, administer appropriate therapies, and improve the life quality of patients. Recent studies of the Yucatan region suggest that the stone composition is 71.3% oxalates and phosphates, but a general characterization has still not been done; this information would benefit clinical practice [4]. Computerized tomography (CT) is the gold standard in the diagnosis of kidney stones; its sensitivity and specificity are high (~94% and ~97%, respectively), and small structures around 1 mm can be identified [5]. A CT scan identifies the number, shapes, locations, and attenuation coefficients of the stones [6,7]

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Discussion

Conclusion