Unenhanced CT findings can predict the development of urinary calculi in stone-free patients.

OBJECTIVES: To determine if calcium deposits in the papillae can be identified by unenhanced computed tomography (uCT) even before renal stones develop. METHODS: A retrospective review of 413 patients with calculi identified 31 patients (stone-forming group) with a history of urinary tract calculi with a calculus demonstrated by uCT and a stone-free uCT before calculi had developed. The control group (n = 31) was composed of live kidney donors with no history of calculi and a stone-free uCT. CT attenuation was measured in all CTs using two regions of interest of 0.05 cm(2) and 0.1 cm(2) over the tip and the neighbouring area of the papillae. Student's and Wilcoxon t-tests were used for comparing results in the two groups. RESULTS: The attenuation of the tip of the papilla was higher in the stone-forming group when compared to the controls after (45.2 HU versus 32.1 HU, P = 0.001) and even before frank calculi had developed (44.2 HU versus 32.1 HU, P = 0.003). There was no significant difference in papillary attenuation in the stone group before and after calculi had developed (45.2 HU versus 44.2 HU, P = 0.82). CONCLUSION: Stone-forming patients exhibit higher papillary density even before calculi develop. This could define a population at risk of developing calculi.

Calcium oxalate kidney stones, where is the organic matter?: A synchrotron based infrared microspectroscopy study.

Kidney stones are collections of microcrystals formed inside the kidneys, which affect 6% to 12% of the population worldwide, with an increasing recurrence (50%-72%) after the first episode. The most abundant type is calcium oxalate (66%), described as monohydrated (COM) and dihydrated (COD). An issue in their chemistry is the transformation process of the metastable specie (COD) into the stable one, which is chemically, and in appearance, monohydrated. Since the origin of these species is different, it is important to differentiate between the transformation stage (and what stabilize COD) to understand the physiopathology and prevent the patients' recurrence. This work focuses on the organic matter distribution along these nephroliths by synchrotron radiation-based infrared microspectroscopy. Differences in the asymmetric stretching of the aliphatic hydrocarbons suggest that lipids may participate in the stabilization of COD and as inhibitors of COM formation/development; however, the presence of proteins in the nucleus could indicate a promoting role.

[Diagnosis and radiological follow up of urinary lithiasis.] / Diagnóstico y seguimiento radiológico de la litiasis.

Urolithiasis is a common disease with increasing prevalence worldwide and a lifetimeestimated recurrence risk of over 50%. Imaging techniques play a critical role in the initial diagnosis, follow-up and urological management of urinary tract stone disease. The are many useful tools for diagnosing urolithiasis, including conventional plain radiography, intravenous urography, ultrasonography, computed tomography and magnetic resonance imaging. All these techniques have their own individual roles to play and also their limitations. Radiological management will depend on the tools available at the center and on the characteristics of the patient. Non-contrast enhanced CT scan has high sensitivity and specificity, although concerns about radiation exposure and costs remain. It is essential to use computed tomography techniques that minimize radiation and to use alternatives like ultrasonography, or magnetic resonance imaging in pregnant patients and children. There is no evidence to support strong recommendations regarding the frequency and type of imaging for follow-up of patients with urolithiasis (treated or under observation). The objective of this article is to review the imaging pathway for comprehensive stone management.

Validation of Randall's plaque theory using unenhanced abdominal computed tomography.

OBJECTIVE: To determine whether nephrolithiasis is associated with radiographic changes in renal papillae. MATERIALS AND METHODS: We performed a prospective study comparing papillae attenuation in a stone-forming group (SFG) and a healthy stone-free control group (CG). The SFG inclusion criteria were active stone disease diagnosed by abdominal computed tomography and stone analysis showing calcium composition. For the CG, we included living kidney donors without stone disease. Papillae tip attenuation was measured using nonenhanced computed tomography scans in Hounsfield units (HUs) for an area with a mean size of 0.1 cm(2). The mean density of the 3 caliceal groups was calculated for each kidney. Student's t test was used for statistical analysis, and the receiver operating characteristic curve was used to determine a threshold separating the CG and SFG. RESULTS: A total of 134 SFG and 134 CG patients met the inclusion criteria. The SFG and CG had similar demographic characteristics. Unilateral lithiasis was encountered in 92 patients (68.6%). The mean HU density of the papillae of the affected side in the SFG was significantly greater than in the CG (43.9 HU vs 33.9 HU, P = .001). No significant difference was seen between the affected and unaffected side in the SFG (43.9 HU vs 42.9 HU, P = .56). The receiver operating characteristic analysis showed an area under the curve of 0.91, with an optimal threshold at 40 HU and a specificity of 92% and a sensitivity of 91%. CONCLUSION: The density of the renal papilla significantly increased in the SFG in both the affected and the nonaffected kidneys compared with the CG. These findings suggest the presence of calcium deposits in the papillae, validating Randall's theory.

Diagnóstico y seguimiento radiológico de la litiasis / Diagnosis and radiological follow up of urinary lithiasis

La urolitiasis es una patología frecuente con un aumento de prevalencia a nivel mundial y con un riesgo de recurrencia a lo largo de la vida de aproximadamente 50%. Las técnicas de imagen tienen un papel muy importante en el diagnóstico inicial, seguimiento y manejo urológico de la enfermedad litiásica. Se incluyen diferentes técnicas para el diagnóstico de la urolitiasis como son: radiografía simple de abdomen, urografía endovenosa, ecografía, tomografía computerizada (TC) y resonancia magnética. Todas ellas tienen su indicación y limitaciones. El uso de una u otra dependerá de la disponibilidad y de las características del paciente. La TC tiene elevada sensibilidad y especificidad, sin embargo, hay que tener en cuenta la exposición a la radiación y el coste. Es esencial utilizar TC baja dosis u otras técnicas alternativas como ecografía (o resonancia magnética) en embarazadas y niños. Además, no hay recomendaciones claras en el tipo y frecuencia de técnica de imagen indicada en el seguimiento de los pacientes litiásicos. El objetivo de este artículo es revisar las diferentes técnicas de imagen actuales, estándares y tendencias en la evaluación de la urolitiasis

Urolithiasis is a common disease with increasing prevalence worldwide and a lifetimeestimated recurrence risk of over 50%. Imaging techniques play a critical role in the initial diagnosis, follow-up and urological management of urinary tract stone disease. The are many useful tools for diagnosing urolithiasis, including conventional plain radiography, intravenous urography, ultrasonography, computed tomography and magnetic resonance imaging. All these techniques have their own individual roles to play and also their limitations. Radiological management will depend on the tools available at the center and on the characteristics of the patient. Non-contrast enhanced CT scan has high sensitivity and specificity, although concerns about radiation exposure and costs remain. It is essential to use computed tomography techniques that minimize radiation and to use alternatives like ultrasonography, or magnetic resonance imaging in pregnant patients and children. There is no evidence to support strong recommendations regarding the frequency and type of imaging for follow-up of patients with urolithiasis (treated or under observation). The objective of this article is to review the imaging pathway for comprehensive stone management