International Urology and Nephrology

, Volume 50, Issue 10, pp 1779–1785 | Cite as

Small-angle X-ray scattering (SAXS) and nitrogen porosimetry (NP): two novel techniques for the evaluation of urinary stone hardness

  • Nick Vordos
  • Stilianos GiannakopoulosEmail author
  • Etienne F. Vansant
  • Christos Kalaitzis
  • John W. Nolan
  • Dimitrios V. Bandekas
  • Ioannis Karavasilis
  • Athanasios Ch. Mitropoulos
  • Stavros Touloupidis
Urology - Original Paper



To evaluate urinary stones using small-angle X-ray scattering (SAXS) and nitrogen porosimetry (NP). Traditionally, stones are categorized as hard or soft based on their chemical composition. We hypothesized that stone hardness is associated not only with its chemical composition but also with its internal architecture. SAXS and NP are well-known techniques in material sciences. We tested whether SAXS and NP are applicable for evaluating human urinary stones and whether they provide information at the nanoscale level that could be useful in clinical practice.


Thirty endoscopically removed urinary stones were studied. Standard techniques for stone analysis were used to determine the stone composition. SAXS was used to evaluate the solid part of the stone by measuring the crystal thickness (T) and the fractal dimension (Dm/Ds), while NP was used to evaluate the porosity of the stone, i.e., the pore radius, pore volume, and specific surface area (SSA).


All stones were successfully analyzed with SAXS and NP. Each stone demonstrated unique characteristics regarding T, Dm/Ds, pore radius, pore volume, and SSA. Significant differences in those parameters were seen among the stones with almost identical chemical compositions. The combination of high T, high SSA, low Dm/Ds, low pore volume, and low pore radius is indicative of a hard material and vice versa.


SAXS and NP can be used to evaluate human urinary stones. They provide information on stone hardness based on their nanostructure characteristics, which may be different even among stones with similar compositions


Stone analysis SAXS Nitrogen porosimetry Urinary calculi 



Shockwave lithotripsy


Small-angle X-ray scattering


Nitrogen porosimetry


Scanning electron microscopy


Kidney stone


Fourier-transform infrared spectroscopy


Specific surface area


Computed tomography


Hounsfield units


Author contributions

NV, SG, and ST conceived the study, participated in its design. NV, SG, JW, and EV analyzed the data. NV, SG, DB, IK, CK, and AM participated in interpretation of data, as well as in drafting the manuscript and revising it critically. All authors have read and approved the final manuscript.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no competing interests.

Ethical approval

The study was approved by the institutional review board of the University Hospital of Alexandroupolis, Greece.

Supplementary material

11255_2018_1961_MOESM1_ESM.docx (187 kb)
Supplementary material 1 (DOCX 63 KB)


  1. 1.
    Dretler SP (1988) Stone fragility—a new therapeutic distinction. J Urol 139:1124–1127CrossRefPubMedGoogle Scholar
  2. 2.
    Bhatta KM, Prien EL Jr, Dretler SP (1989) Cystine calculi—rough and smooth: a new clinical distinction. J Urol 142:937–940CrossRefPubMedGoogle Scholar
  3. 3.
    Williams JC Jr, Saw KC, Paterson RF et al (2003) Variability of renal stone fragility in shock wave lithotripsy. Urology 61:1092–1097CrossRefPubMedGoogle Scholar
  4. 4.
    Li T, Senesi AJ, Lee B (2016) Small angle X-ray scattering for nanoparticle research. Chem Rev 116:11128–11180CrossRefPubMedGoogle Scholar
  5. 5.
    Barrett EP, Joyner LG, Halenda PP (1951) The determination of pore volume and area distributions in porous substances. I. computations from nitrogen isotherms. J Am Chem Soc 73:373–380CrossRefGoogle Scholar
  6. 6.
    Fratzl P, Groschner M, Vogl G et al (1992) Mineral crystals in calcified tissues: a comparative study by SAXS. J Bone Miner Res 7:329–334CrossRefPubMedGoogle Scholar
  7. 7.
    Zhang R, Gong H, Zhu D et al (2015) Multi-level femoral morphology and mechanical properties of rats of different ages. Bone 76:76–87CrossRefPubMedGoogle Scholar
  8. 8.
    Jimenez-Palomar I, Shipov A, Shahar R et al (2015) Mechanical behavior of osteoporotic bone at sub-lamellar length scales. Front Mater 2:1–9CrossRefGoogle Scholar
  9. 9.
    Babic M, Peter K, Igor B et al (2014) Prediction of the hardness of hardened specimens with a neural network. Mater Technol 48:409–414Google Scholar
  10. 10.
    Taniguchi N, Taniguchi S, Fujibayashi S et al (2016) Effect of pore size on bone ingrowth into porous titanium implants fabricated by additive manufacturing: an in vivo experiment. Mat Sci Eng C 5:690–701CrossRefGoogle Scholar
  11. 11.
    Chen B, Penwell D, Benedetti LR et al (2002) Particle-size effect on the compressibility of nanocrystalline alumina. Phy Rev B 66(14):144101CrossRefGoogle Scholar
  12. 12.
    Yoshinari T (2003) The improved compaction properties of mannitol after a moisture-induced polymorphic transition. Int J Pharm 258:121–131CrossRefPubMedGoogle Scholar
  13. 13.
    Vordos N, Giannakopoulos S, Gkika DA et al (2017) Kidney stone nano-structure—is there an opportunity for nanomedicine development? BBA 1861:1521–1529Google Scholar
  14. 14.
    Evan AP, Willis LR, Lingeman JE et al (1998) Renal trauma and the risk of long-term complications in shock wave lithotripsy. Nephron 78:1–8CrossRefPubMedGoogle Scholar
  15. 15.
    Motley G, Dalrymple N, Keesling C et al (2001) Hounsfield unit density in the determination of urinary stone composition. Urology 58:170–173CrossRefPubMedGoogle Scholar
  16. 16.
    Kawahara T, Miyamoto H, Ito H et al (2016) Predicting the mineral composition of ureteral stone using non-contrast computed tomography. Urolithiasis 44:231–239CrossRefPubMedGoogle Scholar
  17. 17.
    Christiansen FE, Andreassen KH, Osther SS et al (2016) Internal structure of kidney calculi as a predictor for shockwave lithotripsy success. J Endourol 30:323–326CrossRefPubMedGoogle Scholar
  18. 18.
    Luo SN, Swadener JG, Ma C et al (2007) Examining crystallographic orientation dependence of hardness of silica stishovite. Phys B 399:138–142CrossRefGoogle Scholar

Copyright information

© Springer Nature B.V. 2018

Authors and Affiliations

  • Nick Vordos
    • 1
    • 4
  • Stilianos Giannakopoulos
    • 2
    Email author
  • Etienne F. Vansant
    • 1
    • 3
  • Christos Kalaitzis
    • 2
  • John W. Nolan
    • 1
  • Dimitrios V. Bandekas
    • 4
  • Ioannis Karavasilis
    • 2
  • Athanasios Ch. Mitropoulos
    • 1
  • Stavros Touloupidis
    • 2
  1. 1.Hephaestus Advanced LaboratoryEastern Macedonia and Thrace Institute of TechnologyKavalaGreece
  2. 2.Department of UrologyDemocritus University of ThraceAlexandroupolisGreece
  3. 3.Laboratory of Adsorption and Catalysis, Department of ChemistryUniversity of AntwerpenWilrijkBelgium
  4. 4.Department of Electrical EngineeringEastern Macedonia and Thrace Institute of TechnologyKavalaGreece

Personalised recommendations