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Comparison of ultrasound attenuation by calcium pyrophosphate, hydroxyapatite and monosodium urate crystals: a proof-of-concept study
  1. Georgios Filippou1,
  2. Giovanni Pacini2,
  3. Silvia Sirotti1,3,
  4. Matthias Zadory4,
  5. Davide Carboni2,
  6. Arianna Damiani2,
  7. Elisa Fiorentini2,
  8. Edoardo Cipolletta5,
  9. Emilio Filippucci5,
  10. Johannes M Froehlich4,
  11. Piercarlo Sarzi Puttini1,3,
  12. Fabio Becce6
  1. 1Rheumatology Unit, Luigi Sacco University Hospital, Milano, Italy
  2. 2Department of Experimental and Clinical Medicine & Division of Rheumatology, Azienda Ospedaliero Universitaria Careggi, Florence, Italy
  3. 3Department of Clinical Sciences and Community Health, Università degli Studi di Milano, Milan, Italy
  4. 4Kluslab Research, Zurich, Switzerland
  5. 5Rheumatology Unit - Department of Clinical and Molecular Sciences, Polytechnic University of Marche, Jesi, Italy
  6. 6Radiology, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
  1. Correspondence to Dr Georgios Filippou, Rheumatology Unit, Luigi Sacco University Hospital, Milano 20157, Lombardia, Italy; gf.filippou{at}gmail.com

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Over the past decade, ultrasound (US) has been extensively used for the diagnosis of crystal arthropathies, in particular gout and calcium pyrophosphate deposition disease.1 2 US has proven to be accurate and reliable for the diagnosis of these diseases, and validated definitions for monosodium urate (MSU) and calcium pyrophosphate (CPP) crystal deposition in and around joints have been released by the Outcome Measures in Rheumatology US working group.3–5 On the other hand, although routinely used in the diagnosis and management of calcific tendinitis/periarthritis, the precise role of US in hydroxyapatite (HA) deposition disease, in particular its validation and reliability assessment, remains to be determined.

The propensity to attenuate the US beam and generate acoustic shadowing are important US imaging features in distinguishing between the different types of crystal deposition. Generally, HA crystals are considered to generate acoustic shadowing, while MSU crystals tend to do the same depending mainly on the concentration and size of aggregates. In contrast, CPP crystals typically do not attenuate the US beam.3–5 Therefore, this proof-of-concept study aimed to investigate the US attenuation characteristics of increasing concentrations of CPP, HA and MSU crystals.

Sixteen synthetic crystal suspensions with known concentrations of CPP (26–109 mg/mL), HA (31–153 mg/mL) and MSU (90–500 mg/mL) were prepared. These specific concentrations were selected to replicate the X-ray attenuation characteristics of those crystals when imaged by conventional radiography, CT and dual-energy CT …

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Footnotes

  • GF and GP are joint first authors.

  • Handling editor Josef S Smolen

  • GF and GP contributed equally.

  • Contributors GF and GP contributed equally to this work and share first authorship: Substantial contributions to the conception and design; of the work, acquisition, analysis and interpretation of data for the work; AND. Drafting the work and revising it critically for important intellectual content; AND. Final approval of the version to be published; AND. Agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. FB: Substantial contributions to the conception and design; of the work, acquisition, analysis and interpretation of data for the work; AND. Drafting the work and revising it critically for important intellectual content; AND. Final approval of the version to be published; AND. Agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. Other authors: Substantial contributions to the design of the work and interpretation of data for the work; AND. Revising it critically for important intellectual content; AND. Final approval of the version to be published; AND. Agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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