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Imaging of gout – An overview

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The diverse clinical states and sites of pathology in gout provide challenges when considering the features apparent on imaging. Ideally, an imaging modality should capture all aspects of disease including monosodium urate crystal deposition, acute inflammation, tophus, tissue remodelling and complications of disease. The modalities used in gout include conventional radiography, ultrasonography, magnetic resonance imaging, computed tomography and dual-energy computed tomography. This review discusses the role of each of these imaging modalities in gout, focussing on the imaging characteristics, role in gout diagnosis and role for disease monitoring. Ultrasonography and dual-energy computed tomography are particularly promising methods for both non-invasive diagnosis and monitoring of disease. The observation that ultrasonographic appearances of monosodium urate crystal deposition can be observed in patients with hyperuricaemia but no other clinical features of gout raises important questions about disease definitions.

Section snippets

Gout: disease states

The central feature of gout is deposition of monosodium urate (MSU) crystals. These crystals form in the context of elevated urate concentrations above saturation levels (>6.8 mg dl−1 at physiological temperature and pH) [1]. MSU crystals frequently deposit within the joint, coating articular cartilage [2]. These crystals may be observed in joints of patients with asymptomatic hyperuricaemia and in clinically uninvolved joints of patients with previous gout attacks [3], [4]. However, these

Conventional radiography (CR)

The basic conventional radiography (CR) technique of passing X-rays through a body part onto a flat detector and thus generating a projectional image has not changed substantially since Roentgen discovered it in 1895. The first description of the CR appearances of gout was in the 19th century, soon after discovery of CR [7]. For almost a century, CR was the dominant method of gout imaging, and the typical CR characteristics of disease are well characterised. Recent decades have seen the

US

The increasing availability of US within the clinic makes this a useful clinical tool for both diagnosis and monitoring. This modality has the potential to assess many aspects of the disease, including MSU crystal deposition, acute inflammatory changes and synovial, bone and soft-tissue involvement. In addition to being reasonably inexpensive and widely available, US has the advantages of using harmless sound rather than ionising radiation and can be combined with clinical examination. It also

MRI

MRI allows assessment of many aspects of gout, with excellent visualisation of involved bone, synovium, cartilage and periarticular soft-tissue structures. It does not involve harmful radiation and can use several methods of generating contrast between different tissues, making it a very powerful imaging technique. However, it is both expensive and of relatively limited availability.

Conventional CT

With the current availability of fast multidetector scanners, there has been a resurgence of interest in CT over the last decade. Modern scanners are capable of generating high-resolution sets of images of a body region such as the feet or hands within seconds. Although ionising radiation is involved, the extremities are less at risk from radiation exposure than regions such as the neck, abdomen and pelvis, making CT a useful technique in imaging gout.

DECT

Dual-source, DECT uses a specific display algorithm that assigns different colours to materials of different chemical composition (such as urate and calcium) and has been well validated as a non-invasive method to determine the chemical composition of kidney stones [51]. This method determines the composition of different tissues by analysing the difference in attenuation in a material exposed to two different X-ray spectra (80 and 140 kVp) simultaneously [52].

Imaging of gout: future directions

It is apparent that many different imaging modalities are in use for assessment of gout. These modalities have provided important insights into the mechanisms of disease in gout, and have great potential to allow non-invasive diagnosis and monitoring of gout. Despite the major advances in gout imaging in the last decade, many questions remain about the place of imaging in general, and also about the role of specific modalities in the assessment of this disease. These questions form the basis of

Summary

Imaging may assist in the assessment of many aspects of disease in gout. Many different imaging modalities have been used for gout. The choice of method depends on many factors, including availability and cost, the stage of disease and most importantly, the clinical question. US and DECT show particular promise in the assessment of gout, both for diagnosis and monitoring. These methods offer the possibility of a new understanding of definitions and mechanisms of disease.

Acknowledgements

Nicola Dalbeth is supported by the Health Research Council of New Zealand.

References (61)

  • E. Pascual

    Persistence of monosodium urate crystals and low-grade inflammation in the synovial fluid of patients with untreated gout

    Arthritis and Rheumatism

    (1991)
  • N. Dalbeth et al.

    Cellular characterization of the gouty tophus: a quantitative analysis

    Arthritis and Rheumatism

    (2010)
  • N. Dalbeth et al.

    Mechanisms of bone erosion in gout: a quantitative analysis using plain radiography and computed tomography

    Annals of the Rheumatic Diseases

    (2009)
  • N. Huber

    Zur Verwertung der Röntgenstrahlen im Gebiete der inneren Medizin

    Deutsche Med Wochnschr

    (1896)
  • M. Körner et al.

    Advances in digital radiography: physical principles and system overview

    Radiographics

    (2007)
  • D. Resnick et al.

    Intraosseous calcifications in tophaceous gout

    AJR American Journal of Roentgenology

    (1981)
  • D.A. Nakayama et al.

    Tophaceous gout: a clinical and radiographic assessment

    Arthritis and Rheumatism

    (1984)
  • N. Dalbeth et al.

    Characterisation of new bone formation in gout: a quantitative site-by-site analysis using plain radiography and computed tomography

    Arthritis Research and Therapy

    (2012)
  • C.R. Barthelemy et al.

    Gouty arthritis: a prospective radiographic evaluation of sixty patients

    Skeletal Radiology

    (1984)
  • S.L. Wallace et al.

    Preliminary criteria for the classification of the acute arthritis of primary gout

    Arthritis and Rheumatism

    (1977)
  • T. Rettenbacher et al.

    Diagnostic imaging of gout: comparison of high-resolution US versus conventional X-ray

    European Radiology

    (2008)
  • V. Devauchelle-Pensec et al.

    Performance of hand radiographs in predicting the diagnosis in patients with early arthritis

    Journal of Rheumatology

    (2006)
  • N. Dalbeth et al.

    Validation of a radiographic damage index in chronic gout

    Arthritis and Rheumatism

    (2007)
  • N. Dalbeth et al.

    Clarification of the modified radiographic damage scoring method for gout

    Journal of Rheumatology

    (2012)
  • D. Perry et al.

    Detection of erosions in the rheumatoid hand; a comparative study of multidetector computerized tomography versus magnetic resonance scanning

    Journal of Rheumatology

    (2005)
  • N. Dalbeth et al.

    Tophaceous joint disease strongly predicts hand function in patients with gout

    Rheumatology (Oxford)

    (2007)
  • N. Dalbeth et al.

    Enhanced osteoclastogenesis in patients with tophaceous gout: urate crystals promote osteoclast development through interactions with stromal cells

    Arthritis and Rheumatism

    (2008)
  • G.M. McCarthy et al.

    Influence of antihyperuricemic therapy on the clinical and radiographic progression of gout

    Arthritis and Rheumatism

    (1991)
  • J.D. Carter et al.

    An analysis of MRI and ultrasound imaging in patients with gout who have normal plain radiographs

    Rheumatology (Oxford)

    (2009)
  • S.A. Wright et al.

    High-resolution ultrasonography of the first metatarsal phalangeal joint in gout: a controlled study

    Annals of the Rheumatic Diseases

    (2007)

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