Gout is an ancient disease. Last decade has brought about significant advancement in imaging technology and real scientific growth in the understanding of the pathophysiology of gout, leading to the availability of multiple effective noninvasive diagnostic imaging options for gout and treatment options fighting inflammation and controlling urate levels. Despite this, gout is still being sub-optimally treated, often by nonspecialists. Increased awareness of optimal treatment options and an increasing role of ultrasound and dual energy computed tomography (DECT) in the diagnosis and management of gout are expected to transform the management of gout and limit its morbidity. DECT gives an accurate assessment of the distribution of the deposited monosodium urate (MSU) crystals in gout and quantifies them. The presence of a combination of the ultrasound findings of an effusion, tophus, erosion and the double contour sign in conjunction with clinical presentation may be able to obviate the need for intervention and joint aspiration in a certain case population for the diagnosis of gout. The purpose of this paper is to review imaging appearances of gout and its clinical applications. 1. Introduction Gout is the most common cause of inflammatory arthritis in men [1] and its prevalence is rapidly expanding in the general population [2]. It is associated with an excess of uric acid in the body. This results in supersaturation of uric acid in body tissues and fluids resulting in urate deposition. Over 80% of the gout patients have a positive family history of gout or hyperuricemia. The disease is best understood as having four phases which include asymptomatic hyperuricemia, acute, intercritical, and chronic gout. The musculoskeletal manifestations of gout are triggered by the deposition of monosodium urate (MSU) crystals in cartilage, joints, and soft tissues. Acute gout attacks are due to the triggering of an inflammation pathway known as the NALP3 inflammasome by MSU crystals in the joint [3] and soft tissues. The diagnosis of gout is confirmed by the presence of intracellular MSU crystals in a joint aspirate [4]. MSU crystals are not radioopaque and are identified on polarized microscopy as negatively birefringent. Chronic gout can take years to develop and its findings include chronic synovitis, tophus formation, and erosions. Thus, the crystal induced tissue reaction in gout is different from other types of inflammatory arthritis where synovial inflammation is thought to be the predominant primary cause of tissue damage. An experienced clinician or a
References
[1]
Y. Zhu, B. J. Pandya, and H. K. Choi, “Prevalence of gout and hyperuricemia in the US general population: the National Health and Nutrition Examination Survey 2007-2008,” Arthritis & Rheumatism, vol. 63, no. 10, pp. 3136–3141, 2011.
[2]
P. Richette and T. Bardin, “Gout,” The Lancet, vol. 375, no. 9711, pp. 318–328, 2010.
[3]
C. A. Agudelo and H. R. Schumacher, “The synovitis of acute gouty arthritis. A light and electron microscopic study,” Human Pathology, vol. 4, no. 2, pp. 265–279, 1973.
[4]
W. Zhang, M. Doherty, T. Bardin et al., “EULAR evidence based recommendations for gout. Part II: management. Report of a task force of the EULAR Standing Committee for International Clinical Studies Including Therapeutics (ESCISIT),” Annals of the Rheumatic Diseases, vol. 65, no. 10, pp. 1312–1324, 2006.
[5]
M. P. Keith and W. R. Gilliland, “Updates in the management of Gout,” American Journal of Medicine, vol. 120, no. 3, pp. 221–224, 2007.
[6]
T. R. Mikuls, J. T. Farrar, W. B. Bilker, S. Fernandes, and K. G. Saag, “Suboptimal physician adherence to quality indicators for the management of gout and asymptomatic hyperuricaemia: results from the UK General Practice Research Database (GPRD),” Rheumatology, vol. 44, no. 8, pp. 1038–1042, 2005.
[7]
J. A. Singh, J. S. Hodges, J. P. Toscano, and S. M. Asch, “Quality of care for gout in the US needs improvement,” Arthritis Care and Research, vol. 57, no. 5, pp. 822–829, 2007.
[8]
A. Therimadasamy, Y. P. Peng, T. C. Putti, and E. P. Wilder-Smith, “Carpal tunnel syndrome caused by gouty tophus of the flexor tendons of the fingers: sonographic features,” Journal of Clinical Ultrasound, vol. 39, no. 8, pp. 463–465, 2011.
[9]
F. Perez-Ruiz, I. Martin, and B. Canteli, “Ultrasonographic measurement of tophi as an outcome measure for chronic gout,” Journal of Rheumatology, vol. 34, no. 9, pp. 1888–1893, 2007.
[10]
F. M. McQueen, A. Chhana, and N. Dalbeth, “Mechanisms of joint damage in gout: evidence from cellular and imaging studies,” Nature Reviews Rheumatology, vol. 8, pp. 173–181, 2012.
[11]
N. Dalbeth, B. Pool, G. D. Gamble et al., “Cellular characterization of the gouty tophus: a quantitative analysis,” Arthritis and Rheumatism, vol. 62, no. 5, pp. 1549–1556, 2010.
[12]
F. M. McQueen, A. Doyle, and N. Dalbeth, “Imaging in gout—what can we learn from MRI, CT, DECT and US?” Arthritis Research & Therapy, vol. 13, p. 246, 2011.
[13]
S. Ottaviani, T. Bardin, and P. Richette, “Usefulness of ultrasonography for gout,” Joint Bone Spine, vol. 79, no. 5, pp. 441–445, 2012.
[14]
R. G. Thiele and N. Schlesinger, “Diagnosis of gout by ultrasound,” Rheumatology, vol. 46, no. 7, pp. 1116–1121, 2007.
[15]
E. Filippucci, M. Gutierrez Riveros, D. Georgescu, F. Salaffi, and W. Grassi, “Hyaline cartilage involvement in patients with gout and calcium pyrophosphate deposition disease. An ultrasound study,” Osteoarthritis and Cartilage, vol. 17, no. 2, pp. 178–181, 2009.
[16]
R. G. Howard, M. H. Pillinger, S. Gyftopoulos, R. G. Thiele, C. J. Swearingen, and J. Samuels, “Reproducibility of musculoskeletal ultrasound for determining monosodium urate deposition: concordance between readers,” Arthritis Care & Research, vol. 63, no. 10, pp. 1456–1462, 2011.
[17]
C. Pineda, L. M. Amezcua-Guerra, C. Solano et al., “Joint and tendon subclinical involvement suggestive of gouty arthritis in asymptomatic hyperuricemia: an ultrasound controlled study,” Arthritis Research and Therapy, vol. 13, no. 1, p. R4, 2011.
[18]
R. G. Thiele, “Role of ultrasound and other advanced imaging in the diagnosis and management of gout,” Current Rheumatology Reports, vol. 13, no. 2, pp. 146–153, 2011.
[19]
S. A. Wright, E. Filippucci, C. McVeigh et al., “High-resolution ultrasonography of the first metatarsal phalangeal joint in gout: a controlled study,” Annals of the Rheumatic Diseases, vol. 66, no. 7, pp. 859–864, 2007.
[20]
E. de Avila Fernandes, E. S. Kubota, G. B. Sandim, S. A. V. Mitraud, A. J. L. Ferrari, and A. R. C. Fernandes, “Ultrasound features of tophi in chronic tophaceous gout,” Skeletal Radiology, vol. 40, no. 3, pp. 309–315, 2011.
[21]
W. Grassi, G. Meenagh, E. Pascual, and E. Filippucci, “‘Crystal Clear’-sonographic assessment of Gout and calcium pyrophosphate deposition disease,” Seminars in Arthritis and Rheumatism, vol. 36, no. 3, pp. 197–202, 2006.
[22]
T. Rettenbacher, S. Ennemoser, H. Weirich et al., “Diagnostic imaging of gout: comparison of high-resolution US versus conventional X-ray,” European Radiology, vol. 18, no. 3, pp. 621–630, 2008.
[23]
J. D. Carter, R. P. Kedar, S. R. Anderson et al., “An analysis of MRI and ultrasound imaging in patients with gout who have normal plain radiographs,” Rheumatology, vol. 48, no. 11, pp. 1442–1446, 2009.
[24]
N. Dalbeth, B. Clark, K. Gregory et al., “Mechanisms of bone erosion in gout: a quantitative analysis using plain radiography and computed tomography,” Annals of the Rheumatic Diseases, vol. 68, no. 8, pp. 1290–1295, 2009.
[25]
M. Karcaaltincaba and A. Aktas, “Dual-energy CT revisited with multidetector CT: review of principles and clinical applications,” Diagnostic and Interventional Radiology, vol. 17, no. 3, pp. 181–194, 2011.
[26]
H. K. Choi, A. M. Al-Arfaj, A. Eftekhari et al., “Dual energy computed tomography in tophaceous gout,” Annals of the Rheumatic Diseases, vol. 68, no. 10, pp. 1609–1612, 2009.
[27]
J. C. Gerster, M. Landry, L. Dufresne, and J. Y. Meuwly, “Imaging of tophaceous gout: computed tomography provides specific images compared with magnetic resonance imaging and ultrasonography,” Annals of the Rheumatic Diseases, vol. 61, no. 1, pp. 52–54, 2002.
[28]
D. G. Palmer, N. Hogg, I. Denholm, C. A. Allen, J. Highton, and P. A. Hessian, “Comparison of phenotype expression by mononuclear phagocytes within subcutaneous gouty tophi and rheumatoid nodules,” Rheumatology International, vol. 7, no. 5, pp. 187–193, 1987.
[29]
A. So and N. Busso, “Update on gout 2012,” Joint Bone Spine, vol. 79, no. 6, pp. 539–543, 2012.
