Imaging in gout: A review of the recent developments

Abstract

Gout is a common inflammatory arthritis and is caused by accumulation of monosodium urate crystals in joints and soft tissues. Apart from joint damage, untreated gout is associated with cardiovascular and renal morbidity. Gout, whilst in principle considered to be well understood and simple to treat, often presents diagnostic and management challenges, with evidence to suggest that it is often inadequately treated and poor compliance is a major issue. Imaging tools can aid clinicians in establishing the correct diagnosis, when histological crystal diagnosis is unable to be established, and also assess the burden of inflammatory and structural disease. Imaging can also be used to monitor treatment response. The imaging techniques that currently have a role in the imaging of gout include conventional radiography, ultrasound, computed tomography, dual energy computed tomography, magnetic resonance imaging and nuclear medicine. Despite the lack of major technological advances in imaging of gout in recent years, scientific studies of existing imaging modalities have improved our understanding of the disease, and how to best utilize imaging techniques in the clinical setting.

Tophaceous gout with rare involvement of the patella

“…Hyperuricemia is defined as a serum urate level of approximately 6.8 mg/dL or higher, which is the upper limit of urate solubility at physiologic body temperature and pH [1], [2]. There are various causes of hyperuricemia including genetic disorders of purine metabolism, purine-rich diets, decreased renal excretion of urate secondary to chronic renal disease, and certain medications.…”

“…High levels of urate in the bloodstream lead to a high concentration of sodium urate crystals, which can deposit in cartilage, bone, and joint spaces causing an inflammatory reaction. A tophus forms from a conglomerate of urate crystals and inflammatory cells [1], [3]. Most patients have hyperuricemia for many years before developing tophi.…”

Overview of Serum Uric Acid Treatment Targets in Gout: Why Less Than 6 mg/dL?

“…Although acute flares appear episodic in nature, ongoing damage during intercritical asymptomatic periods occurs due to continuing MSU crystal deposition and inflammation [26,37,38]. This continuing damage may not be apparent in normal plain radiographs; however, the destructive arthropathy can be detected by more advanced imaging procedures, such as dual-energy computed tomography (DECT), computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound ( Figure 3) [39,40].…”

“…Inadequate or delayed treatment and the failure to reduce sUA levels <6 mg/dL can result in increased crystal deposition and development of comorbidities, which can in turn result in more severe disease that is more difficult to treat and manage [20,26,63]. Imaging studies have found a close relationship between features of structural joint damage and crystal deposition, with MSU crystals frequently observed within the areas of bone erosion [40]. This close relationship between joint damage and MSU crystal formation emphasizes the need to reduce sUA levels before structural damage occurs [26].…”

Ultrasound double contour sign and gout

“…Typical sonographic findings include hyperechoic spots, the double contour sign, a heterogeneous centre, and lesions with a snowstorm appearance. 1 Hyperechoic band with acoustic shadowing suggests hard tophi, whereas sonolucency represents soft tophi which could be aspirated. 2 Our patient improved immediately post-arthrocentesis, and celecoxib and colchicine treatment were effective.…”