Age / Sex : 47 / M

Gouty arthritis with multiple tophi

Discussion

Findings:

1.    
Simple
radiograph

A 4.6x2.3cm calcified soft tissue mass at right lateral malleolar area
without bone change

A 3x1.9cm soft tissue mass at left big toe with erosive changes at
proximal phalanx

2.    
Axial CT
& Dual energy CT

multiple calcified soft tissue masses (tophi) at both ankles & feet,
especially right lateral malleolar, left anterolateral talus, left MTP joint of
the big toe, and right dorsolateral aspect of the foot. Above soft tissue masse
are well demonstrate as green colors on 3D CT scans.

Differential Diagnosis:

RA (Rheumatoid
arthritis)

CPPD (calcium
pyrophosphate deposition disease)

Diagnosis:
 

Gouty arthritis with
multiple tophi, ankles & feet, both

Discussion:

 If there are unusual symptoms or sites, discordant serum urate level,
or mimics of gout, dual-energy computed tomography (DECT) may be used to
differentiate urate crys­tals from calcium by using specific attenuation
characteristics, which may help diagnose gout.

Because
dual-energy CT may directly depict urate crystal deposition, it is specifically
used to evaluate for gout regardless of patients’ serum urate levels. Thus,
dual-energy CT findings may easily con­firm a diagnosis of gout in patients
with normal serum urate levels or exclude it in patients with hyperuricemia.

In patients with known tophaceous gout, dual-energy CT may be used for
serial volumetric quantification of subclinical tophi to evaluate response to
treatment.

Also, it may
depict subclinical urate crystal deposition at other asymptomatic sites that
have been included in the imaging field, which helps establish a diagnosis of
gout and enables initia­tion of treatment before irreversible joint dam­age
occurs.

References: