Advanced imaging in gout

Imaging in Gout and Other Crystal-Related Arthropathies

In this article, the authors consider the manifestations of intraarticular and periarticular crystal deposits. Most cases of crystal deposits are asymptomatic and represent incidental findings at imaging. In symptomatic arthropathies, imaging can play an important role in the diagnosis and assessment of disease progression and the extent of crystal deposits. Conventional radiography is the most common imaging modality. But ultrasound, conventional computerized tomography (CT), dual-energy CT, and MRI play an increasing role. The authors review typical radiographic features of crystal-induced arthropathies and findings that help to differentiate them. The authors also emphasize the increasing role of complementary imaging techniques.

Cross-sectional imaging of adult crystal and inflammatory arthropathies

This article highlights the key aspects and current perspectives of the role of cross-sectional imaging in adult crystal and inflammatory arthropathies in adults, briefly discussing CT, and particularly focusing on MRI and US imaging as it supplements the conventional radiography. The role of conventional and advanced MR imaging techniques and imaging findings in this domain is discussed and illustrated with case examples. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. This article contains images and data, which were collected from patients as a part of a retrospective IRB from the institutional teaching files and informed consent was waived.

Dual-Energy Computed Tomography Demonstrating Destructive Calcium Pyrophosphate Deposition Disease of the Distal Radioulnar Joint Mimicking Tophaceous Gout

Calcium pyrophosphate dihydrate deposition (CPPD) disease is a common etiology of crystalline arthropathy; however, it can manifest in multiple patterns such as acute calcium pyrophosphate (CPP) crystal arthritis, osteoarthritis with CPPD, and chronic CPP crystal inflammatory arthritis. Tumoral or tophaceous-like CPPD is a rare manifestation that is occasionally mistaken for gouty tophus or a soft tissue malignancy. Dual-energy computed tomography (DECT) is a new imaging modality currently utilized in assessing monosodium urate crystal deposition; however, its value in CPPD is uncertain. We describe a case using DECT to diagnose tumoral CPPD mimicking tophaceous gout versus recurrence of a previous synovial sarcoma. The imaging findings on DECT prevented unnecessary surgery to assess for possible malignancy, allowing for the prompt diagnosis of tumoral CPPD. Further studies should be performed to determine the role of DECT in assessing for crystalline deposition disease other than gout.

Comparison Between Dual-Energy Computed Tomography and Ultrasound in the Diagnosis of Gout of Various Joints

RATIONALE AND OBJECTIVES

Dual-energy computed tomography (DECT) and ultrasound are both used to assess gouty arthritis. The present study was designed to compare the diagnostic accuracy of DECT and ultrasound in detecting monosodium urate (MSU) crystal deposition in various joints.

MATERIALS AND METHODS

This study enrolled 40 patients diagnosed with acute gouty arthritis. All affected and contralateral joints were scanned (128 in total) using both DECT and ultrasound to determine the MSU deposition in upper limbs (wrist and elbow) and lower limbs (the first metatarsophalangeal joints, ankles, and knee). The MSU crystal accumulation detected by each method was compared for various joints.

RESULTS

The 128 scanned joints included 52 of the upper limbs and 76 of the lower limbs. For the upper limbs, the percentage of MSU crystal accumulation detected by DECT (22/52, 42.3%) was significantly higher than that by ultrasound (10/52, 19.2%; P = .0027). The detection rates of the two methods for the lower limbs were similar (P = .3173).

CONCLUSIONS

For detection of MSU crystal deposition in the upper limb joints, DECT was superior to ultrasound, whereas there was no difference between the two methods for the lower limbs. Therefore, ultrasound can be used for primary screening, and DECT afterward. Although the modalities are similar in making the initial diagnosis, DECT is far superior at displaying the anatomic extent of the disease.

Imaging modalities for the classification of gout: systematic literature review and meta-analysis

BACKGROUND

Although there has been major progress in gout imaging, no gout classification criteria currently include advanced imaging techniques.

OBJECTIVE

To examine the usefulness of imaging modalities in the classification of gout when compared to monosodium urate (MSU) crystal confirmation as the gold standard, in order to inform development of new gout classification criteria.

METHODS

We systematically reviewed the published literature concerning the diagnostic performance of plain film radiography, MRI, ultrasound (US), conventional CT and dual energy CT (DECT). Only studies with MSU crystal confirmation as the gold standard were included. When more than one study examined the same imaging feature, the data were pooled and summary test characteristics were calculated.

RESULTS

11 studies (9 manuscripts and 2 meeting abstracts) satisfied the inclusion criteria. All were set in secondary care, with mean gout disease duration of at least 7 years. Three features were examined in more than one study: the double contour sign (DCS) on US, tophus on US, and MSU crystal deposition on DECT. The pooled (95% CI) sensitivity and specificity of US DCS were 0.83 (0.72 to 0.91) and 0.76 (0.68 to 0.83), respectively; of US tophus, were 0.65 (0.34 to 0.87) and 0.80 (0.38 to 0.96), respectively; and of DECT, were 0.87 (0.79 to 0.93) and 0.84 (0.75 to 0.90), respectively.

CONCLUSIONS

US and DECT show promise for gout classification but the few studies to date have mostly been in patients with longstanding, established disease. The contribution of imaging over clinical features for gout classification criteria requires further examination.

Use of ultrasound for diagnosis and monitoring of outcomes in crystal arthropathies

PURPOSE OF REVIEW

In the latest recommendations for the diagnosis and management of gout and calcium pyrophosphate dihydrate (CPPD) crystal deposition disease, the diagnostic potential of ultrasound has been recognized. This review highlights the recent advances of research on ultrasound in gout and CPPD crystal deposition disease.

RECENT FINDINGS

Ultrasound allows highly sensitive, noninvasive and quick detection of microcrystal aggregates in multiple anatomic areas. Ultrasound can be used as a safe and reliable guide to aspirate even minimal fluid collections suitable for microscopic analysis, and as a tool for monitoring monosodium urate crystal dissolution induced by urate-lowering therapy. The first metatarsophalangeal joint and the knee should be regarded as the anatomic regions with the highest probability of being respectively positive for monosodium urate and CPPD crystal aggregates.

SUMMARY

The detection of highly evocative signs in patients with equivocal clinical findings may have a deep impact on the clinical decision-making process, narrowing the differential diagnostic spectrum and avoiding time-consuming and expensive diagnostic procedures. Ultrasound differential diagnosis between gout and CPPD crystal deposition disease is based on the characteristics of crystal aggregates and their preferential localization in different anatomical areas.

Tophus resolution with pegloticase: a prospective dual-energy CT study

Objective

To investigate the effect of intensive lowering of serum uric acid (SUA) levels by pegloticase on the resolution of tophi in patients with refractory gout.

Methods

Descriptive study in patients with refractory gout receiving pegloticase treatment. SUA levels were measured before and after each infusion. Dual-energy CT (DECT) scans were taken from all patients before the first infusion and after the last infusion. Computerised tophus volumes were calculated for the baseline and follow-up assessments and compared with each other.

Results

10 patients with refractory gout and baseline mean SUA level of 8.1 mg/dL were enrolled. Patients were treated for a mean of 13.3 weeks. Pegloticase effectively reduced tophi in all patients showing a decrease in volume by 71.4%. Responders, showing reduction of SUA level below 6 mg/dL during at least 80% of the treatment time, were virtually cleared from tophi (−94.8%). Dependent on their anatomical localisation, resolution of tophi showed different dynamics, with articular tophi showing fast, and tendon tophi slow, resolution.

Conclusions

Tophi are highly sensitive to pegloticase treatment, particularly when located at articular sites. Debulking of disease and a tophus-free state can be reached within a few months of pegloticase treatment. DECT allows for comprehensively assessing tophus burden and monitoring treatment responses.

The radiographic and MRI features of gout referred as suspected soft tissue sarcoma: a review of the literature and findings from 27 cases

Gout has been termed the "great mimicker", for its ability to resemble other pathological conditions. Whilst the typical imaging features of gout are well described, there is a relative paucity of literature describing more challenging cases of gout, where a malignant tumour has been considered in the differential diagnosis. The aim of this article is to provide an overview of the radiographic and MRI features of 27 cases of gout that were initially referred to our centre as suspected soft tissue sarcoma, alongside a review of the literature.

Pitfalls in wrist and hand ultrasound

OBJECTIVE

The purpose of this article is to review a number of diagnostic pitfalls related to ultrasound evaluation of the hand and wrist. Such pitfalls relate to evaluation of ten-dons (extensor retinaculum, multiple tendon fascicles, tendon subluxation), inflammatory arthritis (incomplete evaluation, misinterpretation of erosions, failure to evaluate for enthesitis), carpal tunnel syndrome (inaccurate measurements, postoperative assessment), ulnar collateral ligament of the thumb (misinterpretation of the adductor aponeurosis and displaced tear), wrist ganglion cysts (incomplete evaluation and misdiagnosis), and muscle variants.

CONCLUSION

Although ultrasound has been shown to be an effective imaging method for assessment of many pathologic conditions of the wrist, knowledge of potential pitfalls is essential to avoid misdiagnosis and achieve high diagnostic accuracy.

Spondylodiscitis and Achilles tendonitis due to gout

The patient, a 62-year-old man with a 3-year history of hyperuricemia, presented with severe neck pain, Achilles enthesopathy and polyarthralgia. He consumed alcohol heavily. The biochemical profile was normal except for elevated levels of CRP (3.6 mg/dl; normal < 0.3), uric acid (UA) (10.9 mg/dl; normal 2.5-7.5) and creatinine (1.7 mg/dl; normal 0.5-1.0). Bone scintigraphy showed polyarthritis at the right elbow, wrist and bilateral first MTP joints. Notably, bone scintigraphy with computed tomography also revealed spondylodiscitis of C5-C6, which was confirmed by MRI, and left Achilles tendonitis. Moreover, left Achilles tendonitis was also confirmed by ultrasonography, indicating enthesitis with low-echoic lesion and calcification. Needle aspiration yielded a white viscous liquid, with numerous urate crystals identified on polarized light microscopy. He was diagnosed with gouty arthritis associated with spondylodiscitis and Achilles tendonitis. After the treatment with allopurinol, colchicine and predonisolone, his symptoms were improved, and serum CRP and UA levels were normalized. The cervical spine and Achilles tendon are rare and notable sites of involvements in gout, and differential diagnosis of gouty arthritis from spondyloarthritis, rheumatoid arthritis, tumor, pseudogout, and infection is necessary. When the patient was noted to have neck pain and Achilles enthesopathy, we should always recognize gouty arthritis.