Combining non-contrast and dual-energy CT improves diagnosis of early gout

The comprehensive role of dual-energy CT in gout as an advanced diagnostic innovation

Gout is a common and growing health concern globally, marked by the deposition of monosodium urate (MSU) crystals in joints and soft tissues. While diagnosis relies on synovial fluid analysis, it is limited by technical difficulties and a notable rate of false negatives. Over the past decade, dual-energy computed tomography (DECT) has emerged as a highly sensitive and less-invasive modality for detecting MSU crystals. DECT offers several advantages, including the ability to visualize both intra- and extra-articular MSU deposits and to monitor crystal burden over time. It also aids in treatment planning by accurately assessing the therapeutic response. However, sensitivity of DECT can be lower in early-stage gout, and artifacts can occasionally result in false positives. Recent studies have highlighted new values of using DECT, such as predicting future flares in gout patients. In this review, we focus on the comprehensive clinical utility of DECT and its potential pitfalls in the diagnosis and management of gout.

Diagnostic Impact of Subcutaneous Edema in Gouty Feet Detected by Dual-Energy Computed Tomography and Ultrasound

Background: The objective of our study was to evaluate the association and frequency of subcutaneous lymphedema in patients with gout primarily affecting the feet. Methods: In 79 patients with acute gout, ultrasound (US) and dual-energy computed tomography (DECT) were performed to assess the presence of subcutaneous edema and extra- and intra-articular gouty deposits. In addition, the diagnostic utility of two post-processing DECT protocols were evaluated, comprising different minimum attenuation thresholds of 150 HU (DECT 150 protocol) and 120 HU (DECT 120 protocol), with the same maximum attenuation threshold (500 HU) and constant kilovoltage setting of tubes A and B at 80 and 140 kVp. Results: Subcutaneous lymphedema was present in 58.2% of patients, with a significant association with extra-articular monosodium urate (MSU) deposits (p < 0.001). Specifically, 97.8% of patients with lymphedema had extra-articular MSU deposits in DECT or US examination, while no cases of lymphedema were found in patients with exclusively intra-articular deposits. The DECT 120 protocol was significantly more sensitive for detecting peripheral MSU deposits (81%) compared to the DECT 150 protocol (34.2%, p < 0.001). Conclusions: Our findings demonstrate that the presence of lymphedema in patients with gout is frequently associated with extra-articular manifestations of the disease.

Dual-energy computed tomography-based radiomics for differentiating patients with and without gout flares

BACKGROUND

There is a current lack of data pertaining to the potential link between gout flares and dual-energy computed tomography radiomic features. This study aimed to construct and validate a comprehensive dual-energy computed tomography-based radiomics model for differentiating patients with and without gout flares.

METHODS

The analysis included 200 patients, of whom 150 were confirmed to have experienced at least one flare in the past 12 months; the remaining 50 patients did not experience flares. The radiomic features of the tophi at the bilateral first metatarsophalangeal joints were extracted and analyzed. Optimal radiomic features were selected using the least absolute shrinkage and selection operator method, and logistic regression analysis was used to screen clinical characteristics and establish a clinical model. The optimal radiomic features were then combined with the identified independent clinical variables to develop a comprehensive model. The performances of the radiomic, clinical, and comprehensive models were evaluated using receiver operating characteristic curve analysis, calibration curves, and decision curve analysis.

RESULTS

Four radiomic features distinguished patients with at least one flare from those without flares and were used to establish the radiomic model. Disease duration and hypertension were independent factors that differentiated flare occurrences. The radiomic, clinical, and comprehensive models showed favorable discrimination, with areas under the receiver operating characteristic curves of 0.76 (95% CI, 0.69-0.83), 0.72(95% CI, 0.63-0.80), and 0.79(95% CI, 0.73-0.86), respectively. The calibration curves (P > 0.05) showed that the differentiated values of the comprehensive model agreed well with the actual values. Decision curve analysis demonstrated that the comprehensive model achieved higher net clinical benefits than the use of either the radiomic or clinical model alone.

CONCLUSION

The results of this study suggest that a radiomics model can distinguish patients with and without gout flares. Our proposed clinical radiomics nomogram can increase the efficacy of differentiating flare occurrence, which may facilitate the clinical decision-making process.

Systematic literature review to inform the EULAR recommendations for the use of imaging in crystal-induced arthropathies in clinical practice

OBJECTIVE

To summarise current data regarding the use of imaging in crystal-induced arthropathies (CiAs) informing a European Alliance of Associations for Rheumatology task force.

METHODS

We performed four systematic searches in Embase, Medline and Central on imaging for diagnosis, monitoring, prediction of disease severity/treatment response, guiding procedures and patient education in gout, calcium pyrophosphate dihydrate deposition (CPPD) and basic calcium phosphate deposition (BCPD). Records were screened, manuscripts reviewed and data of the included studies extracted. The risk of bias was assessed by validated instruments.

RESULTS

For gout, 88 studies were included. Diagnostic studies reported good to excellent sensitivity and specificity of dual-energy CT (DECT) and ultrasound (US), high specificity and lower sensitivity for conventional radiographs (CR) and CT. Longitudinal studies demonstrated sensitivity to change with regard to crystal deposition by US and DECT and inflammation by US and structural progression by CR and CT. For CPPD, 50 studies were included. Diagnostic studies on CR and US showed high specificity and variable sensitivity. There was a single study on monitoring, while nine assessed the prediction in CPPD. For BCPD, 56 studies were included. There were two diagnostic studies, while monitoring by CR and US was assessed in 43 studies, showing a reduction in crystal deposition. A total of 12 studies with inconsistent results assessed the prediction of treatment response. The search on patient education retrieved two studies, suggesting a potential role of DECT.

CONCLUSION

This SLR confirmed a relevant and increasing role of imaging in the field of CiAs.

Diffuse-Type Tenosynovial Giant Cell Tumor: What Are the Important Findings on the Initial and Follow-Up MRI?

Tenosynovial giant cell tumor (TSGCT) is a rare soft tissue tumor that involves the synovial lining of joints, bursae, and tendon sheaths, primarily affecting young patients (usually in the fourth decade of life). The tumor comprises two subtypes: the localized type (L-TSGCT) and the diffuse type (D-TSGCT). Although these subtypes share histological and genetic similarities, they present a different prognosis. D-TSGCT tends to exhibit local aggressiveness and a higher recurrence rate compared to L-TSGCT. Magnetic resonance imaging (MRI) is the preferred diagnostic tool for both the initial diagnosis and for treatment planning. When interpreting the initial MRI of a suspected TSGCT, it is essential to consider: (i) the characteristic findings of TSGCT-evident as low to intermediate signal intensity on both T1- and T2-weighted images, with a blooming artifact on gradient-echo sequences due to hemosiderin deposition; (ii) the possibility of D-TSGCT-extensive involvement of the synovial membrane with infiltrative margin; and (iii) the resectability and extent-if resectable, synovectomy is performed; if not, a novel systemic therapy involving colony-stimulating factor 1 receptor inhibitors is administered. In the interpretation of follow-up MRIs of D-TSGCTs after treatment, it is crucial to consider both tumor recurrence and potential complications such as osteoarthritis after surgery as well as the treatment response after systemic treatment. Given its prevalence in young adult patents and significant impact on patients' quality of life, clinical trials exploring new agents targeting D-TSGCT are currently underway. Consequently, understanding the characteristic MRI findings of D-TSGCT before and after treatment is imperative.

Optimization of dual energy computed tomography post-processing to reduce lower limb artifacts in gout

BACKGROUND

In gout, several types of dual-energy computed tomography (DECT) artifacts have been described (nail bed, skin, beam hardening, submillimeter and vascular artifacts), which can lead to overdiagnosis. The objective of this study was to determine the optimal DECT settings for post processing in order to reduce the frequency of some common artifacts in patients with suspected gout.

METHODS

Seventy-seven patients hospitalized for suspected gout (feet/ankles and/or knees) who received a DECT imaging were included (final diagnosis of 43 gout and 34 other rheumatic disorders). Different post-processing settings were evaluated using Syngovia software: nine settings (R1 to R9) were evaluated with a combination of different ratio (1.28, 1.36 and 1.55) and attenuation coefficient (120, 150, 170 HU).

RESULTS

Among the nine settings tested, the R2 setting (170 HU, ratio =1.28) significantly reduced the presence of knee and foot/ankle artifacts compared to the standard R1 setting (85% and 94% decrease in beam hardening and clumpy artifacts in the ankle and foot, respectively (P<0.001); a decrease of 71%, 60% and 88% respectively of meniscal beam hardening, beam hardening and submillimeter artifacts in the knee (P<0.001). Compared to standard settings, the use of R2 settings decreased sensitivity [0.79 (95% CI: 0.65, 0.88) versus 0.90 (95% CI: 0.78, 0.96)] and increased specificity [0.86 (95% CI: 0.71, 0.93) versus 0.63 (95% CI: 0.47, 0.77)] (P<0.001). Settings using an attenuation coefficient to 120 HU and/or a ratio to 1.55 were all associated with a significant increasing of artifacts, especially clumpy and beam hardening artifacts.

CONCLUSIONS

Applying a ratio of 1.28 and a minimum attenuation of 170 HU in DECT post-processing eliminates the majority of artifacts located in the lower limbs, particularly clumpy artifacts and beam hardening.

Gouty Arthropathy: Review of Clinical Manifestations and Treatment, with Emphasis on Imaging

Gout, a crystalline arthropathy caused by the deposition of monosodium urate crystals in the articular and periarticular soft tissues, is a frequent cause of painful arthropathy. Imaging has an important role in the initial evaluation as well as the treatment and follow up of gouty arthropathy. The imaging findings of gouty arthropathy on radiography, ultrasonography, computed tomography, dual energy computed tomography, and magnetic resonance imaging are described to include findings of the early, acute and chronic phases of gout. These findings include early monosodium urate deposits, osseous erosions, and tophi, which may involve periarticular tissues, tendons, and bursae. Treatment of gout includes non-steroidal anti-inflammatories, colchicine, glucocorticoids, interleukin-1 inhibitors, xanthine oxidase inhibitors, uricosuric drugs, and recombinant uricase. Imaging is critical in monitoring response to therapy; clinical management can be modulated based on imaging findings. This review article describes the current standard of care in imaging and treatment of gouty arthropathy.

Characteristics of monosodium urate crystal deposition in the foot in the different stages of gout by dual-energy computed tomography

OBJECTIVE

To compare the characteristics of monosodium urate (MSU) crystal deposition at specific anatomical sites of the foot detected by dual-energy computed tomography in patients with different stages of gout.

MATERIALS AND METHODS

This study included 101 patients with gout, 64 had early gout (<3 years) and 37 had late gout (>3 years). We retrospectively compared the total volumes of MSU crystals, the detection rates, and the morphology of MSU crystals at specific anatomical sites in the foot of the patients with different gout durations.

RESULTS

The total volume of MSU crystals in patients with early gout was significantly smaller than that in patients with late gout (P < 0.05). The detection rates and morphology of MSU crystals in the anterior calf tendons, ankle joints, tarsometatarsal joints, and metatarsophalangeal joints differed significantly between the patients with early and late gout (P < 0.05). There were no significant differences in the detection rates of submillimeter MSU crystals at the other specific anatomical sites, except for the tendons of the anterior calf, the ankle joint, and the metatarsal joint (P > 0.05). The submillimeter MSU crystal deposition was most common in the tendons of the posterior calf, the proportions in patients with early gout and late gout were 85.9% and 70.3%. Only submillimeter deposition existed in 52 patients (81.3%) with early gout and 11 patients (29.7%) with late gout at all sites of the foot.

CONCLUSION

Dual-energy computed tomography detection of submillimeter MSU crystal deposits in the foot is of great significance for the diagnosis of gout, especially along tendons.

A novel parameter derived from post-processing procedure of dual energy CT for identification of gout

ROI analysis is frequently used for obtaining acid content on rapid-kV-switching dual energy CT (DECT), providing inadequate accuracy. A new parameter derived from post-processing procedure, maximum lower limit with stain visible (MLLSV), was used by us to diagnose gout. 30 gout patients and 20 healthy volunteers were analyzed by using MLLSV. MLLSV was defined as the maximum lower limit of display window allowing only one stained site visible. Radiologists were asked to continuously increase the lower limit of display window of uric acid to decrease number of stained sites until the last stained site disappeared. MLLSV obtained by this way was compared between gout patients and volunteers. Receiver operating characteristic (ROC) curve was used to determine the performance. MLLSV of gout patients was significantly higher than that of volunteers (1373.3 ± 23.0 mg/cm³ vs. 1315.4 ± 20.7 mg/cm³, p = 0.000). The area under ROC curve of MLLSV was 0.993 in identifying gout. When using the optimal cutoff of 1342 mg/cm³, the sensitivity and specificity of MLLSV in identification of gout were 96.7% and 95% respectively. MLLSV derived from post-processing procedure of DECT is useful in discriminating gout patients from healthy people.

Unravelling the mysteries of gout by multimodality imaging

Gout is a common inflammatory arthritis that manifests as an aggregate of variably symptomatic monosodium urate crystals (MSU) in the joints and surrounding tissues in addition to multisystem involvement such as genitourinary and cardiovascular systems. In recent decades, there has been a documented increase in the prevalence and incidence of gout. Risk factors for gout include obesity, dietary influences, hypertension, renal impairment, and diuretic use. A prompt diagnosis followed by uric acid lowering treatment prior to the onset of bone destruction is the goal in any suspected case of gout. Advanced imaging modalities, such as dual energy computed tomography (DECT) and ultrasonography (US), employed for the diagnosis of gout are each accompanied by advantages and disadvantages. Conventional radiography (CR), although useful in visualizing joint erosions and mineralization, is limited in its ability to diagnose gout flare. Although synovial fluid aspiration remains the gold standard for MSU crystal visualization, less-invasive imaging modalities are preferred to avoid potential complications. DECT and US in particular are useful in the diagnosis of gout. In this review, we will discuss the current state and role of imaging in the detection of gout.

Gout of feet and ankles in different disease durations: diagnostic value of single-source DECT and evaluation of urate deposition with a novel semi-quantitative DECT scoring system

OBJECTIVES

To investigate the diagnostic performance of single-source dual-energy computed tomography (DECT) based on gemstone spectral imaging technology (including Discovery CT750HD and Revolution CT) in patients with suspected feet/ankles gouty arthritis, and evaluate the urate deposition with a novel semi-quantitative DECT scoring system.

METHODS

A total of 196 patients were consecutively included. Feet and ankles were evaluated in all patients by single-source DECT scan. The 2015 EULAR/ACR criteria were used as the reference for the diagnosis of gout. The sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) of DECT for the diagnosis of gout in the early (≤1 year), middle (1-3 years), and late (> 3 years) disease durations were calculated. Besides, a novel semi-quantitative DECT scoring system was assessed for the measurement of urate deposition, and the correlation between the scores and the clinical and serological data were also evaluated. Moreover, the influences of artifacts on the diagnostic performance of DECT were also determined.

RESULTS

The sensitivity, specificity, and AUC of DECT in 196 patients were 38.10, 96.43%, and 0.673 in the early-stage group; 62.96, 100.00%, and 0.815 in the middle-stage group; and 77.55, 87.50%, and 0.825 in the late-stage group, respectively. The overall diagnostic accuracies in the AUC of DECT (Discovery CT750HD and Revolution CT) in the middle and late stages of gout were higher than that in the early stage of gout. Besides, the monosodium urate crystals were deposited on the first metatarsophalangeal joints and ankles/midfeet. Age, the presence of tophus, bone erosion, and disease duration considerably affected the total urate score. No statistical difference in the positive detection of nail artifact, skin artifact, vascular calcification, and noise artifact was found between the case and control groups.

CONCLUSION

DECT (Discovery CT750HD and Revolution CT) showed promising diagnostic accuracy for the detection of urate crystal deposition in gout but had limited diagnostic sensitivity for short-stage gout. Longer disease duration, the presence of tophus, and bone erosion were associated with the urate crystal score system. The artifacts do not remarkably affect the diagnostic performance of DECT in gout.

External validation of Gout-calculator performance on a cohort of acute arthritis (SYNOLACTATE) sparing distal joints such as hallux and midfoot. A cross-sectional study of 170 patients

OBJECTIVE

To evaluate the performance of the Gout-calculator in a cohort of consecutive acute arthritis affecting large and intermediate joints (without an attack on hallux or midfoot joints).

METHODS

A retrospective study. Gout-calculator data were collected in medical records of patients included in the prospective consecutive cohort of acute arthritis called SYNOLACTATE. The diagnosis of gout was defined by the presence of sodium urate crystals in synovial fluid. The diagnostic performance of the Gout-calculator was studied by performing an ROC curve with the calculation of its AUC (95% CI) as well as the calculation of Sensitivity (Se), Specificity (Sp), and positive likelihood ratio (LR+).

RESULTS

170 patients with acute arthritis were included. Variables associated with the diagnosis of gout were as follows: serum uric acid > 350 μmol/L (OR 5.52 (2.52-12.1), p < 0.001), joint redness (OR 5.08 (1.85-14.0), p = 0.001), previous patient-reported arthritis attack (OR 4.04 (1.92-8.49), p < 0.001), male (OR 3.00 (1.17-7.69), p = 0.02), hypertension or cardiovascular disease (OR 2.33 (1.07-5.06), p = 0.03). The median (IQR) of Gout-calculator was significantly higher in gouty arthritis (7.0 [5.5-8.1]) than in associated-CPP acute arthritis (4.0 [2.0-5.8]), septic arthritis (3.0 [2.0-5.1]), or others arthritis (3.5 [2.0-5.5]). The AUC was 0.833 (0.768-0.897) with for the threshold ≥ 8, a Se at 27.5% (0.161-0.428), Sp 97.7% (0.934-0.992), and LR+ 11.9 (3.5-40).

CONCLUSION

Despite diagnostic performances close to those published, the use of the Gout-calculator is not sufficient for the diagnosis of gout or to exclude the differential diagnosis of septic arthritis in the SYNOLACTATE cohort.

KEY POINTS

• For a Gout-calculator threshold of ≤ 4, Sensitivity is 92.5%, Specificity 50.8% and LR- 0.15 to the gout diagnosis. • For a Gout-calculator threshold of > = 8, Sensitivity is 27.5%, Specificity 97.7% and LR+ 11.9 to the gout diagnosis. • In a population of acute arthritis affecting large joints, Gout-calculator is not sufficient to discriminate between gouty arthritis and septic arthritis.

Dual-Energy Computed Tomography Detection of Cardiovascular Monosodium Urate Deposits in Patients With Gout

Importance

The prevalence of gout has increased in recent decades. Several clinical studies have demonstrated an association between gout and coronary heart disease, but direct cardiovascular imaging of monosodium urate (MSU) deposits by using dual-energy computed tomography (DECT) has not been reported to date.

Objective

To compare coronary calcium score and cardiovascular MSU deposits detected by DECT in patients with gout and controls.

Design, Setting, and Participants

This prospective Health Insurance Portability and Accountability Act-compliant study included patients with gout and controls who presented to a rheumatologic clinic from January 1, 2017, to November 1, 2018. All consecutive patients underwent DECT to assess coronary calcium score and MSU deposits in aorta and coronary arteries. In addition, cadavers were assessed by DECT for cardiovascular MSU deposits and verified by polarizing microscope. Analysis began in January 2017.

Main Outcomes and Measures

Detection rate of cardiovascular MSU deposits using DECT in patients with gout and control group patients without a previous history of gout or inflammatory rheumatic diseases.

Results

A total of 59 patients with gout (mean [SD] age, 59 [5.7] years; range, 47-89 years), 47 controls (mean [SD] age, 70 [10.4] years; range, 44-86 years), and 6 cadavers (mean [SD] age at death, 76 [17] years; range, 56-95 years) were analyzed. The frequency of cardiovascular MSU deposits was higher among patients with gout (51 [86.4%]) compared with controls (7 [14.9%]) (χ2 = 17.68, P < .001), as well as coronary MSU deposits among patients with gout (19 [32.2%]) vs controls (2 [4.3%]) (χ2 = 8.97, P = .003). Coronary calcium score was significantly higher among patients with gout (900 Agatston units [AU]; 95% CI, 589-1211) compared with controls (263 AU; 95% CI, 76-451; P = .001) and also significantly higher among 58 individuals with cardiovascular MSU deposits (950 AU; 95% CI, 639-1261) compared with 48 individuals without MSU deposits (217 AU; 95% CI, 37-397; P < .001). Among 6 cadavers, 3 showed cardiovascular MSU deposits, which were verified by polarizing light microscope.

Conclusion and Relevance

Dual-energy computed tomography demonstrates cardiovascular MSU deposits, as confirmed by polarized light microscopy. Cardiovascular MSU deposits were detected by DECT significantly more often in patients with gout compared with controls and were associated with higher coronary calcium score. This new modality may be of importance in gout population being at risk from cardiovascular disease.

Imaging for Acute and Chronic Scaphoid Fractures

The scaphoid is the most commonly fractured bone in the wrist but 20% to 40% of scaphoid fractures are radiographically occult. Delayed or misdiagnosis can have significant consequences with late complications such as nonunion, malunion, or the development of avascular necrosis in the proximal pole. After initial negative radiographs, advanced cross-sectional imaging, including CT and MRI, ultimately may provide more accurate and rapid diagnosis than conventional radiography. With chronic fractures, the preferred modality depends on the clinical question. New techniques are evolving that will further advance imaging for diagnosis and treatment of scaphoid fractures.

The diagnostic performance of dual energy CT for diagnosing gout: a systematic literature review and meta-analysis

Objective

This study aimed to assess the utility of dual energy CT (DECT) for diagnosing gout.

Methods

A systematic literature search was performed in PubMed, EMBASE and Cochrane Library. Studies evaluating the utility of DECT for diagnosing gout were included. Reference standards were detection of monosodium urate crystals at SF assessment or a validated set of criteria. The methodological quality of studies was evaluated according to the Quality Assessment of Diagnostic Accuracy Studies (QUADAS)-2 criteria. Data from person-based and joint-/localization-based evaluations were pooled separately, and subgroup analyses for disease stage/duration and reference standard were performed.

Results

Ten studies were included; in person-based evaluations, the pooled (95% CI) sensitivity and specificity were 0.81 (0.77, 0.86) and 0.91 (0.85, 0.95), respectively. In joint-based evaluations, they were 0.83 (0.79, 0.86) and 0.88 (0.83, 0.92), respectively. At short disease duration (⩽6 weeks), the pooled (95% CI) sensitivity and specificity at the joint level were 0.55 (0.46, 0.64) and 0.89 (0.84, 0.94), respectively.

Conclusion

DECT has a high diagnostic accuracy in established gout, but its diagnostic sensitivity is low in subjects with recent onset gout.