Unravelling the mysteries of gout by multimodality imaging

Development of a multimodal kidney age prediction based on automatic segmentation CT image in patients with normal renal function

Background

For decades, description of renal function has been of interest to clinicians and researchers. Serum creatinine (Scr) and estimated glomerular filtration rate (eGFR) are familiar but also limited in many circumstances. Meanwhile, the physiological volumes of the kidney cortex and medulla are presumed to change with age and have been proven to change with decreasing kidney function.

Methods

We recruited 182 patients with normal Scr levels between October 2021 and February 2022 in Peking Union Medical College Hospital (PUMCH) with demographic and clinical data. A 3D U-Net architecture is used for both cortex and medullary separation, and volume calculation. In addition, we included patients with the same inclusion criteria but with diabetes (PUMCH-DM test set) and diabetic nephropathy (PUMCH-DN test set) for internal comparison to verify the possible clinical value of "kidney age" (K-AGE).

Results

The PUMCH training set included 146 participants with a mean age of 47.5 ± 7.4 years and mean Scr 63.5 ± 12.3 μmol/L. The PUMCH test set included 36 participants with a mean age of 47.1 ± 7.9 years and mean Scr 66.9 ± 13.0 μmol/L. The multimodal method predicted K-AGE approximately close to the patient's actual physiological age, with 92% prediction within the 95% confidential interval. The mean absolute error increases with disease progression (PUMCH 5.00, PUMCH-DM 6.99, PUMCH-DN 9.32).

Conclusion

We established a machine learning model for predicting the K-AGE, which offered the possibility of evaluating the whole kidney health in normal kidney aging and in disease conditions.

Dual Energy Computed Tomography Collagen Material Decomposition for Detection of Lumbar Spine Disc Extrusion and Sequestration: A Comparative Study With Greyscale Computed Tomography

Purpose: To assess value of dual energy computed tomography (DECT) collagen material decomposition algorithm when combined with standard computed tomography (CT) in detection of lumbar disc extrusion and sequestration. Materials and Methods: Retrospective analysis of all patients with acute low back pain who had a diagnosis of lumbar spine disc extrusion and/or sequestration on Magnetic Resonance Imaging (MRI) (reference standard), and had undergone non-contrast DECT of the lumbar spine within 60 days of the MRI. Age and sex-matched control patients (n = 42) were included. Patients were grouped into standard, grey-scale CT only group and standard CT + DECT tendon images group. Two double-blinded radiologists reviewed both groups for presence of extrusion or sequestration. They also rated their diagnostic confidence on Likert 5-point scale. McNemar Chi-square test was used to compare diagnostic accuracy, unpaired t-test to compare reviewers diagnostic confidence, and Cohen's k (kappa) test for interobserver agreement. Results: The combined group showed higher overall sensitivity (96.6% vs 87.2%), specificity (99% vs 95.4%), and diagnostic accuracy (98.7% vs 94.5%) with a lower false positive rate (1.1% vs 4.6%). McNemar Chi-square test confirmed statistical significance (P = .03 and P = .02 for Reviewers R1 and R2, respectively). The mean diagnostic confidence was also significantly higher on combined group (R1: 3.74 ± 1.1 vs 3.47 ± 1.15 (P < .01) and R2: 3.91 ± 1.15 vs 3.72 ± 1.16 [mean ± SD] (P = .02)). Conclusion: Utilizing MRI as a reference standard, DECT tendon application combined with standard CT increases the sensitivity, specificity, and accuracy of detection of lumbar spine disc extrusion and sequestration, when compared to standard CT alone.

Detailed analysis of the association between urate deposition and bone erosion in gout: a dual-energy computed tomography study

Objective

This study aimed to analyze the effect of urate deposition (UD) on bone erosion and examine the association between the volume of monosodium urate (MSU) crystals and an improved bone erosion score method, as measured in the metatarsophalangeal (MTP) joints of patients with gout.

Materials and methods

Fifty-six patients diagnosed with gout using the 2015 European League Against Rheumatism and American College of Rheumatology criteria were enrolled. MSU crystals volume at each MTP joint was measured using dual-energy computed tomography (DECT) images. The degree of bone erosion was evaluated with the modified Sharp/van der Heijde (SvdH) erosion scoring system based on CT images. Differences in clinical features between patients with (UD group) and without (non-UD group) UD were assessed, and the correlation between erosion scores and urate crystal volume was analyzed.

Results

The UD and non-UD groups comprised 30 and 26 patients, respectively. Among the 560 MTP joints assessed, 80 showed MSU crystal deposition, and 108 showed bone erosion. Bone erosion occurred in both groups but was significantly less severe in the non-UD group (p <0.001). Both groups had equivalent levels of serum uric acid (p=0.200). Symptom duration was significantly longer in the UD group (p=0.009). The UD group also had a higher rate of kidney stones (p=0.023). The volume of MSU crystals was strongly and positively associated with the degree of bone erosion (r=0.714, p <0.001).

Conclusion

This study found that patients with UD show significant increased bone erosion than those without UD. The volume of MSU crystals is associated with the improved SvdH erosion score based on CT images, regardless of serum uric acid level, demonstrating the potential of combining DECT and serum uric acid measurements in helping optimize the management of patients with gout.

Assessing tophaceous spinal gout treatment response using dual-energy CT as a point-of-care imaging modality: case report

We describe a case of chronic tophaceous gout affecting the spine, hands, elbows, feet, and knees in a 67-year-old man with serum urate levels at 549 µmol/L whose response to treatment was successfully mapped using dual-energy computed tomography (DECT). The patient presented with exacerbation of acute-on-chronic lumbar back pain. He had received a diagnosis of gout 3 years prior to this presentation yet was not on any urate-lowering therapy. The patient received febuxostat 80 mg and colchicine 0.3 mg once daily and underwent DECT to assess baseline monosodium urate (MSU) burden. At baseline, MSU deposits were seen in the hands, elbows, feet, knees, and lumbar spine including the left L5-S1 facet joint encroaching onto the neural foramen. After 2.5 years of treatment, serum urate level was within the target range (< 360 µmol/L), and the patient underwent a follow-up DECT that revealed almost full resolution of MSU deposition in the spine, including the MSU-burdened facet joint and neural foramen in the lumbar spine, in addition to all the affected peripheral joints. This case is the first report of radiological evidence of nearly complete resolution of MSU deposits in spinal gout on DECT after urate-lowering therapy treatment, which demonstrates the utility of this imaging modality as a non-invasive investigational point-of-care imaging modality for mapping treatment response and identifying the etiology of back pain in a patient with chronic tophaceous spinal gout.

Know your way around acute unenhanced CT during global iodinated contrast crisis: a refresher to ED radiologists

Due to a contrast shortage crisis resulting from the decreased supply of iodinated contrast agents, the American College of Radiology (ACR) has issued a guidance statement followed by memoranda from various hospitals to preserve and prioritize the limited supply of contrast. The vast majority of iodinated contrast is used by CT, with a minority used by vascular and intervention radiology, fluoroscopy, and other services. A direct consequence is a paradigm shift to large volume unenhanced CT scans being utilized for acute and post traumatic patients in EDs, an uncharted territory for most radiologists and trainees. This article provides radiological diagnostic guidance and a pictorial example through systematic review of common unenhanced CT findings in the acute setting.

Periarticular calcifications

Periarticular calcification and ossification is a frequent finding on imaging and may sometimes pose a diagnostic challenge. The differential diagnoses for this radiological finding are wide and can be classified into broad groups such as idiopathic, developmental, trauma, burns, infection, tumor, connective tissue disease, crystalline, metabolic, vascular, and foreign bodies. With careful consideration of the clinical and imaging findings as well as awareness of mimickers of periarticular mineralization, the list of differential diagnoses can be narrowed down. This article aims to review the clinical-radiologic findings of periarticular calcified or ossified lesions with relevant imaging illustrations.

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.

Factors Associated with Bone Erosion in Patients with Gout: A Dual-Energy Gemstone Spectral Imaging Computed Tomography Study

OBJECTIVE

This study aimed to assess the factors influencing bone erosion in patients with gout using dual-energy gemstone spectral imaging CT.

METHODS

We compared the clinical data, laboratory indices, and tissue urate levels at the monosodium urate (MSU)-bone interface measured by dual-energy gemstone spectral imaging computed tomography of 87 gout patients with (n=41) and without (n=46) bone erosion. Logistic regression analysis was used to investigate the risk factors associated with bone erosion.

RESULTS

In total, 47.1% of patients with gout had bone erosion. The disease duration, serum uric acid, tissue urate levels, and the presence of tophi were significantly higher (p<0.05) in gout patients with bone erosion than in those without bone erosion. Longer disease duration (OR=1.11, 95% CI: 1.00-1.24, p<0.05) and increased tissue urate levels (OR=1.01, 95% CI: 1.00-1.02, p<0.05) were independently associated with bone erosion. Tissue urate levels at the MSU-bone interface were correlated with the presence of tophi (r=0.62, p<0.001), bone erosion (r=0.51, p<0.001), renal calculus (r=0.24, p=0.03), and serum uric acid levels (r=0.23, p=0.03).

CONCLUSION

This study found that longer disease duration and elevated tissue urate concentrations at the MSU-bone interface were associated with bone erosion in patients with gout.

Dual-energy computed tomography for the diagnosis of acute gouty arthritis

AIMS

To investigate the diagnostic value of dual-energy computed tomography (DECT) in acute gouty arthritis (AGA) or patients presenting with suspected gouty arthritis.

METHODS

This retrospective study was performed in a single centre from May 2017 to August 2018. Two hundred and twenty-six patients with an initial diagnosis of AGA in the preceding 15 days were included. All patients were referred for a DECT scan of the affected joints. The diagnosis criteria of gout with the American College of Rheumatology Classification Standard were regarded as the reference standard.

RESULTS

Two hundred patients were included in the present study at last. The sensitivity, specificity, positive predictive value, and negative predictive value of DECT in the diagnosis of all AGA were 83.83%, 60.61%, 91.5% and 42.55% respectively. When AGA was subdivided according to the joint site, the sensitivity, specificity, positive predictive value, and negative predictive value were 80.68%, 61.11%, 91.03%, and 39.29% in feet, 93.55%, 40%, 93.55%, and 40% in knees and 87.5%, 71.43%, 91.3%, and 62.5% in ankles, respectively.

CONCLUSIONS

DECT had a high sensitivity for the diagnosis of AGA. However, the specificity was limited, particularly for the diagnosis of acute gouty knee arthritis. Prospective multicenter studies of large samples will enhance the application of DECT among the AGA patients in the future.

Imaging of Joints and Bones in Autoinflammation

Autoinflammatory disorders are commonly characterized by seemingly unprovoked systemic inflammation mainly driven by cells and cytokines of the innate immune system. In many disorders on this spectrum, joint and bone involvement may be observed and imaging of these manifestations can provide essential diagnostic information. This review aimed to provide a comprehensive overview of the imaging characteristics for major diseases and disease groups on the autoinflammatory spectrum, including familial Mediterranean fever (FMF), Behçet disease (BD), crystal deposition diseases (including gout), adult-onset Still's disease (AoSD), and syndromatic synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO)/chronic recurrent multifocal osteomyelitis (CRMO). Herein, we discuss common and distinguishing imaging characteristics, phenotypical overlaps with related diseases, and promising fields of future research.

Frauen und Gicht – eine diagnostische Herausforderung

Hintergrund Von Gicht sind überwiegend Männer betroffen (m:w; 9:1). Zur Diagnosestellung werden daher in der Regel die klinischen Merkmale einer akuten Monarthritis der unteren Extremität beim Mann herangezogen. Im Moment ist die Datenlage zur Gicht bei Frauen begrenzt. Bei ihnen wird die Gicht oft nicht in die Differenzialdiagnosen einer Arthritis einbezogen. Wir untersuchten daher die Epidemiologie und klinische Präsentation der Gicht bei Frauen und verglichen sie mit denen der Gicht bei Männern. In der Folge wurden die Daten auf Merkmale analysiert, welche bei Frauen die Gicht von Arthritiden anderer Genese unterscheiden und damit Fehldiagnosen vermeiden helfen können.

Methoden Retrospektiv wurden alle Patienten eingeschlossen, die zwischen 2012 und 2018 mit einer primären Entlassungsdiagnose einer Gicht (ICD-10 M10.XX) am Universitätsklinikum Dresden behandelt wurden. Es wurden klinische, laborchemische sowie radiologische Befunde erfasst und deskriptiv sowie multivariat mittels SPSS und R analysiert. In einem zweiten Schritt wurden die Daten von Frauen mit Gichtarthritis mit denen ohne Gicht (Monarthritis anderer Genese) verglichen und mittels univariater sowie multivariater Regressionsanalyse auf Signifikanz geprüft.

Resultate Insgesamt wurden 238 Gicht-Patienten (71 Frauen, 167 Männer) eingeschlossen. Frauen dieser Kohorte waren bei Diagnosestellung im Mittel 20 Jahre älter als Männer und hatten dann insgesamt häufiger mehrere Komorbiditäten: 92% aller Gichtpatientinnen litten an einer Hypertonie (Männer 74%), 84% hatten eine eGFR<60 ml/min (Männer 52%) und 40% hatten kardiovaskuläre Vorereignisse (Männer 14%). 90% nahmen regelmäßig Diuretika ein (Männer 47%). Fast die Hälfte der Frauen hatte bereits eine manifeste Polyarthrose (47 vs. 30% der Männer). Klinisch trat bei Frauen seltener die klassische MTP I-Arthritis (69 vs. 84%) auf. Der Vergleich von Frauen mit durch mikroskopischen Kristallnachweis gesicherter Gicht und Frauen mit Kristall-negativer Monarthritis zeigte signifikante Unterschiede: Frauen mit Gicht waren älter und wiesen signifikant häufiger eine Hypertonie oder kardiovaskuläre Erkrankung, einen Diabetes mellitus Typ 2, einen adipösen Habitus auf oder nahmen Diuretika ein. Bestanden zudem eine eingeschränkte Nierenfunktion sowie eine Hyperurikämie, lag mit hoher Sicherheit eine Gicht vor.

Schlussfolgerungen Die Gicht muss bei einer akuten Monarthritis auch bei Frauen in die Differenzialdiagnose einbezogen werden. Das gilt besonders ab dem Rentenalter und wenn Hypertonie, kardiovaskuläre Erkrankungen, Diabetes mellitus Typ 2 oder Adipositas vorliegen und Diuretika Teil der Dauermedikation sind. Die Einschränkung der Nierenfunktion und eine Serumharnsäure von>390 µmol/l (>6,5 mg/dL) machen eine Gicht sehr wahrscheinlich.