Inflammation assessment in patients with arthritis using a novel in vivo fluorescence optical imaging technology

A design specification for Critical Illness Digital Twins to cure sepsis: responding to the National Academies of Sciences, Engineering and Medicine Report: Foundational Research Gaps and Future Directions for Digital Twins

On December 15, 2023, The National Academies of Sciences, Engineering and Medicine (NASEM) released a report entitled: Foundational Research Gaps and Future Directions for Digital Twins. The ostensible purpose of this report was to bring some structure to the burgeoning field of digital twins by providing a working definition and a series of research challenges that need to be addressed to allow this technology to fulfill its full potential. In the work presented herein we focus on five specific findings from the NASEM Report: 1) definition of a Digital Twin, 2) using fit-for-purpose guidance, 3) developing novel approaches to Verification, Validation and Uncertainty Quantification (VVUQ) of Digital Twins, 4) incorporating control as an explicit purpose for a Digital Twin and 5) using a Digital Twin to guide data collection and sensor development, and describe how these findings are addressed through the design specifications for a Critical Illness Digital Twin (CIDT) aimed at curing sepsis.

Photodynamic Therapy and Cardiovascular Diseases

Cardiovascular diseases are the third most common cause of death in the world. The most common are heart attacks and stroke. Cardiovascular diseases are a global problem monitored by many centers, including the World Health Organization (WHO). Atherosclerosis is one aspect that significantly influences the development and management of cardiovascular diseases. Photodynamic therapy (PDT) is one of the therapeutic methods used for various types of inflammatory, cancerous and non-cancer diseases. Currently, it is not practiced very often in the field of cardiology. It is most often practiced and tested experimentally under in vitro experimental conditions. In clinical practice, the use of PDT is still rare. The aim of this review was to characterize the effectiveness of PDT in the treatment of cardiovascular diseases. Additionally, the most frequently used photosensitizers in cardiology are summarized.

Metabolic and molecular imaging in inflammatory arthritis

It is known that metabolic shifts and tissue remodelling precede the development of visible inflammation and structural organ damage in inflammatory rheumatic diseases such as the inflammatory arthritides. As such, visualising and measuring metabolic tissue activity could be useful to identify biomarkers of disease activity already in a very early phase. Recent advances in imaging have led to the development of so-called 'metabolic imaging' tools that can detect these changes in metabolism in an increasingly accurate manner and non-invasively.Nuclear imaging techniques such as 18F-D-glucose and fibroblast activation protein inhibitor-labelled positron emission tomography are increasingly used and have yielded impressing results in the visualisation (including whole-body staging) of inflammatory changes in both early and established arthritis. Furthermore, optical imaging-based bedside techniques such as multispectral optoacoustic tomography and fluorescence optical imaging are advancing our understanding of arthritis by identifying intra-articular metabolic changes that correlate with the onset of inflammation with high precision and without the need of ionising radiation.Metabolic imaging holds great potential for improving the management of patients with inflammatory arthritis by contributing to early disease interception and improving diagnostic accuracy, thereby paving the way for a more personalised approach to therapy strategies including preventive strategies. In this narrative review, we discuss state-of-the-art metabolic imaging methods used in the assessment of arthritis and inflammation, and we advocate for more extensive research endeavours to elucidate their full field of application in rheumatology.

[Can rheuma be scanned? : Review of the current study situation on fluorescence optical imaging]

BACKGROUND

The novel technique of indocyanine green (ICG)-based fluorescence optical imaging (FOI) using the Xiralite® system (Rheumascan) has been the subject of many different studies worldwide since approval for clinical use in the European Union (2009), USA (2014) and Asia. The FOI depicts the disturbed microcirculation in the joints of both hands caused by inflammation.

OBJECTIVE

The aim of this article is to provide an overview of the current state of studies on ICG-based FOI in different rheumatologic indications.

METHODS

A narrative literature review of publications on ICG-based FOI in the diagnosis of various inflammatory rheumatic joint diseases since 2010 is presented, its use in treatment monitoring is explained, and its value in systemic sclerosis is outlined.

RESULTS

In summary, studies have extensively demonstrated the accuracy of FOI in inflammation detection. Therefore, it can be concluded that FOI is a good supplement to existing imaging modalities. Due to characteristic patterns of both skin and nails, FOI is an indicated procedure especially in psoriatic arthritis and can be very helpful in the diagnostic process in early undifferentiated arthritis. The FOI has shown its usefulness in children (juvenile idiopathic arthritis), for monitoring the course of treatment, and for demonstrating disturbed microcirculation in patients with systemic sclerosis.

CONCLUSION

The presented data imply that FOI should be considered as a valuable complementary imaging tool in the diagnostic algorithm of daily rheumatologic practice, both for diagnosis and for follow-up monitoring. In particular, the automated analyses should be able in the future to objectify measurements of inflammatory activity as well as monitoring the response to treatment.

Imaging in inflammatory arthritis: progress towards precision medicine

Imaging techniques such as ultrasonography and MRI have gained ground in the diagnosis and management of inflammatory arthritis, as these imaging modalities allow a sensitive assessment of musculoskeletal inflammation and damage. However, these techniques cannot discriminate between disease subsets and are currently unable to deliver an accurate prediction of disease progression and therapeutic response in individual patients. This major shortcoming of today's technology hinders a targeted and personalized patient management approach. Technological advances in the areas of high-resolution imaging (for example, high-resolution peripheral quantitative computed tomography and ultra-high field MRI), functional and molecular-based imaging (such as chemical exchange saturation transfer MRI, positron emission tomography, fluorescence optical imaging, optoacoustic imaging and contrast-enhanced ultrasonography) and artificial intelligence-based data analysis could help to tackle these challenges. These new imaging approaches offer detailed anatomical delineation and an in vivo and non-invasive evaluation of the immunometabolic status of inflammatory reactions, thereby facilitating an in-depth characterization of inflammation. By means of these developments, the aim of earlier diagnosis, enhanced monitoring and, ultimately, a personalized treatment strategy looms closer.

Fluorescence-optical imaging as a promising easy-to-use imaging biomarker to increase early psoriatic arthritis detection in patients with psoriasis: a cross-sectional cohort study with follow-up

OBJECTIVES

To evaluate the ability of fluorescence-optical imaging (FOI) to detect preclinical musculoskeletal inflammatory signs in patients with skin psoriasis at risk of developing psoriatic arthritis (PsA).

METHODS

This investigator-initiated prospective exploratory study evaluated adult patients with psoriasis with musculoskeletal complaints and/or nail psoriasis within the last 6 months. Patients underwent a comprehensive rheumatological clinical examination (CE) along with musculoskeletal ultrasound (MSUS) and FOI of both hands at a single visit. Patients with CE-/MSUS-/FOI+ findings had MRI performed on the symptomatic or dominant hand within 7 days. If MRI was negative, the patients were followed over 2 years for the onset of clinically manifest PsA.

RESULTS

A total of 389 patients were referred from dermatology centres and evaluated at 14 rheumatology sites in Germany. Seventy-seven (20%) patients with CE-/US-/FOI- were considered to have psoriasis only. PsA was diagnosed in 140/389 patients (36%) based on CE alone and in another 55 patients (14%) by additional MSUS; overall, 50% of the patient cohort was diagnosed with PsA. One hundred sixteen patients (30%) were FOI+ (CE-) of which 40 (37%) were FOI+/MRI+. In the 2-year follow-up of the FOI+/CE- patients, clinical PsA was confirmed in another 12%.

CONCLUSION

FOI is a promising method for the detection of signs of musculoskeletal inflammation in hands that may serve as an early imaging biomarker for transitions from psoriasis to PsA. This imaging technique has the potential to detect PsA in at-risk patients with psoriasis, reduce time to PsA diagnosis and improve patient outcomes.

An objective, automated and robust scoring using fluorescence optical imaging to evaluate changes in micro-vascularisation indicating early arthritis

Fluorescence optical imaging technique (FOI) is a well-established and valid method for visualization of changes in micro vascularization at different organ systems. As increased vascularization is an early feature of joint inflammation, FOI is a promising method to assess arthritis of the hands. But usability of the method is limited to the assessors experience as the measurement of FOI is semi-quantitative using an individual grading system such as the fluorescence optical imaging activity score (FOIAS). The goal of the study was to automatically and thus, objectively analyze the measured fluorescence intensity generated by FOI to evaluate the amount of inflammation of each of the subject’s joints focusing on the distinction between normal joint status or arthritis in psoriatic arthritis patients compared to healthy volunteers. Due to the heterogeneity of the pathophysiological perfusion of the hands, a method to overcome the absoluteness of the data by extracting heatmaps out of the image stacks is developed. To calculate a heatmap for one patient, firstly the time series for each pixel is extracted, which is then represented by a feature value. Secondly, all feature values are clustered. The calculated cluster values represent the relativity between the different pixels and enable a comparison of multiple patients. As a metric to quantify the conspicuousness of a joint a score is calculated based on the extracted cluster values. These steps are repeated for a total number of three features. With this method a tendency towards a classification into unaffected and inflamed joints can be achieved. However, further research is necessary to transform the tendency into a robust classification model.

Features Found in Indocyanine Green-Based Fluorescence Optical Imaging of Inflammatory Diseases of the Hands

Rheumatologists in Europe and the USA increasingly rely on fluorescence optical imaging (FOI, Xiralite) for the diagnosis of inflammatory diseases. Those include rheumatoid arthritis, psoriatic arthritis, and osteoarthritis, among others. Indocyanine green (ICG)-based FOI allows visualization of impaired microcirculation caused by inflammation in both hands in one examination. Thousands of patients are now documented and most literature focuses on inflammatory arthritides, which affect synovial joints and their related structures, making it a powerful tool in the diagnostic process of early undifferentiated arthritis and rheumatoid arthritis. However, it has become gradually clear that this technique has the potential to go even further than that. FOI allows visualization of other types of tissues. This means that FOI can also support the diagnostic process of vasculopathies, myositis, collagenoses, and other connective tissue diseases. This work summarizes the most prominent imaging features found in FOI examinations of inflammatory diseases, outlines the underlying anatomical structures, and introduces a nomenclature for the features and, thus, supports the idea that this tool is a useful part of the imaging repertoire in rheumatology clinical practice, particularly where other imaging methods are not easily available.

Monitoring of patients with rheumatoid arthritis by indocyanine green (ICG)-enhanced fluorescence optical imaging treated with anti-TNFα therapy

BACKGROUND

Fluorescence optical imaging (FOI) enables visualisation of inflammation in both hands in rheumatoid arthritis (RA).

OBJECTIVE

To investigate the usefulness of FOI in treatment monitoring under anti-TNFα therapy with certolizumab pegol (CZP) in patients with RA in comparison to clinical and laboratory outcome parameters.

METHODS

CZP-naïve patients with RA were eligible for this open-label study with an observational period of 52 weeks. Disease activity was monitored by the clinical score DAS28, tender/swollen joint count (TJC-28/SJC-28) and laboratory outcomes for systemic inflammation (CRP and ESR). FOI results were analysed in three different phases (P1-3) and PrimaVistaMode (PVM) by the FOI activity score (FOIAS).

RESULTS

Twenty-eight RA patients (median age 52.5 years, 26 females, thirteen with a history of other biologic therapy) were included. DAS28 (CRP) decreased from moderate disease activity at baseline (median 4.6, IQR 1.8) to low disease activity at week (w)52 (median 2.7, IQR 2.1; p < 0.001). Statistically significant decreases could also be demonstrated for SJC-28 and TJC-28. CRP/ESR were reduced numerically from baseline to w52. FOIAS in P1 (early phase) showed a continuous decrease of enhancement during the course of treatment period: from baseline (median 1.5, IQR 9.3) over w6 (median 1.0, IQR 3.0; p = 0.069), w12 (median 0.5, IQR 3.0; p = 0.171), w24 (n = 27, median 0.0, IQR 3.0; p = 0.004), until w52 (n = 18, median 0.0, IQR 2.8; p = 0.091), which could not be presented for FOIAS in P2, P3 and PVM.

CONCLUSION

FOI in P1 appears to be a valuable tool for fast and easy monitoring of treatment response to certolizumab in a clinical setting.

Imaging of the Nail Unit in Psoriatic Patients - a Systematic Scoping Review of Techniques and Terminology

Background

The growing interest in the visualization of psoriatic nail unit changes has led to the discovery of an abundance of image characteristics across various modalities.

Objective

To identify techniques for non‐invasive imaging of nail unit structures in psoriatic patients and review extracted image features to unify the diverse terminology.

Methods

For this systematic scoping review, we included studies available on PubMed and Embase, independently extracted image characteristics, and semantically grouped the identified features to suggest a preferred terminology for each technique.

Results

After screening 753 studies, 67 articles on the visualization of clinical and subclinical psoriatic changes in the nail plate, matrix, bed, folds and hyponychium were included. We identified 4 optical and 3 radiological imaging techniques for the assessment of surface (dermoscopy [n = 16], capillaroscopy [n = 12]), sub‐surface (ultrasound imaging [n = 36], optical coherence tomography [n = 4], fluorescence optical imaging [n = 3]), and deep‐seated psoriatic changes (magnetic resonance imaging [n = 2], positron emission tomography‐computed tomography [n = 1]). By condensing 244 image feature descriptions into a glossary of 82 terms, overall redundancy was cut by 66.4% (37.5%–77.1%). More than 75% of these image features provide additional disease‐relevant information that is not captured using conventional clinical assessment scales.

Conclusions

This review has identified, unified, and contextualized image features and related terminology for non‐invasive imaging of the nail unit in patients with psoriatic conditions. The suggested glossary could facilitate the integrative use of non‐invasive imaging techniques for the detailed examination of psoriatic nail unit structures in research and clinical practice.

Follow-Up Comparison of Fluorescence Optical Imaging With Musculoskeletal Ultrasound for Early Detection of Psoriatic Arthritis

Objectives

Early diagnosis of psoriatic arthritis (PsA) is crucial for a patient outcome but hampered by heterogenous manifestation and a lack of specific biomarkers. We recently showed that fluorescence optical imaging (FOI) can differentiate between patients with confirmed and suspected PsA. This study aims to follow-up (FU) patients with confirmed and suspected PsA focusing on patients with a change from suspected to confirmed PsA by the use of FOI in comparison with musculoskeletal ultrasound (MSUS).

Methods

Follow-up examination of patients included in the study performed by Erdmann-Keding et al. in which FOI of both hands was performed in a standardized manner using three predefined phases (p1–p3) and PrimaVista Mode (PVM). The comparison was drawn to grayscale–power Doppler (GS/PD) MSUS of the clinically dominant hand (wrist, MCP, PIP, DIP 2–5) from dorsal or palmar.

Results

Patients with a change from suspected to diagnosed PsA showed an increased prevalence of joints with pathological enhancement in FOI (p = 0.046) with an unchanged joint distribution pattern, especially with a dominant involvement of DIP joints. Compared to the baseline, these patients were three times more common to show enhancement in FOI p3 at FU. Newly detected pathologic joints by FOI (PVM, p2) and MSUS at FU were positively associated with the change of diagnosis from suspected to confirmed PsA (FOI: AUC 0.78; GSUS: AUC 0.77).

Conclusion

Fluorescence optical imaging appears to be a helpful tool to detect early PsA and to distinguish between acute and chronic disease stages. It could thereby become a suitable tool as a screening method to select psoriasis patients with an indication for further rheumatological evaluation.

Side-chain modification of collagen-targeting peptide prevents dye aggregation for improved molecular imaging of arthritic joints

Near-infrared (NIR) dye-peptide conjugates are widely used for tissue-targeted molecular fluorescence imaging of pathophysiologic conditions. However, the significant contribution of both dye and peptide to the net mass of these bioconjugates implies that small changes in either component could alter their photophysical and biological properties. Here, we synthesized and conjugated a type I collagen targeted peptide, RRANAALKAGELYKCILY, to either a hydrophobic (LS1000) or hydrophilic (LS1006) NIR fluorescent dye. Spectroscopic analysis revealed rapid self-assembly of both LS1000 and LS1006 in aqueous media to form stable dimeric/H aggregates, regardless of the free dye's solubility in water. We discovered that replacing the cysteine residue in LS1000 and LS1006 with acetamidomethyl cysteine to afford LS1001 and LS1107, respectively, disrupted the peptide's self-assembly and activated the previously quenched dye's fluorescence in aqueous conditions. These results highlight the dominant role of the octadecapeptide, but not the dye molecules, in controlling the photophysical properties of these conjugates by likely sequestering or extruding the hydrophobic or hydrophilic dyes, respectively. Application of the compounds for imaging collagen-rich tissue in an animal model of inflammatory arthritis showed enhanced uptake of all four conjugates, which retained high collagen-binding affinity, in inflamed joints. Moreover, LS1001 and LS1107 improved the arthritic joint-to-background contrast, suggesting that reduced aggregation enhanced the clearance of these compounds from non-target tissues. Our results highlight a peptide-driven strategy to alter the aggregation states of molecular probes in aqueous solutions, irrespective of the water-solubilizing properties of the dye molecules. The interplay between the monomeric and aggregated forms of the conjugates using simple thiol-modifiers lends the peptide-driven approach to diverse applications, including the effective imaging of inflammatory arthritis joints.

New Perspectives on Diagnosing Psoriatic Arthritis by Imaging Techniques

Psoriatic arthritis is a chronic inflammatory condition that can lead to severe functional impairment and irreversible damage. The diagnosis can be difficult in early cases where the clinical exam is often scarce. The lack of a serological biomarker can lead to a considerable delay in diagnosis. In this review, we discuss the existent imaging methods that have improved the diagnosis of psoriatic arthritis (PsA). The degree and type of musculoskeletal involvement cannot be assessed by only one imaging method. We think that a combination of methods is the best approach to evaluate both structural damage and inflammatory lesions and that ultrasound (US) could be the best tool to screen a patient when considering the diagnosis of PsA. US is an accessible, non-ionizing technique that offers information regarding active inflammation in joints, entheses, and soft tissues.

Non-invasive monitoring of arthritis treatment response via targeting of tyrosine-phosphorylated annexin A2 in chondrocytes

BACKGROUND

The development and optimization of therapies for rheumatoid arthritis (RA) is currently hindered by a lack of methods for early non-invasive monitoring of treatment response. Annexin A2, an inflammation-associated protein whose presence and phosphorylation levels are upregulated in RA, represents a potential molecular target for tracking RA treatment response.

METHODS

LS301, a near-infrared dye-peptide conjugate that selectively targets tyrosine 23-phosphorylated annexin A2 (pANXA2), was evaluated for its utility in monitoring disease progression, remission, and early response to drug treatment in mouse models of RA by fluorescence imaging. The intraarticular distribution and localization of LS301 relative to pANXA2 was determined by histological and immunohistochemical methods.

RESULTS

In mouse models of spontaneous and serum transfer-induced inflammatory arthritis, intravenously administered LS301 showed selective accumulation in regions of joint pathology including paws, ankles, and knees with positive correlation between fluorescent signal and disease severity by clinical scoring. Whole-body near-infrared imaging with LS301 allowed tracking of spontaneous disease remission and the therapeutic response after dexamethasone treatment. Histological analysis showed preferential accumulation of LS301 within the chondrocytes and articular cartilage in arthritic mice, and colocalization was observed between LS301 and pANXA2 in the joint tissue.

CONCLUSIONS

We demonstrate that fluorescence imaging with LS301 can be used to monitor the progression, remission, and early response to drug treatment in mouse models of RA. Given the ease of detecting LS301 with portable optical imaging devices, the agent may become a useful early treatment response reporter for arthritis diagnosis and drug evaluation.

Is the fluorescence optical imaging (FOI) able to discriminate between rheumatoid arthritis patients with and without need of rituximab retherapy? A cohort study

OBJECTIVE

To evaluate the ability of fluorescence optical imaging (FOI) Xiralite in the discrimination between rheumatoid arthritis (RA) patients with and without need of rituximab (RTX) retherapy-in comparison to clinical, laboratory and musculoskeletal ultrasound parameters.

PATIENTS AND METHODS

Patients with established RA were prospectively followed over 1 year by Disease Activity Score 28, patient's global disease activity (visual analogue scale 0-100 mm), C reactive protein and erythrocyte sedimentation rate, ultrasound seven joint (US7) score and FOI in phases 1-3 and automatically generated PrimaVista mode (PVM) at baseline (before RTX) and after 3, 6 and 12 months. The need for RTX retherapy was decided by the treating rheumatologist-blinded to imaging data.

RESULTS

31 patients (female 77.4%, mean age 60.1±11.4, mean disease duration 14.9±7.1 years) were included. Fourteen (45.2%) patients received RTX retherapy within 12 months. In the group with RTX retherapy, FOI in PVM mode was the only parameter that presented significant increase over time (β: 0.40, 95% CI: 0.08 to 0.71, p=0.013)-compared with the group without retherapy. In the prediction model via ROC analysis, FOI in PVM reached the highest values of all imaging, clinical and laboratory parameters which was associated with retherapy over 1 year with an area under the curve (AUC) of 0.78 (OR: 0.84, 95% CI: 0.72 to 0.98, p=0.031). US7 GS synovitis score revealed similar association with an AUC of 0.73 (p=0.049).

CONCLUSION

US7 GS synovitis score and FOI in PVM are able to discriminate between patients with and without need for RTX retherapy better than clinical and laboratory parameters.

Fluorescence optical imaging: ready for prime time?

The novel technique of fluorescence optical imaging (FOI, Xiralite), which is approved in the European Union and the USA for clinical use, has been the object of studies since 2009. Indocyanine green-based FOI can demonstrate an impaired microcirculation caused by inflammation in both hands in one examination. Several studies have investigated FOI for detection of joint inflammation by comparing FOI to magnetic resonance imaging (MRI) and/or musculoskeletal ultrasound (MSUS). The results have shown a generally good agreement (>80%) between FOI and clinical examination, MRI and MSUS by power Doppler in inflammatory joint diseases. Moreover, characteristic enhancements in skin and nails are seen in PsA, which potentially can be useful in the diagnostic process of early undifferentiated arthritis. Furthermore, FOI has been investigated for the visualisation of a disturbed microcirculation in the hands and fingers of patients with systemic sclerosis (SSc), highlighting the potential of monitoring vascular changes in SSc and other vasculopathies. The available data indicate that it is time to consider FOI as a useful part of the imaging repertoire in rheumatology clinical practice, particularly where MSUS and MRI are not easily available.

A Novel Fluorescence Optical Imaging Scoring System for Hand Synovitis in Rheumatoid Arthritis - validity and agreement with ultrasound

OBJECTIVES

To develop and validate a new semiquantitative Fluorescence Optical Imaging (FOI) scoring system - the FOI Enhancement-Generated rheumatoid arthritis (RA) Score (FOIE-GRAS) for synovitis assessment in the hand.

METHODS

The development of FOIE-GRAS was based on consensus of 4 experts in musculoskeletal imaging. Forty-six RA patients, eligible for treatment intensification and with ≥1 clinically swollen joint in the hands and 11 healthy controls were included. FOI, ultrasound and clinical assessment of both hands were obtained at baseline and for RA patients after 3- and 6-months' follow-up. Twenty RA patients had an FOI rescan after 4 hours. Synovitis was scored using FOIE-GRAS and the OMERACT ultrasound synovitis scoring system. All FOI images were scored by 2 readers. Inter-scan, inter-and intra-reader reliability were determined. Furthermore, FOIE-GRAS agreement with ultrasound and responsiveness was assessed.

RESULTS

FOIE-GRAS synovitis was defined as early enhancement and scores based on the degree of coverage of the specific joint region after 3 seconds (0-3). Inter-scan, intra- and inter-reader intraclass correlations coefficients (ICC) were good-excellent for all baseline scores (0.76-0.98) and moderate-to-good for change (0.65-76).The FOIE-GRAS had moderate agreement with ultrasound (ICC 0.30-0.54) for total score, a good standardized response mean (>0.80), and moderate correlation with clinical joint assessment and DAS28-CRP. The median (IQR) reading time per FOI examination was 133 (109;161) seconds. Scores were significantly lower in controls 1(0;4) than RA patients 11(6;19).

CONCLUSION

The FOIE-GRAS offers a feasible and reliable assessment of synovitis in RA, with a moderate correlation with ultrasound and DAS28CRP, and good responsiveness.

Multispectral optoacoustic tomography might be a helpful tool for noninvasive early diagnosis of psoriatic arthritis

Currently used imaging methods for diagnosis of psoriatic arthritis (PsA) frequently come along with exposure to radiation and can often only show long-term effects of the disease. The aim of the study was to check the feasibility of a new optoacoustic imaging method to identify PsA. 22 psoriasis patients and 19 healthy volunteers underwent examination using multispectral optoacoustic tomography (MSOT). The presence of arthritis was assessed via quantification of optoacoustic signal intensity of the endogenous chromophores oxy- and deoxyhemoglobin. We conducted high-resolution real-time ultrasound images of the finger joints. The semi quantitative analysis of the optoacoustic signals for both hemoglobin species showed a significant higher blood content and oxygenation in PsA patients compared to healthy controls. Our results indicate that MSOT might allow detection of inflammation in an early stage. If the data is further confirmed, this technique might be a suitable tool to avoid delay of diagnosis of PsA.

Medical imaging examination in psoriasis and early psoriatic arthritis patients: an updated systematic review and meta-analysis

Psoriatic arthritis appears in one in four skin psoriasis patients. Early detection of the presence of joint involvement and early interception of its developments may minimize long-term functional disability, and the radiological methods may be a perfect choice. To summarize and compare different imaging methods for diagnosing early-stage psoriatic arthritis and determine the necessity of joint examination in all psoriasis patients, several electronic databases, including MEDLINE and EMBASE, were searched for English language studies. A specific selection criterion followed the retrieval of studies. Thirteen studies were finally enrolled in the meta-analysis, eight of which compared the bone changes presentat on medical imaging examination between psoriasis patients without psoriatic arthritis and healthy people; three studies focused on differences between psoriatic arthritis patients and free joint involvement psoriasis patients shown on medical imaging tests. Medical imaging examination, including ultrasound (US), high-resolution peripheral quantitative CT scans (HR-pQCT), and magnetic resonance imaging (MRI), can be good choices for detecting the start of asymptomatic joint inflammation in psoriasis patients, which is essential to early detection and interception of joint damage to lower joint deformities and improve the future quality of life for patients. Additionally, the examination for psoriasis patients with arthralgia is also highly recommended.

Associations between Fluorescence Optical Imaging and Magnetic Resonance Imaging and symptoms in hand osteoarthritis

OBJECTIVES

To investigate whether Fluorescence Optical Imaging (FOI) enhancement and Magnetic Resonance Imaging (MRI)-defined synovitis are associated with pain and physical function in hand osteoarthritis (OA) patients.

METHODS

Bilateral FOI scans and MRI of the dominant hand were available for 221 patients. Finger joints were examined for tenderness on palpation. Pain in individual finger joints during the last 24 h and last 6 weeks and hand pain intensity by the Australian/Canadian hand index and Numeric Rating Scale were self-reported. On joint level, we applied logistic regression with generalized estimating equations to examine whether FOI enhancement and MRI-defined synovitis were associated with pain in the same joint. On subject level, we applied linear regression to assess whether FOI and MRI sum scores were associated with pain intensity and physical function.

RESULTS

Metacarpophalangeal and thumb base joints were excluded from analyses due to little/no FOI enhancement. Finger joints with FOI enhancement on the composite image had higher odds (95% confidence interval) of pain during the last 6 weeks (grade 1: 1.4 (1.2-1.6), grade 2-3: 2.1 (1.7-2.6)). Similar results were found for joint pain during the last 24 h and joint tenderness in fingers. Numerically stronger associations were found between MRI-defined synovitis and finger joint pain/tenderness. FOI and MRI sum scores demonstrated no/weak associations with hand pain and physical function.

CONCLUSION

FOI enhancement and MRI-defined synovitis were associated with pain in the same finger joint. None of the imaging modalities demonstrated consistent associations with pain, stiffness and physical function on subject level.

Fluorescence optical imaging in patients with active rheumatoid arthritis: a comparison with ultrasound and an association with biomarkers

Objectives: This study compared indocyanine green (ICG)-enhanced fluorescence optical imaging (FOI) and musculoskeletal ultrasound (MSUS), and explored the significance of the FOI findings based on the association between the FOI and MSUS findings and serum biomarkers in patients with rheumatoid arthritis (RA). The study also explored the association between the FOI findings and patients' joint destruction at the joint-area level.Method: We enrolled 50 consecutive patients with active RA from among the patients hospitalized from May 2014 to March 2016 at Nagasaki University Hospital, Japan. FOI images were acquired with the Xiralite^® fluorescence imaging system and compared with the patients' clinical examination results and MSUS findings. On the same day, the patients' clinical disease activity and levels of serum biomarkers (including vascular endothelial growth factor) were obtained.Results: Although the FOI detected synovitis with high sensitivity, the frequency of positive findings and the diagnostic performance with MSUS as the reference standard for FOI differed considerably among the phases of FOI as well as among the affected joint regions. The FOI scores were positively correlated with clinical disease activity, MSUS scores, and serum biomarkers. The severity of FOI-proven synovitis was associated with the presence of MSUS-proven bone erosion.Conclusion: FOI is effective for detecting joint inflammation in RA patients, with high accuracy. The severity of the FOI score was closely associated with the joint destruction at the joint-area level. However, the significance of positive FOI findings differed depending on not only the phase of FOI but also the affected joint regions.

Innovative Imaging Technique for Visualization of Vascularization and Established Methods for Detection of Musculoskeletal Inflammation in Psoriasis Patients

Psoriasis (PsO) is one of the common chronic inflammatory skin diseases. Approximately 3% of the European Caucasian population is affected. Psoriatic arthritis (PsA) is a chronic immune-mediated disease associated with PsO characterized by distinct musculoskeletal inflammation. Due to its heterogeneous clinical manifestations (e.g., oligo- or polyarthritis, enthesitis, dactylitis, and axial inflammation), early diagnosis of PsA is often difficult and delayed. Approximately 30% of PsO patients will develop PsA. The responsible triggers for the transition from PsO only to PsA are currently unclear, and the impacts of different factors (e.g., genetic, environmental) on disease development are currently discussed. There is a high medical need, recently unmet, to specifically detect those patients with an increased risk for the development of clinically evident PsA early to initiate sufficient treatment to inhibit disease progression and avoid structural damage and loss of function or even intercept disease development. Increased neoangiogenesis and enthesial inflammation are hypothesized to be early pathological findings in PsO patients with PsA development. Different disease states describe the transition from PsO to PsA. Two of those phases are of value for early detection of PsA at-risk patients to prevent later development of PsA as changes in biomarker profiles are detectable: the subclinical phase (soluble and imaging biomarkers detectable, no clinical symptoms) and the prodromal phase (imaging biomarkers detectable, unspecific musculoskeletal symptoms such as arthralgia and fatigue). To target the unmet need for early detection of this at-risk population and to identify the subgroup of patients who will transition from PsO to PsA, imaging plays an important role in characterizing patients precisely. Imaging techniques such as ultrasound (US), magnetic resonance imaging (MRI), and computerized tomography (CT) are advanced techniques to detect sensitively inflammatory changes or changes in bone structure. With the use of these techniques, anatomic structures involved in inflammatory processes can be identified. These techniques are complemented by fluorescence optical imaging as a sensitive method for detection of changes in vascularization, especially in longitudinal measures. Moreover, high-resolution peripheral quantitative CT (HR-pQCT) and dynamic contrast-enhanced MRI (DCE-MRI) may give the advantage to identify PsA-related early characteristics in PsO patients reflecting transition phases of the disease.

Detection of subclinical skin manifestation in patients with psoriasis and psoriatic arthritis by fluorescence optical imaging

OBJECTIVES

To investigate the frequency of subclinical skin inflammation in both hands by fluorescence optical imaging (FOI) in patients with psoriasis/psoriatic arthritis (Pso/PsA) vs. rheumatoid arthritis (RA) and healthy individuals, and to correlate these findings with cardiovascular (CV) risk factors.

PATIENTS AND METHODS

The FOI scans were analyzed retrospectively to detect clinically invisible skin enhancement (0-3 scale) in both hands without relationship to underlying joints or blood vessels. We further characterized the FOI patterns and sorted the scans into groups based on the assumed diagnosis (Pso/PsA, RA, and healthy controls), which was compared with the physician's diagnosis. Furthermore, the associations between CV risk factors and imaging findings were investigated by regression analyses.

RESULTS

We included FOI scans of patients with Pso/PsA (n = 80), RA (n = 78), and healthy controls (n = 25). Subclinical skin enhancement on the back of their hands was more common in Pso/PsA (72.5%) than in RA patients (20.5%) and healthy individuals (28.0%) (p < 0.001). Based on the FOI pattern, the majority of patients with Pso/PsA (72.5%), RA (76.9%), and healthy controls (68.0%) were classified correctly using the physician-based diagnosis as reference (overall agreement of 74%, kappa = 0.57). No CV risk factors except body weight (kg) were associated with subclinical skin enhancement (OR 1.04, 95% CI 1.02-1.06; p < 0.001).

CONCLUSION

Subclinical subdermal skin inflammation was common in Pso/PsA patients using FOI. Based on the FOI pattern, most patients with Pso/PsA and were classified with the correct diagnosis. We demonstrated an important influence of the body weight on our FOI results. FOI may be a helpful novel tool to study microcirculation in rheumatic diseases with skin involvement.

Validity and diagnostic performance of fluorescence optical imaging measuring synovitis in hand osteoarthritis: baseline results from the Nor-Hand cohort

OBJECTIVE

Fluorescence optical imaging (FOI) demonstrates enhanced microcirculation in finger joints as a sign of inflammation. We wanted to assess the validity and diagnostic performance of FOI measuring synovitis in persons with hand OA, comparing it with magnetic resonance imaging (MRI)- and ultrasound-detected synovitis.

METHODS

Two hundred and twenty-one participants with hand OA underwent FOI and ultrasound (gray-scale synovitis and power Doppler activity) of the bilateral hands and contrast-enhanced MRI examination of the dominant hand. Fifteen joints in each hand were scored on semi-quantitative scales (grade 0-3) for all modalities. Four FOI images were evaluated: one composite image (Prima Vista Mode (PVM)) and three images representing phases of fluorescent dye distribution. Spearman's correlation coefficients were calculated between sum scores of FOI, MRI, and ultrasound. Sensitivity, specificity, and area under the curve (AUC) were calculated for FOI using MRI or ultrasound as reference.

RESULTS

FOI did not demonstrate enhancement in the thumb base, and the joint was excluded from further analyses. FOI sum scores showed poor to fair correlations with MRI (rho 0.01-0.24) and GS synovitis sum scores (rho 0.12-0.25). None of the FOI images demonstrated both good sensitivity and specificity, and the AUC ranged from 0.50-0.61 and 0.51-0.63 with MRI and GS synovitis as reference, respectively. FOI demonstrated similar diagnostic performance with PD activity and GS synovitis as reference.

CONCLUSION

FOI enhancement correlated poorly with synovitis assessed by more established imaging modalities, questioning the value of FOI for the evaluation of synovitis in hand OA.

Subclinical Treatment Targets in Rheumatology: Lessons from Randomized Clinical Trials in Rheumatoid Arthritis

In treat-to-target strategies, choosing the correct target is fundamental to success. The target should be associated with future good outcomes for the patient. Most rheumatic diseases are characterized by inflammation, affecting different tissues depending on the condition. Low-grade, subclinical inflammation is by definition not apparent on clinical examination, but may have significant long-term consequences for the individual. It has thus been debated whether targeting subclinical inflammation would improve long-term outcomes in rheumatoid arthritis. The authors use rheumatoid arthritis as an example to describe and discuss the status of subclinical targets in treat-to-target strategies within rheumatology.

[Imaging of psoriatic arthritis and aspects of radiographic progression]

Psoriatic arthritis (PsA) is a heterogeneous multifactorial disease with musculoskeletal involvement, which can be manifested as monoarthritis, oligoarthritis or polyarthritis and in some patients can also affect the axial skeleton. The most frequent indications of inflammation are bone marrow edema and enthesitis. The early and differential diagnosis of PsA is a clinical challenge, particularly as a differential diagnosis from other inflammatory or degenerative diseases of joints. Inflammatory joint and tendon alterations in the region of the extremities and the spine can be visualized with high sensitivity by the use of magnetic resonance imaging (MRI), musculoskeletal sonography (US) and fluorescence optical imaging (FOI). The use of MRI has a prognostic value with respect to the further radiographic course of the disease, particularly in the initial stages of the disease. Structural damage can be specifically and also partially demonstrated 3‑dimensionally in peripheral joints and the spine by the use of computed tomography (CT) and conventional X‑ray imaging. High-resolution peripheral quantitative CT (HR-pQCT) in particular, can visualize pathophysiological processes and the morphological consequences even in early stages of the disease. The values of conventional X‑ray diagnostics, CT, MRI, musculoskeletal US and alternative imaging procedures are presented with respect to the diagnostics and prognosis of the progression of patients with PsA.

Fluorescence optical imaging for the detection of potential psoriatic arthritis in comparison to musculoskeletal ultrasound

OBJECTIVE

Comparison of fluorescence optical imaging (FOI) with grayscale (GS) and power Doppler ultrasound (PDUS) to detect joint inflammation in patients with confirmed or suspected psoriatic arthritis (PsA).

METHODS

Patients (n = 60) with psoriasis and tenderness and/or swelling of joints were separated into two groups: diagnosis confirmed by the treating dermatologist before the start of the study (n = 26), and suspected PsA (n = 34). GS/PDUS of the hand most clinically affected was performed with a dorsal/palmar view (wrist, MCP, PIP, DIP2-5). FOI examination was carried out in a standardized manner by analyzing the predefined Phases 1-3.

RESULTS

FOI was found to be more sensitive than ultrasound (US) for detection of inflammation in PIP/DIP joints (p = 0.035). Confirmed PsA patients showed more findings in FOI P2 and P3, while suspected PsA patients showed more findings in P1. In the confirmed PsA group, most involved joints were MCP joints, while in the suspected PsA group, more involved wrist joints and DIP joints (p = 0.006) were detected with FOI.

CONCLUSIONS

The differences between the confirmed and suspected groups indicate that FOI is helpful in the detection of early PsA since P1 may correspond to acute inflammation, whereas P2 and P3 enhancement reflect chronic inflammation. Fluorescence optical imaging might therefore be a novel diagnostic tool for early PsA diagnosis.

Fluorometric Imaging for Early Diagnosis and Prognosis of Rheumatoid Arthritis

Early diagnosis and monitoring of disease progress are of significant importance in the effective treatment of rheumatoid arthritis (RA), because the continuing inflammation can lead to irreversible joint damage and systemic complications. However, applying imaging modalities for the prognosis of RA remains challenging, because no tissue-specific guidelines are available to monitor the progressive course of RA. In this study, fluorometric imaging of RA is reported using bioengineered targeted agents of the blood vessel, bone, and cartilage in combination with the customized optical fluorescence imaging system. Separate but simultaneous tissue-specific images of synovitis, cartilage destruction, and bone resorption are obtained from a mouse model of RA, which allows quantification of the prognosis of diseases at each stage. Thus, the fluorometric imaging of RA by using tissue-specific contrast agents plays a key role in the systemic treatment of RA by monitoring structural damage and disease progression.

Fluorescence optical imaging for treatment monitoring in patients with early and active rheumatoid arthritis in a 1-year follow-up period

Background

Fluorescence optical imaging (FOI) enables visualization of inflammation in the hands in rheumatic joint diseases with currently a lack of long-term follow-up studies.

Objective

To investigate FOI for treatment monitoring in a homogenous cohort of patients with early (disease duration < 2 years) and active (DAS28 > 3.2) RA over a period of 12 months.

Methods

Thirty-five RA patients (24 (68.6%) females, mean age 53.3 years (SD 13.6)) were investigated clinically by DAS28, tender joint count (TJC) and swollen joint count (SJC) and by FOI in phases 1–3 and PrimaVistaMode (PVM) before therapy change and after 12 months. The FOI activity score (FOIAS) was calculated based on individual joint scores from 0 to 3 in 30 joints per patient, adding up to a sum score (0–90).

Results

We found a statistically significant reduction of FOIAS in phase 1 from baseline (median 5.0, IQR 24.96) to follow-up (median 1.0, IQR 4.0) in all patients (p = 0.0045), both in responders and non-responders according to EULAR response criteria by DAS28. Statistically significant reductions over 12 months were found for median DAS28(ESR) 5.61 to 3.31, TJC 7.0 to 1.0, and SJC 5.0 to 1.0 (each p <  0.001). No statistically significant correlations were detected between the FOIAS change in phase 1 and DAS28(ESR), TJC, or SJC. Correlations between the other phases and clinical outcomes were weak to moderate.

Conclusion

Reduced early enhancement in FOI phase 1 can be observed in clinically responding and non-responding early RA patients under treatment. Regarding potential marker performance, FOI probably shows a reduction of inflammation more objectively.

Potential clinical utility of a novel optical tomographic imaging for the quantitative assessment of hand rheumatoid arthritis

Optical tomographic imaging (OTI) was reported to be a novel technique for the early diagnosis and disease activity assessment of rheumatoid arthritis (RA). This study aimed to evaluate the clinical utility of OTI for the detection of hand synovitis of RA patients. Manu-scan was used to perform imaging targeting the proximal interphalangeal (PIP) and metacarpophalangeal (MCP) joints in 12 RA patients and three controls. The enrolled RA patients also underwent magnetic resonance imaging (MRI) and bone scintigraphy (BS) to provide reference images. Of the 181 joints feasible for OTI analysis, 140 joints (111 in RA patients and 29 in controls, 77.3%) in which the difference of the OTI indices in the two measurements was within 20% were evaluated. The OTI indices in RA joints were significantly lower than those in control joints (p < 0.001). Overall, the OTI indices in RA joints decreased as the synovitis grades on MRI or BS increased. Moreover, OTI was able to discriminate between RA and control joints (AUC = 0.815, 95% CI 0.739-0.891), even if RA joints were normal on physical examination (AUC = 0.714, 95% CI 0.594-0.834). OTI was in good agreement (kappa = 0.60) with MRI for evaluating synovitis in RA patients and showed positive results in 11.4% of clinically asymptomatic joints. OTI in this study showed the potential to be a supplementary imaging modality for the quantification of synovial inflammation in PIP and MCP joints of RA patients. Further large-scale trials are needed to confirm these findings.

Hand osteoarthritis: clinical phenotypes, molecular mechanisms and disease management

Osteoarthritis (OA) is a highly prevalent condition, and the hand is the most commonly affected site. Patients with hand OA frequently report symptoms of pain, functional limitations and frustration in undertaking everyday activities. The condition presents clinically with changes to the bone, ligaments, cartilage and synovial tissue, which can be observed using radiography, ultrasonography or MRI. Hand OA is a heterogeneous disorder and is considered to be multifactorial in aetiology. This Review provides an overview of the epidemiology, presentation and burden of hand OA, including an update on hand OA imaging (including the development of novel techniques), disease mechanisms and management. In particular, areas for which new evidence has substantially changed the way we understand, consider and treat hand OA are highlighted. For example, genetic studies, clinical trials and careful prospective imaging studies from the past 5 years are beginning to provide insights into the pathogenesis of hand OA that might uncover new therapeutic targets in the disease.

[Biomarkers and imaging for diagnosis and stratification of rheumatoid arthritis and spondylarthritis in the BMBF consortium ArthroMark]

Rheumatic diseases are among the most common chronic inflammatory disorders. Besides severe pain and progressive destruction of the joints, rheumatoid arthritis (RA), spondyloarthritides (SpA) and psoriatic arthritis (PsA) impair working ability, reduce quality of life and if treated insufficiently may enhance mortality. With the introduction of biologics to treat these diseases, the demand for biomarkers of early diagnosis and therapeutic stratification has been growing continuously. The main goal of the consortium ArthroMark is to identify new biomarkers and to apply modern imaging technologies for diagnosis, follow-up assessment and stratification of patients with RA, SpA and PsA. With the development of new biomarkers for these diseases, the ArthroMark project contributes to research in chronic diseases of the musculoskeletal system. The cooperation between different national centers will utilize site-specific resources, such as biobanks and clinical studies for sharing and gainful networking of individual core areas in biomarker analysis. Joint data management and harmonization of data assessment as well as best practice characterization of patients with new imaging technologies will optimize quality of marker validation.

Association between baseline clinical and imaging findings and the development of digital ulcers in patients with systemic sclerosis

Objective

Systemic sclerosis (SSc) can lead to ischemic complications such as digital ulcers (DUs). The aim of the study was to find predictors of DUs by clinical and new imaging methods.

Patients and methods

All 79 SSc patients included in the study received a clinical, colour Doppler ultrasound (CDUS), fluorescence optical imaging (FOI) and capillaroscopy examination at baseline, and their capacity to predict new DU development was analysed in 76 patients at 12 months follow-up.

Results

Twenty-two of 76 patients (28.9%) developed new ulcers during follow-up (diffuse SSc 48.1%; limited SSc 18.4%). Receiver operating characteristic (ROC) curve analysis revealed an area under the curve of 0.7576 for DU development, with a specificity of 87% and a sensitivity of 54.6% (p = 0.0003, OR = 8.1 [95%CI 2.5–25.6]) at a cut-off of ≥ 21 points (ACR/EULAR classification criteria for SSc). Capillaroscopy and CDUS had high sensitivity (100% and 95.5%) but low specificity (28.9% and 22.2%) for ulcer occurrence when used alone, but better specificity (46.3%) when combined (OR = 18.1 [95%CI 2.3–144.4]; p = 0.0004). Using FOI, fingers with pathologic staining had a higher risk for new ulcer development in the same finger (p = 0.0153). General future DU (i.e. DU also in other fingers) was associated with a missing FOI signal in the right digit III at baseline (p = 0.048).

Conclusion

New imaging modalities can predict digital ulcer development in SSc patients with high sensitivity for capillaroscopy and CDUS and enhanced specificity when combined. A missing signal of FOI in the right digit III at baseline was associated with general future DU.

Minimally invasive method for the point-of-care quantification of lymphatic vessel function

Current clinical methods for the evaluation of lymphatic vessel function, crucial for early diagnosis and evaluation of treatment response of several pathological conditions, in particular of postsurgical lymphedema, are based on complex and mainly qualitative imaging techniques. To address this unmet medical need, we established a simple strategy for the painless and quantitative assessment of cutaneous lymphatic function. We prepared a lymphatic-specific tracer formulation, consisting of the clinically approved near-infrared fluorescent dye, indocyanine green, and the solubilizing surfactant Kolliphor HS15. The tracer was noninvasively delivered to the dermal layer of the skin using MicronJet600 hollow microneedles, and the fluorescence signal decay at the injection site was measured over time using a custom-made, portable detection device. The decay rate of fluorescence signal in the skin was used as a direct measure of lymphatic vessel drainage function. With this method, we could quantify impaired lymphatic clearance in transgenic mice lacking dermal lymphatics and distinguish distinct lymphatic clearance patterns in pigs in different body locations and under manual stimulus. Overall, this method has the potential for becoming a noninvasive and quantitative clinical "office test" for lymphatic function assessment.

The "green nail" phenomenon in ICG-enhanced fluorescence optical imaging - a potential tool for the differential diagnosis of psoriatic arthritis

BACKGROUND AND OBJECTIVES

Early diagnosis of psoriatic arthritis poses a particular challenge. A novel fluorescence optical imaging technique, the Xiralite® system is very useful in this regard as it allows for visualization of microvasculature and perfusion. The present study is the first to systematically examine fluorescence optical signals in a large psoriatic arthritis cohort.

PATIENTS AND METHODS

In the primary study, we reviewed and analyzed extra-articular fluorescence optical signal patterns in 241 imaging sequences obtained from 187 psoriatic arthritis patients; 36 fluorescence optical sequences from 31 patients with rheumatoid arthritis served as controls. In a follow-up study, 203 consecutive fluorescence optical sequences from 54 psoriatic arthritis patients and 149 control subjects with various inflammatory rheumatic disorders were retrospectively evaluated in order to validate the primary study results in terms of the patterns previously identified.

RESULTS

Psoriatic arthritis patients exhibited three different fluorescence optical signal patterns in projection of the nails that have not been previously described. One of these patterns was the "green nail" sign, which was highly specific (97 %) for psoriatic arthritis. In the follow-up study, the specificity of this phenomenon in psoriatic arthritis was 87 % in comparison to the control cohort.

CONCLUSIONS

In the present study, fluorescence optical signals in the nail region proved to be highly specific for psoriatic arthritis. The "green nail" phenomenon seems to be of particular diagnostic interest as a potential sign of impaired microcirculation of the nail bed.

A Non-Peptidic S100A9 Specific Ligand for Optical Imaging of Phagocyte Activity In Vivo

PURPOSE

Non-invasive assessment of inflammatory activity in the course of various diseases is a largely unmet clinical challenge. An early feature of inflammation is local secretion of the alarmin S100A8/A9 by activated phagocytes. We here evaluate a novel S100A9-targeted small molecule tracer Cy5.5-CES271 for in vivo optical imaging of inflammatory activity in exemplary disease models.

PROCEDURES

Dynamics of Cy5.5-CES271 was characterized in a model of irritant contact dermatitis by sequential fluorescence reflectance imaging (FRI) up to 24 h postinjection (p.i.). Specificity of Cy5.5-CES271 binding to S100A9 in vivo was examined by blocking studies and by employing S100A9^-/- mice. Finally, S100A9 secretion in acute lung inflammation was assessed by Cy5.5-CES271 and FRI of explanted lungs.

RESULTS

In ear inflammation, we were able to non-invasively follow the time course of S100A9 expression using Cy5.5-CES271 and FRI over 24 h p.i. (peak activity at 3 h p.i.). Specificity of imaging could be shown by a significant signal reduction after predosing and using S100A9^-/- mice. In acute lung injury, local and systemic S100A8/A9 levels increased over time and correlated significantly with FRI signal levels in explanted lungs.

CONCLUSIONS

Cy5.5-CES271 shows significant accumulation in models of inflammatory diseases and specific binding to S100A9 in vivo. This study, for the first time, demonstrates the potential of a small molecule non-peptidic tracer enabling imaging of S100A9 as a marker of local phagocyte activity in inflammatory scenarios suggesting this compound class for translational attempts.

A Mobile App With Optical Imaging for the Self-Management of Hand Rheumatoid Arthritis: Pilot Study

Background

Patient outcomes are improved and the burden to the health care system is reduced when individuals are active self-managers of their own health. There is a need for technology that facilitates self-management of rheumatoid arthritis (RA) and can reduce the number of patient visits, promptly identify treatment needs, and reduce the costs associated with poor RA management. A mobile app named LiveWith Arthritis (eTreatMD, Vancouver, BC) has been developed that allows patients with RA to use their mobile device to regularly collect self-management data and to take objective measurements of the impact of RA on their finger joints using optical imaging technology.

Objective

The objectives of this pilot study were to (1) gather preliminary data as to whether a mobile app with hand optical imaging capabilities improves self-management behaviors (self-efficacy in managing symptoms and patient activation), (2) determine if app use shows promise in improving health outcomes (Pain, Health Assessment Questionnaire-II [HAQ-II]), and (3) determine barriers to using the mobile app in adults with RA.

Methods

This pilot study used a mixed-methods design. The quantitative portion was a traditional 2-group experimental design, and the qualitative portion was a follow-up telephone interview for intervention participants who did not complete the study. Measures of self-management included the Patient-Reported Outcomes Measurement Information System (PROMIS) self-efficacy in managing symptoms (P-SEMS) and Patient Activation Measure (PAM). Health outcomes included pain by Visual Analog Scale and disability by HAQ-II.

Results

The final sample consisted of 21 intervention participants and 15 controls. There was a statistically significant improvement in P-SEMS and promising trends for improvement in PAM, HAQ-II, and pain scores for participants who used the app. Of the intervention participants who did not complete the study, 12 completed the qualitative interview on barriers to use. Qualitative content analysis revealed 3 themes for barriers to using the app, including (1) frustration with technology, (2) RA made the app difficult to use, and (3) satisfaction with current self-management system.

Conclusions

The LiveWith Arthritis app shows promise for improving self-management behaviors and health outcomes in adults with RA. Future study with a larger sample size is required to confirm findings. Initial app experience is important for adoption and continual use of the app. Individuals with significant disability to the hand would benefit from voice-activated app features. Participants who already have a system of managing their RA may not feel compelled to switch methods, even when a novel optical imaging feature is available.

Comparison of fluorescence optical imaging, ultrasonography and clinical examination with magnetic resonance imaging as a reference in active rheumatoid arthritis patients

BACKGROUND

Fluorescence optical imaging with indocyanine-green enhancement (FOI) is a new imaging modality for the assessment of hand arthritis. The objective of this study was to compare performance profiles of clinical examination (CE), US and FOI using MRI as a reference in the same active rheumatoid arthritis (RA) patients.

METHODS

CE, US, FOI and MRI were performed on six subjects with active RA. Each sequence of FOI was divided into three phases based on indocyanine-green dynamics and the joints were graded semi-quantitatively. Sensitivities and specificities of CE, US and FOI were calculated using the RAMRIS synovitis score >0 as a reference in a total of 30 joints (the second to fifth metacarpophalangeal (MCP) joints and the wrist of the clinically dominant hand).

RESULTS

FOI showed sensitivities and specificities, respectively, of 85% and of 94% for Phase-1 and 69% and 94% for Phase-2. Sensitivities and specificities were 100% and 35% for CE (tender or swollen), 92% and 41% for gray scale US, and 77% and 100% for color-Doppler US.

CONCLUSIONS

The performance characteristics of FOI in detection of synovitis in patients with active RA are comparable to those of US and more specific than CE. FOI has a potential as an assessment modality of RA.

Magnetic Resonance Imaging of Bilateral Hands Is More Optimal Than MRI of Unilateral Hands for Rheumatoid Arthritis

OBJECTIVE

To explore the advantages of magnetic resonance imaging (MRI) of bilateral hands in rheumatoid arthritis (RA).

METHODS

Consecutive patients with active RA were recruited for clinical assessments, radiographs, and MRI of bilateral hands. Bilateral hands were scanned simultaneously on 3.0 T whole-body MRI system and were scored on synovitis, osteitis, and bone erosion according to the RA MRI scoring (RAMRIS) system.

RESULTS

Among 120 patients included, wrist bones and metacarpophalangeal joint (MCPJ) 2 proximal showed bone erosion in early RA. The second to fifth metacarpal bases and the second to fourth MCPJ distal showed more bone erosion in mid-stage or late-stage RA. When MRI of dominant unilateral hand was analyzed, MRI synovitis and osteitis in 5% of wrists and 3 MRI features in 5-14% of MCPJ were misdiagnosed (McNemar test, all p < 0.05). There were 46% wrist synovitis, 29-52% MCPJ2-5 synovitis, 45% wrist osteitis, and 20%-34% MCPJ2-5 osteitis not detected by joint tenderness and/or swelling. When the clinically more severe hand was selected for MRI of unilateral hand according to physical examination, MRI synovitis in 5% of wrists and 3 MRI features in 7-15% of MCPJ were misdiagnosed (all p < 0.05). Scatter plots and linear regression analyses were used to illustrate RAMRIS between dominant or selected hand (Y values) and nondominant or nonselected hand (X values). All linear models were markedly different from a Y = X linear model, indicating the dominant or clinically more severe hand could not represent the contralateral hand to evaluate RAMRIS.

CONCLUSION

MRI of bilateral hands is more optimal than MRI of the unilateral hand in RA.

Synovitis in mice with inflammatory arthritis monitored with quantitative analysis of dynamic contrast-enhanced NIR fluorescence imaging using iRGD-targeted liposomes as fluorescence probes

BACKGROUND

Rheumatoid arthritis (RA) is a common inflammatory disorder characterized primarily by synovitis and pannus formation in multiple joints, causing joints destruction and irreversible disability in most cases. Early diagnosis and effective therapy monitoring of RA are of importance for achieving the favorable prognosis.

METHODS

We first prepared the targeted fluorescence probes, and then explored the feasibility of near-infrared (NIR) fluorescence molecular imaging to detect and evaluate the RA via the targeted fluorescence probes by quantitative analysis in this study.

RESULTS

The targeted fluorescence probes (indocyanine green-liposomes decorated with iRGD peptide [iLPs]) was successfully prepared. The quantitative analysis found that strong fluorescence signal was detected in inflamed paws and the fluorescence signal in iLPs group was 3.03-fold higher than that in non-targeted (indocyanine green-liposomes decorated without iRGD peptide [LPs]) group (P<0.01) at 15 min after injection, whereas the fluorescence signal from iLPs signal can almost not be observed in the non-inflamed paws, showing the high sensitivity and accuracy for arthritis by the NIR fluorescence imaging based on iLPs.

CONCLUSION

The NIR fluorescence imaging by iLPs may facilitate improved arthritis diagnosis and early assessment of the disease progression by providing an in vivo characterization of angiogenesis in inflammatory joint diseases.

Blood flow characteristics of diabetic patients with complications detected by optical measurement

Background

Diabetes mellitus (DM) is one of the most common diseases worldwide. Uncontrolled and prolonged hyperglycemia can cause diabetic complications, which reduce the quality of life of patients. Diabetic complications are common in DM patients. Because it is impossible to completely recover from diabetic complications, it is important for early detection. In this study, we suggest a novel method of determining blood flow characteristics based on fluorescence image analysis with indocyanine green and report that diabetic complications have unique blood flow characteristics.

Methods

We analyzed time-series fluorescence images obtained from controls, DM patients, and DM patients with complications. The images were segmented into the digits and the dorsum of the feet and hands, and each part has been considered as arterial and capillary flow. We compared the blood flow parameters in each region among the three groups.

Results

The DM patients with complications showed similar blood flow parameters to the controls, except the area under the curve and the maximum intensity, which indicate the blood flow volume. These parameters were significantly decreased in DM patients with complications. Although some blood flow parameters in the feet of DM patients with complications were close to normal blood flow, the vascular response of the macrovessels and microvessels to stimulation of the hands was significantly reduced, which indicates less reactivity in DM patients with complications.

Conclusions

Our results suggest that DM patients, and DM patients with complications, have unique peripheral blood flow characteristics.

Feasibility of photoacoustic/ultrasound imaging of synovitis in finger joints using a point-of-care system

We evaluate a portable ultrasound and photoacoustic imaging (PAI) system for the feasibility of a point-of-care assessment of clinically evident synovitis. Inflamed and non-inflamed proximal interphalangeal joints of 10 patients were examined and compared with joints from 7 healthy volunteers. PAI scans, ultrasound power Doppler (US-PD), and clinical examination were performed. We quantified the amount of photoacoustic (PA) signal using a region of interest (ROI) drawn over the hypertrophic joint space. PAI response was increased 4 to 10 fold when comparing inflamed with contralateral non-inflamed joints and with joints from healthy volunteers (p < 0.001 for both). US-PD and PAI were strongly correlated (Spearman's ρ = 0.64, with 95% CI: 0.42, 0.79). Hence, PAI using a compact handheld probe is capable of detecting clinically evident synovitis. This motivates further investigation into the predictive value of PAI, including multispectral PAI, with other established modalities such as US-PD or MRI.

Detection of Subclinical Arthritis in Mice by a Thrombin Receptor-Derived Imaging Agent

OBJECTIVE

Functional imaging of synovitis could improve both early detection of rheumatoid arthritis (RA) and long-term outcomes. Given the intersection of inflammation with coagulation protease activation, this study was undertaken to examine coagulation protease activities in arthritic mice with a dual-fluorescence ratiometric activatable cell-penetrating peptide (RACPP) that has a linker, norleucine (Nle)-TPRSFL, with a cleavage site for thrombin.

METHODS

K/BxN-transgenic mice with chronic arthritis and mice with day 1 passive serum-transfer arthritis were imaged in vivo for Cy5:Cy7 emission ratiometric fluorescence from proteolytic cleavage and activation of RACPP_NleTPRSFL . Joint thickness in mice with serum-transfer arthritis was measured from days 0 to 10. The cleavage-evoked release of Cy5-tagged tissue-adhesive fragments enabled microscopic correlation with immunohistochemistry for inflammatory markers. Thrombin dependence of ratiometric fluorescence was tested by ex vivo application of RACPP_NleTPRSFL and argatroban to cryosections obtained from mouse hind paws on day 1 of serum-transfer arthritis.

RESULTS

In chronic arthritis, RACPP_NleTPRSFL fluorescence ratios of Cy5:Cy7 emission were significantly higher in diseased swollen ankles of K/BxN-transgenic mice than in normal mouse ankles. A high ratio of RACPP_NleTPRSFL fluorescence in mouse ankles and toes on day 1 of serum-transfer arthritis correlated with subsequent joint swelling. Foci of high ratiometric fluorescence localized to inflammation, as demarcated by immune reactivity for citrullinated histones, macrophages, mast cells, and neutrophils, in soft tissue on day 1 of serum-transfer arthritis. Ex vivo application of RACPP_NleTPRSFL to cryosections obtained from mice on day 1 of serum-transfer arthritis produced ratiometric fluorescence that was inhibited by argatroban.

CONCLUSION

RACPP_NleTPRSFL activation detects established experimental arthritis, and the detection of inflammation by RACPP_NleTPRSFL on day 1 of serum-transfer arthritis correlates with disease progression.

Fibrosis imaging: Current concepts and future directions

Fibrosis plays an important role in many different pathologies. It results from tissue injury, chronic inflammation, autoimmune reactions and genetic alterations, and it is characterized by the excessive deposition of extracellular matrix components. Biopsies are routinely employed for fibrosis diagnosis, but they suffer from several drawbacks, including their invasive nature, sampling variability and limited spatial information. To overcome these limitations, multiple different imaging tools and technologies have been evaluated over the years, including X-ray imaging, computed tomography (CT), ultrasound (US), magnetic resonance imaging (MRI), positron emission tomography (PET) and single-photon emission computed tomography (SPECT). These modalities can provide anatomical, functional and molecular imaging information which is useful for fibrosis diagnosis and staging, and they may also hold potential for the longitudinal assessment of therapy responses. Here, we summarize the use of non-invasive imaging techniques for monitoring fibrosis in systemic autoimmune diseases, in parenchymal organs (such as liver, kidney, lung and heart), and in desmoplastic cancers. We also discuss how imaging biomarkers can be integrated in (pre-) clinical research to individualize and improve anti-fibrotic therapies.

Fluorescence optical imaging in pediatric patients with inflammatory and non-inflammatory joint diseases: a comparative study with ultrasonography

Background

Valid detection of arthritis is essential in differential diagnosis of joint pain. Indocyanin green (ICG)-enhanced fluorescence optical imaging (FOI) is a new imaging method that visualizes inflammation in wrist and finger joints. Objectives of this study were to compare FOI with ultrasonography (US, by gray-scale (GS) and power Doppler (PD)) and clinical examination (CE) and to estimate the predictive power of FOI for discrimination between inflammatory and non-inflammatory juvenile joint diseases.

Methods

FOI and GSUS/PDUS were performed in both hands of 76 patients with joint pain (53 with juvenile idiopathic arthritis (JIA), 23 with non-inflammatory joint diseases). Inflammation was graded by a semiquantitative score (grades 0–3) for each imaging method. Joints were defined clinically active if swollen or tender with limited range of motion. Sensitivity and specificity of FOI in three phases dependent on ICG enhancement (P1–P3) were analyzed with CE and GSUS/PDUS as reference.

Results

For JIA patients, FOI had an overall sensitivity of 67.3%/72.0% and a specificity of 65.0%/58.8% with GSUS/PDUS as reference; specificity was highest in P3 (GSUS 94.3%/PDUS 91.7%). FOI was more sensitive for detecting clinically active joints than GSUS/PDUS (75.2% vs 57.3%/32.5%). In patients with non-inflammatory joint diseases both FOI and US showed positive (i.e., pathological) findings (25% and 14% of joints). The predictive value for discrimination between inflammatory and non-inflammatory joint diseases was 0.79 for FOI and 0.80/0.85 for GSUS/PDUS.

Conclusions

Dependent on the phase evaluated, FOI had moderate to good agreement with CE and US. Both imaging methods revealed limitations and should be interpreted cautiously. FOI may provide an additional diagnostic method in pediatric rheumatology.

Trial registration

Deutsches Register Klinischer Studien DRKS00012572. Registered 31 July 2017.

A hospital-based observational cohort study exploring pain and biomarkers in patients with hand osteoarthritis in Norway: The Nor-Hand protocol

INTRODUCTION

We have limited knowledge about the underlying disease mechanisms and causes of pain in hand osteoarthritis (OA). Consequently, no disease-modifying drug exists, and more knowledge about the pathogenesis of hand OA is needed, as well as a validation of different outcome measures. Our first aim of this study is to explore the validity of various imaging modalities for the assessment of hand OA. Second, we want to gain a better understanding of the disease processes, with a special focus on pain mechanisms.

METHODS AND ANALYSIS

The Nor-Hand study is a hospital-based observational study including 300 patients with evidence of hand OA by ultrasound and/or clinical examination. The baseline examination consists of functional tests and joint assessment of the hands, medical assessment, pain sensitisation tests, ultrasound (hands, acromioclavicular joint, hips, knees and feet), CT and MRI of the dominant hand, conventional radiographs of the hands and feet, fluorescence optical imaging of the hands, collection of blood and urine samples as well as self-reported demographic factors and OA-related questionnaires. Two follow-up examinations are planned. Cross-sectional analyses will be used to investigate agreements and associations between different relevant measures at the baseline examination, whereas the longitudinal data will be used for evaluation of predictors for clinical outcomes.

ETHICS AND DISSEMINATION

The protocol is approved by the Norwegian Regional Committee for Medical and Health Research Ethics (Ref. no: 2014/2057). The participants receive oral and written information about the project and sign a consent form before participation. They can, whenever they want, withdraw from the study, and all de-identified data will be safely stored on the research server at Diakonhjemmet Hospital. Results will be presented at international and national congresses and in peer-reviewed rheumatology journals.

TRIAL REGISTRATION NUMBER

NCT03083548; Pre-results.