Quantitative nailfold capillaroscopy-update and possible next steps

CAPI-Detect: machine learning in capillaroscopy reveals new variables influencing diagnosis

OBJECTIVES

Nailfold videocapillaroscopy (NVC) is the gold standard for diagnosing SSc and differentiating primary from secondary RP. The CAPI-Score algorithm, designed for simplicity, classifies capillaroscopy scleroderma patterns (CSPs) using a limited number of capillary variables. This study aims to develop a more advanced machine learning (ML) model to improve CSP identification by integrating a broader range of statistical variables while minimizing examiner-related bias.

METHODS

A total of 1780 capillaroscopies were randomly and blindly analysed by three to four trained observers. Consensus was defined as agreement among all but one observer (partial consensus) or unanimous agreement (full consensus). Capillaroscopies with at least partial consensus were used to train ML-based classification models using CatBoost software, incorporating 24 capillary architecture-related variables extracted via automated NVC analysis. Validation sets were employed to assess model performance.

RESULTS

Of the 1490 capillaroscopies classified with consensus, 515 achieved full consensus. The model, evaluated on partial and full consensus datasets, achieved 0.912, 0.812 and 0.746 accuracy for distinguishing SSc from non-SSc, among SSc patterns, and between normal and non-specific patterns, respectively. When evaluated on full consensus only, accuracy improved to 0.910, 0.925 and 0.933. CAPI-Detect outperformed CAPI-Score, revealing novel capillary variables critical to ML-based classification.

CONCLUSIONS

CAPI-Detect, an ML-based model, provides an unbiased, quantitative analysis of capillary structure, shape, size and density, significantly improving capillaroscopic pattern identification.

Finger blood flow (FBF) measurement among vibration-exposed groundskeepers: a pilot study in the southeastern USA

OBJECTIVES

This study assessed finger blood flow (FBF) among groundskeepers using laser Doppler flowmetry (LDF) and evaluated the association of the FBF with hand-arm vibration (HAV) exposure dose.

METHODS

Baseline FBF measured before a work shift (FBFbaseline) and daily changes in FBF before and after a work shift (ΔFBFdaily) were measured among 17 groundskeepers and 10 office workers using LDF (PeriFlux 6000, Perimed, Järfälla, Sweden) for 3 days. Study participants' health-related information was obtained through questionnaires, while HAV exposure and demographic information were pulled from our previous study conducted in parallel with the present study. Linear mixed models were employed to estimate the association between HAV exposure dose and FBF.

RESULTS

The average FBFbaseline for right and left hands was 241.5 and 239.9 perfusion units (PUs), respectively, among the exposure group and 305.6 and 307.3 PU, respectively, among the reference group. The average ΔFBFdaily for right and left hands was 44.2 and 25.4 PU, respectively, among the exposure group and -35.2 and -33.2 PU, respectively, among the reference group. A significant negative association between lifetime HAV exposure and FBFbaseline was observed in the linear mixed model after adjusting for age, body mass index, race/ethnicity and hypertension (right hand: β=-0.0006 and p=0.0055; left hand: β=-0.0009 and p=0.0068). Inconsistent significances were observed between lifetime HAV exposure and ΔFBFdaily and between daily HAV exposure and ΔFBFdaily.

CONCLUSIONS

A significant negative association between lifetime HAV exposure and baseline FBF among groundskeepers was observed, supporting FBF measurement using LDF as a promising health indicator for vascular disorders induced by HAV.

Early peripheral perfusion monitoring in septic shock

Septic shock is a frequent critical clinical condition and a leading cause of death in critically ill individuals. However, it is challenging to identify affected patients early. In this article, we discuss new perspectives on the methods and uses of peripheral perfusion monitoring, considering the concept of a dysregulated response. Physical examination, and visual and ultrasonographic techniques are used to measure peripheral microcirculatory blood flow to reflect tissue perfusion. Compared with other monitoring techniques, peripheral perfusion monitoring has the benefits of low invasiveness and good repeatability, and allows for quick therapeutic judgments, which have significant practical relevance. Peripheral perfusion monitoring is an effective tool to detect early signs of septic shock, autonomic dysfunction, and organ damage. This method can also be used to evaluate treatment effectiveness, direct fluid resuscitation and the use of vasoactive medications, and monitor vascular reactivity, microcirculatory disorders, and endothelial cell damage. Recent introductions of novel peripheral perfusion monitoring methods, new knowledge of peripheral perfusion kinetics, and multimodal peripheral perfusion evaluation methods have occurred. To investigate new knowledge and therapeutic implications, we examined the methodological attributes and mechanisms of peripheral perfusion monitoring, in this study.

Nailfold Capillaroscopy Findings in Patients With Psoriasis Vulgaris and Different Domains of Psoriatic Arthritis

Background

Psoriasis is a chronic autoimmune disease with longtime activity and multisystem affection. Nailfold capillaroscopy (NC) is a simple noninvasive microscopic tool useful for identification of nailfold microvasculopathy.

Objective

The present study aimed to compare NC findings in patients with psoriasis vulgaris (PsV) and psoriatic arthritis (PsA) with different clinical domains.

Methods

The present cross-sectional study included 200 psoriasis patients classified into five 40-patient groups: group I (GI) included PsA patients with predominant peripheral arthritis; group II (GII) included PsA patients with predominant peripheral arthritis and dactylitis and/or enthesitis; group III (GIII) included PsA patients with predominant axial affection; group IV (GIV) patients included PsA patients with predominant axial affection and dactylitis and/or enthesitis and group V (GV) included patients with PsV. In addition, there were 40 age and sex-matched healthy controls (GVI).

Results

The studied patients had capillary density of 6.7 ± 3.5/mm with 90 patients (45.0 %) having reduced capillary density. GI-GIV patients had significantly lower capillary density and higher frequency of patients with reduced capillary density as compared to GV patients. The reported capillary dimension in the studied patients is 15.7 ± 7.9 μm and 55 patients (27.5 %) had large/giant capillaries. Patients in GV had significantly lower capillary dimension in comparison to GI-GIV patients. There were 64 patients (32.0 %) with abnormal capillary morphology and 47 patients (23.5 %) with capillary hemorrhages.

Conclusions

PsA patients of all domains have lower capillary density and larger capillary dimensions as compared to PsV patients.

Re-evaluation of nailfold capillaroscopy in discriminating primary from secondary Raynaud's phenomenon and in predicting systemic sclerosis: a randomised observational prospective cohort study

BACKGROUND

Primary Raynaud's phenomenon (pRP) is difficult to distinguish from secondary (sRP). Although nailfold capillaroscopy (NFC) may detect early alterations, no universal criteria yet discriminate between pRP from sRP.

OBJECTIVES

To create and validate two NFC scores that could distinguish pRP from sRP and that could predict systemic sclerosis (SSc), respectively.

METHODS

We performed NFC on two separate cohorts with isolated RP, and recorded number of capillaries per field, enlarged/giant capillaries, crossed/bizarre patterns, microhemorrhages, neoangiogenesis, rarefaction, edema, blood flow velocity, stasis. By multivariate regression analysis, we evaluated the adjusted prognostic role of these features in a derivation cohort of 656 patients. Results were used to construct algorithm-based prognostic scores (A and B). These scores were then tested on a confirmation cohort of 219 patients.

RESULTS

Score A was unable to discriminate sRP from pRP (low negative predictive values with high positive predictive values for any cut-point); score B was unable to discriminate progression to SSc or a SSc-spectrum disorder (low positive predictive values with high negative predictive values for lower cut-points).

CONCLUSION

NFC patterns, believed as specific, showed low discriminatory power and on their own are unable to reliably discriminate sRP from pRP or predict evolution to SSc.

An Experimental Phototherapy Device for Studying the Effects of Blue Light on Patients with Raynaud's Phenomenon

Raynaud's phenomenon (RP) is a condition that causes decreased blood flow to areas perfused by small blood vessels (e.g., fingers, toes). In severe cases, ulceration, gangrene, and loss of fingers may occur. Most treatments focus on inducing vasorelaxation in affected areas by the way of pharmaceuticals. Recently, animal studies have shown that vasorelaxation can be induced by non-coherent blue light (wavelength ~ 430-460 nm) through the actions of melanopsin, a photoreceptive opsin protein encoded by the OPN4 gene. To study this effect in humans, a reliable phototherapy device (PTD) is needed. We outline the construction of a PTD to be used in studying blue light effects on Raynaud's patients. Our design addresses user safety, calibration, electromagnetic compatibility/interference (EMC/EMI), and techniques for measuring physiological responses (temperature sensors, laser Doppler flow sensors, infrared thermal imaging of the hands). We tested our device to ensure (1) safe operating conditions, (2) predictable, user-controlled irradiance output levels, (3) an ability for measuring physiological responses, and (4) features necessary to enable a double-blinded crossover study for a clinical trial. We also include in the Methods an approved research protocol utilizing our device that may serve as a starting point for clinical study. We introduced a reliable PTD for studying the effects of blue light therapy for patients suffering from Raynaud's phenomenon and showed that our device is safe and reliable and includes the required measurement vectors for tracking treatment effects throughout the duration of a clinical study.

Vision transformer assisting rheumatologists in screening for capillaroscopy changes in systemic sclerosis: an artificial intelligence model

OBJECTIVES

The first objective of this study was to implement and assess the performance and reliability of a vision transformer (ViT)-based deep-learning model, an 'off-the-shelf' artificial intelligence solution, for identifying distinct signs of microangiopathy in nailfold capilloroscopy (NFC) images of patients with SSc. The second objective was to compare the ViT's analysis performance with that of practising rheumatologists.

METHODS

NFC images of patients prospectively enrolled in our European Scleroderma Trials and Research group (EUSTAR) and Very Early Diagnosis of Systemic Sclerosis (VEDOSS) local registries were used. The primary outcome investigated was the ViT's classification performance for identifying disease-associated changes (enlarged capillaries, giant capillaries, capillary loss, microhaemorrhages) and the presence of the scleroderma pattern in these images using a cross-fold validation setting. The secondary outcome involved a comparison of the ViT's performance vs that of rheumatologists on a reliability set, consisting of a subset of 464 NFC images with majority vote-derived ground-truth labels.

RESULTS

We analysed 17 126 NFC images derived from 234 EUSTAR and 55 VEDOSS patients. The ViT had good performance in identifying the various microangiopathic changes in capillaries by NFC [area under the curve (AUC) from 81.8% to 84.5%]. In the reliability set, the rheumatologists reached a higher average accuracy, as well as a better trade-off between sensitivity and specificity compared with the ViT. However, the annotators' performance was variable, and one out of four rheumatologists showed equal or lower classification measures compared with the ViT.

CONCLUSIONS

The ViT is a modern, well-performing and readily available tool for assessing patterns of microangiopathy on NFC images, and it may assist rheumatologists in generating consistent and high-quality NFC reports; however, the final diagnosis of a scleroderma pattern in any individual case needs the judgement of an experienced observer.

Nailfold capillaroscopy: tips and challenges

Although nailfold capillaroscopy (NFC) appears to have a bright future in clinical practice, the lack of familiarity with the technique and how to interpret its outcomes is major barriers which have made nailfold capillaroscopy an underutilized method in standard clinical practice. Traditional methods for assessment and measurement of capillary patterns, density, and blood flow are falling behind and face some challenges. In fact, there have been calls for improvement, hence the recent publication of the standardization of NFC by the EULAR Study Group on Microcirculation in Rheumatic Diseases. Nailfold capillaroscopy has the advantage of being a non-invasive technique that provides a window into the digital microcirculation. This paved the way for a rapidly growing interest in using capillaroscopy parameters as outcome measures in research. In standard clinical practice, whilst its main application is in the identification of an underlying systemic sclerosis spectrum disorder in patients presenting with Raynaud's phenomenon, its use has expanded to include other clinical features possibly suggestive of an underlying connective tissue disease. This article presents the challenges, provides tips, and highlights the exciting potential of nailfold capillaroscopy in standard practice.

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.

Automated capillary flow segmentation and mapping for nailfold video capillaroscopy

OBJECTIVE

This study aimed to develop an automated image analysis method for segmentation and mapping of capillary flow dynamics captured using nailfold video capillaroscopy (NVC). Methods were applied to compare capillary flow structures and dynamics between young and middle-aged healthy controls.

METHODS

NVC images were obtained in a resting state, and a region of the vessel in the image was extracted using a conventional U-Net neural network. The approximate length, diameter, and radius of the curvature were calculated automatically. Flow speed and its fluctuation over time were mapped using the Radon transform and frequency spectrum analysis from the kymograph image created along the vessel's centerline.

RESULTS

The diameter of the curve segment (14.4 μm and 13.0 μm) and the interval of two straight segments (13.7 μm and 32.1 μm) of young and middle-aged subjects, respectively, were significantly different. Faster flow was observed in older subjects (0.48 mm/sec) than in younger subjects (0.26 mm/sec). The power spectral analysis revealed a significant correlation between the high-frequency power spectrum and the flow speed.

CONCLUSIONS

The present method allows a spatiotemporal characterization of capillary morphology and flow dynamics with NVC, allowing a wide application such as large-scale health assessment.

Detection of microvascular changes in systemic sclerosis and other rheumatic diseases

Morphological and functional analysis of the microcirculation are objective outcome measures that are recommended for use in the presence of clinical signs of altered peripheral blood flow (such as Raynaud phenomenon), which can occur in systemic sclerosis (SSc) and other autoimmune rheumatic diseases. Several advanced non-invasive tools are available for monitoring the microcirculation, including nailfold videocapillaroscopy, which is the best-studied and most commonly used method for distinguishing and quantifying microvascular morphological alterations in SSc. Nailfold videocapillaroscopy can also be used alongside laser Doppler techniques to assist in the early diagnosis and follow-up of patients with dermatomyositis or mixed connective tissue disease. Power Doppler ultrasonography, which has been used for many years to evaluate the vascularity of synovial tissue in rheumatoid arthritis, is another promising tool for the analysis of skin and nailbed capillary perfusion in other autoimmune rheumatic diseases. Other emerging methods include raster-scanning optoacoustic mesoscopy, which offers non-invasive high-resolution 3D visualization of capillaries and has been tested in psoriatic arthritis and SSc. The principle functions and operative characteristics of several non-invasive tools for analysing microvascular changes are outlined in this Review, and the clinical roles of validated or tested imaging methods are discussed for autoimmune rheumatic diseases.

Capillaroscopic Evidence of Microvascular Damage in Volleyball Players

Volleyball players experience repetitive stress that involves their hands and, in particular, their fingers. Literature reports that repetitive trauma can lead to local vascular abnormalities, such as reduced capillarization and lower resting blood flow. These anomalies could be related to the presence of dysfunctional endothelium. The aim of this study is to correlate the capillaroscopic findings by nailfold video capillaroscopy (NVC) to volleyball practice in order to early detect possible anomalies and perform an adequate follow-up to avoid damages that could negatively affect sport practice and the players' health status. In this study, 38 subjects were enrolled, 19 volleyball players and 19 healthy non-players as a comparison group. In almost all the players, we found capillaroscopic alterations of the "aspecific pattern" type without substantial gender differences. We may assume that the repeated traumas involving players' fingers can negatively modify their microcirculation. Based on these observations, it could be a desirable clinical practice to screen professional volleyball players with NVC in order to implement preventive strategies aimed at protecting the health of athletes.

New mechanism-based approaches to treating and evaluating the vasculopathy of scleroderma

PURPOSE OF REVIEW

Utilizing recent insight into the vasculopathy of scleroderma (SSc), the review will highlight new opportunities for evaluating and treating the disease by promoting stabilization and protection of the microvasculature.

RECENT FINDINGS

Endothelial junctional signaling initiated by vascular endothelial-cadherin (VE-cadherin) and Tie2 receptors, which are fundamental to promoting vascular health and stability, are disrupted in SSc. This would be expected to not only diminish their protective activity, but also increase pathological processes that are normally restrained by these signaling mediators, resulting in pathological changes in vascular function and structure. Indeed, key features of SSc vasculopathy, from the earliest signs of edema and puffy fingers to pathological disruption of hemodynamics, nutritional blood flow, capillary structure and angiogenesis are all consistent with this altered endothelial signaling. It also likely contributes to further progression of the disease including tissue fibrosis, and organ and tissue injury.

SUMMARY

Restoring protective endothelial junctional signaling should combat the vasculopathy of SSc and prevent further deterioration in vascular and organ function. Indeed, this type of targeted approach has achieved remarkable results in preclinical models for other diseases. Furthermore, tracking this endothelial junctional signaling, for example by assessing vascular permeability, should facilitate insight into disease progression and its response to therapy.