Methods of Assessing Nailfold Capillaroscopy Compared to Video Capillaroscopy in Patients with Systemic Sclerosis-A Critical Review of the Literature

INTRODUCTION

Nailfolds of patients with systemic sclerosis (SSc) provide an opportunity to directly visualize microvascular remodeling in SSc. Nailfold video capillaroscopy (NVC) remains the gold standard for assessing nailfold capillaroscopy (NFC). However, access to NVC is limited by expense and expertise. This review aims to synthesize current research on other NFC devices compared to NVC.

METHODS

The literature search included the primary research of adult patients with SSc as defined by the 2013 ACR/EULAR criteria. Methods of assessing NFC included stereomicroscopy/wide-field microscopy, ophthalmoscopy, dermatoscopy, smartphone devices, and digital USB microscopy. Primary outcomes included both qualitative (normal vs. abnormal nailfolds, overall pattern recognition, presence/absence of giant capillaries, hemorrhages, and abnormal morphology) and quantitative (capillary density and dimension) measures.

RESULTS

The search yielded 471 studies, of which 9 were included. Five studies compared NVC to dermatoscopy, two compared it to widefield/stereomicroscopy, one to smartphone attachments, and one to USB microscopy. In dermatoscopy studies, NVC had a higher percentage of images that were interpretable (63-77% vs. 100%), classifiable (70% vs. 84%), or gradable (70% vs. 79.3%) across three studies. Dermatoscopy had a lower sensitivity (60.2% vs. 81.6%) and higher specificity (92.5% vs. 84.6%) compared to NVC. One stereomicroscopy study found a significant difference between methods in capillary density in limited cutaneous SSc, while another found correlations in all parameters between stereomicroscopy and NVC. One smartphone lens had good agreement with NVC on abnormal capillary morphology and density. USB microscopy was able to differentiate between SSc and healthy controls using mean capillary width but not by capillary density.

DISCUSSION

A dermatoscope may serve as a more portable and affordable screening tool to identify a normal "scleroderma pattern", and images that need further corroboration by NVC. NFC parameters reported are heterogenous and the standardization of these parameters is important, especially in non-gold-standard devices.

Nailfold capillaroscopy

Nailfold capillaroscopy is a safe and well-established method for the assessment of structural alterations of the microcirculation. It is a crucial tool in the investigation and monitoring of patients presenting with Raynaud's phenomenon. Detection of the characteristic "scleroderma pattern" on capillaroscopy may indicate an underlying rheumatic disease, particularly systemic sclerosis (SSc). Herein, we highlight the practical aspects of videocapillaroscopy, including image acquisition and analysis, with mention of dermoscopy. Special emphasis is placed on standardized use of terminology to describe capillary characteristics. Systematic evaluation of images in discerning the normal from the abnormal using the validated European Alliance of Associations for Rheumatology (EULAR) Study Group consensus reporting framework is paramount. In addition to the relevance of capillaroscopy in the (very) early diagnosis of SSc, its emerging predictive value (especially capillary loss) for new organ involvement and disease progression is underscored. We further provide capillaroscopic findings in selected other rheumatic diseases.

Role of short courses on nailfold capillaroscopy in obtaining abilities for the identification of microvasculopathy in patients with Raynaud's phenomenon

INTRODUCTION

An early distinction between "normal" and "abnormal" capillaroscopic pattern during the first visit to a dermatologist has a crucial significance for a diagnostic management of Raynaud's phenomenon (RP). There exists a question about the level of expertise sufficient to evaluate the microcirculation.

AIM

To evaluate the utility of short courses on NFC among dermatologists and medical students in obtaining sufficient abilities for the identification of microvasculopathy in patients with RP using videocapillaroscope and handheld dermoscope.

METHODS

Both groups participated in 1-h course on NFC. Before the course, participants were asked to classify 20 videocapillaroscopic and 10 dermoscopic capillaroscopic pictures into "normal" or "abnormal" pattern. Each picture was displayed on a separate slide MS PowerPoint for 10 s. The evaluation was repeated soon after the course.

RESULTS

A total of 36 dermatologists and 49 medical students were enrolled. The rate of properly classified dermoscopic and videodermoscopic pictures increased after the course in both groups, but students improved the accuracy of classification on dermoscopic pictures to the greater extent than dermatologists. The rate of correctly recognized pictures with "abnormal" pattern was significantly greater than ones with "normal" pattern at the baseline and after the course, independently of imagining tool.

CONCLUSIONS

Short courses on NFC may improve the classification of capillaroscopic images, even in medical staff with no previous experience in NFC. The recognition of capillaroscopic abnormalities seems to be easier than obtaining the confidence that evaluated picture has "normal pattern."

Imaging techniques for assessment of vascular involvement in systemic sclerosis

PURPOSE OF REVIEW

Vascular assessment in systemic sclerosis (SSc) is included in classification criteria for this disease, thus routinely used in the evaluation of patients in which this diagnosis is being considered. In this review, imaging techniques for assessment of vascular involvement in SSc hands and skin are discussed.

RECENT FINDINGS

Longitudinal use of imaging techniques has important implications for understanding the progressive vasculopathy and fibrotic transition in SSc. Nailfold and oral capillaroscopy as well as laser speckle contrast analysis are established techniques for vascular functional assessment, but longitudinal use is challenged by equipment costs and clinical time constraints. Ultrasound techniques are well described but require technical training. Advances in mobile infrared thermography and optical coherence tomography could potentially provide a point-of-care, quantitative outcome measure in clinical trials and practice.

SUMMARY

The equipment cost, technical training, data standardization, and invasiveness of vascular assessment techniques that quantify morphological (microangiopathy) and functional (blood flow reduction) are critical for implementation into SSc clinical trials and practice to understand progressive vasculopathy, such as wound development.

Practical issues in assessing nailfold capillaroscopic images: a summary

Nailfold capillaroscopy (NC) is a highly sensitive, safe, and non-invasive technique to assess involvement rate of microvascularity in dermatomyositis and systemic sclerosis. A large number of studies have focused on NC pattern description, classification, and scoring system validation, but minimal information has been published on the accuracy and precision of the measurement. The objective of this review article is to identify different factors affecting the reliability and validity of the assessment in NC. Several factors can affect the reliability of the examination, e.g., physiological artifacts, the nailfold imaging instrument, human factors, and the assessment rules and standards. It is impossible to avoid all artifacts, e.g., skin transparency, physically injured fingers, and skin pigmentation. However, minimization of the impact of some of these artifacts by considering some protocols before the examination and by using specialized tools, training, guidelines, and software can help to reduce errors in the measurement and assessment of NC images. Establishing guidelines and instructions for automatic characterization and measurement based on machine learning techniques also may reduce ambiguities and the assessment time.

Evidence-based management of Raynaud's phenomenon

Raynaud's phenomenon (RP) is relevant to the rheumatologist because it may signify an underlying connective tissue disease and also because it can be very challenging to treat, especially when it has progressed to digital ulceration or critical ischaemia. This review article discusses diagnosis (does this patient have an underlying connective tissue disease?), including the role for nailfold capillaroscopy, and treatment. Management of 'uncomplicated' RP is first described and then treatment of RP complicated by progression to digital ulceration or critical ischaemia, highlighting recent advances (including phosphodiesterase type 5 inhibition, and endothelin 1 receptor antagonism) and the evidence base underpinning these. Possible future therapies are briefly discussed.

An EULAR study group pilot study on reliability of simple capillaroscopic definitions to describe capillary morphology in rheumatic diseases

OBJECTIVE

To propose simple capillaroscopic definitions for interpretation of capillaroscopic morphologies and to assess inter-rater reliability.

METHODS

The simple definitions proposed were: normal--hairpin, tortuous or crossing; abnormal--not hairpin, not tortuous and not crossing; not evaluable--whenever rater undecided between normal and abnormal. Based upon an aimed kappa of 0.80 and default prevalences of normal (0.4), abnormal (0.4) and not evaluable (0.2) capillaries, 90 single capillaries were presented to three groups of raters: experienced independent raters, n = 5; attendees of the sixth EULAR capillaroscopy course, n = 34; novices after a 1-h course, n = 11. Inter-rater agreement was assessed by calculation of proportion of agreement and by kappa coefficients.

RESULTS

Mean kappa based on 90 capillaries was 0.47 (95% CI: 0.39, 0.54) for expert raters, 0.40 (95% CI: 0.36, 0.44) for attendees and 0.46 (95% CI: 0.41, 0.52) for novices, with overall agreements of 67% (95% CI: 63, 71), 63% (95% CI: 60, 65) and 67% (95% CI: 63, 70), respectively. Comparing only normal vs the combined groups of abnormal and not evaluable capillaries did increase the kappa: 0.51 (95% CI: 0.37 ,: 0.65), 0.53 (95% CI: 0.49, 0.58) and 0.55 (95% CI: 0.49, 0.62). On the condition that the capillaries were classifiable, the mean kappa was 0.62 (95% CI: 0.50, 0.74) for expert raters (n = 65), 0.76 (95% CI: 0.69, 0.83) for attendees (n = 20) and 0.81 (95% CI: 0.74, 0.89) for novices (n = 44).

CONCLUSION

This multicentre, international study showed moderate reliability of simple capillaroscopic definitions for describing morphology of capillaries by rheumatologists with varying levels of expertise. Novices were capable of distinguishing normal from abnormal capillaries by means of a 1-h training session. In future studies, the class not evaluable may be obsolete.

Dermoscopy: not just for dermatologists

Use of dermoscopy has been proven to increase diagnostic accuracy for melanoma. It is frequently used by dermatologists and other healthcare providers during skin cancer screening and in the evaluation of concerning skin lesions. Studies have shown that it is useful in the diagnosis of many nononcologic cutaneous diseases as well as in the monitoring of disease progression and treatment response. Furthermore, dermoscopy has the potential to aid in pathology specimen sectioning, translational research and medical technology development. Its broad applications and ease of use will make it an increasingly influential tool in healthcare. In this article, we review the established uses of dermoscopy by different healthcare providers and its potential future applications.

Assessment of nailfold capillaroscopy in systemic sclerosis by different optical magnification methods

BACKGROUND

Systemic sclerosis (SSc) is characterized by target-organ fibrosis and microvascular dysfunction, which can be assessed using nailfold capillaroscopy. Dermoscopy is a useful and easily performed method for diagnosing skin lesions.

AIM

To compare conventional capillaroscopy, using the gold-standard method (conventional stereomicroscope nailfold capillaroscopy; SNFC), with polarized light noncontact dermoscopy (PNCD) and nonpolarized light contact dermoscopy (NPCD), and to evaluate their accuracy in diagnosing characteristic SSc-related alterations.

METHODS

The study enrolled 45 patients with SSc. Capillaroscopy images and photographs were taken with three devices, SNFC, NPCD and PNCD, and these images were randomly analysed by a blinded observer.

RESULTS

The scleroderma pattern was found in 83% of patients. PNCD and NPCD were highly sensitive in identifying the presence of focal capillary loss (96.4% and 100%, respectively), haemorrhage (96.2% and 92%, respectively), and scleroderma (91.9%, 94.6%), and showed high specificity for haemorrhage and enlarged loops. The intra-observer kappa values for detection of the scleroderma pattern by SNFC images, NPCD and PNCD were moderate to good: (κ = 0.71 (95% CI 0.44-0.95), κ = 0.60 (95% CI 0.35-0.83) and κ = 0.60 (95% CI 0.32-0.86), respectively. Evaluation of haemorrhage presence gave high kappa values for all methods: κ = 0.77 (95% CI 0.57-0.95), κ = 0.90 (95% CI 0.76-1.00) and κ = 0.95 (95% CI 0.85-1.00), respectively.

CONCLUSIONS

Both polarized and nonpolarized dermoscopy are reliable methods for valuation of nailfold capillaroscopy in patients with SSc. They are easy to perform, with good rates of accuracy and results that are comparable with traditional capillaroscopy.

Nailfold capillary patterns in healthy subjects: a real issue in capillaroscopy

Nailfold capillaroscopy has been extensively applied in a broad spectrum of pathologic conditions, but very few data have been published in healthy individuals. The aim of this study was to describe the nailfold capillary findings on a large series of healthy subjects using the video-capillaroscopy technique. Nailfold capillaries were studied based on their morphology, dimensions and density. Then, to evaluate jointly the association between different capillary findings in groups of subjects which were homogeneous for their characteristics, cluster analysis was performed. The results (median) of capillary measurements were as follows: loop length 207μm, external diameter 39μm, internal diameter 17μm, apical diameter 17μm, and intercapillary distance 143μm. Based on the cluster analysis three major "normal" morphologic capillaroscopic patterns were depicted: 1) the "normal" pattern mainly with 2 to 5 U-shaped loops/mm and ≤2 tortuous loops/mm; 2) the "perfect normal" pattern with ≥5 U-shaped loops/mm and 3) the "unusual normal" with at least 1 meandering or bushy loop, or at least 1 microhemorrhage, or with >4 crossed loops/mm. Regarding the loop measurements, the majority of subjects had a median of 7capillaries/mm with a median length of 198μm.

Capillaroscopy

Microscopy of the nailfold capillaries has found increasing use in dermatology, rheumatology and angiology particularly as an important tool to distinguish between primary and secondary Raynaud disease. The best evidence is available in systemic sclerosis where specific capillaroscopic patterns have a high positive predictive value for the development of the disease. Conversely, a regular capillary pattern rules out systemic sclerosis with high degree of probability. PRINCE (prognostic index for nailfold capillaroscopic examination) was developed to identify patients at high risk of developing systemic sclerosis. CSURI (capillaroscopic skin ulcer risk index) should predict the risk of developing digital ulcers in patients with systemic sclerosis with high specificity and sensitivity. As a consequence of recent results a pathologic capillary pattern was integrated by the EULAR Scleroderma Trials and Research Group (EUSTAR) in the diagnostic algorithm of the VEDOSS-Project (very early diagnosis of systemic sclerosis). Capillary patterns may correlate with visceral involvement and capillaroscopy thus has the potential as a screening tool to enable early diagnosis of organ involvement in systemic sclerosis.