Naifold capillaroscopy in mixed connective tissue disease patients.

INTRODUCTION: Mixed connective tissue disease (MCTD) is a rare systemic disease characterized by overlapping features of systemic lupus erythematosus (SLE), systemic sclerosis (SSc), dermato-/polymyositis (DM/PM), and rheumatoid arthritis (RA). Naifold capillaroscopy (NFC) is a non-invasive test for evaluating the capillaries of the nail shaft used in the diagnosis of rheumatic diseases. OBJECTIVES: To determine whether there are characteristic abnormalities in NFC in MCTD patients, and whether the type of NFC lesions correlates with organ involvement in these patients. METHODS: Clinical picture and NFC patterns were analyzed in 43 patients with MCTD. Capillaroscopic images were divided into scleroderma-like pattern (SD-like pattern) according to the Cutolo classification, non-specific lesions, and normal images. Relationships between the clinical aspects considered in the MCTD classification criteria and the changes in the capillaroscopic images were evaluated. RESULTS: SD-like pattern was present in 20 MCTD patients (46.51%) with a predominance of the "early" pattern. Giant, branched, dilated capillaries and reduced capillary density were found more frequently in MCTD patients compared to the control group (p-values 0.0005, 0.005, 0.02, < 0.0001 respectively). There were associations found between the presence of a reduced number of vessels, avascular areas, and SD-like pattern with the presence of sclerodactyly in MCTD patients (p = 0.002, p = 0.006, p = 0.02, respectively), alongside an association between the presence of branched vessels and the subpapillary plexus with pulmonary arterial hypertension (PAH) (p = 0.04 and p = 0.005, respectively). CONCLUSIONS: MCTD patients are significantly more likely to have abnormalities upon NFC. It is worthwhile to perform capillaroscopic examination in MCTD patients. Key Points • Scleroderma-like pattern was found in more than half of the MCTD patients. • Reduced capillary density was found to be a significant predictor of the diagnosis of MCTD. • There were relationships between the presence of reduced capillary density, avascular areas, and SD-like with the presence of sclerodactyly in the MCTD patients. • There was an association between the presence of branched vessels and the visibility of the subpapillary plexus and pulmonary arterial hypertension (PAH).

Decreased retinal capillary density as a beneficial response to 24-week high-speed circuit resistant training in healthy older adults.

PURPOSE: To determine the changes in retinal microvascular density after a 24-week high-speed circuit resistance training program (HSCT) in healthy older adults. METHODS: Thirty healthy older adults were recruited and randomly assigned to either a training group (HSCT) or a non-training (CON) group. Fifteen subjects (age 73.3 ± 7.76 yrs) in the HSCT group exercised three times per week on non-consecutive days for 24 weeks. Fifteen subjects in the CON group (age 72.2 ± 6.04 yrs) did not have formal physical training. Both eyes of each subject were imaged using optical coherence tomography angiography (OCTA) at baseline and at the 24-week follow-up. The vessel densities of the retinal vascular network (RVN), superficial vascular plexus (SVP), and deep vascular plexus (DVP) were measured. RESULTS: There were no demographic differences between the study groups. There were significant decreases in the retinal vessel densities of RVN, SVP and DVP in the HSCT group (P < 0.05). However, there were no significant changes in all three vascular measurements in the CON group (P > 0.05), although the changes showed a decreasing trend. The decreased vessel densities were doubled in the HSCT group in comparison to the CON group. However, the differences between groups did not reach a significant level (P > 0.05). CONCLUSIONS: This is the first study to reveal the decreased retinal vessel densities as a possible imaging marker for the beneficial effects of the 24-week HSCT program in older adults.

Microvascular status in juvenile Sjögren's disease: the first nailfold videocapillaroscopy investigation.

INTRODUCTION: Juvenile Sjögren's disease (jSjD) is a rare autoimmune disease characterized by exocrine gland involvement and systemic manifestations, including small vessel vasculitis and Raynaud's phenomenon (RP). We aimed to investigate the microvascular status in jSjD patients by nailfold videocapillaroscopy (NVC) and the potential correlations with clinical and serological features. METHODS: Clinical data from thirteen consecutive jSjD patients (11 females and 2 males), with a mean age of 16 ± 4 years, diagnosed before 16 years of age (mean age at diagnosis 12 ± 3) according to the 2016 American College of Rheumatology/EULAR criteria for adult SjD, were collected including age- and sex-matched healthy controls (HCs). Clinical, laboratory, and instrumental data were collected, together with NVC examination. Non-specific and specific NVC parameters were investigated, such as capillary density, capillary dilations, giant capillaries, microhaemorrhages and abnormal shapes. Associations between NVC findings and clinical/serological features were explored and analysed using parametrical and non-parametrical tests. RESULTS: Capillary density reduction correlated significantly with articular involvement (arthralgias) (p = 0.024). Microhaemorrhages correlated with lower C3 levels (p = 0.034). No specific NVC pattern for jSjD was identified, whereas abnormal capillary shapes were significantly higher in jSjD patients than HCs (p = 0.005). NVC abnormalities were not associated with SjD-specific instrumental tests (biopsy, imaging, Schirmer's test). RP was present in 8% of jSjD patients. CONCLUSIONS: The reduction of capillary density, as well as microhaemorrhages at NVC analysis, are significantly associated with some clinical aspects like articular involvement and serum biomarkers (C3 reduction). The NVC is suggested as safe and further analysis in jSjD patients.

Analysis of microvascular pattern in diabetes mellitus condition using the nailfold capillaroscopy images.

Diabetes is often considered a vascular disease due to its impact on blood vessels, it is a complex condition with various metabolic and autoimmune factors involved. One of the long term comorbidities of diabetes includes microvascular complications. The microvascular complications can be analyzed using the Nailfold capillaroscopy, a non-invasive technique that allows for the visualization and analysis of capillaries in the proximal nailfold area. Using advanced video capillaroscopy with high magnification, capillary images can be captured from and processed to analyze their morphology. The capillary images of normal group and diabetic group are acquired from 118 participants using nailfold capillaroscopy and the obtained images are preprocessed using image processing filters. The identification and segmentation of the capillaries are the challenges to be addressed in the processing of the images. Hence segmentation of capillaries is done using morphological operations, thresholding and convolutional neural networks. The performance of the filters and segmentation methods are evaluated using Mean Square Error (MSE), Peak signal to Noise Ratio (PSNR), Structural Similarity Index Measure (SSIM), Jaccard Index and Sorensen coefficient. By analyzing the morphological features namely the capillary diameter, density, distribution, presence of hemorrhage and the shape of the capillaries from both the groups, the capillary changes associated with diabetic condition were studied. It was found that the non diabetic participants considered in this study has capillary diameter in the range of 8-14 µm and the capillary density in the range of 10-30 capillaries per mm2 whereas the diabetic participants has capillary diameter greater than 30 µm and the capillary density is less than 10 capillaries per mm2. In addition to capillary density and diameter, the presence of hemorrhage, the orientation and distribution of the capillaries are also considered to differentiate the diabetic group from the non diabetic group. The classification of the participants are validated with the clinical history of the participants.

Microvascular changes on nailfold capillaroscopy in acute stage of Kawasaki disease: a new diagnostic paradigm for an enigmatic condition.

OBJECTIVES: Kawasaki disease (KD) is a medium vessel vasculitis with a predilection to involve coronary arteries. However, there is a paucity of literature on microvascular changes in patients with KD. METHODS: Children diagnosed with KD based on American Heart Association guidelines 2017 were enrolled prospectively. Demographic details and echocardiographic changes in coronaries were recorded. Nailfold capillaries were assessed using Optilia Video capillaroscopy and data were analysed using Optilia Optiflix Capillaroscopy software at acute (prior to IVIG administration) and subacute/convalescent phase. RESULTS: We enrolled 32 children with KD (17 boys) with a median age of 3 years. Nailfold capillaroscopy (NFC) was performed in 32 patients in the acute phase (compared with 32 controls) and in 17 during the subacute/convalescent phase at a median follow-up of 15 (15-90) days after IVIG treatment. The following findings were seen in NFC in the acute phase of KD: reduced capillary density (n = 12, 38.6%), dilated capillaries (n = 3, 9.3%), ramifications (n = 3, 9.3%) and capillary haemorrhages (n = 2, 6.2%). Capillary density was reduced significantly in the acute phase of KD (38.6%) as compared with the subacute/convalescent phase (25.4%) (P-value <0.001) and controls (0%) (P-value = 0.03). We observed no correlation between coronary artery involvement and mean capillary density (P = 0.870). CONCLUSION: Results show that patients with KD have significant nailfold capillary changes in the acute phase. These findings may provide a new diagnostic paradigm for KD and a window to predict coronary artery abnormalities.

Simulation of coronary capillary transit time based on full vascular model of the heart.

Capillary transit time (CTT) is a fundamental determinant of gas exchange between blood and tissues in the heart and other organs. Despite advances in experimental techniques, it remains difficult to measure coronary CTT in vivo. Here, we developed a novel computational framework that couples coronary microcirculation with cardiac mechanics in a closed-loop system that enables prediction of hemodynamics in the entire coronary network, including arteries, veins, and capillaries. We also developed a novel "particle-tracking" approach for computing CTT where "virtual tracers" are individually tracked as they traverse the capillary network. Model predictions compare well with blood pressure and flow rate distributions in the arterial network reported in previous studies. Model predictions of transit times in the capillaries (1.21 ± 1.5 s) and entire coronary network (11.8 ± 1.8 s) also agree with measurements. We show that, with increasing coronary artery stenosis (as quantified by fractional flow reserve, FFR), intravascular pressure and flow rate downstream are reduced but remain non-stationary even at 100 % stenosis because some flow (∼3 %) is redistributed from the non-occluded to the occluded territories. Importantly, the model predicts that occlusion of a large artery results in higher CTT. For moderate stenosis (FFR > 0.6), the increase in CTT (from 1.21 s without stenosis to 2.23 s at FFR=0.6) is caused by a decrease in capillary flow rate. In severe stenosis (FFR = 0.1), the increase in CTT to 14.2 s is due to both a decrease in flow rate and an increase in path length taken by "virtual tracers" in the capillary network.

Mapping the human parafoveal vascular network to understand flow variability in capillaries.

Capillary flow is known to be non-homogenous between vessels and variable over time, for reasons that are poorly understood. The local properties of individual vessels have been shown to have limited explanatory power in this regard. This exploratory study investigates the association of network-level properties such as vessel depth, branch order, and distance from the feeding arteriole with capillary flow. Detailed network connectivity analysis was undertaken in 3 healthy young subjects using flood-illuminated adaptive optics retinal imaging, with axial depth of vessels determined via optical coherence tomography angiography. Forty-one out of 70 vessels studied were of terminal capillary type, i.e. fed from an arterial junction and drained by a venous junction. Approximately half of vessel junctions were amenable to fitting with a model of relative branch diameters, with only a few adhering to Murray's Law. A key parameter of the model (the junction exponent) was found to be inversely related to the average velocity (r = -0.59, p = 0.015) and trough velocity (r = -0.67, p = 0.004) in downstream vessels. Aspects of cellular flow, such as the minimum velocity, were also moderately correlated (r = 0.46, p = 0.009) with distance to the upstream feeding arteriole. Overall, this study shows that capillary network topology contributes significantly to the flow variability in retinal capillaries in human eyes. Understanding the heterogeneity in capillary flow is an important first step before pathological flow states can be properly understood. These results show that flow within capillary vessels is not affected by vessel depths but significantly influenced by the upstream feeder distance as well as the downstream vessel junction exponents, but there remains much to be uncovered regarding healthy capillary flow.

Observation and density estimation of a large number of skin capillaries using wide-field portable video capillaroscopy and semantic segmentation.

Significance: Skin capillaries are non-invasively observable; their structure and blood flow can reflect tissue and systemic conditions. Quantitative analysis of video-capillaroscopy images yields novel diagnostic methods. Because the capillary structure is heterogeneous, analyzing more capillaries can increase the evaluation reliability. Aim: We developed a system that can observe and quantify numerous capillaries and verified the performance on human skin. Approach: We developed a portable video-capillaroscope with a spatial resolution higher than 3.5 µm and a wide field of view (7.4 mm×5.5 mm) and a method to evaluate capillary numbers and areas using U-Net. The model was trained and tested with 22 and 11 cropped images (2.4 mm×1.9 mm) obtained from 11 participants, respectively. They were then applied to the 7.2 mm×5.3 mm images from four participants. Segmentation results were compared to ground-truth at the pixel level and capillary-region level. Results: Over 1000 capillaries were simultaneously observed using the proposed system. Although pixel-level segmentation performance was low [intersection over union (IoU) = 24.5%], the number and area could be estimated. These values differed among four participants and seven sites, and they changed after skin barrier destruction. Conclusions: The proposed system allows for observing and quantifying numerous skin capillaries simultaneously, suggesting its potential for evaluating tissue and systemic conditions.

Assessment of nail fold capillary changes by hand-held dermoscopy in adult dermatomyositis: A single-centre prospective study.

BACKGROUND: Hand-held dermoscopy is a valuable tool for dermatologists, but it has been rarely used to assess the nail fold capillary (NFC) in patients with dermatomyositis (DM). METHODS: Patients were collected from the Department of Dermatology and Venereology from July 2020 to July 2021, and the follow-up was conducted until January 2022. Demographic features, disease activity and NFC changes were analysed using a hand-held dermoscopy. RESULTS: The most common NFC finding in our study was bushy capillary (87.0%). There was no significant improvement in scleroderma-dermatomyositis (SD)-like nail fold changes or enlarged capillaries from baseline to 12 weeks of treatment (p > 0.05) or from 12 weeks to 24 weeks of treatment (p > 0.05), but there was a significant improvement from baseline to 24 weeks of treatment (p < 0.05). The avascular area did not improve from baseline to 12 weeks of follow-up, but the changes were significant from 12 weeks to 24 weeks of treatment (p < 0.05) and baseline to 24 weeks of treatment (p < 0.05). Periungual erythema improved significantly from baseline to 12 weeks of treatment (p < 0.05) and baseline to 24 weeks of treatment (p < 0.05), but it did not improve significantly from 12 weeks to 24 weeks of treatment (p > 0.05). There was no significant difference in disease activity between patients with or without specific NFC changes. However, some NFC features improved as disease activity decreased. CONCLUSION: Dermoscopy of NFC is a cost-effective option for the preliminary diagnosis of DM. Further, long-term follow-up is necessary to study the relationship between disease activity and NFC changes.

Automated Stabilization, Enhancement and Capillaries Segmentation in Videocapillaroscopy.

Oral capillaroscopy is a critical and non-invasive technique used to evaluate microcirculation. Its ability to observe small vessels in vivo has generated significant interest in the field. Capillaroscopy serves as an essential tool for diagnosing and prognosing various pathologies, with anatomic-pathological lesions playing a crucial role in their progression. Despite its importance, the utilization of videocapillaroscopy in the oral cavity encounters limitations due to the acquisition setup, encompassing spatial and temporal resolutions of the video camera, objective magnification, and physical probe dimensions. Moreover, the operator's influence during the acquisition process, particularly how the probe is maneuvered, further affects its effectiveness. This study aims to address these challenges and improve data reliability by developing a computerized support system for microcirculation analysis. The designed system performs stabilization, enhancement and automatic segmentation of capillaries in oral mucosal video sequences. The stabilization phase was performed by means of a method based on the coupling of seed points in a classification process. The enhancement process implemented was based on the temporal analysis of the capillaroscopic frames. Finally, an automatic segmentation phase of the capillaries was implemented with the additional objective of quantitatively assessing the signal improvement achieved through the developed techniques. Specifically, transfer learning of the renowned U-net deep network was implemented for this purpose. The proposed method underwent testing on a database with ground truth obtained from expert manual segmentation. The obtained results demonstrate an achieved Jaccard index of 90.1% and an accuracy of 96.2%, highlighting the effectiveness of the developed techniques in oral capillaroscopy. In conclusion, these promising outcomes encourage the utilization of this method to assist in the diagnosis and monitoring of conditions that impact microcirculation, such as rheumatologic or cardiovascular disorders.

Multivariate Parametric Study of Nailfold Capillary Images for Disease Detection.

Nailfold capillaroscopy is a tool which is non-invasive in nature and can be useful for diagnosis, research, therapeutic study and prognosis. Research shows that specific capillary morphology patterns are identified for diabetic subjects, hypertensive subjects and normal controls. In this study, we have proposed RATHEW approach of classifying these three classes of subjects. RATHEW approach employs a three step process for classifying nailfold images: one, identify six abnormality parameters from the image dataset; two, score these abnormality parameters based on the defined scoring rules; and three, combine them mathematically to segregate them into three classes. This technique can be further enhanced to grade the severity of disease and organ involvement. This can bring in a paradigm shift to the disease detection and therapeutic study mechanism.

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.

Imaging the time course, morphology, neuronal tissue compression, and resolution of cerebral microhemorrhages in mice using intravital two-photon microscopy: insights into arteriolar, capillary, and venular origin.

Cerebral microhemorrhages (CMHs, microbleeds), a manifestation of age-related cerebral small vessel disease, contribute to the pathogenesis of cognitive decline and dementia in older adults. Histological studies have revealed that CMHs exhibit distinct morphologies, which may be attributed to differences in intravascular pressure and the size of the vessels of origin. Our study aimed to establish a direct relationship between the size/morphology of CMHs and the size/anatomy of the microvessel of origin. To achieve this goal, we adapted and optimized intravital two-photon microscopy-based imaging methods to monitor the development of CMHs in mice equipped with a chronic cranial window upon high-energy laser light-induced photodisruption of a targeted cortical arteriole, capillary, or venule. We assessed the time course of extravasation of fluorescently labeled blood and determined the morphology and size/volume of the induced CMHs. Our findings reveal striking similarities between the bleed morphologies observed in hypertension-induced CMHs in models of aging and those originating from different targeted vessels via multiphoton laser ablation. Arteriolar bleeds, which are larger (> 100 µm) and more widely dispersed, are distinguished from venular bleeds, which are smaller and exhibit a distinct diffuse morphology. Capillary bleeds are circular and smaller (< 10 µm) in size. Our study supports the concept that CMHs can occur at any location in the vascular tree, and that each type of vessel produces microbleeds with a distinct morphology. Development of CMHs resulted in immediate constriction of capillaries, likely due to pericyte activation and constriction of precapillary arterioles. Additionally, tissue displacement observed in association with arteriolar CMHs suggests that they can affect an area with a radius of ~ 50 µm to ~ 100 µm, creating an area at risk for ischemia. Longitudinal imaging of CMHs allowed us to visualize reactive astrocytosis and bleed resolution during a 30-day period. Our study provides new insights into the development and morphology of CMHs, highlighting the potential clinical implications of differentiating between the types of vessels involved in the pathogenesis of CMHs. This information may help in the development of targeted interventions aimed at reducing the risk of cerebral small vessel disease-related cognitive decline and dementia in older adults.

Nailfold capillaroscopy reveals early peripheral microcirculation abnormalities in children affected by heterozygous familial hypercholesterolemia.

BACKGROUND: nailfold capillaroscopy (NCF) is a non-invasive imaging technique to seek peripheral microcirculation abnormalities in children and adults. Familial hypercholesterolemia is a genetic disorder caused by mutations capable of increasing blood levels of low-density lipoproteins cholesterol (LDL-C), thus triggering early atherosclerosis. The study aims at evaluating peripheral microcirculation in children with heterozygous familial hypercholesterolemia (HeFH) by means of NFC in comparison with healthy peers and at searching for possible correlations between these abnormalities and patients' lipid panel. METHODS: thirty-six HeFH patients were enrolled (13 males and 23 females. Mean age 8 ± 3 years; age range 3-13 years). They had increased levels of total cholesterol (237.9 ± 34.2 mg/dl) and LDL-C (154.2 ± 37.6 mg/dl). Both values were ≥95th gender and age specific centile. All the subjects in the study underwent NFC. RESULTS: In 69.4 % of HeFH children nailfold capillaries were tortuous (p < 0.00001 compared to healthy controls). In 41.6 % the number of capillaries was markedly reduced (<7 capillaries/mm). The mean number of capillaries was 8.4 ± 2.6/mm in HeFH and 12.2 ± 1.4/mm in healthy controls (p < 0.00001). In 100 % of the sample size capillary blood flow was slowed down (p < 0.00001). In 50 % of the sample size a blood "sludge" phenomenon was seen (p < 0.00001). No gender differences were detected. Sludge phenomenon was seen only in those with LDL-C over 99th centile (p < 0.00001). CONCLUSION: NCF allows the identification of an early peripheral microvascular dysfunction in HeFH children which is similar to that already seen in atherosclerotic disease. Prompt identification of these capillary abnormalities may be crucial in implementing early prevention measures.

External clinical validation of automated software to identify structural abnormalities and microhaemorrhages in nailfold videocapillaroscopy images.

OBJECTIVES: Automated systems to analyse nailfold videocapillaroscopy (NVC) images are needed to promptly and comprehensively characterise patients with systemic sclerosis (SSc) or Raynaud's phenomenon (RP). We previously developed, and validated in-house, a deep convolutional neural network-based algorithm to classify NVC-captured images according to the presence/absence of structural abnormalities and/or microhaemorrhages. We present its external clinical validation. METHODS: A total of 1,164 NVC images of RP patients were annotated by 5 trained capillaroscopists according to the following categories: normal capillary; dilation; giant capillary; abnormal shape; tortuosity; microhaemorrhage. The images were also presented to the algorithm. Matches and discrepancies between algorithm predictions and those annotations obtained by consensus of ≥3 or ≥4 interobservers were analysed. RESULTS: Consensus among ≥3 capillaroscopists was achieved in 86.9% of images, 75.8% of which were correctly predicted by the algorithm. Consensus among ≥4 experts occurred in 52.0% of cases, in which 87.1% of the algorithm's results matched with those of the expert panel. The algorithm's positive predictive value was >80% for microhaemorrhages and unaltered, giant or abnormal capillaries. Sensitivity was >75% for dilations and tortuosities. Negative predictive value and specificity were >89% for all categories. CONCLUSIONS: This external clinical validation suggests that this algorithm is useful to assist in the diagnosis and follow-up of SSc or RP patients in a timely manner. It may also be helpful in the management of patients with any pathology presenting with microvascular changes, as the algorithm has been designed to also be useful for research aiming at extending the usage of nailfold capillaroscopy to more conditions.

Increased peripapillary capillaries in patients with acute leukemia by using optical coherence tomography angiography.

PURPOSE: To evaluate the radial peripapillary capillary vessel density (RPC-VD) and thickness of the retinal nerve fiber layer (RNFL) in acute leukemia (AL) and the associations of these characteristics with blood laboratory parameters. METHODS: A cross-sectional study was performed at the Ophthalmology Department of the Sun Yat-sen Memorial Hospital from February 2019 to April 2022. Sixty eyes of 30 patients diagnosed with AL and sixty eyes of 30 matched healthy controls were included. Optical coherence tomography angiography (OCTA) in the 4.5-mm Angio Disc scan mode and the Ganglion cell complex scan mode were performed for all participants. Correlation analyses were used to examine the associations of RPC-VD and RNFL with blood laboratory parameters. RESULTS: Patients in the AL group had significantly increased RPC-VD in the whole-image (51.42±0.35 vs. 49.52±0.36) and peripapillary fields (53.90±0.43 vs. 51.17±0.50) compared with people in the control group (all P<0.001), while no difference was found for RPC-VD in the inside optic disk fields in the two groups. The RNFL in the AL group was significantly thicker than that in the control group (131.10±3.89 µm vs. 115.03±2.22 µm, P<0.05). Complete blood count (CBC) parameters, including red blood cells, hemoglobin and hematocrit, had a significant negative correlation with RPC-VD and RNFL (all P <0.05). CONCLUSION: An increased RPC-VD and a thicker RNFL are evidence of fundus changes in patients with early-stage AL, and these metrics may be related to decreases in red blood cells, hemoglobin and hematocrit.

The velocity-diffusion equation in the exchange microvessels.

In human and animal microvascular networks, the exchange microvessels are the capillaries and postcapillary venules where material transport between the circulating blood and tissue takes place. For small-size molecules, this material transport is done by the physical mechanism of diffusion through the endothelium wall and the diffusion rate J in relation to blood volume flow Q is described by the flow-diffusion (Q-J) equation. However, the volume flow is not easy to be measured in vivo. The objective of this work was to transform the classical flow-diffusion equation into a new form with axial velocity V as an independent variable instead of volume flow Q. The new form was called the velocity-diffusion (V-J) equation and has the advantage that V can be measured directly in vivo by optical imaging techniques. The V-J equation could have important applications in the calculation of the mass diffusion rate of various substances in vivo.

Microvascular damage evaluation based on nailfold videocapillarosopy in sarcoidosis.

OBJECTIVES: Microvascular damage is thought to play a role in the pathogenesis of sarcoidosis. We aimed to evaluate the nailfold capillaroscopy (NVC) pattern to detect microvascular changes in patients with sarcoidosis and the relationship of capillaroscopic parameters with clinical variables and disease-related measurements. PATIENTS AND METHODS: Forty-two patients with sarcoidosis and 42 age- and sex-matched patients with systemic sclerosis (SSc) and healthy individuals were included in this cross-sectional case-control study. Patients aged 18-80 years who met the current American Thoracic Society criteria for sarcoidosis were included. NVC was performed by a digital microscope under a magnification of × 200. Capillary density, number of dilated, giant and neoangiogenic capillaries, capillary loop diameter, capillary shape, micro-hemorrhages, and number of avascular areas, were evaluated by an assessor who was blind to the groups allocation. RESULTS: Among the capillaroscopic parameters, neoangiogenesis and dilated capillaries, which can be seen in the pattern of scleroderma, were detected in patients with sarcoidosis but not significantly different from the control group (p = 0.055; p = 0.433, respectively). The rate of tortuosity and crossing capillaries of 50% and above was significantly higher in the sarcoidosis group than in SSc and healthy controls (p < 0.05). In patients with sarcoidosis, the only statistically significant finding was; forced expiratory volume (FEV1) in one second was lower in patients with a crossed capillary rate > 50% than in patients with a crossed capillary rate of less than 50% (FEV1; 87.21 ± 19.3, 102.5 ± 14.8, p = 0.04; respectively). CONCLUSION: Patients with a diagnosis of sarcoidosis have different capillaroscopic patterns. The presence of these nonspecific abnormal patterns may reflect microvascular damage in the pathophysiology of sarcoidosis. Key Points • Microvascular damage may play a role in the pathogenesis of sarcoidosis. • There may be some nonspecific abnormal findings in capillaroscopy findings in sarcoidosis. • Capillaroscopy may be valuable in reflecting sarcoidosis lung injury.