Near-infrared spectroscopic imaging of the whole hand: A new tool to assess tissue perfusion and peripheral microcirculation in scleroderma

Application of Near Infrared Spectroscopy to Enhance Safety and Individualize Distraction of Severely Contracted Joints in Far-Advanced Dupuytren's Disease

Background: Slow distraction of contracted joints is a well-established treatment in far-advanced stages of Dupuytren's disease (DD). To assess finger perfusion and avoid malperfusion, we studied near infrared spectroscopy (NIRS) to evaluate the maximum extent of distraction that would not harm microcirculation to the finger. This technique also allows an optimized treatment in accordance with sufficient blood perfusion during distraction. Methods: Eligible patients with stage IV finger contractures who needed treatment for Dupuytren's contracture were included and prospectively investigated. The operation was performed with local anaesthesia. First, the Dupuytren strand of the treated finger was dissected in the palm to allow distraction. Under X-ray control, the distraction device was applied. Then, slow distraction of the treated joint was performed to evaluate the finger perfusion. To assess perfusion of the treated finger, NIRS was used to measure tissue oxygen saturation. If impaired finger perfusion was detected, traction was reduced until sufficient oxygen levels and perfusion patterns were reestablished. Results: NIRS was performed after application of the distraction device in seven cases. We treated six male and one female patient (mean age 70 years, range 51-80 years). Rapid distraction resulted in malperfusion of the treated fingers. Using NIRS proved to render reliable and reproducible information on finger perfusion and oxygenation in all seven patients. Conclusions: Application of NIRS enhances safety in the treatment of far-advanced DD finger contractures with an external skeletal distraction device. It is non-invasive, reproducible, easy to use and allows for an individualized adapted distraction velocity.

What have we learned on pre, very early, and early systemic sclerosis microcirculatory pathophysiology? A scoping review

OBJECTIVE

Microvascular dysfunction is an early event in the pathogenesis of systemic sclerosis (SSc). The objective of this scoping review is to update the current information and the level of knowledge about the mechanisms of microvascular dysfunction in pre-SSc, very early diagnosis of SSc (VEDOSS) and early SSc.

METHODS

A PubMed® database search allowed us to include original data from full-length articles in English in which the main topic was microvascular dysfunction in pre-SSC, VEDOSS or early SSc. Data was extracted using a customized form.

RESULTS

In the present review 437 articles were identified, and 42 studies included, reporting data from a total of 1069 patients with pre-SSc, VEDOSS or early-SSc. Distinct mechanisms of microvascular injury were identified comprising, angiogenesis and vasculogenesis, cell surface proteins and adhesion, molecules expression, cytokines profile, inflammatory and oxidation pathways, and skin perfusion determinants. Most of the studies were conducted in early SSc, with a reduced number in pre-disease stages, in which the prompt recognition of specific mechanisms and biomarkers may allow targeted treatment to prevent disease progression.

CONCLUSIONS

Although different molecular expression patterns and signaling pathways related to microvascular dysfunction in pre-SSc, VEDOSS, and early SSc were identified, additional prospective longitudinal studies and combined work with functional evaluation of peripheral skin perfusion are needed.

Chronic PCSK9 inhibitor therapy leads to sustained improvements in endothelial function, arterial stiffness, and microvascular function

BACKGROUND

Proprotein convertase subtilisin/kexin type 9 inhibitors (PCSK9i) effectively decrease low-density lipoprotein cholesterol (LDL-C) and reduce cardiovascular events in patients at very high cardiovascular risk. Recent short-term studies suggest a partially LDL-C independent beneficial effect of PCSK9 inhibitor (PCSK9i) therapy on endothelial function and arterial stiffness, whereas it is unknown if this effect persists and what the effect is on microcirculation.

OBJECTIVE

To investigate the effects of PCSK9i therapy on vascular parameters beyond its lipid lowering effect.

METHODS

In this prospective trial, 32 patients at very high cardiovascular risk and indication for PCSK9i therapy were included. Measurements were performed at baseline and after 6 months of PCSK9i treatment. Endothelial function was assessed as flow-mediated dilation (FMD). Arterial stiffness was measured as pulse wave velocity (PWV) and aortic augmentation index (AIx). Peripheral tissue oxygenation (StO₂) as a marker of microvascular function was assessed at the distal extremities using near-infrared spectroscopy camera.

RESULTS

Six months of PCSK9i therapy decreased LDL-C levels from 141 ± 54 to 60 ± 30 mg/dl (-56 ± 21 %, p < 0.001), FMD significantly increased from 5.4 ± 1.7 % to 6.4 ± 1.9 % (+19 ± 10 %, p < 0.001), PWV decreased in male patients significantly from 8.9 ± 2.1 to 7.9 ± 1.5 m/s (-12 ± 9 %, p = 0.025). AIx decreased from 27.1 ± 10.4 % to 23.0 ± 9.7 % (-16 ± 14 %, p < 0.001), StO₂ significantly increased from 67 ± 12 % to 71 ± 11 % (+7 ± 6 %, p = 0.012). Brachial and aortic blood pressure showed no significant changes after six months. There was no correlation between LDL-C reduction and changes in vascular parameters.

CONCLUSIONS

Chronic PCSK9i therapy is associated with sustained improvements in endothelial function, arterial stiffness, and microvascular function independent from lipid lowering.

Open-source mobile multispectral imaging system and its applications in biological sample sensing

Visible-near-infrared spectroscopy data can be utilized as an important quantitative indicator of biomolecular quantitative analysis. When acquiring spectral information, hyperspectral/multispectral imaging systems can obtain the spatial information of the object of interest. This allows the complete spatial-spectral information of the object of interest to be acquired and the spatial distribution of biomolecules to be analyzed. In this study, we present an open-source mobile multispectral imaging system, test the influence of the utilization of LEDs on the multispectral image, and design image-processing algorithms to correct this influence. Todemonstrate the effectivenessofthesystem, the system is applied to meat freshness analysis, small-animal tumor in-vivo imaging, and chlorophyll spatial distribution imaging. The experimental results verify that our system has stable performance and is compatible with a wide range of spectral imaging applications.

Endothelial Dysfunction in Systemic Lupus Erythematosus and Systemic Sclerosis: A Common Trigger for Different Microvascular Diseases

This review describes the complex interplay between inflammation, vasculopathy and fibrosis that involve the heart and peripheral small vessels, leading to endothelial stiffness, vascular damage, and early aging in patients with systemic lupus erythematosus and systemic sclerosis, which represents two different models of vascular dysfunction among systemic autoimmune diseases. In fact, despite the fact that diagnostic methods and therapies have been significantly improved in the last years, affected patients show an excess of cardiovascular mortality if compared with the general population. In addition, we provide a complete overview on the new techniques which are used for the evaluation of endothelial dysfunction in a preclinical phase, which could represent a new approach in the assessment of cardiovascular risk in these patients.

[Modern concept about trophic venous ulcers]

Venous trophic ulcer is a common complication of chronic venous diseases that have a negative impact on the quality of life and result negative socio-economic consequences. There are three main theories of development of venous trophic ulcers. The criterion is visible trophic changes of skin (CEAP class C4). If correction of etiological factor of ulcer is impossible, local management is preferred. There are various wound coverings which can be used for the treatment of trophic ulcers. However, data on their effectiveness are sometimes unavailable. Therefore, it is necessary to systematize knowledge about modern measures and methods of exposure to trophic ulcers. The authors also discuss current understanding of pathophysiology, symptoms and diagnosis of venous trophic ulcers.

High-resolution functional photoacoustic monitoring of vascular dynamics in human fingers

Functional imaging of microvascular dynamics in extremities delivers intuitive information for early detection, diagnosis, and prognosis of vascular diseases. High-resolution and high-speed photoacoustic microscopy (PAM) visualizes and measures multiparametric information of microvessel networks in vivo such as morphology, flow, oxygen saturation, and metabolic rate. Here, we demonstrate high-resolution photoacoustic monitoring of vascular dynamics in human fingers. We photoacoustically monitored the position displacement of blood vessels associated with arterial pulsation in human fingers. Then, during and after arterial occlusion, we photoacoustically quantified oxygen consumption and blood perfusion in the fingertips. The results demonstrate that high-resolution functional PAM could be a vital tool in peripheral vascular examination for measuring heart rate, oxygen consumption, and/or blood perfusion.

The Core of Medical Imaging: State of the Art and Perspectives on the Detectors

In this review, the roles of detectors in various medical imaging techniques were described. Ultrasound, optical (near-infrared spectroscopy and optical coherence tomography) and thermal imaging, magnetic resonance imaging, computed tomography, single-photon emission tomography, positron emission tomography were the imaging modalities considered. For each methodology, the state of the art of detectors mainly used in the systems was described, emphasizing new technologies applied.

Systemic vascular distensibility relates to exercise capacity in connective tissue disease

OBJECTIVE

Exercise intolerance is a common clinical manifestation of CTD. Frequently, CTD patients have associated cardio-pulmonary disease, including pulmonary hypertension or heart failure that impairs aerobic exercise capacity (pVO2). The contribution of the systemic micro-vasculature to reduced exercise capacity in CTD patients without cardiopulmonary disease has not been fully described. In this study, we sought to examine the role of systemic vascular distensibility, α in reducing exercise capacity (i.e. pVO2) in CTD patients.

METHODS

Systemic and pulmonary vascular distensibility, α (%/mmHg) was determined from multipoint systemic pressure-flow plots during invasive cardiopulmonary exercise testing with pulmonary and radial arterial catheters in place in 42 CTD patients without cardiopulmonary disease and compared with 24 age and gender matched normal controls.

RESULTS

During exercise, systemic vascular distensibility, α was reduced in CTD patients compared with controls (0.20 ± 0.12%/mmHg vs 0.30 ± 0.13%/mmHg, P =0.01). The reduced systemic vascular distensibility α, was associated with impaired stroke volume augmentation. On multivariate analysis, systemic vascular distensibility, α was associated with a decreased exercise capacity (pVO2) and decreased systemic oxygen extraction.

CONCLUSION

Systemic vascular distensibility, α is associated with impaired systemic oxygen extraction and decreased aerobic capacity in patients with CTD without cardiopulmonary disease.

Vascular endothelial injury assessed with functional techniques in systemic sclerosis patients with pulmonary arterial hypertension versus systemic sclerosis patients without pulmonary arterial hypertension: a systematic review and meta-analysis

Microvascular dysfunction is one of the hallmarks of systemic sclerosis (SSc). The presence of pulmonary-arterial-hypertension (PAH) in SSc-patients is associated with poor prognosis. This is a systematic review and meta-analysis of studies assessing microvascular and endothelial injury with functional techniques in SSc-patients with PAH (SSc-PAH) compared to those without PAH (SSc-non-PAH) (PROSPERO: CRD42021236212). Literature search involved PubMed, the-Cochrane-Library, Web-of-Science, Scopus and manual search of article references. Studies assessing microvascular function by all available functional methods were considered eligible. Preclinical studies and studies using structural nailfold-videocapillaroscopy or biomarkers were excluded. Newcastle-Ottawa-Scale (NOS) was applied to evaluate the quality of retrieved studies. From a total of 602 retrieved articles, four studies (n = 159 participants) were included in meta-analysis; three studies were of high quality (NOS ≥ 7). In pooled analysis, a marginally significant impaired microvascular function was observed in SSc-PAH compared to SSc-non-PAH patients [SMD - 0.71, 95% CI (- 1.53, 0.12)], with significant between-study heterogeneity (I² = 80%, p = 0.002). Among the studies examining endothelium-dependent and -independent vasodilation with LDF-iontophoresis, SSc-PAH subjects had significantly impaired endothelium-dependent-vasodilation [Ach-stimulated %change WMD - 216.79, 95% CI (- 337.87, - 95.71), I² = 0%, p = 0.40], but no significant differences in endothelium-independent-vasodilation [SNP-stimulated %change WMD 90.84, 95% CI (- 82.52, 264.19), I² = 44%, p = 0.18] compared with SSc-non-PAH subjects. In sensitivity analysis including only studies where SSc-PAH patients were diagnosed by right-heart-catheterization, a borderline difference between the two groups was noted [SMD - 1.09, 95% CI (- 2.30, 0.13), I² = 82%, p = 0.004]. SSc-PAH patients showed marginally impaired microvascular function in the pooled analysis, as well as impaired endothelium-dependent-vasodilation in subgroup analysis compared with SSc-non-PAH patients. Vascular endothelial dysfunction could be involved in high cardiovascular risk of patients with SSc and PAH.

Monitoring the microcirculation in the diagnosis and follow-up of systemic sclerosis patients: Focus on pulmonary and peripheral vascular manifestations

Systemic sclerosis (SSc) is a connective tissue disease, characterized by vascular damage and progressive fibrosis, affecting the skin and internal organs. The vascular changes include functional and structural abnormalities in the microcirculation, which play a central role not only in diagnosis but also in the prognosis and follow-up of systemic sclerosis patients. Nailfold videocapillaroscopy (NVC) is a safe, validated, noninvasive, inexpensive, reliable, and reproducible method that allows for the evaluation of structural changes in scleroderma microangiopathy. However, capillary blood flow/perfusion cannot be measured by NVC under standard conditions and, consequently, must rely on various laser techniques and thermography for the assessment and quantification of cutaneous blood perfusion. Other emerging technologies, such as optical Doppler tomography and spectroscopy, may be used to evaluate the skin flow. This review updates current knowledge on the use of microvascular evaluation techniques in SSc, including complications such as digital ulcers and pulmonary arterial hypertension.

State-of-the-art technologies provide new insights linking skin and blood vessel abnormalities in SSc-related disorders

OBJECTIVE

A key unanswered question in systemic sclerosis (SSc) is how microvascular abnormality and fibrosis inter-relate. Our aim was to use state-of-the-art non-invasive imaging methods to gain new insights into pathophysiology, comparing patients with different subtypes of SSc, including early dcSSc, not only to healthy controls but also to patients with causes of Raynaud's phenomenon not progressing to fibrosis.

METHODS

Laser Doppler imaging, nailfold capillaroscopy, spectroscopy, and ultrasound measured (respectively) perfusion, microvascular structure, oxygenation/oxidative stress, and skin thickening in the hands of 265 subjects: 31 patients with primary Raynaud's phenomenon (PRP), 35 with undifferentiated connective tissue disease (UCTD), 93 with limited cutaneous SSc (lcSSc), 46 with diffuse cutaneous SSc (dcSSc, including 27 'early') and 60 healthy controls.

RESULTS

Mean perfusion was reduced in SSc groups compared to controls (lcSSc 172 perfusion units [standard deviation 157], late-dcSSc 90 [145], early-dcSSc 68 [137] vs. controls 211 [146]; p = 0.0002) as was finger-oxygenation (lcSSc 12.1 [13.6] arbitrary units [AU], late-dcSSc 12.2 [8.4], early-dcSSc 11.1 [11.3] vs controls 14.9 [10.5]; p = 0.0049). Oxidative stress was increased at the hand-dorsum in SSc groups (p = 0.0007). Perfusion positively correlated with oxygenation (r = 0.23, p < 0.001), and capillary density negatively with skin thickness (r = -0.26, p < 0.001).

CONCLUSION

Our findings lend support to the hypothesis that in SSc, particularly early dcSSc, (but not in PRP or UCTD), reduced perfusion (together with structural microvascular abnormality) associates with reduced oxygenation, with oxidative stress and with skin thickening/fibrosis, most likely driving a vicious cycle which ultimately results in irreversible tissue injury. Findings in skin may mirror alterations in internal organs.