Human Lymphatic Architecture and Dynamic Transport Imaged Using Near-infrared Fluorescence

Case Report: The effect of automated manual lymphatic drainage therapy on lymphatic contractility in 4 distinct cases

Introduction

Automated manual lymphatic drainage therapy (AMLDT) is available for home use in the form of a pneumatic mat of 16 pressurized air channels that inflate and deflate to mimic the stretch and release action of manual lymphatic drainage therapy. Four cases (a patient with complex regional pain syndrome and lymphedema, a healthy patient, a breast cancer survivor with chronic pain, and a patient with a history of abdominal surgery) underwent near-infrared fluorescence lymphatic imaging (NIRFLI) with AMLDT to evaluate the effect of AMLDT on lymphatic pumping and pain.

Methods

Each patient received 32-36 injections of 25 μg indocyanine green (ICG) on the anterior and posterior sides of their body and underwent 1 h of NIRFLI to assess the drainage of ICG laden lymph toward regional nodal basins at baseline. Each patient lay supine on the mat for 1 h of AMLDT with NIRFLI to assess lymphatic flow during treatment. A final NIFRFLI assessment was done 30-60 min posttreatment with the patient in the supine and prone position. Patients reported baseline and posttreatment pain using the Visual Analogue Scale. An imager analyzed NIRFLI images using ImageJ (US National Institutes of Health). Using time stamps of the first and last images to determine time lapsed and the number of pulses observed in a timeframe, pulsing frequency (pulses/min) was obtained to assess lymphatic function.

Results

All 4 cases completed the NIRFLI and AMLDT without complications; all 3 patients with baseline pain reported reduced pain posttreatment. AMLDT appeared to alter lymphatic contractility, with both increased and decreased pulsing frequencies observed, including in nonaffected limbs. Pulsing frequencies were very heterogeneous among patients and varied within anatomic regions of the same patient.

Discussion

This proof-of-concept study suggests that AMLDT may impact lymphatic contractility. Further research on its effect on lymphatic function is warranted.

Association Between Symptom Burden and Early Lymphatic Abnormalities After Regional Nodal Irradiation for Breast Cancer

PURPOSE

Dermal backflow visualized on near-infrared fluorescence lymphatic imaging (NIRF-LI) signals preclinical lymphedema that precedes the development of volumetrically defined lymphedema. We sought to evaluate whether dermal backflow correlates with patient-reported lymphedema outcomes (PRLO) surveys in breast cancer patients treated with regional nodal irradiation (RNI).

METHODS AND MATERIALS

Patients with breast cancer planned for axillary dissection and RNI prospectively underwent perometry, NIRF-LI, and PRLOs (the Lymphedema Symptom Intensity and Distress Survey [LSIDS] and QuickDASH) at baseline, after surgery, and at 6, 12, and 18 months after radiation. Clinical lymphedema was defined as an arm volume increase ≥5% over baseline. Trends over time were assessed using analysis of variance testing. The association between survey responses and both dermal backflow and lymphedema was assessed using a linear mixed-effects model.

RESULTS

Sixty participants completed at least 2 sets of measurements and surveys and were eligible for analysis. Fifty-four percent of patients had cT3-T4 disease, 53% cN3 disease, and 75% had a body mass index >25. Dermal backflow and clinical lymphedema increased from 10% to 85% and from 0% to 40%, respectively, from baseline to 18 months. In the adjusted model, soft tissue sensation, neurologic sensation, and functional LSIDS subscale scores were associated with presence of dermal backflow (all P < .05). Both dermal backflow and lymphedema were associated with QuickDASH score (P < .05).

CONCLUSIONS

In this high-risk cohort, we found highly prevalent early signs of lymphedema, with increased symptom burden from baseline. Presence of dermal backflow correlated with PRLO measures, highlighting a potential NIRF-LI use to identify patients for early intervention trials after RNI.

High Pressure 3 × 30 Minute Compression Methods for Advanced Lower Limb Lymphedema Patients

Introduction: In advanced lymphedema of lower limbs, stage III bandaging under the routinely applied pressure of 40-60 mmHg remains largely ineffective. This is caused by skin and subcutaneous tissue stiffness due to fibrosis. Edema fluid accumulates deep in the subcutaneous tissue. Evacuating this fluid requires a high external compression force to overcome the resistance of fibrous tissue. We aimed to investigate the effectiveness of the compression method, with high pressure lasting for 3 days. Methods and Results: Twenty-one patients with lower limb lymphedema, stage III, of the postinflammatory type were included. Patients with acute inflammatory symptoms, venous thrombosis, profuse varicose veins, diabetes, and cardiac insufficiency with edema were excluded. A 10-cm-wide rubber bandage was applied to the foot and calf. The interface pressure measured using PicoPress ranged from 58 to 120 mmHg. Skin and deep tissue tonometry, skin water concentration, leg circumference, and drop of interface pressure were measured. Ultrasound examination was done before and after each compression session. The calf circumference decreased by 15.9 ± 5.4%, deep tissue stiffness by 58.9 ± 18.9%, skin stiffness by 69.6 ± 13.5%, and skin water concentration by 43.8 ± 11.5%. Interface pressure dropped to 66.3 mmHg (28-110 mmHg); ultrasonography images showed less fluid in the tissue. Conclusions: High-pressure 30-minute leg compression can remove excess edema fluid within 3 days and enable adjustment of nonstretch compression stockings. This method is more effective in advanced lymphedema at the beginning of therapy than the standard 30-50-mmHg bandaging as it provides an immediate effect.

Lymphatic Vascular Insufficiency and Focal Edema in Early Stages of Noncancer-Related Lymphedema

Introduction: Lymph flows along the lymphatics due to spontaneous contraction. However, injury and inflammation may deteriorate lymphatic' s endothelial and muscle cells and valves. In consequence, lymphatic vessels (LVs) become insufficient. Their contraction strength and rate slow down, and then lymph flow stops. Our study aimed to investigate the changes in lymph flow in early lymphedema cases. Methods and Results: In 36 patients with unilateral lymphedema stages 0 and I, we performed indocyanine green (ICG) lymphography, lymphoscintigraphy, skin water concentration, and stiffness measurement. We compared lymph flow velocity, LVs' appearance, contraction pattern, and rate between swollen and healthy limbs. ICG lymphography revealed (1) slower lymph flow after 3 minutes of foot movement; in lower calf level, lymphatics are seen in 22 (61.1%) swollen limbs compared with 36 (100%) healthy limbs (p < 0.0001); (2) dye spots in the foot (47.1%) and calves (13.9%) in swollen limbs; (3) dilated foot (41.7%) and calves' lymphatics (52.8%); (4) different patterns of lymphatics contractility with slower contractions rate and (5) higher fluorescent intensity in edema limbs. There was higher skin water concentration at foot and ankle level and higher skin stiffness in the foot. Conclusions: Our studies have shown the distortion in lymphatic function as dilatation, slower lymph flow, slower contraction rate, presence of areas with occluded lymphatics (dermal backflow in foot and calves-focal edema), and higher skin water concentration in these regions in limbs with early lymphedema. ICG lymphography can be used for the early detection of LV insufficiency, which allows early prophylactic implementation.

In Vivo Dynamic and Static Analysis of Lymphatic Dysfunction in Lymphedema Using Near-Infrared Fluorescence Indocyanine Green Lymphangiography

BACKGROUND

Near-infrared fluorescence indocyanine green lymphangiography, a primary modality for detecting lymphedema, which is a disease due to lymphatic obstruction, enables real-time observations of lymphatics and reveals not only the spatial distribution of drainage (static analysis) but also information on the lymphatic contraction (dynamic analysis).

METHODS

We have produced total lymphatic obstruction in the upper limbs of 18 Sprague-Dawley rats through the dissection of proximal (brachial and axillary) lymph nodes and 20-Gy radiation (dissection limbs). After the model formation for 1 week, 9 animal models were observed for 6 weeks using near-infrared fluorescence indocyanine green lymphangiography by injecting 6-μL ICG-BSA (indocyanine green-bovine serum albumin) solution of 20-μg/mL concentration. The drainage pattern and leakage of lymph fluid were evaluated and time-domain signals of lymphatic contraction were observed in the distal lymphatic vessels. The obtained signals were converted to frequency-domain spectrums using signal processing.

RESULTS

The results of both static and dynamic analyses proved to be effective in accurately identifying the extent of lymphatic disruption in the dissection limbs. The static analysis showed abnormal drainage patterns and increased leakage of lymph fluid to the periphery of the vessels compared with the control (normal) limbs. Meanwhile, the waveforms were changed and the contractile signal frequency increased by 58% in the dynamic analysis. Specifically, our findings revealed that regular lymphatic contractions, observed at a frequency range of 0.08 to 0.13 Hz in the control limbs, were absent in the dissection limbs. The contractile regularity was not fully restored for the follow-up period, indicating a persistent lymphatic obstruction.

CONCLUSIONS

The dynamic analysis could detect the abnormalities of lymphatic circulation by observing the characteristics of signals, and it provided additional evaluation indicators that cannot be provided by the static analysis. Our findings may be useful for the early detection of the circulation problem as a functional evaluation indicator of the lymphatic system.

Imaging peripheral lymphatic dysfunction in chronic conditions

The lymphatics play important roles in chronic diseases/conditions that comprise the bulk of healthcare worldwide. Yet the ability to routinely image and diagnose lymphatic dysfunction, using commonly available clinical imaging modalities, has been lacking and as a result, the development of effective treatment strategies suffers. Nearly two decades ago, investigational near-infrared fluorescence lymphatic imaging and ICG lymphography were developed as routine diagnostic for clinically evaluating, quantifying, and treating lymphatic dysfunction in cancer-related and primary lymphedema, chronic venous disease, and more recently, autoimmune and neurodegenerative disorders. In this review, we provide an overview of what these non-invasive technologies have taught us about lymphatic (dys) function and anatomy in human studies and in corollary animal studies of human disease. We summarize by commenting on new impactful clinical frontiers in lymphatic science that remain to be facilitated by imaging.

Plasma Cytokines/Chemokines as Predictive Biomarkers for Lymphedema in Breast Cancer Patients

Breast cancer-related lymphedema (BCRL) occurs in ~ 40% of patients after axillary lymph node dissection (ALND), radiation therapy (RT), or chemotherapy. First-line palliative treatment utilizes compression garments and specialized massage. Reparative microsurgeries have emerged as a second-line treatment, yet both compression and surgical therapy are most effective at early stages of LE development. Identifying patients at the highest risk for BCRL would allow earlier, more effective treatment. Perometric arm volume measurements, near-infrared fluorescent lymphatic imaging (NIRF-LI) data, and blood were collected between 2016 and 2021 for 40 study subjects undergoing treatment for breast cancer. Plasma samples were evaluated using MILLIPLEX human cytokine/chemokine panels at pre-ALND and at 12 months post-RT. A Mann-Whitney t-test showed that G-CSF, GM-CSF, IFN-2α, IL-10, IL-12p40, IL-15, IL-17A, IL-1β, IL-2, IL-3, IL-6, and MIP-1β were significantly higher at pre-ALND in those presenting with BCRL at 12 months post-RT. MIP-1β and IL-6 were significantly higher at pre-ALND in those who developed dermal backflow, but no BCRL, at 12 months post-RT. Plasma IL-15, IL-3, and MIP-1β were elevated at 12 months after RT in those with clinical BCRL. These findings establish BCRL as a perpetual inflammatory disorder, and suggest the use of plasma cytokine/chemokine levels to predict those at highest risk.

Imaging of the Lymphatic Vessels for Surgical Planning: A Systematic Review

BACKGROUND

Secondary lymphedema is a common complication after surgical or radiotherapeutic cancer treatment. (Micro) surgical intervention such as lymphovenous bypass and vascularized lymph node transfer is a possible solution in patients who are refractory to conventional treatment. Adequate imaging is needed to identify functional lymphatic vessels and nearby veins for surgical planning.

METHODS

A systematic literature search of the Embase, MEDLINE ALL via Ovid, Web of Science Core Collection and Cochrane CENTRAL Register of Trials databases was conducted in February 2022. Studies reporting on lymphatic vessel detection in healthy subjects or secondary lymphedema of the limbs or head and neck were analyzed.

RESULTS

Overall, 129 lymphatic vessel imaging studies were included, and six imaging modalities were identified. The aim of the studies was diagnosis, severity staging, and/or surgical planning.

CONCLUSION

Due to its utility in surgical planning, near-infrared fluorescence lymphangiography (NIRF-L) has gained prominence in recent years relative to lymphoscintigraphy, the current gold standard for diagnosis and severity staging. Magnetic resonance lymphography (MRL) gives three-dimensional detailed information on the location of both lymphatic vessels and veins and the extent of fat hypertrophy; however, MRL is less practical for routine presurgical implementation due to its limited availability and high cost. High frequency ultrasound imaging can provide high resolution imaging of lymphatic vessels but is highly operator-dependent and accurate identification of lymphatic vessels is difficult. Finally, photoacoustic imaging (PAI) is a novel technique for visualization of functional lymphatic vessels and veins. More evidence is needed to evaluate the utility of PAI in surgical planning.

Lymphatic Function Decreases over Time in the Arms of Breast Cancer Patients following Treatment

In patients with breast cancer-related lymphedema, distinct lymphatic patterns and changed lymphatic contractile function have been described, but it is unknown how these characteristics change over time and to what extent they appear before clinical edema is detectable. Recently, we described the lymphatic morphology and function in a cohort of breast cancer patients shortly after radiation therapy (RT). In the current study, we investigate lymphatic function and morphology in the same cohort after 1 year of follow-up.

Methods

The study population consisted of 28 breast cancer patients investigated 12 months after adjuvant locoregional RT. Lymphatic contraction frequency (CF), propulsion velocity, and the morphology of lymphatic vessels in the upper extremities were described in vivo using near-infrared fluorescence imaging. Lymphatic stress test was performed using hyperthermia.

Results

At 1 year after RT, (n = 28) 46% of the patients presented with lymphatic morphological abnormalities with a degree of dermal backflow and 21% had developed clinical breast cancer-related lymphedema. In the ipsilateral arm, CF was 23% lower than in the contralateral arm (P = 0.04). Since primary examination, CF in the ipsilateral arm decreased by 40% (P = 0.03), whereas no change was observed in the contralateral arm. During hyperthermia, the ipsilateral arms with lymphatic complications were not able to increase CF as the remaining subgroups.

Conclusions

Lymphatic function in the ipsilateral arm deteriorated over time after adjuvant breast cancer therapy. Furthermore, the presence of abnormal torturous lymphatic vessels in asymptomatic arms appeared to be associated with weak lymphatic reserve pumping capacity.

Prediction of breast cancer-related lymphedema by dermal backflow detected with near-infrared fluorescence lymphatic imaging

PURPOSE

Mild breast cancer-related lymphedema (BCRL) is clinically diagnosed as a 5%-10% increase in arm volume, typically measured no earlier than 3-6 months after locoregional treatment. Early BCRL treatment is associated with better outcomes, yet amid increasing evidence that lymphedema exists in a latent form, treatment is typically delayed until arm swelling is obvious. In this study, we investigated whether near-infrared fluorescence lymphatic imaging (NIRF-LI) surveillance could characterize early onset of peripheral lymphatic dysfunction as a predictor of BCRL.

METHODS

In a prospective, longitudinal cohort/observational study (NCT02949726), subjects with locally advanced breast cancer who received axillary lymph node dissection and regional nodal radiotherapy (RT) were followed serially, between 2016 and 2021, before surgery, 4-8 weeks after surgery, and 6, 12, and 18 months after RT. Arm volume was measured by perometry, and lymphatic (dys) function was assessed by NIRF-LI.

RESULTS

By 18 months after RT, 30 of 42 study subjects (71%) developed mild-moderate BCRL (i.e., ≥ 5% arm swelling relative to baseline), all manifested by "dermal backflow" of lymph into lymphatic capillaries or interstitial spaces. Dermal backflow had an 83% positive predictive value and 86% negative predictive value for BCRL, with a sensitivity of 97%, specificity of 50%, accuracy of 83%, positive likelihood ratio of 1.93, negative likelihood ratio of 0.07, and odds ratio of 29.00. Dermal backflow appeared on average 8.3 months, but up to 23 months, before the onset of mild BCRL.

CONCLUSION

BCRL can be predicted by dermal backflow, which often appears months before arm swelling, enabling early treatment before the onset of edema and irreversible tissue changes.

Lymphoedema conditions disrupt endothelial barrier function in vitro

Lymphatic vessel contractions generate net antegrade pulsatile lymph flow. By contrast, impaired lymphatic vessels are often associated with lymphoedema and altered lymph flow. The effect of lymphoedema on the lymph flow field and endothelium is not completely known. Here, we characterized the lymphatic flow field of a platelet-specific receptor C-type lectin-like receptor 2 (CLEC2) deficient lymphoedema mouse model. In regions of lymphoedema, collecting vessels were significantly distended, vessel contractility was greatly diminished and pulsatile lymph flow was replaced by quasi-steady flow. In vitro exposure of human dermal lymphatic endothelial cells (LECs) to lymphoedema-like quasi-steady flow conditions increased intercellular gap formation and permeability in comparison to normal pulsatile lymph flow. In the absence of flow, LECs exposed to steady pressure (SP) increased intercellular gap formation in contrast with pulsatile pressure (PP). The absence of pulsatility in steady fluid flow and SP conditions without flow-induced upregulation of myosin light chain (MLCs) regulatory subunits 9 and 12B mRNA expression and phosphorylation of MLCs, in contrast with pulsatile flow and PP without flow. These studies reveal that the loss of pulsatility, which can occur with lymphoedema, causes LEC contraction and an increase in intercellular gap formation mediated by MLC phosphorylation.

Lymphatic function and anatomy in early stages of lipedema

OBJECTIVE

Lipedema is an inflammatory subcutaneous adipose tissue disease that develops in women and may progress to lipolymphedema, a condition similar to lymphedema, in which lymphatic dysfunction results in irresolvable edema. Because it has been shown that dilated lymphatic vessels, impaired pumping, and dermal backflow are associated with presymptomatic, cancer-acquired lymphedema, this study sought to understand whether these abnormal lymphatic characteristics also characterize early stages of lipedema prior to lipolymphedema development.

METHODS

In a pilot study of 20 individuals with Stage I or II lipedema who had not progressed to lipolymphedema, lymphatic vessel anatomy and function in upper and lower extremities were assessed by near-infrared fluorescence lymphatic imaging and compared with that of a control population of similar age and BMI.

RESULTS

These studies showed that, although lower extremity lymphatic vessels were dilated and showed intravascular pooling, the propulsion rates significantly exceeded those of control individuals. Upper extremity lymphatics of individuals with lipedema were unremarkable. In contrast to individuals with lymphedema, individuals with Stage I and II lipedema did not exhibit dermal backflow.

CONCLUSIONS

These results suggest that, despite the confusion in the diagnoses between lymphedema and lipedema, their etiologies differ, with lipedema associated with lymphatic vessel dilation but not lymphatic dysfunction.

Gravity and lymphodynamics

The lymphatic system is compromised in different groups of patients. To recognize pathology, we must know what is healthy. We use Near-Infrared Fluorescence (NIRF) to assess peripheral lymphatic function in humans. We have shown that external factors such as exercise, hyperthermia, and pharmacological mediators influence the function of peripheral lymphatic vessels. In this study, we explored the impact on lymphatic vessels by the ever-present external factor-gravity. We used NIRF imaging to investigate the lymphatic changes to gravity. Gravity was assessed by changing body position from supine to standing. We extracted following lymphatic functional parameters: lymphatic packet propulsion frequency (contractions/min), velocity (cm/s), and pressure (mmHg). Raw data analysis was performed using a custom-written Labview program. All sequences were analyzed by two observers and interclass correlation scores were calculated. All statistical analysis was performed using RStudio Team (2021). RStudio: Integrated Development Environment for R. RStudio, PBC. Healthy participants (n = 17, 11 males, age 28.1 ± 2.6 years) were included. The lymphatic packet propulsion frequency at baseline was 0.5 ± 0.2 contractions/min and rose within 3 min significantly to a maximum of 1.2 ± 0.5 contractions/min during upright posture and remained significantly higher than the baseline lymphatic packet propulsion frequency after lying down again for up to 6 min. The lymph velocity was 1.5 ± 0.4 cm/s at baseline and changed in both directions and without a specific pattern at different points in time during standing. Lymph pressure was significantly higher while standing (mean increase 9 mmHg, CI: 2-15 mmHg). The ICC scores were 89.8% (85.9%-92.7%), 59.3% (46.6%-69.6%) and 89.4% (79.0%-94.8%) in lymphatic packet propulsion frequency (130 observations), velocity (125 observations), and pressure (30 observations), respectively. The lymphatic system responds within few minutes to gravitational changes by increasing lymphatic packet propulsion frequency and pressure.

Lymphatic Function in the Arms of Breast Cancer Patients-A Prospective Cohort Study

Background:

Lymphedema is a highly feared complication of breast cancer treatment, but the underlying complex mechanisms are still unknown. Thus, we investigated the lymphatic morphology and contractility in the lymphatic vessels of arms of high-risk breast cancer patients treated for node-positive early breast cancer.

Methods:

In this prospective cohort study 32 women treated for unilateral node-positive breast cancer were enrolled and studied 36 ± 23 days after loco-regional radiotherapy. Near-infrared fluorescence imaging was used to assess morphology and function of the superficial lymphatic vessels. Strain-gauge plethysmography was performed to evaluate the capillary filtration of fluid.

Both arms were investigated, with the non-treated arm acting as control. The patients were questioned about the presence of lymphedema yearly and finally 574 ± 118 days after ended radiotherapy.

Results:

Morphologically, 25% of the treated arms expressed lymphatic vessel abnormalities compared to the control arms (p = 0.0048). No difference in functional parameters (maximal pumping pressure, p = 0.20; contraction frequency, p = 0.63; contraction velocity, p = 0.55) was found between the treated and control arms. Patients who later developed lymphedema had a difference in velocity compared to those who did not develop lymphedema (p = 0.02). The capillary filtration rate was similar between the two arms (p = 0.18).

Conclusions:

Peripheral lymphatic vessels were morphologically changed in the ipsilateral arm in 25% of the patients and patients who later developed lymphedema showed an early increase in velocity. Other functional parameters and capillary filtration were unchanged in this early phase. These discrete changes might be early indicators of later development of lymphedema.

Degradation of lymphatic anatomy and function in early venous insufficiency

OBJECTIVE

We used near-infrared fluorescence lymphatic imaging in a pilot study to assess the lymphatics in preulcerative (C2-C4) venous insufficiency and determine whether involvement and/or degradation of lymphatic anatomy or function could play a role in the progression of chronic venous insufficiency. We also explored the role of lymphatics in early peripheral arterial disease.

METHODS

After informed consent and intradermal injections of indocyanine green for rapid lymphatic uptake, near-infrared fluorescence lymphatic imaging was used to assess the lymphatic anatomic structure and quantify the lymphatic propulsion rates in subjects with early venous insufficiency. The anatomic observations included interstitial backflow, characterized by the abnormal spreading of indocyanine green from the injection site primarily into the surrounding interstitial tissues; dermal backflow, characterized by the retrograde movement of dye-laden lymph from collecting lymphatics into the lymphatic capillaries; and lymphatic vessel segmentation and dilation.

RESULTS

Ten subjects with venous insufficiency were enrolled, resulting in two legs with C2 disease, nine legs with C3 disease, eight legs with C4 disease, and one leg with C5 disease. Interstitial and/or dermal backflow were observed in 25%, 33%, and 41% of the injection sites in each limb with C2, C3, and C4 disease, respectively. Distinct vessel segmentation and dilation were observed in limbs with a C3 and higher classification, and dermal backflow proximal to the injection sites was observed in two legs with C4 disease and in the inguinal region of the C5 study subject. The overall average lymph propulsion rates were 1.3 ± 0.4, 1.2 ± 0.7, and 0.8 ± 0.5 contractile events/min for limbs with C2, C3, and C4 disease, respectively. One subject with peripheral arterial disease, who had previously undergone bypass surgery, presented with extensive dermal backflow and lymphatic reflux.

CONCLUSIONS

Near-infrared fluorescence lymphatic imaging demonstrated that, compared with normal health subjects, the lymphatic anatomy and contractile function generally degrade with the severity of venous insufficiency. Lymphatic abnormalities mimic those in early cancer-acquired lymphedema subjects, as previously observed by us and others. Additional studies are needed to decipher the relationship, including any causality, between lymphatic dysfunction and peripheral vascular disease and venous insufficiency.

Lymphatic Dissemination and Axillary Web Syndrome in Primary Cutaneous Tuberculosis Secondary to Needlestick Injury

Cutaneous tuberculosis secondary to skin inoculation of Mycobacterium tuberculosis is uncommon but it can occur in the health care settings. Herein, we report an unusual case of primary cutaneous tuberculosis of the thumb following a needlestick injury. The infection progressed with a necrotic granuloma, lymphatic dysfunction as visualized by near-infrared fluorescence lymphatic imaging, and the development of an axillary web syndrome.

Impact of a compression garment, on top of the usual care, in patients with breast cancer with early disturbance of the lymphatic transport: protocol of a randomised controlled trial

INTRODUCTION

Breast cancer-related lymphoedema (BCRL) is a common phenomenon. When lymphoedema is diagnosed late, options for treatment are diminished. Therefore, early diagnosis and treatment are very important to alter the potential deleterious evolution. Lymphofluoroscopy visualises the superficial lymphatic architecture in detail, giving the opportunity to detect a disturbance in the lymphatic transport (ie, dermal backflow) before the lymphoedema is clinically visible.The main objective is to investigate if there is an additional effect of a compression garment on top of the usual care (ie, information and exercises) in patients with early disturbance of the lymphatic transport after breast cancer treatment. Development of clinical lymphoedema and/or deterioration of the dermal backflow visualised by lymphofluoroscopy is investigated.

METHODOLOGY

All patients scheduled for breast cancer surgery with unilateral axillary lymph node dissection or sentinel node biopsy in the Multidisciplinary Breast Clinic of the University Hospitals Leuven are being considered. Patients are assessed before surgery and at 1, 3, 6, 9, 12, 18, 24 and 36 months postoperatively. At each visit, a clinical assessment is performed determining the volume difference between both arms and hands (through circumference measurements and water displacement), the water content, the extracellular fluid, the pitting status and the skinfold thickness. Quality of life questionnaires are filled in. At each visit, a lymphofluoroscopy is performed as well. When a disturbance of the lymphatic transport is seen on lymphofluoroscopy, without the presence of clinical lymphoedema, the patient is randomised in either a control group receiving usual care or a preventive treatment group receiving usual care and a compression garment (whether or not combined with a glove).

ETHICS AND DISSEMINATION

The trial is conducted in compliance with the principles of the Declaration of Helsinki (2008), the principles of Good Clinical Practice and in accordance with all applicable regulatory requirements. This protocol has been approved by the Ethical Committee of the University Hospitals Leuven. Results will be disseminated by peer-reviewed scientific journals and presentation at international congresses.

TRIAL REGISTRATION NUMBER

NCT03210311 CONCLUSION: The investigators hypothesise that development of clinical BCRL can be prevented and/or the dermal backflow can be stabilised or improved, if a preventive treatment with compression garment is started in the early phase of disturbance.

Multimodality lymphatic imaging of postoperative chylothorax in an infant with Noonan syndrome: a case report

BACKGROUND

Chylothorax is a rare complication of pediatric cardiac operations that occurs more frequently in children with Noonan syndrome, a genetic disorder associated with cardiac defects and lymphatic anomalies.

CASE PRESENTATION

We report a case of postoperative chylothorax in a 6-month-old infant with Noonan syndrome where multimodality lymphatic imaging guided management was followed. Drainage patterns of the lymphatic capillaries in the lower and upper extremities were visualized during near-infrared fluorescence lymphatic imaging (NIRFLI). Dynamic magnetic resonance lymphangiography (MRL) further identified the site of leakage in the thoracic duct and subsequently guided surgical intervention.

CONCLUSIONS

Application of multimodality imaging allows for greater individualization of treatment and should be considered in patients with complex cases such as those with syndromes associated with a higher incidence of chylothorax. IRB Number: HSC-MS-13-0754, December 10, 2013.

Lymphatic Valves Separate Lymph Flow Into a Central Stream and a Slow-Moving Peri-Valvular Milieu

The lymphatic system plays a pivotal role in the transport of fats, waste, and immune cells, while also serving as a metastatic route for select cancers. Using live imaging and particle tracking, we experimentally characterized the lymph flow field distal from the inguinal lymph node in the vicinity of normal bileaflet and malformed unileaflet intraluminal valves. Particle tracking experiments demonstrated that intraluminal lymphatic valves concentrate higher velocity lymph flow in the center of the vessel, while generating adjacent perivalvular recirculation zones. The recirculation zones are characterized by extended particle residence times and low wall shear stress (WSS) magnitudes in comparison to the rest of the lymphangion. A malformed unileaflet valve skewed lymph flow toward the endothelium on the vessel wall, generating a stagnation point and a much larger recirculation zone on the opposite wall. These studies define physical consequences of bileaflet and unileaflet intraluminal lymphatic valves that affect lymph transport and the generation of a heterogeneous flow field that affects the lymphatic endothelium nonuniformly. The characterized flow fields were recreated in vitro connecting different flow environments present in the lymphangion to a lymphatic endothelial cell (LEC) pro-inflammatory phenotype. Unique and detailed insight into lymphatic flow is provided, with potential applications to a variety of diseases that affect lymph transport and drug delivery.

The Development and Treatment of Lymphatic Dysfunction in Cancer Patients and Survivors

Breast-cancer-acquired lymphedema is routinely diagnosed from the appearance of irreversible swelling that occurs as a result of lymphatic dysfunction. Yet in head and neck cancer survivors, lymphatic dysfunction may not always result in clinically overt swelling, but instead contribute to debilitating functional outcomes. In this review, we describe how cancer metastasis, lymph node dissection, and radiation therapy alter lymphatic function, as visualized by near-infrared fluorescence lymphatic imaging. Using custom gallium arsenide (GaAs)-intensified systems capable of detecting trace amounts of indocyanine green administered repeatedly as lymphatic contrast for longitudinal clinical imaging, we show that lymphatic dysfunction occurs with cancer progression and treatment and is an early, sub-clinical indicator of cancer-acquired lymphedema. We show that early treatment of lymphedema can restore lymphatic function in breast cancer and head and neck cancer patients and survivors. The compilation of these studies provides insights to the critical role that the lymphatics and the immune system play in the etiology of lymphedema and associated co-morbidities.

Indocyanine Green Lymphography and Lymphoscintigraphy Severity Stage Showed Strong Correlation in Lower Limb Lymphedema

Background: To examine the correlation between lymphedema severity on lymphoscintigraphy and indocyanine green (ICG) lymphography in patients with secondary lower extremity lymphedema. Methods and Results: The maximal circumference difference (MCD) between the two legs was recorded. Lymphoscintigraphy and ICG lymphography images were classified into type I to V according to dermal backflow (DB) stage and MD Anderson Cancer Center (MDACC) stage based on lymphatic flow preservation and how DB was extended. Correlation between the scales was analyzed. Forty-four patients attended our hospital for evaluation of secondary lower extremity lymphedema. The most common cause of lymphedema was a postoperative complication of a malignant tumor (32 patients; 72.5%). Correlation analysis showed that lymphoscintigraphy and ICG DB (anterior) stage (r = 0.92), lymphoscintigraphy and ICG DB (posterior) stage (r = 0.94), and lymphoscintigraphy and MDACC stage (r = 0.93) exhibited very strong positive correlations. Intrarater agreement between lymphoscintigraphy and ICG DB (posterior) stage was substantial (κ = 0.65), and moderate between lymphoscintigraphy and ICG DB (anterior) stage (κ = 0.59) and lymphoscintigraphy and MDACC stage (κ = 0.52). Lymphedema severity stages and MCDs exhibited moderate positive correlations. Conclusion: Lymphoscintigraphy and ICG lymphography stage were strongly and positively correlated. These studies can work synergistically as complementary studies of lymphedema severity.

A Novel Approach to Quantifying Lymphatic Contractility during Indocyanine Green Lymphangiography

Lymphedema arises from impaired lymphatic function. Quantification of lymphatic contractility has previously been shown using a custom-built near-infrared imaging system. However, to broaden the clinical use of functional lymphatic measurements, these measurements need to be performed using a standard-of-care, clinically available camera. The authors propose an objective, algorithmic, and clinically accessible approach to quantify lymphatic contractility using a 3-minute indocyanine green lymphangiograph recorded with a commercially available near-infrared camera. A retrospective review of the authors' indocyanine green lymphangiography video repository maintained in a Research Electronic Data Capture database was performed. All patients with a newly diagnosed unilateral breast cancer undergoing preoperative indocyanine green lymphangiography were included in the analysis. Patient medical records were then analyzed for patient demographics, and videos were analyzed for contractility. Seventeen consecutive patients with unilateral breast cancers underwent video processing to quantify lymphatic contractility of the ipsilateral extremity in contractions per minute. All patients were women, with an average age of 60.5 years (range, 38 to 84 years). The average lymphatic contractility rate was 1.13 contractions per minute (range, 0.67 to 2.5 contractions per minute). Using a clinically accessible standard-of-care device for indocyanine green lymphangiography, the authors were able to determine lymphatic contractility rates of a normal extremity. The authors' finding falls within the range of previously published data quantifying lymphatic contractility using a research device, suggesting that the authors' technique provides a clinically accessible, time-effective means of assessing lymphatic contractility. Potential future applications include both lymphedema surveillance and evaluation of nonsurgical and surgical interventions. CLINICAL QUESTION/LEVEL OF EVIDENCE:: Diagnostic, IV.

Conjugated polymers as nanoparticle probes for fluorescence and photoacoustic imaging

In this review, the role of conjugated polymer nanoparticles (CPNs) in emerging bioimaging techniques is described.

Visualization of Accessory Lymphatic Pathways, before and after Manual Drainage, in Secondary Upper Limb Lymphedema Using Indocyanine Green Lymphography

Manual Lymphatic Drainage (MLD) appears to stimulate lymphatic contraction, aid in the development of secondary derivation pathways, and stimulate the appearance of collateral pathways that could function as the main drainage routes of the limb in case of lymphedema. Through stretching, call up maneuvers are used to stimulate lymphangion reflex contraction and, therefore, lymphatic function. The aim was to describe the presence of areas and pathways of collateral lymphatic drainage under basal conditions and to determine, using Indocyanine Green (ICG) lymphography, whether an increase in these pathways occurs after 30 min of manual lymphatic stimulation with only call up maneuvers according to the Leduc Method^®®. In this prospective analytical study (pretest–posttest), the frequency of presentation of areas and collateral lymphatic pathways was analyzed in 19 patients with secondary lymphedema of the upper limb after breast cancer using an infrared camera. Analyses were completed at three time points: after ICG injection, at baseline (pretest), and after the application of MLD (post-test). The Leduc Method maneuvers were applied to the supraclavicular and axillary nodes, chest, back, Mascagni, and Caplan pathways. The areas visualized in the pretest continued to be visible in the posttest. Additional pathways and fluorescent areas were observed after the maneuvers. The McNemar test showed statistical significance (p = 0.008), the odds ratio was infinite, and the Cohen’s g value was equal to 0.5. Manual stimulation by call up maneuvers increased the observation frequency of areas and collateral lymphatic pathways. Therefore, ICG lymphography appears to be a useful tool for bringing out the routes of collateral bypass in secondary lymphoedema after cancer treatment.

Recognition and management of adults with Turner syndrome: From the transition of adolescence through the senior years

Turner syndrome is recognized now as a syndrome familiar not only to pediatricians and pediatric specialists, medical geneticists, adult endocrinologists, and cardiologists, but also increasingly to primary care providers, internal medicine specialists, obstetricians, and reproductive medicine specialists. In addition, the care of women with Turner syndrome may involve social services, and various educational and neuropsychologic therapies. This article focuses on the recognition and management of Turner syndrome from adolescents in transition, through adulthood, and into another transition as older women. It can be viewed as an interpretation of recent international guidelines, complementary to those recommendations, and in some instances, an update. An attempt was made to provide an international perspective. Finally, the women and families who live with Turner syndrome and who inspired several sections, are themselves part of the broad readership that may benefit from this review.

Cancer-associated secondary lymphoedema

Lymphoedema is an oedematous condition with a specific and complex tissue biology. In the clinical context of cancer, the pathogenesis of lymphoedema ensues most typically from the modalities employed to stage and treat the cancer (in particular, surgery and radiotherapy). Despite advances in cancer treatment, lifelong lymphoedema (limb swelling and the accompanying chronic inflammatory processes) affects approximately one in seven individuals treated for cancer, although estimates of lymphoedema prevalence following cancer treatment vary widely depending upon the diagnostic criteria used and the duration of follow-up. The natural history of cancer-associated lymphoedema is defined by increasing limb girth, fibrosis, inflammation, abnormal fat deposition and eventual marked cutaneous pathology, which also increases the risk of recurrent skin infections. Lymphoedema can substantially affect the daily quality of life of patients, as, in addition to aesthetic concerns, it can cause discomfort and affect the ability to carry out daily tasks. Clinical diagnosis is dependent on comparison of the affected region with the equivalent region on the unaffected side and, if available, with pre-surgical measurements. Surveillance is indicated in this high-risk population to facilitate disease detection at the early stages, when therapeutic interventions are most effective. Treatment modalities include conservative physical strategies that feature complex decongestive therapy (including compression garments) and intermittent pneumatic compression, as well as an emerging spectrum of surgical interventions, including liposuction for late-stage disease. The future application of pharmacological and microsurgical therapeutics for cancer-associated lymphoedema holds great promise.

Lymphatic Function in Autoimmune Diseases

Lymphatic vessels are critical for clearing fluid and inflammatory cells from inflamed tissues and also have roles in immune tolerance. Given the functional association of the lymphatics with the immune system, lymphatic dysfunction may contribute to the pathophysiology of rheumatic autoimmune diseases. Here we review the current understanding of the role of lymphatics in the autoimmune diseases rheumatoid arthritis, scleroderma, lupus, and dermatomyositis and consider the possibility that manual therapies such as massage and acupuncture may be useful in improving lymphatic function in autoimmune diseases.

Head and Neck Lymphedema: Treatment Response to Single and Multiple Sessions of Advanced Pneumatic Compression Therapy

Ten head and neck cancer survivors diagnosed with head and neck lymphedema (HNL) were imaged using near-infrared fluorescence lymphatic imaging (NIRFLI) prior to and immediately after an initial advance pneumatic compression device treatment and again after 2 weeks of daily at-home use. Images assessed the impact of pneumatic compression therapy on lymphatic drainage. Facial composite measurement scores assessed reduction/increase in external swelling, and survey results were obtained. After a single pneumatic compression treatment, NIRFLI showed enhanced lymphatic uptake and drainage in all subjects. After 2 weeks of daily treatment, areas of dermal backflow disappeared or were reduced in 6 of 8 subjects presenting with backflow. In general, reductions in facial composite measurement scores tracked with reductions in backflow and subject-reported improvements; however, studies are needed to determine whether longer treatment durations can be impactful and whether advanced pneumatic compression can be used to ameliorate backflow characteristic of HNL.

Near-infrared fluorescence lymphatic imaging of Klippel-Trénaunay syndrome

The relationship between lymphatic and venous malformations in Klippel-Trénaunay syndrome is difficult to assess. Herein the authors describe near-infrared fluorescence lymphatic imaging to assess the lymphatics of a subject with a large port-wine stain and right leg edema. Although lymphatic vessels in the medial, affected knee appeared dilated and perhaps tortuous, no definitive abnormal lymphatic pooling or propulsion was observed. The lymphatics in the affected limb were well defined but less numerous than in the contralateral limb, and active, contractile function was observed in all vessels. As demonstrated, near-infrared fluorescence lymphatic imaging enables the clinical assessment of lymphatics in lymphovenous malformations.

Targeting lymphatic function as a novel therapeutic intervention for rheumatoid arthritis

Although clinical outcomes for patients with rheumatoid arthritis (RA) have greatly improved with the use of biologic and conventional DMARDs, approximately 40% of patients do not achieve primary clinical outcomes in randomized trials, and only a small proportion achieve lasting remission. Over the past decade, studies in murine models point to the critical role of the lymphatic system in the pathogenesis and therapy of inflammatory-erosive arthritis, presumably by the removal of catabolic factors, cytokines and inflammatory cells from the inflamed synovium. Murine studies demonstrate that lymphatic drainage increases at the onset of inflammatory-erosive arthritis but, as inflammation progresses to a more chronic phase, lymphatic clearance declines and both structural and cellular changes are observed in the draining lymph node. Specifically, chronic damage to the lymphatic vessel from persistent inflammation results in loss of lymphatic vessel contraction followed by lymph node collapse, reduced lymphatic drainage, and ultimately severe synovitis and joint erosion. Notably, clinical pilot studies in patients with RA report lymph node changes following treatment, and thus draining lymphatic vessels and nodes could represent a potential biomarker of arthritis activity and response to therapy. Most importantly, targeting lymphatics represents an innovative strategy for therapeutic intervention for RA.

Protocol of a randomised controlled trial regarding the effectiveness of fluoroscopy-guided manual lymph drainage for the treatment of breast cancer-related lymphoedema (EFforT-BCRL trial)

OBJECTIVES

Lymphoedema is a dreadful complication following breast cancer therapy. According to the International Society of Lymphology, the consensus treatment for breast cancer-related lymphoedema (BCRL) is the decongestive lymphatic therapy. This is a two-phase treatment and combines different treatment modalities including skin care, manual lymphatic drainage (MLD), compression therapy and exercise. However, the additional effect of MLD is debated since pooled data only demonstrated a limited non-significant additional value. A possible explanation is that in previous studies MLD has been applied blind, without knowledge of patient-specific lymphatic routes of transport. In addition, the MLD hand manoeuvres used by the therapists in previous studies, possibly did not optimally stimulate lymphatic transport. Recently, near-infrared fluorescence imaging has been introduced to visualise the superficial lymphatic network which allows MLD at the most needed location. The aim of the present study is to determine the effectiveness of the fluoroscopy-guided MLD, additional to the other parts of the decongestive lymphatic therapy and compared to the traditional or a placebo MLD, in the treatment of BCRL.

STUDY DESIGN

A three-arm double-blinded randomised controlled trial will be conducted in different university hospitals in Belgium. Based on a sample size calculation, 201 participants with chronic BCRL stage 1 or 2 of the arm or hand, with at least 5% difference between both sides (corrected for hand dominance) need to be recruited. All participants receive the standard treatment: skin care, compression therapy and exercises. The intervention group additionally receives fluoroscopy-guided MLD. One control group additionally receives the traditional 'blind' MLD and a second control group receives a placebo MLD. All subjects receive 3 weeks of daily intensive treatments and 6 months of maintenance treatment. Follow-up period is 6 months. The primary outcomes are the reduction in lymphoedema volume of the arm/hand and the change in stagnation of lymph fluid at level of the shoulder/trunk.

Near-Infrared Fluorescence Lymphatic Imaging of a Toddler With Congenital Lymphedema

Primary lymphedema in the pediatric population remains poorly diagnosed and misunderstood due to a lack of information on the causation and underlying anatomy of the lymphatic system. Consequently, therapeutic protocols for pediatric patients remain sparse and with little evidence to support them. In an effort to better understand the causation of primary pediatric lymphedema and to better inform clinical care, we report the use of near-infrared fluorescence lymphatic imaging on the extremities of an alert, 21-month-old boy who presented with unilateral right arm and hand lymphedema at birth. The imaging results indicated an intact, apparently normal lymphatic anatomy with no obvious malformation, but with decreased lymphatic contractile function of the affected upper extremity relative to the contralateral and lower extremities. We hypothesized that the lack of contraction of the lymphatic vessels rather than an anatomic malformation was the source of the unilateral extremity swelling, and that compression and manual lymphatic drainage could be effective treatments.

Effect of pneumatic compression therapy on lymph movement in lymphedema-affected extremities, as assessed by near-infrared fluorescence lymphatic imaging

Previous studies have shown cost effectiveness and quality-of-life benefit of pneumatic compression therapy (PCT) for lymphedema. Insurers, such as the Centers for Medicare/Medicaid (CMS), however, desire visual proof that PCT moves lymph. Near-infrared fluorescence lymphatic imaging (NIRFLI) was used to visualize lymphatic anatomy and function in four subjects with primary and cancer treatment-related lymphedema (LE) of the lower extremities before, during, and after pneumatic compression therapy (PCT). Optically transparent and windowed PCT garments allowed visualization of lymph movement during single, one-hour PCT treatment sessions. Visualization revealed significant extravascular and lymphatic vascular movement of intradermally injected dye in all subjects. In one subject with sufficient patent lymphatic vessels to allow quantification of lymph pumping velocities and frequencies, these values were significantly increased during and after PCT as compared to pre-treatment values. Lymphatic contractile activity in patent lymphatic vessels occurred in concert with the sequential cycling of PCT. Direct visualization revealed increased lymphatic function, during and after PCT therapy, in all lymphedema-affected extremities. Further studies are warranted to assess the effects of PCT pressure and sequences on lymph uptake and movement.

New diagnostic modalities in the evaluation of lymphedema

OBJECTIVE

Currently, lymphedema (LED) is typically diagnosed clinically on the basis of a patient's history and characteristic physical findings. Whereas the diagnosis of LED is sometimes confirmed by lymphoscintigraphy (LSG), the technique is limited in both its ability to identify disease and to guide therapy. Recent advancements provide opportunities for new imaging techniques not only to assist in the diagnosis of LED, based on anatomic changes, but also to assess contractile function and to guide therapeutic intervention. The purpose of this contribution was to review these imaging techniques.

METHODS

Literature for each technique is reviewed and discussed, and the evidence for each of these new diagnostic techniques was assessed on several criteria to determine if each could (1) establish whether disease is present, (2) determine the severity of the disease process, (3) define the pathophysiologic mechanism of the disease process, (4) demonstrate whether intervention is possible as well as what type, and (5) objectively grade the response to therapy.

RESULTS

LSG is currently the standard test to confirm LED. Duplex ultrasound (DUS) is a simple, readily available noninvasive test that can identify LED by specific tissue characteristics as well as the response to therapy. Magnetic resonance imaging and computed tomography scans similarly demonstrate the alterations in epidermal and subcutaneous tissue, but the latter can also detect obstructing neoplasms as a cause of secondary LED. Moreover, magnetic resonance lymphangiography details lymphatic vessels and nodes and their function. Newer fluorescence imaging techniques provide opportunities to image lymphatic anatomy and function. Visible microlymphangiography by fluorescein sodium is limited by tissue light absorption to imaging depths of 200 μm. Near-infrared fluorescence lymphatic imaging, a newer test using intradermal injection of indocyanine green, can penetrate several centimeters of tissue and can visualize the initial and conducting lymphatics, the lymph node basins, and the active function of lymphangions (the key module) in exquisite detail.

CONCLUSIONS

The availability and the noninvasive nature of DUS should make this modality the first choice for establishing the diagnosis of LED based on tissue changes. Further studies comparing DUS with LSG, however, are needed. The costs of magnetic resonance imaging and computed tomography limit their adoption as a means to regularly assess the lymphatics. Whereas lymphatic truncal anatomy and transit times can be delineated by the older technique of LSG, near-infrared fluorescence lymphatic imaging is rapid, highly sensitive, and repeatable and provides exquisite detail for lymphatic vessel anatomy and function of the lymphangions as well as the response to therapy.

Diphtheria toxin-mediated ablation of lymphatic endothelial cells results in progressive lymphedema

Development of novel treatments for lymphedema has been limited by the fact that the pathophysiology of this disease is poorly understood. It remains unknown, for example, why limb swelling resulting from surgical injury resolves initially, but recurs in some cases months or years later. Finding answers for these basic questions has been hampered by the lack of adequate animal models. In the current study, we used Cre-lox mice that expressed the human diphtheria toxin receptor (DTR) driven by a lymphatic-specific promoter in order to noninvasively ablate the lymphatic system of the hind limb. Animals treated in this manner developed lymphedema that was indistinguishable from clinical lymphedema temporally, radiographically, and histologically. Using this model and clinical biopsy specimens, we show that the initial resolution of edema after injury is dependent on the formation of collateral capillary lymphatics and that this process is regulated by M2-polarized macrophages. In addition, we show that despite these initial improvements in lymphatic function, persistent accumulation of CD4⁺ cells inhibits lymphangiogenesis and promotes sclerosis of collecting lymphatics, resulting in late onset of edema and fibrosis. Our findings therefore provide strong evidence that inflammatory changes after lymphatic injury play a key role in the pathophysiology of lymphedema.

Lymphatic imaging to assess rheumatoid flare: mechanistic insights and biomarker potential

Proliferation of draining lymphatic vessels coupled with dynamic changes in lymph node volume and flow are characteristic features in rheumatoid arthritis (RA). Furthermore, impaired lymph egress from inflamed synovium is associated with joint flare in murine models of inflammatory-erosive arthritis. Unfortunately, advances towards a greater understanding of lymphatic changes in RA pathogenesis have been slow due to the absence of outcome measures to quantify lymphatic function in vivo. While lymphoscintigraphy is the current standard to assess lymphedema and sentinel lymph nodes in cancer patients, its sensitivity and specificity are inadequate to study lymphatics in RA. The emergence of high-resolution MRI, power Doppler ultrasound, and near-infrared imaging that permits real-time quantification of lymphatic function in animal models has been a major advance, and these techniques have produced a new paradigm of altered lymphatic function that underlies both acute arthritic flare and chronic inflammation. In acute flare, lymphatic drainage increases several fold, whereas no lymphatic contractions are detected in lymph vessels draining chronic arthritic joints. Moreover, these outcomes are now being adapted to study lymphatics in RA towards the development of novel biomarkers of arthritic flare and the discovery of new therapeutic targets. In particular, interventions that directly increase lymphatic egress from diseased joints by opening collateral lymphatic vessels, and that restore lymphatic vessel contractions, provide novel therapeutic approaches with potential for minimal toxicity and immunosuppression. To summarize the origins of this field, recent advances, and future directions, we herein review: current knowledge of lymphatics in RA based on classic literature; new in-vivo imaging modalities that have elucidated how lymphatics modulate acute versus chronic joint inflammation in murine models; and how these preclinical outcome measures are being translated to study lymphatic function in RA inflammation and how effective RA therapies alter lymphatic flow and lymph nodes draining flaring joints.

Trial registration: ClinicalTrials.gov NCT02680067. Registered 7 December 2015; ClinicalTrials.gov NCT01098201. Registered 30 March 2010; and ClinicalTrials.gov NCT01083563. Registered 8 March 2010.

Optical imaging probes in oncology

Cancer is a complex disease, characterized by alteration of different physiological molecular processes and cellular features. Keeping this in mind, the possibility of early identification and detection of specific tumor biomarkers by non-invasive approaches could improve early diagnosis and patient management.Different molecular imaging procedures provide powerful tools for detection and non-invasive characterization of oncological lesions. Clinical studies are mainly based on the use of computed tomography, nuclear-based imaging techniques and magnetic resonance imaging. Preclinical imaging in small animal models entails the use of dedicated instruments, and beyond the already cited imaging techniques, it includes also optical imaging studies. Optical imaging strategies are based on the use of luminescent or fluorescent reporter genes or injectable fluorescent or luminescent probes that provide the possibility to study tumor features even by means of fluorescence and luminescence imaging. Currently, most of these probes are used only in animal models, but the possibility of applying some of them also in the clinics is under evaluation.The importance of tumor imaging, the ease of use of optical imaging instruments, the commercial availability of a wide range of probes as well as the continuous description of newly developed probes, demonstrate the significance of these applications. The aim of this review is providing a complete description of the possible optical imaging procedures available for the non-invasive assessment of tumor features in oncological murine models. In particular, the characteristics of both commercially available and newly developed probes will be outlined and discussed.

Near-Infrared Fluorescence Lymphatic Imaging to Reconsider Occlusion Pressure of Superficial Lymphatic Collectors in Upper Extremities of Healthy Volunteers

BACKGROUND

There are very little scientific data on occlusion pressure for superficial lymphatic collectors. Given its importance in determining the transport capacity of lymphatic vessels, it is crucial to know its value. The novel method of near-infrared fluorescence lymphatic imaging (NIRFLI) can be used to visualize lymphatic flow in real time. The goal of this study was to see if this method could be used to measure the lymphatic occlusion pressure.

METHODS

We observed and recorded lymph flow in the upper limb of healthy volunteers through a transparent cuff using near-infrared fluorescence lymphatic imaging. After obtaining a baseline of the lymph flow without pressure inside the cuff, the cuff was inflated by increments of 10 mm Hg starting at 30 mm Hg. A NIRFLI guided manual lymphatic drainage technique named "Fill & Flush Drainage Method" was performed during the measurement to promote lymph flow. Lymphatic occlusion pressure was determined by observing when lymph flow stopped under the cuff.

RESULTS

We measured the lymphatic occlusion pressure on 30 healthy volunteers (11 men and 19 women). Mean lymphatic occlusion pressure in the upper limb was 86 mm Hg (CI ±3.7 mm Hg, α = 0.5%). No significant differences were found between age groups (p = 0.18), gender (p = 0.12), or limb side (p = 0.85).

CONCLUSIONS

NIRFLI, a transparent sphygmomanometer cuff and the "Fill and Flush" manual lymphatic drainage method were used to measure the lymphatic occlusion pressure in 30 healthy humans. That combination of these techniques allows the visualization of the lymph flow in real time, while ensuring the continuous filling of the lymph collectors during the measurement session, reducing false negative observations. The measured occlusion pressures are much higher than previously described in the medical literature.

Review on near-infrared heptamethine cyanine dyes as theranostic agents for tumor imaging, targeting, and photodynamic therapy

A class of near-infrared fluorescence (NIRF) heptamethine cyanine dyes that are taken up and accumulated specifically in cancer cells without chemical conjugation have recently emerged as promising tools for tumor imaging and targeting. In addition to their fluorescence and nuclear imaging-based tumor-imaging properties, these dyes can be developed as drug carriers to safely deliver chemotherapy drugs to tumors. They can also be used as effective agents for photodynamic therapy with remarkable tumoricidal activity via photodependent cytotoxic activity. The preferential uptake of dyes into cancer but not normal cells is co-operatively mediated by the prevailing activation of a group of organic anion-transporting polypeptides on cancer cell membranes, as well as tumor hypoxia and increased mitochondrial membrane potential in cancer cells. Such mechanistic explorations have greatly advanced the current application and future development of NIRF dyes and their derivatives as anticancer theranostic agents. This review summarizes current knowledge and emerging advances in NIRF dyes, including molecular characterization, photophysical properties, multimodal development and uptake mechanisms, and their growing potential for preclinical and clinical use.

Evaluation of intraoperative fluorescence imaging-guided surgery in cancer-bearing dogs: a prospective proof-of-concept phase II study in 9 cases

The objective was to prospectively evaluate the application of intraoperative fluorescence imaging (IOFI) in the surgical excision of malignant masses in dogs, using a novel lipid nanoparticle contrast agent. Dogs presenting with spontaneous soft-tissue sarcoma or subcutaneous tumors were prospectively enrolled. Clinical staging and whole-body computed tomography (CT) were performed. All the dogs received an intravenous injection of dye-loaded lipid nanoparticles, LipImage 815. Wide or radical resection was realized after CT examination. Real-time IOFI was performed before skin incision and after tumor excision. In cases of radical resection, the lymph nodes (LNs) were imaged. The margin/healthy tissues fluorescence ratio or LN/healthy tissues fluorescence ratio was measured and compared with the histologic margins or LN status. Nine dogs were included. Limb amputation was performed in 3 dogs, and wide resection in 6. No adverse effect was noted. Fluorescence was observed in all 9 of the tumors. The margins were clean in 5 of 6 dogs after wide surgical resection, and the margin/healthy tissues fluorescence ratio was close to 1.0 in all these dogs. Infiltrated margins were observed in 1 case, with a margin/healthy tissues fluorescence ratio of 3.2. Metastasis was confirmed in 2 of 3 LNs, associated with LN/healthy tissues fluorescence ratios of 2.1 and 4.2, whereas nonmetastatic LN was associated with a ratio of 1.0. LipImage 815 used as a contrast agent during IOFI seemed to allow for good discrimination between tumoral and healthy tissues. Future studies are scheduled to evaluate the sensitivity and specificity of IOFI using LipImage 815 as a tracer.

A novel mutation in CELSR1 is associated with hereditary lymphedema

BACKGROUND

Biological evidence reported in the literature supports the role of CELSR1 as being essential for valvular function in murine lymphatics. Yet thus far, there have been no variants in CELSR1 associated with lymphatic dysfunction in humans.

CASE PRESENTATION

In this report, a rare early inactivating mutation in CELSR1 is found to be causal for non-syndromic, lower extremity lymphedema in a family across three generations. Near-infrared fluorescence lymphatic imaging shows that instead of being propelled within the lumen of well-defined lymphatic vessels, lymph moved in regions of both legs in an unusual fashion and within sheet-like structures.

CONCLUSION

CELSRI may be responsible for primary, non-syndromic lymphedema in humans.

Near-infrared fluorescence lymphatic imaging in a patient treated for venous occlusion

Although lower extremity edema/lymphedema can result from venous and/or lymphatic abnormalities, effective treatment depends upon understanding their relative contributions to the condition. Herein we use near-infrared fluorescence lymphatic imaging in a 16 year-old female diagnosed with unilateral lymphedema of the right leg and previously treated with left iliac vein stenting in an attempt to alleviate lymphedema. The imaging shows that abnormal lymphatic anatomy, rather than venous occlusion, was likely responsible for unilateral swelling.

Near-Infrared Fluorescence Lymphatic Imaging in Lymphangiomatosis

BACKGROUND

Lymphangiomatosis is a rare disorder of the lymphatic system that can impact the dermis, soft tissue, bone, and viscera and can be characterized by lymphangiomas, swelling, and chylous discharge. Whether disordered lymphangiogenesis in lymphangiomatosis affects the function and anatomy of the entire systemic lymphatic circulation or is localized to specific sites is not fully known.

METHODS AND RESULTS

A 35-year-old Caucasian female diagnosed with whole-body lymphangiomatosis at 2 months of age and who continues to present with progressive disease was imaged with near-infrared fluorescence lymphatic imaging. While the peripheral lymphatics in the extremities appeared largely normal compared to prior studies, we observed tortuous lymphatic vessels, fluorescence drainage from the peripheral lymphatics into lymphangiomas, and extensive dermal lymphatics in the left thigh and inguinal regions where the subject had previously had surgical assaults, potentially indicating defective systemic lymphangiogenesis.

CONCLUSIONS

Further research into anatomical and functional lymphatic changes associated with the progression and treatment of lymphangiomatosis could aid in understanding the pathophysiology of the disease as well as point to treatment strategies.

Lymphatic transport in patients with chronic venous insufficiency and venous leg ulcers following sequential pneumatic compression

BACKGROUND

Recent advancements in near-infrared fluorescence lymphatic imaging (NIRFLI) technology provide opportunities for non-invasive, real-time assessment of lymphatic contribution in the etiology and treatment of ulcers. The objective of this study was to assess lymphatics in subjects with venous leg ulcers using NIRFLI and to assess lymphatic impact of a single session of sequential pneumatic compression (SPC).

METHODS

Following intradermal microdoses of indocyanine green (ICG) as a lymphatic contrast agent, NIRFLI was used in a pilot study to image the lymphatics of 12 subjects with active venous leg ulcers (Clinical, Etiologic, Anatomic, and Pathophysiologic [CEAP] C6). The lymphatics were imaged before and after a single session of SPC to assess impact on lymphatic function.

RESULTS

Baseline imaging showed impaired lymphatic function and bilateral dermal backflow in all subjects with chronic venous insufficiency, even those without ulcer formation in the contralateral limb (C0 and C4 disease). SPC therapy caused proximal movement of ICG away from the active wound in 9 of 12 subjects, as indicated by newly recruited functional lymphatic vessels, emptying of distal lymphatic vessels, or proximal movement of extravascular fluid. Subjects with the longest duration of active ulcers had few visible lymphatic vessels, and proximal movement of ICG was not detected after SPC therapy.

CONCLUSIONS

This study provides visible confirmation of lymphatic dysfunction at an early stage in the etiology of venous ulcer formation and demonstrates the potential therapeutic mechanism of SPC therapy in removing excess fluid. The ability of SPC therapy to restore fluid balance through proximal movement of lymph and interstitial fluid may explain its value in hastening venous ulcer healing. Anatomical differences between the lymphatics of longstanding and more recent venous ulcers may have important therapeutic implications.

Lymphedema and subclinical lymphostasis (microlymphedema) facilitate cutaneous infection, inflammatory dermatoses, and neoplasia: A locus minoris resistentiae

Whether primary or secondary, lymphedema is caused by failure to drain protein-rich interstitial fluid. Typically affecting a whole limb, it has become apparent that lymphedema can also affect localized regions of the skin, or it can be clinically silent but histologically evident, denoted by dilated lymphangiectases (latent lymphedema). Chronic lymph stasis has numerous consequences, including lipogenesis, fibrosis, inflammation, lymphangiogenesis, and immunosuppression. For example, lymphedema's disruption of immune cell trafficking leads to localized immune suppression, predisposing the area affected to chronic inflammation, infection (cellulitis and verrucosis), and malignancy (angiosarcoma and nonmelanoma skin cancer). The pathogenesis of lymphedema is reviewed and exemplified by describing how a combination of lymph stasis-promoting factors such as trauma, obesity, infection, and inflammatory disorders produces localized elephantiasis; furthermore, the finding of lymphangiectases is found to be common in numerous dermatologic disorders and argued to play a role in their pathogenesis. Lastly, it is discussed how antigen burden, which is controlled by lymphatic clearance, affects the immune response, resulting in immune tolerance, immunopathology, or normal adaptive immunity.