The role of lymphatics in cancer as assessed by near-infrared fluorescence imaging

A Review of Image Sensors Used in Near-Infrared and Shortwave Infrared Fluorescence Imaging

To translate near-infrared (NIR) and shortwave infrared (SWIR) fluorescence imaging into the clinic, the paired imaging device needs to detect trace doses of fluorescent imaging agents. Except for the filtration scheme and excitation light source, the image sensor used will finally determine the detection limitations of NIR and SWIR fluorescence imaging systems. In this review, we investigate the current state-of-the-art image sensors used in NIR and SWIR fluorescence imaging systems and discuss the advantages and limitations of their characteristics, such as readout architecture and noise factors. Finally, the imaging performance of these image sensors is evaluated and compared.

Etiology and treatment of cancer-related secondary lymphedema

Lymphedema and specifically cancer-related lymphedema is not the main focus for both patients and physicians dealing with cancer. Its etiology is an unfortunate complication of cancer treatment. Although lymphedema treatments have gained an appreciable consensus, many practitioners have developed and prefer their own specific protocols and this is especially true for conventional (manual) versus surgical treatments. This collection of presentations explores the incidence and genetics of cancer-related lymphedema, early detection and monitoring techniques, both conventional and operative treatment options, and the importance and role of exercise for patients with cancer-related lymphedema. These assembled presentations provide valuable insights into the challenges and opportunities presented by cancer-related lymphedema including the latest research, treatments, and exercises available to improve patient outcomes and quality of life.

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.

Secondary lymphedema from cancer therapy

This manuscript is a summary of findings focusing on various aspects of secondary lymphedema specifically as a sequelae of treatment for cancer. The topic was addressed at a session held during the 8th International Congress on Cancer Metastasis that was unique a for the inclusion of patients with lymphedema and therapists joining physicians, healthcare professionals, and researchers in an effort to give an overview of secondary lymphedema following cancer therapy as well as highlighting the unknowns in the field. Lymphedema is defined and both diagnosis and incidence of cancer-related lymphedema are explored. Further, exploration of imaging options for lymphedema and information on the genetic research for patients with cancer-related secondary lymphedema are presented. Patient education and early detection methods are then explored followed by conservative treatment. Finally, an examination of surgical treatment methods available for patients with lymphedema is covered. Overall, this manuscript presents valuable information and updates for those not familiar with incidence, diagnosis, early detection, and rehabilitation of patients with cancer-related secondary 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.

Relationship between perimetric increase and fluoroscopic pattern type in secondary upper limb lymphedema observed by Indocyanine green lymphography

To ascertain the relationship between the perimetric differences obtained between the limbs and the type of fluoroscopic pattern observed by Indocyanine green (ICG) lymphography in patients with upper limb lymphedema.A correlational descriptive study was carried out in 19 patients with upper limb lymphedema secondary to breast cancer. The perimetric increase was recorded in 11 anatomical regions after ICG injection, fluoroscopic patterns were identified using an infrared camera. The ICG patterns were categorized into worse (stardust, diffuse) or better (linear, splash) patterns.The pattern coincidence between the anterior and posterior regions of the edematous extremities was 45%. At the wrist level, a difference of 2 cm was associated with the presence of a worse fluoroscopic pattern, whereas perimeter differences of 4.25 cm in the elbow and 2.25 cm in the arm (12 cm from the epicondyle) were associated with the presence of a better fluoroscopic pattern.The perimetric differences observed between the healthy and affected upper limbs in 4 specific anatomical areas allowed us to predict the type of fluoroscopic pattern. ICG lymphography has facilitated the study of the posterior regions of edema, which are difficult to visualize using other imaging techniques.

Changes in Indocyanine Green Lymphography Patterns after Physical Treatment in Secondary Upper Limb Lymphedema

Indocyanine green (ICG) lymphography is used to evaluate the lymphatic function before and after pneumatic compression or post-manual lymphatic drainage. The aim of this study was to ascertain the changes in the fluoroscopic pattern produced by the provision of complex physical therapy. This prospective analytic (pretest-posttest) study was conducted in 19 patients with upper lymphedema secondary to breast cancer. Nine patients were excluded due to ICG found after 3 weeks. The ICG patterns were analyzed under basal conditions and after three weeks of treatment. After the treatment, 45% of the patients presented tracer remains in the affected limb, and this finding was significantly related to time of the lymphedema development. In one subject, the patterns remain unchanged or cannot be defined. Three of the ten patients observed present the worsening of at least 1 of the patterns and in the rest of the subjects, six cases, the improvement of the patterns is observed. In 60% of the cases, the most severe pattern reversed towards slight (splash) cases, and moderate cases reversed towards a slight case in 70% of cases. Therefore, after treatment with complex physical therapy, the pathological patterns observed in the pretest, which evolved positively, reverted their severity toward milder disease patterns or towards normality.

Simultaneous measurements of lymphatic vessel contraction, flow and valve dynamics in multiple lymphangions using optical coherence tomography

Lymphatic dysfunction is involved in many diseases including lymphedema, hypertension, autoimmune responses, graft rejection, atherosclerosis, microbial infections, cancer and cancer metastasis. Expanding our knowledge of lymphatic system function can lead to a better understanding of these disease processes and improve treatment options. Here, optical coherence tomography (OCT) methods were used to reveal intraluminal valve dynamics in 3 dimensions, and measure lymph flow and vessel contraction simultaneously in 3 neighboring lymphangions of the afferent collecting lymphatic vessels to the popliteal lymph node in mice. Flow measurements were based on Doppler OCT techniques in combination with exogenous lymph labeling by Intralipid. Through these imaging methods, it is possible to study lymphatic function and pumping more comprehensively. These capabilities can lead to a better understanding of the regulation and dysregulation of lymphatic vessels in health and disease. The image depicts the dynamic measurements of lymphatic valves, lymphatic vessels cross-sectional area and lymph velocity simultaneously measured in vivo with optical coherence tomography.

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.

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.

Longitudinal monitoring of the head and neck lymphatics in response to surgery and radiation

BACKGROUND

The lymphatic vasculature provides a route for cancer metastases, and its dysfunction after cancer treatment can result in lymphedema. However, changes in the lymphatics before, during, and after surgery and radiation remain unclear.

METHODS

Near-infrared fluorescence lymphatic imaging was performed before and after lymph node dissection and fractionated radiotherapy to assess changes in external lymphatic function.

RESULTS

Patients who underwent both lymph node dissection and radiotherapy developed lymphatic dermal backflow on treated sides ranging from days after the start of radiotherapy to weeks after its completion, whereas contralateral regions that were not associated with lymph node dissection but also treated with radiotherapy experienced no such changes in external lymphatic anatomies.

CONCLUSION

The external lymphatics undergo transient changes during and weeks after lymph node dissection and radiotherapy. © 2017 Wiley Periodicals, Inc. Head Neck 39: 1177-1188, 2017.

A review of performance of near-infrared fluorescence imaging devices used in clinical studies

Near-infrared fluorescence (NIRF) molecular imaging holds great promise as a new "point-of-care" medical imaging modality that can potentially provide the sensitivity of nuclear medicine techniques, but without the radioactivity that can otherwise place limitations of usage. Recently, NIRF imaging devices of a variety of designs have emerged in the market and in investigational clinical studies using indocyanine green (ICG) as a non-targeting NIRF contrast agent to demark the blood and lymphatic vasculatures both non-invasively and intraoperatively. Approved in the USA since 1956 for intravenous administration, ICG has been more recently used off label in intradermal or subcutaneous administrations for fluorescence imaging of the lymphatic vasculature and lymph nodes. Herein, we summarize the devices of a variety of designs, summarize their performance in lymphatic imaging in a tabular format and comment on necessary efforts to develop standards for device performance to compare and use these emerging devices in future, NIRF molecular imaging studies.

Recent progress in the treatment and prevention of cancer-related lymphedema

This article provides an overview of the recent developments in the diagnosis, treatment, and prevention of cancer-related lymphedema. Lymphedema incidence by tumor site is evaluated. Measurement techniques and trends in patient education and treatment are also summarized to include current trends in therapeutic and surgical treatment options as well as longer-term management. Finally, an overview of the policies related to insurance coverage and reimbursement will give the clinician an overview of important trends in the diagnosis, treatment, and management of cancer-related lymphedema.

Emerging lymphatic imaging technologies for mouse and man

The lymphatic circulatory system has diverse functions in lipid absorption, fluid homeostasis, and immune surveillance and responds dynamically when presented with infection, inflammation, altered hemodynamics, and cancer. Visualization of these dynamic processes in human disease and animal models of disease is key to understanding the contributory role of the lymphatic circulatory system in disease and to devising effective therapeutic strategies. Longitudinal, non-destructive, and repeated imaging is necessary to expand our understanding of disease progression and regression in basic science and clinical investigations. Herein we summarize recent advances in in vivo lymphatic imaging employing magnetic resonance, computed tomography, lymphoscintigraphy, and emerging optical techniques with respect to their contributory roles in both basic science and clinical research investigations.

Toward nodal staging of axillary lymph node basins through intradermal administration of fluorescent imaging agents

As part of a proof-of-concept study for future delivery of targeted near-infrared fluorescent (NIRF) tracers, we sought to assess the delivery of micrograms of indocyanine green to all the axillary lymph nodes following intraparenchymal breast injections and intradermal arm injections in 20 subjects with advanced breast carcinoma and undergoing complete axillary lymph node dissection. Lymphatic vessels and nodes were assessed in vivo. Ex vivo images demonstrated that 87% of excised lymph nodes, including 81% of tumor-positive lymph nodes, were fluorescent. Future clinical studies using microdose amounts of tumor-targeting NIRF contrast agents may demonstrate improved surgical intervention with reduced morbidity.

Photons across medicine: relating optical and nuclear imaging

The Optics in the Life Sciences conference sponsored by the Optical Society of America was held in Waikoloa Beach, HI on April 14 - 18, 2013. Papers were presented in the areas of Bio-Optics: Design & Application, Novel Techniques in Microscopy, Optical Molecular Probes, Imaging & Drug Delivery, and Optical Trapping Applications. A focal point of the meeting was a special symposium entitled "Photons Across Medicine", organized by Adam Wax, Duke University, highlighting activities of joint interest between the Optical Society of America (OSA) and the Society for Nuclear Medicine and Molecular Imaging (SNMMI). This paper is a synopsis of the presentations made at this joint symposium. Central to the special symposium presentations was the fact that the optical and nuclear imaging communities share common interests and challenges. These are highlighted in this article. Also discussed was the fact that the nuclear technologies in imaging have found their way into general clinical utility, a feat that has yet to be achieved by optical methods. Because of the common ground shared by the two technologies, coordination between the two societies should be planned.

Optical techniques for the intraoperative assessment of nodal status

The lymphatic system is an important pathway in the metastatic spread of many malignancies and a key prognostic indicator. Nondestructive assessment of the nodal status during surgery could limit the amount of lymph nodes that need to be resected and allow for immediate regional lymphadenectomy during sentinel lymph node biopsy procedures. This review looks into the possibilities of conventional medical imaging methods that are capable of intraoperative nodal assessment and discusses multiple newly developed optical techniques. The physical background behind these techniques is reviewed and a concise overview of their main advantages and disadvantages is provided. These recent innovations show that while the application of optical modalities for intraoperative nodal staging is not yet applied routinely, there is reason enough to expect their introduction in the near future.

Direct visualization of changes of lymphatic function and drainage pathways in lymph node metastasis of B16F10 melanoma using near-infrared fluorescence imaging

The lymphatic system provides an initial route for cancer cell dissemination in many cancers including melanoma. However, it is largely unknown how the lymphatic system changes during tumor progression due in part to the lack of imaging techniques currently available. In this study, we non-invasively imaged changes of lymphatic function and drainage patterns using near-infrared fluorescence (NIRF) imaging. Dynamic NIRF imaging following intradermal injection of indocyanine green (ICG) was conducted in C57BL/6 mice prior to inoculation of B16F10 murine melanoma cells to the dorsal aspect of the left hindpaw for baseline data or directly to the popliteal lymph node (PLN) and until 21 days post-implantation (p.i.). A series of acquired fluorescent images were quantified to measure lymphatic contractile function. Computed tomography (CT) was also performed to measure the volume of tumor-draining lymph nodes (LNs). We observed significant reduction of lymphatic contractility from 7 days p.i. until 21 days p.i.. Altered lymphatic drainage patterns were also detected at 21 days p.i. in mice with tumor in the paw and at 11 days p.i. in mice with tumor in the PLN, due to lymphatic obstruction of normal lymphatic drainages caused by extensive tumor invasion of draining LNs. Since lymphatic function and architecture were progressively altered during tumor growth and metastasis, non-invasive NIRF imaging may provide a new method to stage disease. In addition, this novel technique can be used as a diagnostic method to non-invasively assess lymphatic response as mechanism of therapeutic action.

Best Practice Guidelines in Assessment, Risk Reduction, Management, and Surveillance for Post-Breast Cancer Lymphedema

Breast cancer-related lymphedema (LE) is a progressive, chronic disease that affects millions of cancer survivors and primarily results from surgical lymphatic vessel/node removal and radiation therapy. Patient education and support for importance of early detection is essential in helping health care providers detect lymphedema early, when there is the best chance to prevent progression. Improved imaging and surgical techniques have decreased the incidence of LE; however, effective risk-reduction and treatment have historically lacked the level of evidence necessary to standardize effective treatment. The purpose of this article is to report an extensive review of literature, including highlighted multidisciplinary studies within the past three years, in order to update best practice guidelines in assessment, risk reduction, management, and surveillance for post-breast cancer lymphedema.

Nanotechnology: toxicologic pathology

Nanotechnology involves technology, science, and engineering in dimensions less than 100 nm. A virtually infinite number of potential nanoscale products can be produced from many different molecules and their combinations. The exponentially increasing number of nanoscale products will solve critical needs in engineering, science, and medicine. However, the virtually infinite number of potential nanotechnology products is a challenge for toxicologic pathologists. Because of their size, nanoparticulates can have therapeutic and toxic effects distinct from micron-sized particulates of the same composition. In the nanoscale, distinct intercellular and intracellular translocation pathways may provide a different distribution than that obtained by micron-sized particulates. Nanoparticulates interact with subcellular structures including microtubules, actin filaments, centrosomes, and chromatin; interactions that may be facilitated in the nanoscale. Features that distinguish nanoparticulates from fine particulates include increased surface area per unit mass and quantum effects. In addition, some nanotechnology products, including the fullerenes, have a novel and reactive surface. Augmented microscopic procedures including enhanced dark-field imaging, immunofluorescence, field-emission scanning electron microscopy, transmission electron microscopy, and confocal microscopy are useful when evaluating nanoparticulate toxicologic pathology. Thus, the pathology assessment is facilitated by understanding the unique features at the nanoscale and the tools that can assist in evaluating nanotoxicology studies.