Development of a Noninvasive Skin Evaluation Method for Lower Limb Lymphedema

The Usefulness of a Three-Microneedle Device for Indocyanine Green Fluorescence Lymphography

Background: Indocyanine green (ICG) fluorescence lymphography is widely used to diagnose lymphedema. There is little consensus on the appropriate injection method for ICG fluorescence lymphangiography. We used a three-microneedle device (TMD) for skin injection of ICG solution and investigated its usefulness. Methods and Results: Thirty healthy volunteers were injected with ICG solution using a 27-gauge (27G) needle in one foot and a TMD in the other foot. Injection-related pain was evaluated using the Numerical Rating Scale (NRS) and Face Rating Scale (FRS). The skin depth of the injected ICG solution was evaluated by injecting the solution into the skin of amputated lower limbs using a 27G needle or TMD using ICG fluorescence microscopy. The median and interquartile range of the NRS scores was 3 (3-4) and 2 (2-4) in the 27G needle and TMD groups, respectively; that of the FRS scores was 2 (2-3) and 2 (1-2) in the 27G needle and TMD groups, respectively. Injection-related pain was significantly lower with the TMD than with the 27G needle. The lymphatic vessels were similarly visible using both needles. The depth of the ICG solution varied for each injection with a 27G needle (400-1200 μm) and was consistent at ∼300-700 μm below the skin surface using the TMD. Injection depth was significantly different between the 27G needle and the TMD. Conclusions: Injection-related pain decreased using the TMD, and ICG solution depth was consistent on fluorescence lymphography. A TMD may be useful for ICG fluorescence lymphography. Clinical Trials Registry (UMIN-CTR; ID: UMIN000033425).

Use of a novel indentometer to evaluate skin stiffness in healthy and diseased human skin

BACKGROUND

Mechanical behavior of the skin can be evaluated by different non-invasive methods. In this study, we applied a new measurement device based on indentometry to determine the skin mechanical properties in healthy individuals and in patients with systemic sclerosis (SSc).

MATERIAL AND METHODS

Three studies were performed. Study 1 included 100 healthy individuals (46 male and 54 female) divided into four age groups with mean ages of 21.5, 28.9, 51.2, and 69.3 years, respectively. Test sites were located on the center of the forehead and the middle of both volar forearms. Study 2 included 16 healthy individuals (two males and 14 females). Test sites were on both volar forearms. Measurements were made before and after the application of Vaseline and emulsion with 12% urea. Study 3 included 20 patients (one male and 19 females) with SSc and 60 age-matched healthy individuals (23 males and 37 females). Test sites were on the center of the forehead and the middle of both volar forearms. Skin stiffness was measured with skin Indentometer IDM 800 (Courage + Khazaka, Cologne, Germany) equipped with two probes with pin diameters of 3 and 5 mm, respectively. The stiffer the skin, the less deep the displacement by the indenter. The smaller the diameter, the deeper the pin will go into the skin when using the same force. In addition, the Corneometer CM 820 (Courage + Khazaka) was used to determine epidermal water content in study 2.

RESULTS

Indentometric (IDM) values of healthy subjects measured with both probes were lower on the forehead compared to volar forearms. There was no significant difference between both forearms. In all age groups, the IDM values on the male forearms were lower than on the female forearms whereas there was no significant difference on the forehead. In both sex and on all test locations a significant positive correlation between age and IDM values measured with both probes was observed. There was a significant positive correlation between IDM values measured with both probes. The application of moisturizers induced significant changes in epidermal water content whereas the IDM values remained unchanged. At both the forehead and volar forearms, the IDM values in patients with SSc were significantly lower compared to the healthy control skin.

CONCLUSION

The non-invasive indentometric method used can successfully distinguish the changes in normal skin mechanical properties related to age, sex, and anatomical location, as well as in patients with SSc. The method is not appropriate to study the changes related to epidermal hydration.

Non-invasive biomechanical assessment of the prolapsed vaginal wall: an explorative pilot study on cutometry and indentometry

The clinical assessment of pelvic organ prolapse (POP) and associated treatment strategies is currently limited to anatomical and subjective outcome measures, which have limited reproducibility and do not include functional properties of vaginal tissue. The objective of our study was to evaluate the feasibility of using cutometry and indentometry for non-invasive biomechanical assessment of the vaginal wall in women with POP. Both techniques were applied on the vaginal wall of 20 women indicated for surgical correction of POP stage two or higher. The primary outcome was the measurement success rate. Measurements were considered successful if biomechanical parameters were generated after a maximum of three attempts. Secondary outcomes included acquisition time, number of attempts to obtain a successful measurement, and biomechanical parameters. Measurements were successfully performed on the anterior vaginal wall of 12 women with cystocele and the posterior vaginal wall of eight women with rectocele. The success rate was 100% for both techniques and acquisition time was under 1 minute for all 20 measurements. Tissue fast elasticity of the posterior vaginal wall (rectocele) was significantly higher than that of the anterior vaginal wall (cystocele) and negatively correlated with age (r = - 0.57, P < 0.05). In women with POP, measuring the biomechanical properties of the vaginal wall using cutometry and indentometry is technically feasible. Objective evaluation of biomechanical properties may help to understand the pathophysiology behind surgical outcomes, providing an opportunity for the identification of patients at risk for (recurrent) prolapse, and individualized treatment decisions.

The Clinical Usefulness of Ultrasonographic Measurement Technique in Patients with Lower Extremity Lymphedema

Background: A previous study reported a new ultrasonography (US) measurement technique to evaluate the cross-sectional area (ΔCSA) of lymphedema in the upper extremity. This ΔCSA correlated well with parameters, such as the circumference, volumetry, and bioimpedance analysis (BIA) in healthy people and upper extremity lymphedema patients. This study examined whether a US measurement technique is clinically useful in patients with lymphedema in the lower extremity. Methods and Results: Forty patients diagnosed with unilateral lower extremity lymphedema were enrolled in this study. The subjects' leg circumference, BIA, isokinetic strength, and ΔCSA were examined on the same day. The leg circumference was measured at 15 cm above the knee (AK) and below the knee (BK) crease using a tape measure. BIA was performed by a trained physical therapist, and the data of impedance (Z) at 1 and 5 kHz of each side of the lower limbs and extracellular water (ECW) were used. A fully experienced physician measured soft tissue thickness, the distance between the skin and the fascia of the muscle, three times each at the anterior, medial, posterior, and lateral aspects of the bilateral legs by US at 15 cm AK and BK. The amount of soft tissue in the ΔCSA was calculated using the designed formula from the mean values of the thicknesses. Each parameter was calculated as the ratio of the sound side to the lesion side. The Pearson and Spearman correlation coefficients were used to assess the significance of these parameters. The ratio of ΔCSA measured at 15 cm AK and BK showed strong positive correlations with the circumference difference at the same level (rho = 0.790, p = 0.000, and rho = 0.882, p = 0.000, respectively). In addition, it showed moderate or strong correlations with the ratio of Z at 5 and 1 kHz in the BIA of the lower limbs (AK15, r = -0.511, p = 0.001 and r = -0.497, p = 0.001; BK15, r = -0.780, p = 0.000 and r = -0.756, p = 0.000, respectively). Although ECW and body mass index showed weak positive correlations with the ratio of ΔCSA measured at 15 cm BK, there was no significant correlation between the ratio of ΔCSA and the isokinetic muscle strength. Conclusion: The ΔCSA results showed moderate-to-strong correlations with other conveniently used methods except for the isokinetic muscle strength. As the US ΔCSA technique could measure lymphedema status with a structural consideration, it could also be recommended as a conventional measurement method in patients with upper and lower extremity lymphedema.

Bayesian Inference With Gaussian Process Surrogates to Characterize Anisotropic Mechanical Properties of Skin From Suction Tests

One of the intrinsic features of skin and other biological tissues is the high variation in the mechanical properties across individuals and different demographics. Mechanical characterization of skin is still a challenge because the need for subject-specific in vivo parameters prevents us from utilizing traditional methods, e.g., uniaxial tensile test. Suction devices have been suggested as the best candidate to acquire mechanical properties of skin noninvasively, but capturing anisotropic properties using a circular probe opening-which is the conventional suction device-is not possible. On the other hand, noncircular probe openings can drive different deformations with respect to fiber orientation and therefore could be used to characterize the anisotropic mechanics of skin noninvasively. We propose the use of elliptical probe openings and a methodology to solve the inverse problem of finding mechanical properties from suction measurements. The proposed probe is tested virtually by solving the forward problem of skin deformation by a finite element (FE) model. The forward problem is a function of the material parameters. In order to solve the inverse problem of determining skin properties from suction data, we use a Bayesian framework. The FE model is an expensive forward function, and is thus substituted with a Gaussian process metamodel to enable the Bayesian inference problem.

Role of Subcutaneous Adipose Tissues in the Pathophysiology of Secondary Lymphedema

Background: Secondary lymphedema (LE) occurs due to the disruption of lymphatic circulation. Lymphatic fluid accumulation in subcutaneous tissues induces adipocyte proliferation. Obesity is an important risk factor for the occurrence and deterioration of LE. Although the relationship between LE and subcutaneous adipose tissue increase has been reported clinically, their pathophysiological relationship remains unknown. Thus, we aimed to verify whether subcutaneous adipose tissue increase is involved in the pathophysiology of secondary LE. Methods and Results: The hindlimb model of secondary LE was created using male Sprague-Dawley rats (control and LE groups; n = 5 each). Skin samples were obtained on postoperative day 168. Histological examination and quantitative real-time polymerase chain reaction analysis of inflammatory adipokines, tumor necrosis factor-alpha (Tnf-α), C-C chemokine ligand 2 (Ccl2), and interleukin-6 (Il-6) were performed. Limb volume and subcutaneous adipose tissues significantly increased in the LE group compared with those in the control. Macrophages aggregated in the augmented adipose tissues, around the adipocytes, and formed crown-like structures (CLSs). The number of CLSs significantly increased in the LE group. These macrophages expressed transforming growth factor-beta 1 (TGF-β1). Inflammatory adipokine secretion was not observed. Although Il-6 expression increased in the LE group, IL-6 was expressed in subcutaneous myofibroblasts but not in subcutaneous adipocytes. Conclusion: As TGF-β1 derived from subcutaneous myofibroblasts is involved in skin fibrosis during LE, TGF-β1 derived from adipose tissues may also play a similar role. Drug treatment for subcutaneous adipose tissue reduction may improve the skin condition in secondary LE and may be a new therapeutic strategy.

Use of a novel Indentometer to evaluate skin induration in localized scleroderma and psoriasis vulgaris

INTRODUCTION

Diseased skin in localized scleroderma (LS) and plaque psoriasis (PPs) is characterized by induration that can be evaluated by non-invasive bioengineering methods. In this study, we applied a new measurement device based on indentometry to determine the changes of skin mechanical properties in patients with LS and PPs.

MATERIAL AND METHODS

A total of 30 sclerodermatous plaques in 12 patients with LS and 46 psoriatic plaques in 19 patients with PPs were measured with Indentometer IDM 800 (Courage + Khazaka, Cologne, Germany). The device measures the penetration depth of the probe indenter (pin) into the skin in mm. We used two probes with pin diameters 3 and 5 mm, respectively. The stiffer the skin, the less deep is the displacement by the indenter. The smaller the diameter, the deeper the pin will go into the skin when using the same force. The measurements were made on diseased skin and in adjacent normal skin served as control. In addition, the psoriatic plaques were measured before and after treatment.

RESULTS

The sclerodermatous skin and the psoriatic skin showed lower Indentometer values compared to adjacent normal skin as measured with both probes. This suggests that diseased skin is stiffer than healthy skin. The values of psoriatic plaques increased after treatment applied that correlates with the clinical improvement. The Indentometric readings significantly negatively correlated with clinical scores of skin induration. There was a significant correlation between the measurements with probe 3 mm and probe 5 mm.

CONCLUSION

The non-invasive method used is appropriate for objective and quantitative determination of the degree of skin induration in LS and PPs as well as for assessment of the disease evaluation and treatment efficacy.

Hardness Sensed by Skin Palpation in Legs with Lymphedema Is Predominantly Correlated with Dermal Thickening

Background: We aimed to clarify whether pathological changes in skin and subcutaneous tissue with lymphedema affected the skin hardness sensed by palpation. Methods and Results: In 50 patients with unilateral legs with lymphedema (LE), the skin hardness of the lower inner thigh and lower inner calf was determined using a scale ranging from 1 (softest) to 7 (hardest) based on palpation. Then, the skin hardness was correlated with the measurements of skin/subcutaneous tissue ultrasonography images obtained from the palpated parts. Multivariate logistic regression analysis demonstrated that dermal thickness was a significant factor that affected the difference in skin hardness between the LE and the contralateral asymptomatic leg for both thigh (p < 0.05) and calf (p < 0.01). When the thigh and calf in the LE were individually studied, subcutaneous echogenicity (p < 0.05), indicating subcutaneous inflammation/fibrosis, and subcutaneous thickness (p < 0.01) also seemed to affect skin hardness, respectively. Conclusions: The skin hardness sensed in the LE seemed to be affected predominantly by dermal thickening. In addition, the pathological changes in the subcutaneous tissue caused by LE seemed to have an impact on skin hardness. Clinical Trial Registration number 2020-150.

Estimation of the Lymph Flow Through Thoracic Duct in Human Subjects Using the Urine Osmolarity: Applicable for Evaluating the Effectiveness of Manual Lymph Drainage

Currently, there are many methods to evaluate the effectiveness of manual lymph drainage in the treatment of lymphedema, that is, limb volume measurement, bio-electrical impedance measurement, computer tomography, and ultrasound imaging. However, it is difficult for these methods to accurately address the lymph flow generated by manual lymph drainage. Therefore, we aimed at developing a concise and accurate method to measure the lymph flow through the thoracic duct in human subjects, which is applicable for evaluating the effectiveness of manual lymph drainage. In the present mini-review, we demonstrate the developed method in detail and its scientific evidence for the effectiveness obtained with animal and human clinical experiments. In rat in vivo experiments, intragastric administration of distilled water significantly increased mesenteric flow, which was transported via the cisterna chyli and then the thoracic duct. The manual massage on the cisterna chyli in the anesthetized rabbit significantly accelerated the lymph flow through the thoracic duct, resulting in marked hemodilution. Abdominal respiration in the supine position in human subjects produced similar hemodilution, with a marked decrease in the concentration of vasopressin in the blood. On this basis, we developed a new method to accurately measure the lymph flow through the thoracic duct by using changes in the concentration of vasopressin in the blood. In addition, with changes in urine osmolarity depending on the concentration of vasopressin in the blood, we developed a more concise and noninvasive method for evaluating the lymph flow through the thoracic duct in human subjects. These methods may be applicable for evaluating the effectiveness for the manual lymph drainage in the patients with lymphedema.

Potential role of transforming growth factor-beta 1/Smad signaling in secondary lymphedema after cancer surgery

Secondary lymphedema often develops after cancer surgery, and over 250 million patients suffer from this complication. A major symptom of secondary lymphedema is swelling with fibrosis, which lowers the patient's quality of life, even if cancer does not recur. Nonetheless, the pathophysiology of secondary lymphedema remains unclear, with therapeutic approaches limited to physical or surgical therapy. There is no effective pharmacological therapy for secondary lymphedema. Notably, the lack of animal models that accurately mimic human secondary lymphedema has hindered pathophysiological investigations of the disease. Here, we developed a novel rat hindlimb model of secondary lymphedema and showed that our rat model mimics human secondary lymphedema from early to late stages in terms of cell proliferation, lymphatic fluid accumulation, and skin fibrosis. Using our animal model, we investigated the disease progression and found that transforming growth factor‐beta 1 (TGFB1) was produced by macrophages in the acute phase and by fibroblasts in the chronic phase of the disease. TGFB1 promoted the transition of fibroblasts into myofibroblasts and accelerated collagen synthesis, resulting in fibrosis, which further indicates that myofibroblasts and TGFB1/Smad signaling play key roles in fibrotic diseases. Furthermore, the presence of myofibroblasts in skin samples from lymphedema patients after cancer surgery emphasizes the role of these cells in promoting fibrosis. Suppression of myofibroblast‐dependent TGFB1 production may therefore represent an effective pharmacological treatment for inhibiting skin fibrosis in human secondary lymphedema after cancer surgery.

The Influence of Pulsed Electromagnetic Field Therapy on Lymphatic Flow During Supermicrosurgery

Background: The influence of pulsed electromagnetic field therapy (PEMFT) on medium-sized vessels as well as capillary microcirculation is well known. Effects on lymphatic vessels, however, are difficult to visualize and have not been investigated to date. One of the operative treatment options in primary and secondary lymphedemas is lymphovenous anastomoses using supermicrosurgery. To prove patency of the anastomosis, the lymphatic flow is visualized by fluorescence using indocyanine green. The aim of this study was to investigate the influence of PEMFT on the lymphatic microcirculation, and compare it with conventional manual lymphatic drainage (MLD) during supermicrosurgery. Methods and Results: Ten patients with lymphedema were included. Indocyanine green was injected before the operation for intraoperative visualization of the lymphatic vessels using a microscope equipped with an integrated near-infrared illumination system (Zeiss). The PEMFT system (Bio-Electro-Magnetic-Energy Regulation [BEMER]) was used as our standard device during a single 2-minute application period (AP) followed by MLD or vice versa. The mean light intensity in the calibration period (CP) was 46.53 ± 24.3 and 33.41 ± 12.92 for PEMFT and MLD, respectively. During the AP, the mean light intensity changed to 45.61 ± 24.40 for PEMFT and 57.05 ± 18.80 during MLD. This change between CP and AP did not differ significantly for the PEMFT application (p = 0.26), but showed an increase in light intensity during MLD (p < 0.001). Conclusion: We found a light intensity enhancement equivalent to a flow increase during MLD of 78.7% ± 45.7% (range 20%-144%) and no significant difference during the PEMFT application. A single period application of PEMFT did not affect the lymphatic flow.