Minimum Detectable Changes Associated with Tissue Dielectric Constant Measurements as Applicable to Assessing Lymphedema Status

Intra-day variations in volar forearm skin hydration

BACKGROUND

Skin hydration (SKH) measurements are used for multiple purposes: to study skin physiology, to clinically investigate dermatological issues, and to assess localized skin water in pathologies like diabetes and lymphedema. Often the volar forearm is measured at various times of day (TOD). This report aims to characterize intra-day variations in volar forearm SKH to provide guidance on expected TOD dependence.

MATERIALS AND METHODS

Forty medical students (20 male) self-measured tissue dielectric constant (TDC) on their non-dominant forearm in triplicate as an index of local skin tissue water every 2 h starting at 0800 and ending at 2400 h. All were trained and pre-certified in the procedure and had whole-body fat (FAT%) and water (H2O%) measured. Day average TDC (TDCAVG) was determined as the average of all time points expressed as mean ± SD.

RESULTS

Males versus females had similar ages (25.1 ± 2.2 years vs. 25.1 ± 1.5 years), higher H2O% (56.6 ± 5.0 vs. 51.8 ± 5.7, p = 0.002), and higher TDCAVG (32.7 ± 4.1 vs. 28.5 ± 5.1, p = 0.008). TDC values were not significantly impacted by H2O% or FAT%. Female TDC exhibited a significant decreasing trend from morning to night (p = 0.004); male TDC showed no trend.

CONCLUSION

Skin water assessed by TDC shows some intra-day variations for females and males but with quite different temporal patterns. Clinical relevance relates to the confidence level associated with skin hydration estimates when measured at different times of day during normal clinic hours which, based on the present data, is expected to be around 5% for both males and females.

Breast Cancer-Related Lymphedema Assessed via Tissue Dielectric Constant Measurements

This review describes the use of tissue dielectric constant (TDC) measurements mainly in the assessment of breast cancer-related lymphedema (BCRL). PubMed, Web of Science, and EMBASE databases were initially searched using criteria that included the terms "dielectric" and "lymphedema." The initial search yielded a total of 131 titles. After removing studies not focused on upper extremity lymphedema, 56 articles remained. These articles, together with relevant articles from their bibliographies, formed the basis of the review. The findings show the potential utility and applications of TDC measurements to help detect and track BCRL, whether present in limbs, breasts, or trunks. It is reported as a non-invasive, simple-to-use method, with each measurement requiring less than 10 seconds, suggesting its practicality and useability as an in-office or in-clinic screening and tracking method. Although there are various ways to quantitatively evaluate lymphedema, most, if not all, are restricted to measurements on limbs. Thus, one significant advantage of the TDC approach is that almost any local region of interest can be effectively measured and tracked, which, for BCRL, could include specific regions of arms or hands, breasts, and truncal areas.

Medical Applications of Skin Tissue Dielectric Constant Measurements

Tissue dielectric constant (TDC) values assess certain skin properties that are dependent on multiple factors but mainly on the relative amount of water content within a locally measured tissue volume. Because of the non-invasive nature of these measurements and their ease of use, the method has been widely used in various medically related applications. The goal of this paper was to review and describe the uses and findings of such TDC measurements, considering and including the wide array of medical applications. The review is in part based on information derived from an analysis of published material obtained via literature searches of four major electronic databases and, in part, based on the author's experience with the TDC measurement methods and their various applications and his professional experiences. The databases searched were PubMed, Web of Science, EMBASE, and CINAHL Complete. Based on the initial search criteria, a total of 1257 titles were identified. After removing duplicates and filtering according to relevancy, 160 remained for detailed further review. In some cases, the bibliography of these retrieved articles provided additional sources. The findings demonstrate multiple research and medical uses and applications of TDC measurements, focusing on detecting and quantifying localized edema and lymphedema in multiple target sites. These include the upper and lower extremities, breasts, and trunk as regions involved in medical conditions causing lymphedema. In addition, the findings suggest that TDC evaluations are a convenient, non-invasive method to study and evaluate other conditions impacting skin, including diabetes mellitus and skin wounds or ulcers. Its ability to detect aspects of tissue changes simply and rapidly at almost any anatomical location makes it a useful tool for investigating multiple dermatological conditions and their treatment as future applications of this method.

Tissue Dielectric Constant and Skin Stiffness Relationships in Lower Extremity Lymphedema

Background: Lower extremity lymphedema or edema (LELE) may progressively transition from a state of excess tissue fluid to increased fat accumulation and collagen deposition, with tissue fibrosis and hardening. Such changes may lead to altered tissue water holding and thereby impact tissue dielectric constant (TDC). This study seeks to evaluate the relationship between TDC and tissue indentation force (TIF) in patients with LELE and assess the utility of the leg/arm TDC ratio (LAR) as an indicator of LELE. Methods and Results: Thirty females (49-91 years) with previously diagnosed LELE were evaluated during a scheduled session. TDC and TIF were measured 8 cm proximal to the medial malleolus on the medial and lateral aspects of both legs and on one forearm 8 cm distal to the antecubital fossa. The TDC-TIC relationship and the LAR were subsequently determined. Main results showed an absence of a significant correlation between TDC and TIF on medial or lateral leg sites but a positive correlation on the normal forearm site. Further, LAR values exceeded the published proposed threshold of 1.35 for 29/30 patients when using medial-side TDC values and 28/30 patients when using lateral-side TDC values. Conclusions: Findings suggest that for patients with LELE, TDC values are significantly elevated on medial and lateral standardized sites. The LAR determined using either medial or lateral sites that are similar to each other and have values consistent with a lymphedema threshold of 1.35. In edematous legs of the type evaluated herein, there is no apparent relationship between TDC values and indentation force.

Chronic Venous Insufficiency With Emphasis on the Geriatric Population

The underpinning of Chronic Venous Insufficiency (CVI) is valvular dysfunction, which manifests on a spectrum depending on the severity of insufficiency and duration of the disease. The mainstay of treatment relies on compression therapy of a proper type and intensity. In older adults, special consideration must be taken during the patient encounter to account for age-related factors. This review discusses the clinical presentation, diagnosis, and mimicking of CVI, focusing mainly on older adults. The epidemiology, risk factors, disease burden, and grave complications -- such as thrombosis and ulceration, are reviewed. The physiological impacts of CVI are described, providing the background for treatment strategies, including non-invasive, medical, and surgical therapies. The findings show advanced age to be an important risk factor contributing to CVI and that other age-related factors add to the risk of severe complications. Clinical assessments combined with objective measurements that assess localized skin water using tissue dielectric constant values or whole limb assessments may aid in the differential diagnosis. Furthermore, understanding the mechanism of action of compression therapy, the mainstay of CVI treatment, and its physiological impacts, allows for its informed use in geriatric patients with increased risks of potential compression-related side effects.

Variation in Leg Tissue Dielectric Constant Values of Healthy Young Adult Females With and Without Compression Bandaging

Background The clinical efficacy of a compression application has been often limited to the assessment of the change in limb volume, change in clinical symptoms (i.e., wound size, pain, range of motion, incidence of cellulitis), or vascular hemodynamics of the whole limb. Assessing compression-related biophysical changes of a localized area, such as around a wound, or in an area outside of an extremity cannot be objectively assessed by these measurements. Tissue dielectric constant (TDC) values, which provide a measure of the local tissue water (LTW) content, offer an alternative method to document variation in the LTW content of the skin in a specific location. The goals of the present research were (1) to characterize TDC values, expressed as percentage tissue water, from multiple areas along the medial aspect of the lower leg of healthy volunteers and (2) to explore the potential utilization of the TDC values to assess change in tissue water content in a localized area following compression applications. Methods TDC was measured at 10, 20, 30, and 40 cm proximal to the medial malleolus on the medial aspect of the right leg of 18 young adult healthy women with an age range of 18-23 years and a body mass index of 18.7 to 30.7kg/m^2.. TDC was measured at baseline and after 10 minutes of exercise with compression in place on three separate days during which three different compression applications were assessed: a longitudinal elastic stockinette, a two-layer cohesive compression kit, and a combination of the two. Leg circumferences and compression-related interface pressures were also measured. Results Test-Retest Reliability of circumferential measurements and TDC values evaluated using Intraclass correlation coefficient (ICC _3,1) revealed excellent and moderate-to-good reliability, respectively. Analysis of TDC values along the length of the limb using Friedman's test, revealed a small but statistically significant overall difference among baseline TDC values attributable to a smaller value at 40 cm. The largest difference in cumulative average was 7.7% which occurred between 20 and 40 cm, with all other differences between locations less than 1%. No significant differences between the compression applications were observed. Conclusion  The present findings demonstrate the utility of TDC measurements as a modality to assess compression-related changes in the legs of healthy women as a foundation for their potential use in assessing outcomes of compression treatments for persons with lower extremity edema or lymphedema. The absence of a significant change in TDC values in these healthy non-edematous conditions and the demonstrated reliability of the TDC measurements on three different days provides further support for the utility of such applications of TDC measurements. The extension to patients with lower extremity edema or lymphedema needs to be evaluated.

Physiological, Pathological, and Circadian Factors Impacting Skin Hydration

Thismanuscript focuses on the physiological, environmental, nutritional, circadian, and aging factors affecting skin tissue water and hydration parameters. The literature findings indicate a multiplicity of interacting processes among these parameters, ultimately impacting skin hydration in normal skin and playing a role in conditions such as atopic dermatitis and psoriasis. The maintenance of adequate skin hydration, aided by the proper functioning of the skin’s protective barrier, is facilitated by stratum corneum integrity with the presence of tight junctions and lipids such as ceramides, each of which is impacted by changes in most of the evaluated parameters. Abnormalities in aquaporin 3 (AQP3) expression and associated deficits in skin hydration appear to have a role in atopic dermatitis and psoriasis. AQP3 hydration-related aspects are influenced by circadian rhythms via modulations associated with CLOCK genes that alter AQP3 protein expression. Ultraviolet exposure, aging, and low temperatures are among those factors that affect skin ceramide composition, potentially leading to increased transepidermal water loss and negatively impacting skin hydration. Vitamin C, collagen, and probiotics may increase ceramide production and improve skin hydration. The extent to which each of the different evaluated factors affects skin hydration varies but is usually large enough to consider their potential effects when investigating skin in research and clinical settings.

Early intervention with compression garments prevents progression in mild breast cancer-related arm lymphedema: a randomized controlled trial

BACKGROUND

Early diagnosis and compression treatment are important to prevent progression in breast cancer-related arm lymphedema (BCRAL). However, some mild BCRAL can be reversible, and therefore, compression treatment may not be needed. The aim of this study was to investigate the proportion of women with mild BCRAL showing progression/no progression of lymphedema after treatment with or without compression garments, differences in changes of lymphedema relative volume (LRV), local tissue water and subjective symptoms during 6 months. Also, adherence to self-care was examined.

MATERIAL AND METHODS

Seventy-five women diagnosed with mild BCRAL were randomized to a compression group (CG) or noncompression group (NCG). Both groups received self-care instructions, and the CG were treated with a standard compression garment (ccl 1). Women in the NCG who progressed in LRV ≥2%, or exceeded 10% dropped out, and received appropriate treatment. The proportion showing progression/no progression of LRV, and changes in LRV was measured by Water Displacement Method. Changes in local tissue water were measured by Tissue Dielectric Constant (TDC), subjective symptoms by Visual Analogue Scale, and self-care by a questionnaire.

RESULTS

A smaller proportion of LRV progression was found in the CG compared to the NCG at 1, 2 and 6 months follow-up (p ≤ 0.013). At 6 months, 16% had progression of LRV in the CG, compared to 57% in the NCG, (p = 0.001). Thus, 43% in the NCG showed no progression and could manage without compression. Also, CG had a larger reduction in LRV, at all time-points (p ≤ 0.005), and in the highest TDC ratio, when same site followed, at 6 months (p = 0.025). Subjective symptoms did not differ between the groups, except at 1 month, where the CG experienced more reduced tension (p = 0.008). There were no differences in adherence to self-care.

CONCLUSION

Early treatment with compression garment can prevent progression in mild BCRAL. Trial registration: ISRCT nr ISRCTN51918431.

The Breast Edema Enigma: Features, Diagnosis, Treatment, and Recommendations

Breast edema most commonly occurs after breast cancer treatment involving breast-conserving therapy, although it may have a variety of other causes. As compared to research on breast cancer treatment-related lymphedema, breast edema and its objective measurement and diagnosis is far behind. Consequences of this disparity contribute to uncertainty and variability in its diagnosis, its treatment, and even the characterization of its incidence and morbidity. Moreover, consensus on a standardized definition, objective diagnostic method, and treatment techniques for breast edema has not yet been reached, making it difficult to provide appropriate guidelines with respect to its management. Given the recent rise in breast edema incidence as an outcome of the increasing use of breast-conserving therapy, this timely review examines the current state of breast edema assessment and makes a case for standardization in part via quantitative methods to diagnose and track breast edema.

Breast Tissue Dielectric Constant as a Potential Breast Edema Assessment Parameter

Background: Many methods can quantitatively assess limb lymphedema, but methods to assess breast edema/lymphedema are quite limited. Thus, there is a need for a convenient and accurate way to quantify and track changes in this condition. Herein, breast tissue dielectric constant (TDC) values that depend on tissue water were used to obtain reference TDC values and interbreast TDC ratios. Methods and Results: TDC was measured in both breasts of 61 women who were about to undergo an ultrasound-guided diagnostic biopsy of a single mass (tumor) in 1 breast. Patient age and body mass index were (mean ± SD) 65.1 ± 11.6 (41-87 years) and 28.9 ± 5.1 (19.1-43.7 kg/m2). TDC was measured at a standardized site (12 o'clock position) with the TDC probe placed with its outer edge at the periphery of the subareolar region. TDC values of healthy breasts versus tumor breasts showed tumor breasts 3% greater (30.4 ± 4.6 vs. 29.5 ± 4.6, p = 0.02). Patients with benign tumors (N = 33) showed no difference between breasts (30.5 ± 4.4 vs. 30.8 ± 4.6 p = 0.434) and had an interbreast TDC ratio (tumor breast/healthy breast) of 1.013 ± 0.077. Patients with malignant tumors (N = 28) had tumor breast values 5% greater (29.8 ± 4.8 vs. 28.4 ± 4.6, p = 0.018) and an interbreast ratio of 1.056 ± 0.117. The overall interbreast ratio (N = 61) was 1.033 ± 0.099. Conclusion: Breast TDC values from nonedematous breasts provide the basis for calculating potential edematous/lymphedematous threshold values based on the measured means +2.5 standard deviation (SD). Accordingly, a TDC threshold value of 41 and an interbreast ratio of 1.28 were determined. These parameters have potential applicability for early detection in at-risk patients and those suspected of having breast edema/lymphedema.

Tissue Dielectric Constant and Water Displacement Method Can Detect Changes of Mild Breast Cancer-Related Arm Lymphedema

Background: Most commonly, volume measurements are used to evaluate the effect of lymphedema treatment, but as the accumulation of lymph fluid can be local, this method may not always be the best. Tissue dielectric constant (TDC) can be applied to identify local lymphedema changes, but has not been used before when evaluating treatment in mild arm lymphedema. Thus, the overall aim of this study was to examine if TDC and water displacement method (WDM) can measure changes in mild breast cancer-related lymphedema during the 6-month standard treatment. More specifically, we examined changes within and between three defined groups based on lymphedema thresholds of TDC and WDM at start of treatment, as well as changes of the highest TDC ratio and site. Methods and Results: Forty-six women with mild arm lymphedema, received treatment with compression sleeves, mostly ccl 1, and instructions about self-care. Local tissue water was measured by TDC at six defined sites and lymphedema relative volume (LRV) by WDM before treatment and at first, second, third, and sixth month. There was a significant decrease in the site with the highest TDC ratio, as well as LRV at all follow-up visits. At 6 months, TDC ratio had decreased mean 0.26 (p < 0.001) and LRV mean - 3.3% (p < 0.001). There was a significant difference between the groups in change of TDC ratio, but not in LRV. Sixty percent changed the overall highest TDC ratio to another site during 6 months. Conclusion: Both TDC and WDM could detect changes in mild arm lymphedema but should be interpreted separately.

An Approach Toward Assessing Head-and-Neck Lymphedema Using Tissue Dielectric Constant Ratios: Method and Normal Reference Values

Background: There are multiple methods to quantitatively assess limb lymphedema, but quantitative methods to assess external lymphedema in persons with head-and-neck lymphedema are quite limited. Quantification in this difficult condition currently uses multiple time-consuming head, face, and neck metric measurements, the accuracy of which is unclear. Thus, there is an important need for a new approach that is sufficiently convenient yet accurate to quantify head-and-neck lymphedema. The approach adopted was to use tissue dielectric constant (TDC) measurements that depend on tissue water, at neck and a submental area, and normalize these to TDC values at the forearm as a way to develop subject-independent indices. Methods and Results: TDC was measured in 60 self-reported healthy nonlymphedematous adults (34 female, 18-81 years, 18.5-45.7 Kg/m²) at two neck sites and one arm site bilaterally and at a submental area. Neck-to-arm-index (NAI) and submental-to-arm-index (SAI) ratios were calculated. TDC values (mean ± standard deviation [SD]) for neck, submental, and arm were, respectively, 37.4 ± 6.9, 35.9 ± 7.7, and 30.1 ± 4.6. Mean NAI and SAI values were 1.253 ± 0.222 and 1.214 ± 0.296 respectively. Head-and-neck lymphedema thresholds calculated as mean + 2.5 SD were for NAI and SAI 1.80 and 1.95, respectively. Conclusions: An approach to help quantify and track head-and-neck lymphedema using TDC neck and/or submental values normalized to a person's forearm TDC values indicates threshold values between 1.80 and 1.95. These ratios, denoted as NAI and SAI, are suggested for use to detect and track changes in lymphedema status based on a patient's changing indices associated with lymphedema treatment.