Spatial and Temporal Variability of Upper Extremity Edema Measures After Breast Cancer Surgery

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.

A Tissue Dielectric Constant Evaluation of Knee Edema: A Retrospective Intra-rater Reliability and Association Study of Repeated Measures

BACKGROUND

This research compared the reliability and association of tissue dielectric constant (TDC) measures of knee edema to circumferential measurements of knee girth recorded as part of a physical therapy examination.

METHODS

Twenty adults having observable unilateral knee edema were enrolled. A single examiner measured edematous knee swelling with a TDC device and a tape measure across two visits. The presence of edema was recorded as a positive number in reporting side-to-side differences and a positive percentage in documenting change over time. Intra-rater reliability of the measures was assessed with an intra-class correlation coefficient (ICC). Percent change in edema was evaluated independently for both methods using a paired t-test, and the association between measures was assessed by a Pearson's statistic.

RESULTS

Both measures were reliable (ICC ≥ 0.81), and both detected a significant percentage decrease (p < 0.05) in edema across visits. The TDC measure changed by 8.3%, an amount nearly four times larger compared to knee girth (2.4%). The subsequent follow-up comparison revealed an inverse relationship (p = 0.049; r = -0.44) between the two percent change measurements of edema.

CONCLUSION

The two methods capture different physical attributes of edema. The TDC records the water content of the tissue, while the use of a tape measure records circumferential limb girth. The TDC measurement was reliable and more responsive in detecting a percentage decrease in knee edema in comparison to a circumferential measure of knee girth. The TDC method may have wider use in directly measuring edema in other tissue structures and regions of the body.

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.

Five-Year Cumulative Incidence of Axillary Web Syndrome and Comparison in Upper Extremity Movement, Function, Pain, and Lymphedema in Survivors of Breast Cancer With and Without Axillary Web Syndrome

OBJECTIVE

To determine the cumulative incidence and natural history of axillary web syndrome (AWS) and its related postoperative risk for physical impairments in a cohort of women followed for 5 years post breast cancer surgery.

DESIGN

Prospective, longitudinal study.

SETTING

Academic health center.

PARTICIPANTS

Women (N=36) with and without AWS after breast cancer surgery with sentinel node biopsy or axillary lymph node dissection.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Participants were assessed for AWS, shoulder goniometric flexion and abduction range of motion, function (Disability of the Arm, Shoulder, and Hand), lymphedema (bioimpedance spectroscopy, girth measures, tissue dielectric constant), and pain (visual analog scale) at 2, 4, 12, and 78 weeks and 5 years after breast cancer surgery. Analysis of variance compared range of motion, function, lymphedema, and pain in women identified with AWS with those without AWS across visits. Univariate logistic regression assessed if AWS was a risk factor for physical impairment at 5 years.

RESULTS

The cumulative incidence of AWS was 57%. Fifty percent (14/28) of the women who completed all study visits had signs of AWS at 5 years. Abduction active range of motion was significantly lower in women with AWS at 2 and 4 weeks post surgery. AWS was identified as a risk factor for reduced shoulder motion at 5 years. Regardless of AWS, 75% of the women experienced 1 or more upper extremity physical impairments at 5 years, which is an increase from 66% at 78 weeks in the same cohort.

CONCLUSIONS

AWS is associated with reduced shoulder range of motion in the early postoperative time period, can persist for 5 years after breast cancer surgery, and increases the risk of long-term reduced shoulder range of motion. Long-term physical issues are apparent after breast cancer surgery regardless of AWS.

Circumferential and Depth Variations in Tissue Dielectric Constant Values as Indices of Lower Leg Localized Skin Water

The primary goal of this study was to quantify circumferential (medial, anterior, lateral) and measurement depth variations (0.5 mm, 1.5 mm, 2.5 mm) in tissue dielectric constant (TDC) values as an aid to their use to assess the presence and progression of lower extremity edema and lymphedema. Measurements were done in 30 healthy non-edematous women to provide reference data to estimate expected values and thresholds when evaluating clinical edematous or lymphedematous conditions. A second goal was to determine the extent to which TDC values evaluated at lower leg sites depend on body mass index (BMI). The study protocol (#12180901) was approved by the university’s institutional review board and subjects were evaluated after signing an approved informed consent. The study group had an age range of 19-54 years with a mean age and SD of 30.6 ± 10.1 years and had a BMI between 18.1-44.1 Kg/m² with a mean BMI and SD of 24.5 ± 5.4 Kg/m². The main findings show that at the three circumferential sites (medial, anterior, and lateral) located eight cm from the mid-malleolus, there are small but statistically significant differences in TDC values at every measurement depth (0.5 mm, 1.5 mm and 2.5 mm). For each depth, the maximum difference occurs between the medial and lateral locations with lateral locations having a greater TDC value at all depths. Despite the wide range of BMI values of the subjects evaluated, no significant relationship between TDC value and BMI was detected. It is concluded that TDC measurements in the lower leg reveal statistically significant differences among circumferential sites and measurement depths that should be considered when evaluating or tracking lower extremity tissue water changes associated with edema, lymphedema or other conditions related to skin water. The absolute values of these non-edematous TDC values herein determined may provide a basis for calculating TDC thresholds applicable to edematous or lymphedematous lower leg conditions.

Tissue Dielectric Constant of the Lower Leg as an Index of Skin Water: Temporal Variations

Tissue dielectric constant (TDC) measurements are a convenient, reliable, and accurate way to noninvasively access local tissue water content and its change with time or treatment. The method has been widely used for upper extremity lymphedema assessments but less so for lower extremities. For lower extremity assessments, it would be useful to have an estimate of the expected inter-leg TDC differentials of normal non-affected legs to help interpret measured inter-leg differentials when such measurements are done in patients with lower extremity edema or lymphedema. The goals of this study were to determine normal inter-leg TDC differences, quantify TDC temporal changes during 60 minutes of supine lying in a group of 10 middle-aged women (42-57 years), and evaluate the change in TDC values as measured throughout the day from 0800 to 2000 hours in a group of 10 younger women (23-28 years). The overall findings indicate that TDC measurements, as an assessment parameter of lower extremity localized skin-to-fat tissue water, are only minimally dependent on potential confounding factors such as 60-minute supine lying or the time of day at which the measurements are made. If the small sample size of the present study is reflective of the larger population, an inter-leg TDC ratio exceeding a value of 1.2 is suggested as a threshold for judging unilateral lower extremity edema or lymphedema. This possibility needs assessment in women with these conditions.

Noninvasive Measurements of Breast Cancer-Related Lymphedema

Breast cancer-related lymphedema (BCRL) presents as swelling in the arm, hand, trunk, or breast at varying times after completion of breast cancer treatment. Its reported incidence varies widely in part due to its dependence on the type and extent of the treatment, co-present pre-treatment risk factors, and the criteria used to define its presence. Central to this issue is the quantitative measures that are variously used to specify lymphedema thresholds for its detection and tracking over time and during treatment. The goal of this paper is to discuss these issues and the methods available for the non-invasive quantitative assessment of BCRL. Operational principles and advantages and limitations of the various methods and their clinical history of use and effectiveness are discussed. 

Heat-related changes in skin tissue dielectric constant (TDC)

The impact of 20 min of whole-body heating (WBH) on the tissue dielectric constant (TDC) of forearm and hand skin was evaluated in 24 young adults. TDC was measured in triplicate at 300 MHz using an open-ended transmission line method in which the effective measurement depth was about 2 mm. TDC measurements are an effective way to assess and track localized oedema and lymphoedema. The underlying hypothesis was that heat-induced eccrine gland activation would increase TDC values via an increase in fluid within the TDC measurement volume. The goal was to test this concept and to determine the magnitude of the change when environmental temperatures were elevated to near 42°C and to estimate TDC recovery time. The practical aspect of this research is motivated by the fact that patients in whom such measurements are made may arrive at the clinic in various states of sweat gland activation. Thus, knowledge of the effect of such activation on measured TDC values permits better understanding of possible relationships between such activation and TDC values. Results showed that increasing environmental temperature from 23·3 ± 1·6 to 41·5 ± 1·3°C increased forearm and thenar eminence skin temperatures to 37·8 ± 0·5 and 37·9 ± 0·4°C, respectively. These changes were associated with increases in TDC at arm from 30·7 ± 4·6 to 36·3 ± 5·7 (18·2%) and at hand from 34·7 ± 4·9 to 45·1 ± 5·5 (30%). Based on calculated TDC recovery rates, it is concluded that temperature-related TDC variability can be minimized using a wait time of at least 15 min after bandage removal prior to TDC measurements in affected limbs.