Skin tissue dielectric constant in women with high body fat content

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.

Test-Retest Reliability of Local Tissue Water and Circumference Measurements in the Head and Neck Area of Healthy Women and Men

Background: Measurements of local tissue water and circumferences are methods to evaluate lymphedema. Knowledge about reference values and reproducibility needs, however, to be determined for the head and neck (HN) area of healthy persons before it can be used in persons with HN lymphedema. The objective of this study was to evaluate the test-retest reliability including measurement errors of local tissue water and neck circumference measurements (CM) in the HN area in a healthy cohort. Methods and Results: Thirty-one women and 29 men were measured on 2 occasions, 14 days apart. The percentage of tissue water content (PWC) were calculated in four facial points and neck CM at three levels. Intraclass correlation coefficient (ICC), changes in mean, standard error of measurement (SEM%), and smallest real difference (SRD%) were calculated. Reliability for PWC was fair to excellent for both women (ICC 0.67-0.89) and men (ICC 0.71-0.87). Measurement errors were acceptable in all points in both women (SEM% 3.6%-6.4%, SRD% 9.9%-17.7%) and men (SEM% 5.1%-10.9%, SRD% 14.2%-30.3%). For the CM, ICCs were excellent both for women (ICC 0.85-0.90) and men (ICC 0.92-0.94), and measurement errors were low (SEM% for women 1.9%-2.1%, SRD% 5.1%-5.9%; SEM% for men 1.6%-2.0%, SRD% 4.6%-5.6%). Most of the lowest values were found close to bone and vessels. Conclusion: Measurements for PWC and CM in the HN area are reliable in healthy women and men, with acceptable to low measurement errors. PWC points close to bony structures and vessels should, however, be used with caution.

Anatomical variability of sub-epidermal moisture and its clinical implications

BACKGROUND

Technologies have been developed to monitor changes in dermal oedema, indicative of the early signs of pressure ulcers. However, there is limited information on the effects of regional differences in tissue morphology on these sub-epidermal moisture (SEM) parameters. This study was designed to investigate the absolute SEM readings across different anatomical sites using a commercial device.

METHODS

Twenty-four healthy participants were recruited to evaluate basal SEM values at different bony prominences, sampled by an experienced operator.

RESULTS

Distinct differences were observed in unloaded SEM values across different anatomical sites, notably between the upper and lower extremities. A high degree of variability was observed in particular sites, such as the heels. Moreover, SEM values at certain locations revealed significant relationships with age, BMI and gender (p < 0.05).

CONCLUSION

The study revealed a high level of variability between and within anatomical sites in a healthy cohort of participants. Determining the changes in local skin and sub-dermal tissue status using SEM may require consideration of both site specific and individual demographic factors, with further research needed in cohorts at risk of pressure ulcers.