Compilation of recent publications on tissue dielectric constant (TDC)

Tissue dielectric constant (TDC) is increasingly being recognised as an important tool for lymphoedema assessment and management. The following is a compilation of research, although not exhaustive, on this assessment tool.

Date range: December 2009 to May 2020

1. Tissue Dielectric Constant Measures in Women With and Without Clinical Trunk Lymphedema Following Breast Cancer Surgery: A 78-Week Longitudinal Study – May 2020

Tissue Dielectric Constant Measures in Women With and Without Clinical Trunk Lymphedema Following Breast Cancer Surgery: A 78-Week Longitudinal Study.

Koehler LA; Mayrovitz HN, Physical therapy [Phys Ther], ISSN: 1538-6724, 2020

Abstract

Objective. Following breast cancer surgery with lymph node removal, women are at risk of developing lymphedema in the upper extremity or trunk. Currently, trunk lymphedema diagnosis relies on a clinical assessment because no quantifiable standard method exists. Tissue dielectric constant (TDC) values are quantifiable measures of localized skin tissue water and may be able to detect trunk lymphedema.

The goal of this study was to (1) compare parameters derived from TDC measurements with those derived from clinically accepted criteria for trunk lymphedema in women following breast cancer surgery and (2) explore the potential utility of TDC to detect trunk lymphedema early in its progression.

Methods. This prospective longitudinal study, a secondary analysis from a larger study, observed women with and without clinically determined truncal lymphedema following breast cancer surgery. TDC was measured on the lateral trunk wall at post-surgery weeks 2, 4, 12, and 78 in women who had surgical breast cancer treatment with lymph node removal. Clinical assessment for trunk lymphedema was determined at 78 weeks by a lymphedema expert. Comparison of TDC measurements in women with and without clinical trunk lymphedema was analyzed.

Results. Clinical assessment identified trunk lymphedema in 15 out of 32 women at 78 weeks. These women had TDC ratios statistically higher than women without truncal lymphedema.

Conclusion. The overall findings indicate that TDC has the ability to quantify trunk lymphedema and might be valuable in early detection.

2. Heat‐related changes in skin tissue dielectric constant (TDC) – March 2020

3. Skin tissue dielectric constant in women with high body fat content – November 2019

4. Palpation of Increased Skin and Subcutaneous Thickness, Tissue Dielectric Constant, and Water Displacement Method for Diagnosis of Early Mild Arm Lymphedema – October 2019

5. Assessment of Skin Properties in Chronic Lymphedema: Measurement of Skin Stiffness, Percentage Water Content, and Transepidermal Water Loss – October 2019

6. Minimum Detectable Changes Associated with Tissue Dielectric Constant Measurements as Applicable to Assessing Lymphedema Status – June 2019

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

Mayrovitz, H.N.; Mikulka, A.; Woody, D.. Lymphatic Research and Biology, June 2019, 17(3):322-328.

Abstract

Background: Tissue dielectric constant (TDC) measurements are increasingly being used as a tool to help characterize lymphedema features, detect its presence, and assess treatment related changes. Although the underlying physics of this technology has been well described in the literature, there has been little systematic study of in vivo reliability aspects. A central unanswered question is the minimal detectable change (MDC) that, with a given level of confidence, may be ascribed to this technology. Our goal was to address this issue using test-retest measurements from which intraclass correlations coefficients (ICC) and MDC could be estimated.

Methods and Results: Forty volunteers (20 females) aged 19–61 years with body mass indices of 14.7– 47 kg/m2 and body fat percentages of 12.0%–48.9% were evaluated. Two measurers (M1 and M2) used two different TDC measuring devices (multiprobe and compact) to measure TDC in triplicate sequentially and bilaterally at three locations; anterior forearm, hand palmar mid-thenar eminence, and dorsum mid-web. These measurements were made by each measurer twice constituting test-retest values (T1 and T2). From these measurements ICC2,1 and MDC at 95% confidence were determined for each site and probe for absolute TDC values and for inter-side ratios. MDC values for absolute TDC ranged from 2 to 9 TDC units, and for inter-side ratios ranged from 5.3% to 8.0% depending on site and probe. ICC2,1 values ranged from 0.765 to 0.982.

Conclusions: The MDC values herein documented may be used to provide guidance to aid interpretation of measured TDC changes or differences in a clinical environment.

7. Role of handedness on forearm skin tissue dielectric constant (TDC) in relation to detection of early-stage breast cancer-related lymphedema – September 2018

8. Reliability of the MoistureMeterD Compact Device and the Pitting Test to Evaluate Local Tissue Water in Subjects with Breast Cancer-Related Lymphedema – August 2019

9. Assessing Lower Extremity Lymphedema Using Upper and Lower Extremity Tissue Dielectric Constant Ratios: Method and Normal Reference Values – February 2019

10. Possible applications of normative lower to upper limb ratios of tissue dielectric constant to lower extremity edema. – February 2019

Possible applications of normative lower to upper limb ratios of tissue dielectric constant to lower extremity edema.

Mayrovitz, H.N, Alvarez, A., Labra, M., Mikulka, A., Woody, D. International Angiology

Volume 38, Issue 1, February 2019, Pages 70-75

Abstract

Background: Lower extremity edema occurs in many conditions including congestive heart failure, lymphedema, diabetes-related, kidney and liver disease, chronic venous insufficiency with venous hypertension. Clinical edema assessment methods are often subjective and variable. Our goals were to introduce a simple noninvasive measurement procedure potentially useful to characterize lower extremity edema by providing normative values from which edema thresholds might emerge.

Methods: Tissue dielectric constant (TDC) values, as indices of skin-to-fat tissue water, were measured on foot dorsum, lower medial leg and anterior forearm of 88 adults (44 female) with ages ranging from 19-77 years with BMI ranging from 18.3-40.6 kg/m 2 . From these direct measurements lower-to-upper extremity TDC ratios (foot/ arm and leg/arm) were determined for each gender. Possible edema threshold ratios were calculated as the mean lower-to-upper ratio to which was added two standard deviations of the overall ratio thereby providing initial thresholds for future testing.

Results: Results showed that at each anatomical site absolute TDC values for males significantly exceed those of females (P<0.001). Male vs. female TDC values were 33.0±5.4 vs. 27.7±4.0 for the forearm, 34.8±6.5 vs. 27.5±4.6 for the leg, and 32.5±6.5 vs. 28.7±5.1 for the foot. In contrast, the foot/arm and leg/arm ratios were similar between genders ranging 0.990±0.144 to 1.063±0.170. Corresponding lower extremity to upper extremity threshold ratios ranged from 1.278 for foot/arm to 1.403 for leg/arm. The composite ratios considering both gender ration (N.=88) yielded a composite threshold foot/arm ratio of 1.387 and a leg/arm threshold ratio of 1.324.

Conclusions: This assessment method together with the normative ratios and calculated thresholds may aid in rapid detection of lower extremity edema in patients and possibly as a way to quantitatively track changes in edema status with time or treatment. However, the suitability of these thresholds is subject to future validation in persons with clearly defined lower extremity edema for which this report’s findings serve as an initial quantitative starting point.

11. Minimum Detectable Changes Associated with Tissue Dielectric Constant Measurements as Applicable to Assessing Lymphedema Status – January 2019

12. Assessing Upper and Lower Extremities Via Tissue Dielectric Constant: Suitability of Single Versus Multiple Measurements Averaged – October 2019

13. Reference values for assessing localized hand lymphedema using interhand tissue dielectric constant ratios. – October 2018

Reference values for assessing localized hand lymphedema using interhand tissue dielectric constant ratios.

Mayrovitz, H.N.; Arzanova, E.; Somarriba, S.; Eisa, S.. Lymphatic Research and Biology, October 2018, 16(5):442-445.

Abstract

Background: Early detection and tracking of breast cancer treatment-related lymphedema have been helped by quantitative assessment methods and parameters, including bioelectrical impedance spectroscopy and tissue dielectric constant (TDC). Such measurements are evaluated with respect to interarm differences or ratios that (when exceeding specified thresholds) are suggestive of lymphedema. Specific threshold ratios depend on the assessment method and have been reported for arms. However, there is far less information available on thresholds to assess lymphedema that manifests in at-risk hands and essentially nothing known about TDC ratios in healthy hands. Such information is essential to establish reference values from which lymphedema threshold TDC values may be estimated. The specific aim of this research was to determine such interhand TDC ratios applicable to both young and mature women.

Methods and Results: A total of 70 women (35 under 30 years of age, YOUNG, and 35 over 50 years of age, MATURE) participated after signing an approved institutional review board informed consent. TDC values of the hand dorsum web were measured bilaterally in triplicate with participants in a supine resting position. Results showed MATURE TDC values to be about 15% less than YOUNG ( p < 0.01) on dominant and nondominant hands, but no statistical difference in dominant/nondominant interarm ratios (1.026 – 0.100).

Conclusions: Based on this data set’s overall mean and two standard deviation value, an age-independent interhand TDC threshold ratio of 1.23 emerges as potentially useful for lymphedema detection. This is a good initial start threshold that is usable in future clinical and research assessments.

14. Tissue Dielectric Constant and Circumference Measurement in the Follow-Up of Treatment-Related Changes in Lower-Limb Lymphedema – February 2018 – Download article

15. Tissue Dielectric Constant: Suitability of Single Versus Multiple Measurements Averaged – October 2018

16. Skin indentation firmness and tissue dielectric constant assessed in face, neck, and arm skin of young healthy women. - February 2017

Skin indentation firmness and tissue dielectric constant assessed in face, neck, and arm skin of young healthy women.

Mayrovitz HN; Corbitt K; Grammenos A; Abello A; Mammino J, Skin research and technology : official journal of International Society for Bioengineering and the Skin (ISBS) [and] International Society for Digital Imaging of Skin (ISDIS) [and] International Society for Skin Imaging (ISSI) [Skin Res Technol], ISSN: 1600-0846, 2017 Feb; Vol. 23 (1), pp. 112-120.

Abstract

Purpose: Our goal was to test the hypothesis that skin firmness correlates with skin hydration.

Methods: Dermal water was assessed by tissue dielectric constant (TDC) at 0.5 mm (TDC0.5) and 2.5 mm (TDC2.5) depths on four face sites and two arm sites of 35 women (25.0  1.6 years). Firmness was determined by force (mN) to indent skin to 0.3 mm (F0.3) and 1.3 mm (F1.3).

Results: F0.3 was similar among face sites (avg = 16.2  7.2 mN) but F1.3 varied (avg = 32.5  4.1 mN). TDC2.5 was similar among face sites (avg = 37.7  4.2) but TDC0.5 varied (avg = 36.2  4.8). F1.3 of arm sites was similar (avg = 60.2  18.6 mN) and both greater than F1.3 of neck (28.3  7.1 mN) and face. Regression analysis showed a near-zero correlation between forces and TDC at all sites.

Conclusion: The near-zero correlation may be due to low skin interstitial hydraulic resistance to mobile water movement in healthy young skin. If true, then conditions in which dermal hydraulic conductance is reduced as in lymphedematous, diabetic, or aged skin are more likely show the hypothesized relationship. Our findings provide normalized reference values and suggest that such persons are an important population to study to test for a possible skin water–indentation force relationship and its utilization for early diagnosis.

17. Patterns of Temporal Changes in Tissue Dielectric Constant as Indices of Localized Skin Water Changes in Women Treated for Breast Cancer: A Pilot Study – July 2017

18. Experimental and Analytical Comparisons of Tissue Dielectric Constant (TDC) and Bioimpedance Spectroscopy (BIS) in Assessment of Early Arm Lymphedema in Breast Cancer Patients after Axillary Surgery and Radiotherapy. – July 2017

19. Assessing Localized Skin-To-Fat Water in Arms of Women With Breast Cancer via Tissue Dielectric Constant Measurements in Pre- And Post-Surgery Patients – May 2015

Assessing Localized Skin-To-Fat Water in Arms of Women With Breast Cancer via Tissue Dielectric Constant Measurements in Pre- And Post-Surgery Patients

Harvey N Mayrovitz 1, Daniel N Weingrad, Lidice Lopez. Ann Surg Oncol. 2015 May;22(5):1483-9.

Abstract

Background: Skin-to-fat tissue dielectric constant (TDC) values at 300 MHz largely depend on tissue water and provide a rapid way to assess skin water by touching skin with a probe for approximately 10 s. This method has been used to investigate lymphedema features accompanying breast cancer (BC), but relationships between TDC and nodes removed or symptoms is unclear. Our goals were: (1) to compare TDC values in BC patients prior to surgery (group A) and in patients who had BC-related surgery (group B) to determine if TDC of group B were related to nodes removed and reported symptoms and (2) to develop tentative lymphedema-detection thresholds.

Methods: Arm volumes and TDC values of at-risk and contralateral forearms and biceps were determined in 103 women awaiting surgery for BC and 104 women who had BC-related surgery 26.3 ± 17.5 months prior to evaluation. Inter-arm ratios (at-risk/contralateral) were determined and patients answered questions about lymphedema-related symptoms.

Results: Inter-arm TDC ratios for group A forearm and biceps were respectively 1.003 ± 0.096 and 1.012 ± 0.143. Group B forearm ratios were significantly greater, and among group B patients who reported at least one symptom there was a significant correlation between TDC ratios and symptom burden and nodes removed.

Conclusions: Inter-arm TDC ratios are significantly related to symptoms and nodes removed. Ratios increase with increasing symptom score and might be used to detect pre-clinical unilateral lymphedema using TDC ratio thresholds of 1.30 for forearm and 1.45 for biceps. Threshold confirmation awaits targeted prospective studies but can serve as guideposts to provide quantitative and easily done tracking assessments during follow-up visits.

20. Age-related differences in tissue dielectric constant values of female forearm skin measured noninvasively at 300 MHz. – May 2016

Age-related differences in tissue dielectric constant values of female forearm skin measured noninvasively at 300 MHz.

Mayrovitz HN; Singh A; Akolkar S, Skin research and technology : official journal of International Society for Bioengineering and the Skin (ISBS) [and] International Society for Digital Imaging of Skin (ISDIS) [and] International Society for Skin Imaging (ISSI) [Skin Res Technol], ISSN: 1600-0846, 2016 May; Vol. 22 (2), pp. 189-95.

Abstract

Background/Purpose: We hypothesized that reported agerelated shifts in skin water from less-to-more mobile states would result in increased skin tissue dielectric constant (TDC) values as TDC values depend strongly on water content and state. One aim was to test this hypothesis. Further, as skin-tofat TDC values are used as a tool for edema and lymphedema assessment, a second aim was to establish reference values suitable for young and older women.

Methods: TDC was measured bilaterally on volar forearm skin in young (20–40 years) and older (≥60 years) women. There were four groups with 50, 50, 100, and 50 subjects per age group measured to depths of 0.5, 1.5, 2.5, and 5.0 mm, respectively.

Results: For each age group, TDC values decreased with increasing depth (P < 0.001). TDC values at 0.5 and 1.5 mm were greater for older women (P < 0.001). At 2.5 mm, there was no age-group difference (P = 0.108). At 5.0 mm the direction of the difference reversed with older TDC values less than the younger (P < 0.001).

Conclusion: Results are consistent with age-related shifts in water state from less-to-more mobile and explain depth-dependence differences between age groups. Data also give agerelated TDC reference values for assessing local edematous or lymphedematous states.

21. Experimental and Analytical Comparisons of Tissue Dielectric Constant (TDC) and Bioimpedance Spectroscopy (BIS) in Assessment of Early Arm Lymphedema in Breast Cancer Patients After Axillary Surgery and Radiotherapy. – September 2015

22. Tissue Dielectric Constant (TDC) Measurements as a Means of Characterizing Localized Tissue Water in Arms of Women With and Without Breast Cancer Treatment Related Lymphedema – September 2014

Tissue Dielectric Constant (TDC) Measurements as a Means of Characterizing Localized Tissue Water in Arms of Women With and Without Breast Cancer Treatment Related Lymphedema

H N Mayrovitz, D N Weingrad, S Davey. Lymphology. 2014 Sep;47(3):142-50.

Abstract

Quantitative measurements to detect lymphedema early in persons at-risk for breast cancer (BC) treatment-related lymphedema (BCRL) can aid clinical evaluations. Since BCRL may be initially manifest in skin and subcutis, the earliest changes might best be detected via local tissue water (LTW) measurements that are specifically sensitive to such changes. Tissue dielectric constant (TDC) measurements, which are sensitive to skin-to-fat tissue water, may be useful for this purpose. TDC differences between lymphedematous and non-lymphedematous tissue has not been fully characterized. Thus we measured TDC values (2.5 mm depth) in forearms of three groups of women (N = 80/group): 1) healthy with no BC (NOBC), 2) with BC but prior to surgery, and 3) with unilateral lymphedema (LE). TDC values for all arms except LE affected arms were not significantly different ranging between 24.8 ± 3.3 to 26.8 ± 4.9 and were significantly less (p < 0.001) as compared to 42.9 ± 8.2 for LE affected arms. Arm TDC ratios, dominant/non-dominant for NOBC, were 1.001 ± 0.050 and at-risk/ contralateral for BC were 0.998 ± 0.082 with both significantly less (p < 0.001) than LE group affected/control arm ratios (1.663 ± 0.321). These results show that BC per se does not significantly change arm LTW and that the presence of BCRL does not significantly change LTW of non-affected arms. Further, based on 3 standard deviations of measured arm ratios, our data demonstrates that an at-risk arm/contralateral arm TDC ratio of 1.2 and above could be a possible threshold to detect pre-clinical lymphedema. Further prospective measurement trial are needed to confirm this value.

23. Can Tissue Dielectric Constant Measurement Aid in Differentiating Lymphoedema From Lipoedema in Women With Swollen Legs? - January 2014

Can Tissue Dielectric Constant Measurement Aid in Differentiating Lymphoedema From Lipoedema in Women With Swollen Legs?

S Birkballe 1, M R Jensen, S Noerregaard, F Gottrup, T Karlsmark. Br J Dermatol. 2014 Jan;170(1):96-102

Abstract

Background: Distinguishing lymphoedema from lipoedema in women with swollen legs can be difficult. Local tissue water content can be quantified using tissue dielectric constant (TDC) measurements.

Objectives: To examine whether TDC measurements can differentiate untreated lower extremity lymphoedema from lipoedema, and to test interobserver agreement.

Methods: Thirty-nine women participated in the study; 10 patients with lipoedema (LipP), nine patients with untreated lymphoedema (U-LP), 10 patients with lymphoedema treated with compression bandaging for ≥ 4 weeks (T-LP) and 10 healthy controls. All subjects were measured at three predefined sites (foot, ankle and lower leg). All groups except U-LP were measured by three blinded investigators. Using a handheld device, a 300-MHz electromagnetic wave is transmitted into the skin via a 2.5-mm depth probe. TDC calculated from the reflected wave is directly proportional to tissue water content ranging from 1 (vacuum) to 78.5 (pure water).

Results: Mean ± SD TDC values for U-LP were 48.8 ± 5.2. TDC values of T-LP, LipP and controls were 34.0 ± 6.6, 29.5 ± 6.2 and 32.3 ± 5.7, respectively. U-LP had significantly higher TDC values in all measurement sites compared with all other groups (P < 0.001). A cut-off value of 40 for ankle and lower-leg measurements correctly differentiated all U-LP from LipP and controls. Intraclass correlation coefficients were 0.94 for the ankle and the lower leg and 0.63 for the foot.

Conclusions: TDC values of U-LP were significantly higher than those of T-LP, LipP and controls and may aid in differentiating lymphoedema from lipoedema. Interobserver agreement was high in ankle and lower-leg measurements but low in foot measurements.

24. Validity and interobserver agreement of lower extremity local tissue water measurements in healthy women using tissue dielectric constant. – July 2012

Validity and interobserver agreement of lower extremity local tissue water measurements in healthy women using tissue dielectric constant.

Jensen, Mads R.; Birkballe, Susanne; Nørregaard, Susan; Karlsmark, Tonny, Clinical Physiology & Functional Imaging Jul2012, Vol. 32 Issue 4, p317.

Abstract

Background Tissue dielectric constant ( TDC) measurement may become an important tool in the clinical evaluation of chronic lower extremity swelling in women; however, several factors are known to influence TDC measurements, and comparative data on healthy lower extremities are few.

Methods Thirty-four healthy women volunteered. Age, BMI, moisturizer use and hair removal were registered. Three blinded investigators performed TDC measurements in a randomized sequence on clearly marked locations on the foot, the ankle and the lower leg. The effective measuring depth was 2·5 mm.

Results The mean TDC was 37·8 ± 5·5 (mean ± SD) on the foot, 29·0 ± 3·1 on the ankle and 30·5 ± 3·9 on the lower leg. TDC was highly dependent on measuring site ( P<0·001) but did not vary significantly between investigators ( P = 0·127). Neither age, BMI, hair removal nor moisturizer use had any significant effect on the lower leg TDC. Intraclass correlation coefficients were 0·77 for the foot, 0·94 for the ankle and 0·94 for the lower leg.

Conclusion The TDC on the foot was significantly higher compared with ankle and lower leg values. Foot measurements should be interpreted cautiously because of questionable interobserver agreement. The interobserver agreement was high on lower leg and ankle measurements. Neither age, BMI, hair removal nor moisturizer use had any significant on effect on the lower leg TDC. TDC values of 35·2 for the ankle and 38·3 for the lower leg are suggested as upper normal reference limits in women.

25. Suitability of single tissue dielectric constant measurements to assess local tissue water in normal and lymphedematous skin. - December 2009

Suitability of single tissue dielectric constant measurements to assess local tissue water in normal and lymphedematous skin.

Mayrovitz HN, Davey S, Shapiro E. Clinical Physiology and Functional Imaging, 29(2), 123–127. 2009.

Abstract

Previous reports described the use of average tissue dielectric constant (TDC) measurements to assess local tissue water and its change. Our goal was to determine if a single TDC measurement could be used in place of the average of multiple measurements. The comparison criteria used to test this was the extent to which single and averaged measurements yielded similar TDC values in both normal and lymphedematous tissue. Measurements were made in two groups of women; a control group (n = 20) and a group with unilateral arm lymphedema (n = 10). In the control group, TDC was measured to multiple depths (0.5-5.0 mm) on both ventral forearms and to a depth of 2.5 mm on the lateral thorax on both body sides. In the lymphedematous group, TDC was measured on both ventral forearms to a depth of 2.5 mm. Results showed that the 95% confidence interval for differences between single and averaged TDC values was less than +/-1 TDC unit and that the limits of agreement between methods was less than +/-2.5 TDC units (+/-6.5%) for each condition, site and depth measured. This finding suggests that where this level of agreement is acceptable suitable clinical assessments can be made using a single TDC measurement.