Tissue Water Measurement   Bioimpedance  Dielectric Constant

When tissue fluid removal mechanisms (vascular resorption and lymphatic drainage) become inadequate, fluid
accumulates in the interstitial spaces. This fluid, which is mostly water, causes certain physical properties of
of the tissue to take on features that reflect the now larger proportion of water within the tissue.


Because of the relatively higher electrical conductivity of water relative to most tissues, tissues containing increased
amounts of water will experience a reduced electrical resistance. In theory then, changes in tissue electrical
resistance may be useful to detect either changes in tissue water or as an indicator of abnormally elevated amounts.

This change in electrical resistance, associated with changes in tissue water, forms the primary basis for use of the method called Bioimpedance in the assessment of lymphedematous limbs. Electrodes are strategically placed to measure limb electrical impedance (Cornish et al. 1999) using a sophisticated multifrequency
approach (Cornish et al., 1996). Research indicates that this multifrequency method may be useful in unilateral and bilateral lymphedema (Cornish et al., 2002). A commercial device that uses a single frequency is currently available. This device is potentially useful for assessing limb lymphedema but is not useful to assess local changes in tissue water nor is it useful to assess changes in other body areas that are edematous or are at risk for developing lymphedema. A method suitable to determine local tissue water would be useful for this purpose..

1992`Multi-frequency bioelectrical impedance augments the diagnosis and management of lymphoedema in post-mastectomy patients.

1996 Bioelectrical impedance for monitoring the efficacy of lymphoedema treatment programmes.

2001 Early diagnosis of lymphedema using multiple frequency bioimpedance.

2002 A new technique for the quantification of peripheral edema with application in both unilateral and bilateral cases.

2007 The use of bioimpedance analysis to evaluate lymphedema.

An increase in the relative amount of water also alters other electrical features of the tissue. One of these is the
tissue dielectric constant, which is related to the tissue's electrical capacitance . The dielectric constant of water
is about 78 whereas whereas other tissue components have lessor values. Thus if relative water content increases
the composite tissue dielectric constant increases. In simplified terms this is the basis for assessing local water.

Tissue Dielectric Constant
There have been several approaches to develop a local tissue water assessment device that would satisfy the need to assess edema or lymphedema at any body site. One, that appears to have significant merit, is based on measurements of tissue dielectric constant (TDC), the value of which depends on the relative amount of water contained within the tissue volume being measured. A commercial device 
is currently available and a number of recent research studies have been done demonstrating its utility.

Mayrovitz HN (2007)
Assessing local tissue edema in postmastectomy lymphedema
Lymphology 2007;40:87-94

Mayrovitz HN, Brown-Cross D, Washington Z (2007)
Skin tissue water and laser Doppler blood flow during a menstural cycle

Clinical Physiology and Functional Imaging

Mayrovitz HN, Davey S, Shapiro E (2008)
Localized Tissue Water Changes Accompanying One Manual Lymphatic Drainage (MLD)Therapy Session Assessed by Changes in Tissue Dielectric Constant in Patients with Lower Extremity Lymphedema
Lymphology 2008;41:87-92

Mayrovitz HN, Davey S, Shapiro E (2008)

Local tissue water changes assessed by tissue dielectric constant: Single measurements versus averaging of multiple measurements
Lymphology 2008;41:186-188
Mayrovitz HN, Davey S, Shapiro E (2008)

Local Tissue Water Assessed by Dielectric Constant: Anatomical Site and Depth Dependence in Women Prior to Breast Cancer-Related Surgery
Clinical Physiology and Functional Imaging 2008;28:337-342

Mayrovitz HN, Davey S, Shapiro E (2009)
Suitability of Single Tissue Dielectric Constant Measurements to Access Local Tissue Water in Normal and Lymphedematous Skin
Clinical Physiology and Functional Imaging 2009;(29):23–127

Mayrovitz HN (2009)
Assessing Lymphedema by Tissue Indentation Force and Local Tissue Water  
Lymphology 2009;42:88-98

Mayrovitz HN, Weingrad D, Davey S. (2009)
Local Tissue Water in At-Risk and Contralateral Forearms of Women with and without Breast Cancer Treatment-Related Lymphedema
Lymphedema Research and Biology 2009;7(3):153-8
Mayrovitz HN (2010)

Local Tissue Water Assessed by Measuring Forearm Skin Dielectric Constant: Dependence on Measurement depth, Age and Body Mass Index
Skin Research and Technology 2010;16:16-22
Mayrovitz HN, Carson S, Luis M (2010)

Male-Female Differences in Forearm Skin Tissue Dielectric Constant
Clinical Physiology and Functional Imaging 2010;30(5):328-332
Mayrovitz HN, Luis M (2010)

Spatial Variations in Forearm Skin Tissue Dielectric Constant
Skin Research and Technology 2010;16:438-443

Imaging Methods
Other ways to characterize tissue water depend on various imaging modalities.