TISSUE DIELECTRIC CONSTANT (TDC) AS AN INDEX OF SKIN WATER IN WOMEN WITH AND WITHOUT BREAST CANCER: UPPER LIMB ASSESSMENT VIA A SELF-CONTAINED COMPACT MEASUREMENT DEVICE

Abstract

Previous work showed tissue dielectric
constant (TDC) measurements at 300 MHz
useful to evaluate local skin water and then
a hand-held compact version provided values
similar to the original multi-probe system
when assessed in healthy subjects. Our current
goals were to use the compact portable device
to determine: 1) its utility in assessing agerelated
differences between younger healthy
women vs. women with breast cancer (BC);
2) upper-arm site differences in women with
BC and 3) its utility and limitations of a single
measurement vs. averaging triplicate measurements.
A total of 84 women were included;
42 were young (24.0 ± 2.4 years) self-described
healthy women (group A) and 42 were older
(65.5 ± 1.6 years) women with recently
diagnosed BC who were awaiting surgery
(group B). In both groups TDC values were
assessed on the anterior forearm and in group
B at the hand, forearm and biceps with all
measurements bilateral and in triplicate.
Results showed the following. 1) Forearm
TDC values are similar for younger and older
groups with no significant differences (NSD)
between groups or between dominant and nondominant
sides or inter-arm ratios. 2) Hand
TDC values are about 21% greater than
forearm and biceps values but inter-arm ratios
(at-risk/contralateral) are NSD among sites with values for hand, forearm and biceps of 1.027 ± 0.180, 0.997 ± 0.066 and 1.010 ± 0.075 respectively. 3) Based on limits of agreement analyses, single TDC measurements are adequate for most forearm and biceps evaluations but multiple measurements are likely needed for hand measurements. 4) Theoretical detection thresholds for nilateral lymphedema using a 3SD limit of inter-arm ratios are 1.57, 1.20 and 1.24 for and, forearm and biceps. These ratios indicate likely useful forearm and biceps thresholds but a less useful ratio at the hand due primarily to the large variance in hand TDC values among patients.