Bioimpedance Spectroscopy of the Breast

Determination of resistance at zero and infinite frequencies in bioimpedance spectroscopy for assessment of body composition in babies

Objective. Bioimpedance spectroscopy (BIS) is a popular technique for the assessment of body composition in children and adults but has not found extensive use in babies and infants. This due primarily to technical difficulties of measurement in these groups. Although improvements in data modelling have, in part, mitigated this issue, the problem continues to yield unacceptably high rates of poor quality data. This study investigated an alternative data modelling procedure obviating issues associated with BIS measurements in babies and infants.Approach.BIS data are conventionally analysed according to the Cole model describing the impedance response of body tissues to an appliedACcurrent. This approach is susceptible to errors due to capacitive leakage errors of measurement at high frequency. The alternative is to model BIS data based on the resistance-frequency spectrum rather than the reactance-resistance Cole model thereby avoiding capacitive error impacts upon reactance measurements.Main results.The resistance-frequency approach allowed analysis of 100% of data files obtained from BIS measurements in 72 babies compared to 87% successful analyses with the Cole model. Resistance-frequency modelling error (percentage standard error of the estimate) was half that of the Cole method. Estimated resistances at zero and infinite frequency were used to predict body composition. Resistance-based prediction of fat-free mass (FFM) exhibited a 30% improvement in the two-standard deviation limits of agreement with reference FFM measured by air displacement plethysmography when compared to Cole model-based predictions.Significance.This study has demonstrated improvement in the analysis of BIS data based on the resistance frequency response rather than conventional Cole modelling. This approach is recommended for use where BIS data are compromised by high frequency capacitive leakage errors such as those obtained in babies and infants.

Quantification of breast lymphoedema following conservative breast cancer treatment: a systematic review

PURPOSE

Breast lymphoedema is a possible side effect of breast conserving surgery, but it is poorly understood. This is due, in part, to difficulty assessing the breast. This systematic review described outcome measures that quantify breast lymphoedema signs and symptoms and evaluated the measurement properties for these outcome measures.

METHOD

Seven databases were searched using terms in four categories: breast cancer, lymphoedema and oedema, clinician reported (ClinROM) and patient reported outcome measures (PROM) and psychometric and measurement properties. Two reviewers independently reviewed studies and completed quality assessments. The Consensus-based Standards for the Selection of Health Measurement Instruments (COSMIN) methodology was used for studies including measurement property evidence.

RESULTS

Fifty-six papers were included with thirteen questionnaires, eight patient-reported rating scales, seven physical measures, seven clinician-rating scales and four imaging techniques used to quantify breast lymphoedema. Based on COSMIN methodology, one ClinROM had sufficient reliability, ultrasound measuring dermal thickness. Tissue dielectric constant (TDC) measuring local tissue water had promising reliability. Four questionnaires had sufficient content validity (BLYSS, BLSQ, BrEQ and LYMQOL-Breast).

CONCLUSIONS

Ultrasound is recommended to reliably assess breast lymphoedema signs. No PROM can be recommended with confidence, but BLYSS, BLSQ, BrEQ and LYMQOL-Breast are promising. Further research is recommended to improve evidence of measurement properties for outcome measures.

IMPLICATIONS FOR CANCER SURVIVORS

There are many approaches to assess breast lymphoedema, but currently, only ultrasound can be recommended for use, with others, such as TDC and questionnaires, showing promise. Further research is required for all approaches to improve evidence of measurement properties.

Three Decades of Bioelectrical Impedance Spectroscopy in Lymphedema Assessment: An Historical Perspective

Bioelectrical impedance spectroscopy (BIS) is a technology that is widely used for the assessment of body composition. The method is based on the measurement of the electrical resistance of the body or a body region that can be quantitatively related to the amount of water in the tissues. Lymphedema is characterized, at least in its early stages, as an accumulation of lymph, an extracellular fluid. In the late 1980s, it was recognized that it might be possible to adapt BIS protocols to measure this increase in lymph volume. Subsequently, the use of BIS for the early detection of breast cancer-related lymphedema was demonstrated in the early 1990s, with BIS reference values indicative of lymphedema published in 2001. The subsequent two decades have seen BIS become a widely accepted method for lymphedema assessment. This review traces the evolution of the BIS technique since its inception and presents the current state of the art, with particular emphasis on utility in clinical practice.