Ultrasound Elastography Use in Lower Extremity Lymphedema: A Systematic Review of the Literature

Biomarkers in lymphedema assessment: integrating elastography and muti-frequency bioimpedance analysis

Aim: Multi-frequency bioimpedance analysis (MFBIA) is used to measure lymphedema, but it is a biomarker that is sensitive to stiffness. Lymphedema is a condition that can be accompanied by stiffness, but no studies have considered this, so we tried to use non-invasive elastography as a biomarker for stiffness.Methods & results: This retrospective study included 102 patients with lymphedema, divided into two groups according to the elastography strain ratio: stiff group (elastography strain ratio <0.7, n = 48) and non-stiff group (elastography strain ratio >0.7, n = 54). We estimated the volume of the affected arm based the extracellular water (ECW) volume calculated using MFBIA through a simple linear regression method. The adjusted R2 was 0.044 in the stiff group and 0.729 in the non-stiff group. Stepwise multivariate linear regression was used to investigate the significant factors for estimating the affected arm volume for each group. In the non-stiff group, the significantly associated factors were impedance at 50 kHz, weight, and height (adjusted R2 = 0.724; p = 0.003). In the stiff group, significant associations were observed among impedance at 250 kHz, impedance at 1 kHz, weight, and height (adjusted R2 = 0.705, p = 0.041).Conclusion: Considering the characteristics of lymphedema, using MFBIA concurrently with elastography can be useful biomarker for estimating lymphedema.

Current diagnostic and quantitative techniques in the field of lymphedema management: a critical review

Lymphedema evaluation entails multifaceted considerations for which options continue to evolve and emerge. This paper provides a critical review of the current status of diagnostic and quantitative measures for lymphedema, from traditional and novel bedside assessment tools for volumetric and fluid assessment, to advanced imaging modalities. Modalities are contrasted with regard to empirical support and feasibility of clinical implementation. The manuscript proposes a grid framework for comparing the ability of each modality to quantify specific lymphedema characteristics, including distribution, dysmorphism, tissue composition and fluid content, lymphatic anatomy and function, metaplasia, clinical symptoms, and quality of life and function. This review additionally applies a similar framework approach to consider how well assessment tools support important clinical needs, including: (1) screening, (2) diagnosis and differential diagnosis, (3) individualization of treatment, and (4) monitoring treatment response. The framework highlights which clinical needs are served by an abundance of assessment tools and identifies others that have problematically few. The framework clarifies which tools have greater or lesser empirical support. The framework is designed to assist stakeholders in selecting appropriate diagnostic and surveillance modalities, gauging levels of confidence when applying tools to specific clinical needs, elucidating overarching patterns of diagnostic and quantitative strengths and weaknesses, and informing future investigation.

Skin mechanical properties measured with skin elasticity measurement device in patients with lymphedema: Scoping review

BACKGROUND

Skin conditions in patients with lymphedema have been identified according to changes in skin mechanical properties. The skin elasticity meter is a non-invasive tool for measuring the mechanical properties of the skin; however, its potential use in patients with lymphedema has received little attention. This review aimed to provide an overview of studies measuring the skin mechanical properties of patients with lymphedema using a skin elasticity meter.

MATERIALS AND METHODS

Search terms and synonyms related to lymphedema and skin mechanical property measurement using a skin elasticity meter were identified, and electronic databases containing articles in English were searched.

RESULTS

A total of 621 articles were retrieved, and four articles were analyzed after screening. Despite this research subject receiving increasing attention, no consensus has been reached regarding the best methods.

CONCLUSION

Measurement methods are expected to be standardized in the future to elucidate the skin mechanical properties of patients with lymphedema.

Segmentation of Arm Ultrasound Images in Breast Cancer-Related Lymphedema: A Database and Deep Learning Algorithm

OBJECTIVE

Breast cancer treatment often causes the removal of or damage to lymph nodes of the patient's lymphatic drainage system. This side effect is the origin of Breast Cancer-Related Lymphedema (BCRL), referring to a noticeable increase in excess arm volume. Ultrasound imaging is a preferred modality for the diagnosis and progression monitoring of BCRL because of its low cost, safety, and portability. As the affected and unaffected arms look similar in B-mode ultrasound images, the thickness of the skin, subcutaneous fat, and muscle have been shown to be important biomarkers for this task. The segmentation masks are also helpful in monitoring the longitudinal changes in morphology and mechanical properties of tissue layers.

METHODS

For the first time, a publicly available ultrasound dataset containing the Radio-Frequency (RF) data of 39 subjects and manual segmentation masks by two experts, are provided. Inter- and intra-observer reproducibility studies performed on the segmentation maps show a high Dice Score Coefficient (DSC) of 0.94±0.08 and 0.92±0.06, respectively. Gated Shape Convolutional Neural Network (GSCNN) is modified for precise automatic segmentation of tissue layers, and its generalization performance is improved by the CutMix augmentation strategy.

RESULTS

We got an average DSC of 0.87±0.11 on the test set, which confirms the high performance of the method.

CONCLUSION

Automatic segmentation can pave the way for convenient and accessible staging of BCRL, and our dataset can facilitate development and validation of those methods.

SIGNIFICANCE

Timely diagnosis and treatment of BCRL have crucial importance in preventing irreversible damage.

Acoustic Radiation Force Impulse Elastography Assessment of Lymphoedema Tissue: An Insight into Tissue Stiffness

Palpation remains essential for evaluating lymphoedema to detect subtle changes that may indicate progression. As palpation sense is not quantifiable, this study investigates the utility of ultrasound elastography to quantify stiffness of lymphoedema tissue and explore the influence of the pitting test on tissue stiffness. Fifteen women with unilateral arm lymphoedema were scanned using a Siemens S3000 Acuson ultrasound (Siemens, Germany) with 18 MHz and 9 MHz linear transducers to assess tissue structure and tissue stiffness with Acoustic Radiation Force Impulse elastography. Ninety sites were assessed, three on each of the lymphoedema-affected and contralateral unaffected arms. A subgroup of seven lymphoedema-affected sites included additional elastography imaging after a 60-s pitting test. Dermal tissue stiffness was greater than subcutaneous tissue stiffness regardless of the presence of pathology (p < 0.001). Lymphoedematous tissue exhibited a higher dermal to subcutaneous tissue stiffness ratio than contralateral sites (p = 0.005). Subgroup analysis indicated that the pitting test reduces dermal tissue stiffness (p = 0.018) and may alter the stiffness of the subcutaneous tissue layer. Elastography demonstrates potential as a complement to lymphoedema palpation assessment. The novel pre-test and post-pitting elastography imaging protocol yielded information representative of lymphoedema tissue characteristics that could not be ascertained from pre-test elastography images alone.

Effects of Lymphovenous Anastomosis Surgery Using Ultrasonography in Lymphedema From a Pressure Perspective

Objective

To analyze the effects of lymphovenous anastomosis (LVA) surgery after 1 year using the elastic index (EI) and volume.

Methods

This study was a retrospective study of 41 patients, with lymphedema, who underwent LVA surgery between July 2018 and June 2020. Limb circumference, used to determine the volume of the limb with lymphedema, and EI, which reflects tissue stiffness and measured using ultrasonography were measured for each patient before and 1 year after LVA surgery. To examine the effect of LVA, differences in the preoperative and 1-year postoperative volumes and EIs were analyzed using the Wilcoxon signed-rank test.

Results

The mean volume and EI of the dominant site in upper-extremity lymphedema were 2,309.4 cm³ and 1.4, respectively, preoperatively and 2,237.1 cm³ and 0.9, respectively, at 1 year postoperatively. The mean volume and EI difference of the dominant site 1 year after surgery was −16.6 cm³ (p=0.22) and −0.5 (p<0.001). The mean volume and EI of dominant site in lower-extremity lymphedema were 6,137.0 cm³ and 1.2, respectively, preoperatively, and 5,832.6 cm³ and 1.1, respectively, at 1 year postoperatively. The mean volume and EI difference of the dominant site 1 year postoperatively were −320.9 cm³ (p=0.04) and −0.2 (p=0.09), respectively.

Conclusion

LVA surgery is more effective in reducing pressure than in reducing volume, which may be helpful in preventing the progression of lymphedema.

Activity of keloids evaluated by multimodal photoacoustic/ultrasonic imaging system

Multiple objective assessments have been used to assess the activity of keloids to compare different therapeutic regimens and facilitate the best individual treatment choice for patients, but none of them are standardized. A multimodal photoacoustic/ultrasonic (PA/US) imaging system, including photoacoustic imaging, elastography, ultra-micro-angiography, and conventional US technologies (gray scale US, color Doppler US, and power Doppler US), was applied to evaluate keloids by a radiologist. Growing stages were defined by patients, and Vancouver Scar Scale (VSS) was assessed by a plastic surgeon. A comprehensive model based on multimodal ultrasound parameters (poor-echo pattern, high vascular density, decreased elasticity, and low SO₂ within the keloid) and VSS might be a potential indicator of active keloids, comparing with VSS alone. The multimodal PA/US imaging system could be a promising technique for keloids assessment.

Lymphaticovenous Anastomosis for Lower Extremity Lymphedema: A Systematic Review

Background  Lymphedema is an accumulation of protein-rich fluid in the interstitial spaces resulting from impairment in the lymphatic circulation that can impair quality of life and cause considerable morbidity. Lower extremity lymphedema (LEL) has an overall incidence rate of 20%. Conservative therapies are the first step in treatment of LEL; however, they do not provide a cure because they fail to address the underlying physiologic dysfunction of the lymphatic system. Among several surgical alternatives, lymphaticovenous anastomosis (LVA) has gained popularity due to its improved outcomes and less invasive approach. This study aims to review the published literature on LVA for LEL treatment and to analyze the surgical outcomes. Methods  PubMed database was used to perform a comprehensive literature review of all articles describing LVA for treatment of LEL from Novemeber 1985 to June 2019. Search terms included "lymphovenous" OR "lymphaticovenous" AND "bypass" OR "anastomosis" OR "shunt" AND "lower extremity lymphedema." Results  A total of 95 articles were identified in the initial query, out of which 58 individual articles were deemed eligible. The studies included in this review describe notable variations in surgical techniques, number of anastomoses, and supplementary interventions. All, except one study, reported positive outcomes based on limb circumference and volume changes or subjective clinical improvement. The largest reduction rate in limb circumference and volume was 63.8%. Conclusion  LVA demonstrated a considerable reduction in limb volume and improvement in subjective findings of lymphedema in the majority of patients. The maintained effectiveness of this treatment modality in long-term follow-up suggests great efficacy of LVA in LEL treatment.