Speakers
Description
Lymphedema is a chronic disorder of the lymphatic system characterized by the accumulation of interstitial fluid in soft tissues. Clinical signs such as swelling, fibro-adipose tissue accumulation, and skin thickening often manifest at advanced stages, making early detection essential to prevent irreversible tissue changes and functional impairment.
Various diagnostic methods are currently available to assess lymphatic function and tissue status, each with distinct advantages and limitations. Lymphoscintigraphy remains the gold standard for functional imaging of lymphatic transport. It relies on subcutaneous injection of radiolabeled tracers (typically 99mTc-labeled colloids) and gamma camera imaging to monitor tracer uptake and clearance. To overcome some of these limitations, indocyanine green (ICG) fluorescence lymphography has gained popularity. ICG is injected intradermally and visualized in real time using near-infrared (NIR) cameras, offering high-resolution imaging of superficial lymphatic vessels. Magnetic resonance lymphangiography (MRL) offers high-resolution, non-radioactive imaging of both superficial and deep lymphatic anatomy. It has been increasingly used to map lymphatic networks and detect anatomical anomalies, especially in primary lymphedema. Non-imaging techniques such as bioimpedance spectroscopy (BIS) provide an indirect measure of extracellular fluid content by analyzing the tissue’s electrical resistance. Complementary methods such as perometry and water displacement volumetry are commonly used for monitoring limb swelling over time. Ultrasound has also been applied to assess dermal and subdermal changes in tissue architecture, such as fluid accumulation or fibrosis.
Nevertheless, there is a significant gap in the current diagnostic landscape for Lymphedema. While some existing techniques listed above qualify as highly informative, they are either invasive, require expensive infrastructure, or offer limited functional information. As such, there remains a clear clinical need for a method that combines non-invasiveness, portability, depth sensitivity, and functional insight.
A novel diagnostic method for lymphedema that may prove particularly sensitive to accumulation of interstitial fluid in soft tissues is based on a combined technique known as Active Microwave Thermography (AMT). AMT was first introduced as a nondestructive testing (NDT) approach for civil and aerospace applications, amongst others. The premise behind AMT has a foundation in thermography, a well-known and well-established NDT technique, which has also been peripherally utilized in the medical field through the use of NIR cameras (mentioned previously). What is unique to AMT is the manner by which the thermal excitation is achieved – via absorption of high frequency non-ionizing electromagnetic energy. AMT has strong potential to serve as an additional diagnostic tool for medical applications, offering a noninvasive, noncontact, and portable approach capable of providing quantified diagnostic outcomes
This contribution will present our first and latest results in investigating AMT as a novel diagnostic tool for lymphedema. In particular, we will present a skin phantom tailored to the requirements of in-vitro AMT experiments. We select suitable materials, characterize the relevant electromagnetic and thermal properties, and combine them into a skin phantom. We will support the design with multi-physics simulation and provide first measurement results.
