New diagnostic modalities in the evaluation of lymphedema

Abstract

Objective Currently lymphedema (LED) is typically diagnosed clinically on the basis of a patient’s history and characteristic physical findings. While the diagnosis of LED is sometimes confirmed by lymphoscintigraphy (LSG), the technique is limited in its ability to identify pathology and guide therapy. Recent advancements provide opportunities for new imaging techniques to not only assist in the diagnosis of LED, based on anatomical changes, but also to assess contractile function and to guide therapeutic intervention. The purpose of this contribution is to review these imaging techniques. Methods Literature for each technique is reviewed and discussed and the evidence for each of these new diagnostic techniques were assessed on several criteria to determine if each could: 1) establish whether disease is present; 2) determine the severity of the disease process; 3) define the pathophysiology of the disease process; 4) demonstrate whether intervention is possible as well as what type; and 5) objectively grade the response to therapy. Results LSG is currently the standard test to confirm LED. Duplex ultrasound (DUS) is a simple, readily available non-invasive test that can identify LED by specific tissue characteristics and the response to therapy. MRI and CT scans similarly demonstrate the alterations in epidermal and subcutaneous tissue, but the latter can also detect obstructing neoplasms as a cause of secondary LED. Moreover, MR lymphangiography details lymphatic vessels and nodes and their function. Newer fluorescence imaging techniques provide opportunities to imaging lymphatic anatomy and function. Visible micro lymphangiography by fluorescein sodium is limited by tissue light absorption to imaging depths of 200 μm. Near-infrared fluorescence (NIRF) lymphatic imaging [NIRF-LI], a newer test using intradermal injection of indocyanine green, can penetrate several centimeters of tissue and can visualize the initial and conducting lymphatics, the lymph node basins, as well as the active function of lymphangions (the key module) in exquisite detail. Conclusions The availability and the non-invasive nature of DUS should make this modality the first choice for establishing the diagnosis of LED based on tissue changes. Further studies comparing DUS to LSG, however, are needed. The costs of MRI and CT limit their adoption as a means to regularly assess the lymphatics. While lymphatic truncal anatomy and transit times can be delineated by the older technique of LSG, NIRF-LI is rapid, highly sensitive, repeatable, and provides exquisite detail for lymphatic vessel anatomy/function of the lymphangions as well as the response to therapy.

The Unresolved Pathophysiology of Lymphedema

“…Methods to diagnose lymphedema have primarily focused on the detection of edema, lymphatic vessel transport, and lymph flow, until the recent advances in our knowledge of disease pathophysiology prompted the development of methods to assess tissue transformation including fibrosis and fat deposition (O'Donnell et al, 2017). These novel approaches may be more effective modalities to monitor the progression of the disease and the response to treatments that are, to our knowledge, still lacking in the clinic.…”

Lymphedema and Lymphovenous Bypass: Perioperative Nursing Implications

“…Providers may use computed tomography and magnetic resonance imaging to confirm the presence of excess fluid in tissues. The most commonly used diagnostic method for confirming lymphedema in the extremities is lymphoscintigraphy . A nuclear medicine provider injects the radioisotope technetium Tc 99m‐sulfur colloid intradermally into the affected extremity and takes scintigrams (ie, images produced by detection of radiation).…”

Clinical and duplex ultrasound evaluation of lower extremities varicose veins – a practical guideline

“…In clinical practice, the distinction between lymph-, lip-, and phleboedema is often diffi cult to establish due to a considerable overlap. In these cases, the ultrasound examination can sometimes help to further characterize the oedema (e. g. exclusion of relevant vein pathology, diff use hyperechogenic subcutis in lipoedema, and low-echogenicity subcutaneous spaces in lymphoedema [37]). …”