Evaluation of Interstitium by Lymphatic Uptake Method in Chronic Bilateral Lower Extremity Edema

Abstract

Objective: Symmetrical bilateral lower extremity edema (BLEE) needs to be treated effectively. Finding the cause of this condition increases the success of treatment. Fluid increase in the interstitial space (FIIS) is always present as a cause or a result. Subcutaneously administered nanocolloid is transported by uptake by lymphatic pre-collectors, and this uptake takes place in the interstitium. We aimed to evaluate the interstitium with labeled nanocolloid and contribute to the differential diagnosis in cases with BLEE.

Methods: Our retrospective study included 74 female patients who underwent lymphoscintigraphy for bilateral lower extremity edema. Technetium 99m (Tc-99m) albumin colloid (nanocolloid), a marked colloidal suspension, was applied subcutaneously to two different areas on the dorsum of both feet with a 26 gauge needle The dose volume administered intradermally is approximately 0.2-0.3 ml, and each injector has 22-25MBq of activity. Siemens E-Cam dual-headed SPECT gamma camera was used for imaging. Dynamic and scanning images were taken with a high-resolution parallel hole collimator. Ankle images were re-evaluated by two nuclear medicine specialists, independent of physical examination and scintigraphy findings.

Results: 74 female patients with bilateral lower extremity edema were divided into two groups based on physical examination and lymphoscintigraphy findings. There were 40 and 34 patients in Groups I and II, respectively. In the physical examination, patients in Group I were evaluated as lymphedema, and patients in Group II were evaluated as lipedema. The main lymphatic channel (MLC) was not observed in any of the patients in Group I in the early images, and the MLC was observed at a low level in the late imaging in 12 patients. The sensitivity of the presence of distal collateral flows (DCF) in the presence of significant MLC in early imaging in demonstrating increased fluid in the interstitial space (FIIS) was calculated as 80%, specificity as 80%, PPV 80%, and NPV 84%.

Conclusions: While MLC is present in early images, concomitant DCF occurs in cases of lipoedema. The transport of increased lymph fluid production in this group of patients can be covered by the existing MLC. Although MLC is evident, the presence of significant DCF supports the presence of lipedema. It can be used as an important parameter in the diagnosis in early cases where physical examination findings are not evident.

Keywords: edema; interstitium; lipoedema; lower extremity; lymphoscintigraphy; nanocolloid.