Reverse Lymphatic Flow in Lower Extremity Lymphedema Visualized on Single-Photon Emission Computed Tomography-A "Downflow Effect".

Background

Patients who undergo pelvic lymphadenectomy for gynecologic or genitourinary cancers have an increased risk of developing lower extremity lymphedema. Although total lymphadenectomy is performed, bilateral lower extremity lymphedema is rare. A state-of-the-art radiologic technique, single-photon emission computed tomography (SPECT) with radioisotope injection, was used to establish lymph flow physiology and identify retrograde lymphatic flow in patients with lower extremity lymphedema after lymphadenectomy.

Methods

Data from patients who underwent treatment for lower extremity lymphedema were collected from January 2017 to December 2018. These patients had gynecological or genitourinary cancers and had undergone pelvic lymphadenectomy. Among them, 10 were evaluated for reverse lymph flow using SPECT. The radioisotope was injected solely into the subdermal area of the healthy foot, not the affected foot, in contrast to other studies. Four hours later, SPECT images were obtained and analyzed. The radiologic results were correlated with clinical observations.

Results

Most patients had undergone surgery for gynecological cancers. The mean disease duration was 9.4 ± 8.1 years. Retention in the pelvis and hip was confirmed in seven out of ten patients; six patients showed reverse lymphatic flow in the affected limb.

Conclusions

SPECT-CT imaging after tracer injection into the unaffected limb revealed retrograde lymphatic flow toward the clinically affected side in a substantial proportion of patients with unilateral lower-extremity lymphedema.