Single-Photon Emission Computed Tomographic Reverse Lymphatic Mapping for Groin Vascularized Lymph Node Transplant Planning

Background: Superficial inguinal (groin) vascularized lymph node transplantation is the most common option for the treatment of lymphedema, particularly in combination with free abdominal flap breast reconstruction. This study examines the utility of single-photon emission computed tomographic (SPECT/CT) lymphoscintigraphy for lower extremity reverse lymphatic mapping in presurgical planning for groin vascularized lymph node transplantation and appraises the physiologic lymphatic drainage to the superficial inguinal lymph nodes. Methods: All patients who underwent bilateral lower extremity SPECT/CT reverse lymphatic mapping over a 5-year period were included. Retrospective case note analysis was performed to collect demographic, surgical, and outcomes data. Results: The study included 84 patients; 56 of these subsequently underwent groin vascularized lymph node transplantation (58 flaps). Fifty-four of these flaps were combined with free abdominal flaps for breast reconstruction (55 flaps). Using SPECT/CT reverse lymphatic mapping investigation of 168 inguinal regions, drainage to at least one superficial inguinal region was visualized in 38.1 percent of patients; in 13.1 percent, drainage was visualized to both superficial inguinal regions. Using this information for presurgical planning, groin vascularized lymph node flap harvest was performed from the contralateral side in 57 of 58 cases (98.3 percent) using intraoperative gamma probe guidance, and no patient developed donor lower extremity lymphedema during follow-up (mean ± SD, 34.5 ± 15.4 months). Conclusions: The authors' use of presurgical SPECT/CT reverse lymphatic mapping together with limited flap dissection and intraoperative gamma probe guidance resulted in no clinical cases of iatrogenic donor lower extremity lymphedema. The high incidence of drainage from the lower extremity to the superficial inguinal region mandates the use of reverse lymphatic mapping when performing groin vascularized lymph node transplantation. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.