Quantifying Real-Time Lymphatic Clearance of the Extremity Using Molecular Imaging: A Porcine Pilot Study
Bao Ngoc Tran, MD1, Qing Ruan, MD1, Joseph P. Angelo, MS1,2, Rita Lauren, BS3, Bernard T. Lee, MD, MPH, MBA, FACS1, Dhruv Singhal, MD1, Hak Soo Choi, PhD4.
1Department of Surgery, Division of Plastic and Reconstructive Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA, 2Department of Biomedical Engineering, Boston University, Boston, MA, USA, 3Division of Cardiac Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA, 4Division of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
PURPOSE: Breast cancer related lymphedema affects more than 400,000 survivors in the United States. In 2009, Lymphatic Microsurgical Preventing Healing Approach (LYMPHA) was first described as a surgical technique to prevent lymphedema by performing a prophylactic bypass at the time of an axillary node dissection (ALND). We describe the first animal model evaluating the efficacy of LYMPHA.
METHODS: In Yorkshire pigs, each distal hind limb lymphatic system was cannulated and injected with a different fluorophore (human serum albumin conjugated indocyanine green (ICG-HSA) or Evans Blue (EB-HSA)). Fluorescence-Assisted Resection and Exploration (FLARE) imaging was used to map the respective lymphatic systems. Lymphatic clearance of each hind limb was measured via fluorescence of each dye from centrally obtained blood samples. A lymphadenectomy (control side) versus lymphadenectomy with LYMPHA (study side) was then performed. The injections were then repeated.
RESULTS: ICG-HSA and EB-HSA allowed for lymphatic mapping of each respective hind limb utilizing FLARE imaging. (Figure 1) Lymphatic clearance of ICG-HSA from the distal hind limb dropped 64% when comparing no intervention versus a groin lymphadenectomy. (Figure 2a) In comparison, lymphatic clearance of EB-HSA dropped only 22% from the distal hind limb when comparing no intervention versus a lymphadenectomy with LYMPHA. (Figure 2b)
CONCLUSION: We describe the first animal model for LYMPHA. Moreover, we demonstrate the power of molecular imaging to provide real time rates of lymphatic clearance for each respective hind limb.
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