Subcutaneous Lymphatic Vessels in the Lower Extremities: Comparison between Photoacoustic Lymphangiography and Near-Infrared Fluorescence Lymphangiography

Abstract

V ascular and lymphatic vessel networks closely approximate each other in the interstitial environment, and a detailed visualization of these systems is essential to understanding their involvement in both normal physiologic processes and development of pathologic conditions. It is inherently difficult to visualize lymphatic vessels because of their small diameter and because lymph fluid is colorless. Traditionally, lymphatic vessels in the human body are visualized with lymphoscintigraphy, MR lymphangiography, or near-infrared fluorescence (NIRF) lymphography. The primary indication for these technologies is evaluation of lymphedema due to the obstruction of lymph flow (1-7). These modalities, however, do not provide clear visualization of the lymphatic vessels.In this study, we describe a method for detailed three-dimensional visualization of the lymphatic vessels in the lower extremities of healthy individuals by using photoacoustic imaging (PAI). Although the feasibility of PAI technology has been previously documented in case reports and pilot studies (8,9), herein we expand on those preliminary findings with a larger sample size and demonstrate the practical effectiveness and accuracy of PAI lymphangiography in comparison to NIRF lymphangiography. Materials and Methods Study ParticipantsIn this prospective study conducted from March 2018 to January 2019, we recruited 15 participants (three men and 12 women; average age 6 standard deviation, 45 years 6 12) at our hospital and imaged the lymphatic vessels of each volunteer by using both NIRF and PAI. This study was conducted with the approval of the appropriate local ethics committee. Oral and written informed

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