Microsurgery guided by sequential preoperative lymphography using Ga-NEB PET and MRI in patients with lower-limb lymphedema.

Objective: The popularity of contemporary microsurgical techniques in treatment of lower-limb lymphedema calls for better visualization of the lymphatic system, both preoperatively and intra-operatively. The aim of this prospective study was to investigate the feasibility of a novel combination of Ga-NEB positron emission tomography (PET) with magnetic resonance lymphography (MRL) in evaluating lymphedema and guiding surgical intervention. Methods: A total of 11 patients (F 9, M 2, age range 29-69 y) with lower-limb lymphedema classified into stage I to III were recruited. PET acquisition was performed at 30, 60 and 90 min after subcutaneous injection of the albumin-binding radiotracer Ga-NEB into the bilateral first web spaces of the feet. All the patients were also subjected to Tc-sulfur colloid (SC) lymphoscintigraphy for comparison. Gd-DTPA-enhanced magnetic resonance imaging (MRI) was performed using sequences specialized for lymphatic vessel scans. All the patients underwent surgical interventions within a week. The surgical approach includes the use of a linear marker for edema localization and indocyanine green (ICG) lymphography with a near-infrared surgical navigation system intra-operatively. Results: Lymph transport in lymphatic channels was clearly observed by visualization of Ga-NEB activity in the lymphatic vessels and within lymph nodes for all 11 patients as well as the visualization of the edema section plane with dermal backflow (DB), abnormally increased and disconnected uptake along the lymphatic channels. Preoperative Ga-NEB PET combined with MRL provides advantageous three-dimensional images, higher temporal resolution, significantly shorter time lapse before image acquisition after tracer injection and more accurate pathological lymphatic vessel distribution than Tc-SC lymphoscintigraphy combined with MRI. Conclusion: This study documented an effective imaging pattern to combine Ga-NEB PET and MRL in patients with lower-limb lymphedema. This strategy demonstrated significant advantage over Tc-SC lymphoscintigraphy/MRL in the evaluation of lymphedema severity, staging and pathological location of lymph vessels to make an individualized treatment plan. Dual Ga-NEB PET/MRL is thus recommended before the operation for staging and therapy planning. [ABSTRACT FROM AUTHOR]