Lymphoscintigraphy for the evaluation of limb lymphatic flow disorders: Report of technical procedural standards from an Italian Nuclear Medicine expert panel.

Lymphoscintigraphy represents the "gold standard" for diagnosis of lymphedema, but an important limitation is the lack of procedural standardization. The aim of this Italian expert panel was to provide a procedural standard for lymphoscintigraphy in the evaluation of lymphatic system disorders. Topic anaesthetic gels containing lidocaine should be avoided. Patients should remove compressive dressings. Total recommended activity for 99mTc-nanocolloid administration in adults is 74MBq, or 37MBq per limb and per investigated compartment, in single or multiple aliquots. 2-3 subcutaneous injections should be performed (II-III±I interdigital space of each hand/foot), avoiding intravascular injection. Deep lymphatic system of lower limbs should be evaluated in presence of dermal back-flow or lymphatic stasis (1-2 subfascial administrations in retro-malleolar or plantar region). Planar images should be acquired from injection site to liver with whole-body or serial static acquisitions 20' and 90' after subcutaneous administration. Additional information on lymphatic pathways is obtained after a quick and/or prolonged exercise protocol. SPECT/CT is recommended to study the thoracic, abdominal and pelvic territories. When required, deep lymphatic system of lower limbs should be evaluated with static acquisition 90' after subfascial administration. The report should describe administration and imaging procedure, exercise protocol, qualitative and semi-quantitative analysis (wash-out rate, transport index), potential sources of error. Due to the essential role fulfilled by lymphoscintigraphy in clinical management of primary and secondary lymphedema, an effort for the standardization of this technique should be made to provide the clinicians with a homogeneous and reliable technical methodology.