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Lymphoscintigraphy in Limb Lymphoedema

Lymphatic · 2 min read

Reading dermal backflow, node timing, collaterals and the transport index

A swollen limb is not always lymphoedema. Lymphoscintigraphy separates the two, shows how the lymphatics have failed, and gives surgeons a stage to plan from. Reading it well means judging timing and pattern, not just whether the nodes appear.

Technique shapes the images

  • The International Society of Lymphology notes that protocols are not standardised: tracers, activities, injection routes, exercise and imaging times all vary. Know your own protocol.
  • An Italian expert panel suggests ⁹⁹ᵐTc-nanocolloid, 37 MBq per limb per compartment (74 MBq total in adults), in 2–3 subcutaneous interdigital injections.
  • Image from the injection sites to the liver at about 20 and 90 minutes, with a defined exercise protocol. Remove compression garments and avoid lidocaine gels beforehand.
  • Massage, exercise and standing all speed transport, so keep them the same for both limbs and for repeat studies.
  • Add a subfascial injection to study the deep system when there is dermal backflow or stasis.

Reading the patterns

FindingWhat it means
Dermal backflowTracer refluxing into dermal lymphatics: the key sign of lymphatic failure
Delayed, asymmetric or absent regional nodesReduced transport capacity
Collateral or asymmetric lymphatic channelsRerouting around an obstruction
Popliteal nodes after a web-space injectionFlow diverted into the deep system
Few or no channels versus many dilated onesAplasia or hypoplasia versus hyperplasia in primary lymphoedema
  • Pattern reading separates lymphoedema from other swelling well: sensitivity 92%, specificity 100% in one series of 190 examinations.
  • It does not reliably separate primary from secondary lymphoedema.

Quantitative indices

  • Transport index. Five visual criteria are each scored 0–9: transport kinetics, distribution pattern, time to node appearance, node visualisation and vessel visualisation. The total runs from 0 to 45; healthy limbs score under 10.
  • In the original study it had a sensitivity of 97.4%, a specificity of 90.3% and interobserver correlation of 0.96.
  • Numbers find early disease that the eye misses. In 308 lymphoedematous limbs, qualitative reading alone made the diagnosis in 70.1%; quantitative clearance parameters were abnormal in all.
Pearl

Image and score both limbs. Unilateral swelling can come with an abnormal transport index on the other side too, so the clinically normal limb is not automatically a safe reference.

Staging

  • ISL stages 0–III are clinical. Stage 0 is impaired lymph transport with no visible swelling; quantitative scintigraphy can detect this incipient disease.
  • Taiwan Lymphoscintigraphy Staging grades drainage as normal, partial obstruction or total obstruction. In 285 unilateral limbs the split was 3.9%, 44.9% and 51.2%.
  • It showed high interobserver agreement (0.89) and correlated with CT volume difference (r = 0.66). Microsurgical teams use it to select procedures.
  • Its correlation with ISL clinical stage is only moderate (r = 0.49). Report both.
Take home
  • Dermal backflow, delayed or absent nodes, collaterals and deep rerouting are the signs of lymphatic failure; describe each one you see.
  • Add a transport index or other quantitative measure: it detects early disease that visual reading misses.
  • Scintigraphic stage and clinical stage measure different things; image both limbs and report both stages.
Sources
  1. Executive Committee of the International Society of Lymphology. The diagnosis and treatment of peripheral lymphedema: 2023 Consensus Document of the International Society of Lymphology. Lymphology. 2023;56(4):133-51.
  2. Maccauro M, Villa G, Manzara A, et al. Lymphoscintigraphy for the evaluation of limb lymphatic flow disorders: report of technical procedural standards from an Italian Nuclear Medicine expert panel. Rev Esp Med Nucl Imagen Mol. 2019;38(5):335-40.
  3. Villa G, Campisi CC, Ryan M, et al. Procedural recommendations for lymphoscintigraphy in the diagnosis of peripheral lymphedema: the Genoa protocol. Nucl Med Mol Imaging. 2019;53(1):47-56.
  4. Szuba A, Shin WS, Strauss HW, Rockson S. The third circulation: radionuclide lymphoscintigraphy in the evaluation of lymphedema. J Nucl Med. 2003;44(1):43-57.
  5. Gloviczki P, Calcagno D, Schirger A, et al. Noninvasive evaluation of the swollen extremity: experiences with 190 lymphoscintigraphic examinations. J Vasc Surg. 1989;9(5):683-9.
  6. Kleinhans E, Baumeister RG, Hahn D, et al. Evaluation of transport kinetics in lymphoscintigraphy: follow-up study in patients with transplanted lymphatic vessels. Eur J Nucl Med. 1985;10(7-8):349-52.
  7. Weissleder H, Weissleder R. Lymphedema: evaluation of qualitative and quantitative lymphoscintigraphy in 238 patients. Radiology. 1988;167(3):729-35.
  8. Campisi CC, Ryan M, Villa G, et al. Rationale for study of the deep subfascial lymphatic vessels during lymphoscintigraphy for the diagnosis of peripheral lymphedema. Clin Nucl Med. 2019;44(2):91-8.
  9. Cheng MH, Pappalardo M, Lin C, et al. Validity of the novel Taiwan Lymphoscintigraphy Staging and correlation of Cheng Lymphedema Grading for unilateral extremity lymphedema. Ann Surg. 2018;268(3):513-25.
  10. Cheng MH, Liu TT. Lymphedema microsurgery improved outcomes of pediatric primary extremity lymphedema. Microsurgery. 2020;40(7):766-75.
  11. Li Q, Tang Q, Luo K, et al. Comparative analysis of the International Society of Lymphology and Taiwan Lymphoscintigraphy Staging systems: correlation, reliability, and a quantitative severity index in extremity lymphedema. Quant Imaging Med Surg. 2025;15(3):1822-33.
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