A comprehensive overview of lymphedema covering subjects as symptoms, diagnostics, research, causes and pictures

Lymphedema Lymphoscintigraphy

     Lymphoscintigraphy is the preferred method for the study of lymphedema.

     a) The basic principle is simple.

     Lymphoscintigraphy is an indirect method of exploration of the lymphatic system based on the study of drainage of particles injected into the subcutaneous tissue, which can pass through the capillaries because of too large diameter. The rapidity of their progress depends on their nature, size, permeability of lymphatic vessels and lymph integrity.

     The structure explains how the initial lymphatic filling lymphatic ducts. The cell edges connected by filaments to the surrounding collagen fibers are stretched by the separation of these fibers because of the arrival of the liquid. This mechanism opens the doors interendotheliales and allows passage of radiotracer from the connective to the lymphatic vessel lumen.

     b) Technical details about lymphoscintigraphy:

     The product used is Technetium-99m radiocolloid labeled. Was injected bilaterally and simultaneously subcutaneously at the dorsal first web space (hand or foot). The dose is 37-74 MBq (1-2 mCi) injection in 0.2 ml of saline.

     The increase in activity is followed by a gamma camera that performs the registration of the climb through the lymphatic channels to the limb. Sometimes the injection can be performed in the external malleolar region or the sole of the foot for the study of deep lymphatic system of lower limbs.

     c) Results of lymphoscintigraphy:

     1) The images are initially analyzed visually.

     After subcutaneous injection, the radioactive particles diffuse into the tissue, enter the lymphatic capillaries and progress through the channels to the lymph nodes where they are arrested, or simply slowed. When injecting the foot lymph vessels are visualized as a straight path single or double leg and single leg. Iliac lymph nodes and paraaortic are highlighted. When injecting hand and axillary lymph external breast are visualized.

     Lymph flow is considered normal when the activity inguinal or axillary appears before the 40th minute. Poor or non lymphocentres viewing at the root of a member in the 40th minute after injection, is the best argument today in favor of lymphatic dysfunction.

     Pictures of dilated lymphatic channels, collateral network, interruption of a journey lymphatic drainage side cross between normal and pathological distribution subcutaneous total absence of migration with prolonged stasis at the point of injection reflects a disturbance of the lymphatic circulation.

     The default setting node can take on various causes: invasion, necrosis, sclerosis of the lymphoid tissue, decreased granulopexique its function, particularly after radiotherapy.

     If the lymph node uptake is decreased in case of lymphedema, it does not indicate that the disease is nodal. An absence of migration from the injection site does not view the lymph nodes, which can be quite functional but does not receive or delay the radiocolloid. Non visualization of nodes is not necessarily related to their absence. Taking delayed images can provide useful information.

     In case of venous obstruction (chronic venous insufficiency, thrombosis) time to onset of activity at the axillary or inguinal lymph nodes is generally less than 40 minutes.

     In the absence of edema, delayed the infiltration of inguinal or axillary lymph nodes is not necessarily pathological, but may be explained by a physiological slowing of lymph flow due to bed rest or prolonged rest. Indeed, the lymphatic circulation is slow during rest. It is accelerated by muscle activity. On the other hand, the lymphatic function declines with age.

     2) A kinetic analysis is sometimes carried out:

  • Study of the disappearance of the radioactive tracer from the injection to measure the half-life and clearance of interstitial colloid;
  • Study of the onset of activity in a region of interest located at a distance from the injection to measure blood flow velocity in lymphatic migration of colloid;
  • Studying the amount of tracer arriving at lymphocentres (sometimes compared to the amount injected distally). After a steady uptake of radioactivity, a plateau is obtained which indicates the maximum node concerned.

     In summary:

     Lymphoscintigraphy is a simple to perform, non-aggressive for the patient, and efficient for the diagnosis of lymphedema.

     It does not allow to distinguish primary lymphedema secondary lymphedema.

     Finally, information obtained may have value for lymphatic drainage in connection with the injection.

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