Main findings

• Imaging procedures included:
  • Phase one Observation of any spontaneous movement of ICG via the lymphatics for approximately 10min. Patients were encouraged to clench and unclench their hand ten times to facilitate lymphatic uptake of the ICG.
  • Phase two Manual lymphatic drainage (MLD) massage was then performed by an accredited lymphoedema therapist to facilitate ICG transit via the lymphatics. They found that MLD facilitated dye movement more efficiently compared to post-injection exercise and delayed scanning although this was not formally evaluated. When lymphatic vessels were identified, their course was marked on the patient’s skin with a coloured pen.
  • Phase three Demarcation lines of dermal backflow were marked on the skin, and collection of imaging data through still photography with both near infrared and digital cameras were taken.
• Lymphoedematous upper limbs were also classified by MDACC
  • Stage as 0: normal lymphatics,
  • Stage 1: many patent lymphatic vessels with minimal patchy dermal backflow,
  • Stage 2: moderate number of patent lymphatic vessels with segmental dermal backflow,
  • Stage 3: few patent lymphatic vessels with extensive dermal backflow involving the entire arm,
  • Stage 4: no patent lymphatic vessels seen with dermal backflow involving the entire arm with extension to the dorsum of the hand and
  • Stage 5: ICG does not move from injection sites

• Overall the percentage of drainage to the ipsilateral axilla was 67%. They found drainage to the ipsilateral axilla decreased as MDACC stage increased. As drainage to the axilla decreased by stage, they found drainage to the ipsilateral clavicular pathway increased reaching a peak of 55% for patients with MDACC Stage 3 lymphoedema.
• Patients with MDACC Stage 4 lymphoedema had the highest rate of drainage to the parasternal pathway and contralateral axilla (17%). In these cases, dermal backflow in the upper limb extended to the anterior midline of the chest and rerouted to the contralateral axilla via the intact lymphatic vessels in the contralateral breast. Of note, if there was a functional pathway to the proximal region of the ipsilateral upper limb, ICG did not extend beyond this region. For example, dermal backflow extended either to the parasternal region or to the contralateral axilla only when the pathway to the ipsilateral axilla or clavicular region was obstructed.
• The drainage pathway to the clavicular region was commonly identified for patients with MDACC ICG Stage 2 or 3 lymphoedema and occurred in 52-55% of patients respectively. It was apparent that sternal and contralateral pathway groups were found in Stage 4 lymphoedema.
• In recent, stress lymphoscintigraphy including exercise was introduced to improve lymphatic visualization but radiation exposure prevents applying MLD for facilitating tracer transit. In comparison ICG mixture moves faster than the lymphoscintigraphy tracer and facilitation of ICG transit with MLD can reduce examination time to specify the lymphatic drainage pathway and provides additional direct therapeutic guidance to the patient and the therapist.
• Another advantage of ICG lymphography is that some patients may indeed not suffer from lymphoedema. In this study four limbs in four patients were diagnosed as not having BCRL as they had normal lymphatic drainage without any dermal backflow. Future research should address the correlation of ICG lymphography with subclinical lymphedema detected by bioimpedance spectroscopy.
• The ipsilateral axilla is still considered a vital pathway. Axillary pathway was restricted functionally instead of complete obstruction in over two-thirds of patients.