Painless Indocyanine Green Lymphography

Although lymphoscintigraphy is currently considered the gold standard diagnostic method for patients with peripheral lymphatic disorders, indocyanine green lymphography (ICG-L) is gaining widespread acceptance worldwide as imaging tool for peripheral lymphedema diagnosis and staging.[1] [2] [3]

Both diagnostic tools can be considered physiologic methods. In fact, the concept behind these methods is to inject the contrast in the interstitial space (intradermic) so that the tracer can be picked up by lymphatic capillaries and finally drained by the lymphatic network. As different diagnostic information is provided by these two imaging methods, nowadays, they are considered complementary rather than alternatives. Moreover, ICG-L has been demonstrated to be useful to guide the supermicrosurgical approach in the treatment of lymphedema with lymphaticovenular anastomosis.

The main difference between the two imaging method is that ICG-L is a radiation-free exam and it can be performed virtually anywhere because the hardware is portable. The tracer used in this method is ICG, which comes as powder in a vial to be diluted with not ionic solvent, such as injection water. Ionic solvents must be avoided as they can lead to precipitation of the dye.

One of the main drawbacks with ICG-L is that the intradermal injection is particularly painful. In our experience on 41 patients with primary and secondary lymphedema, the injection pain has been scored from 8 to 10 on a visual analog scale. The maximal intensity of pain was reported during the injection and it subsided within 3 minutes from the end of injection. In two cases, we had to interrupt the procedure because patients cannot tolerate the pain. One patient experienced a vasovagal faint during injections.

We notice that pain does not diminish if the injections are made very slowly, thus excluding dermis stretching as main factor.

So far, the pain can be related to pH solution (acid, pH 5.65) and to direct irritation provided by the dye itself.

Since 6 months, we started to dilute ICG powder (ICC-Pulsion, Pulsion Medical System, Germany) with 5-mL sterile water containing xylocaine 0.5%. This solvent can be easily found in common injectable antibiotic packages.

The pH of this new solution is very similar to that obtained with sterile injection water alone (acid, pH 5.78). We have used this new solution on 35 patients and we noticed that patients did not complain anymore about pain, which was judged as 1 to 3 on a visual analog scale.

This finding further confirms a possible direct irritating effect of ICG on tissues, which can be easily controlled by using xylocaine-containing solvent.

We did not notice any modification in imaging quality, Tracer appearance time (TAT), and lymphatic dynamic evaluation compared with standard solution both in healthy and in lymphedematous limbs.

• References

• 1 International Society of Lymphology. The diagnosis and treatment of peripheral lymphedema: 2013 Consensus Document of the International Society of Lymphology. Lymphology 2013; 46 (1) 1-11
• 2 Narushima M, Yamamoto T, Ogata F, Yoshimatsu H, Mihara M, Koshima I. Indocyanine green lymphography findings in limb lymphedema. J Reconstr Microsurg 2016; 32 (1) 72-79
• 3 Yamamoto T, Narushima M, Doi K , et al. Characteristic indocyanine green lymphography findings in lower extremity lymphedema: the generation of a novel lymphedema severity staging system using dermal backflow patterns. Plast Reconstr Surg 2011; 127 (5) 1979-1986