Another ICG update, do we need to change anything?

The most recent paper on ICG imaging of arm lymphoedema provides interesting visual data on how the lymph obligatory load escapes the affected arm in people affected by BCRL. I love the way imaging can help us to understand the lymph system better, but I challenge that what has been found changes anything about how we perform MLD for unilateral BCRL of the arm.

ICG used pre-operatively. Image from https://scitemed.com/article/2458/scitemed-imj-2018-00049

Currently ICG imaging is used with great success to identify patent lymph vessels and to guide micro-vascular surgery. This is within the existing TGA approval for the use of ICG in intra-operative diagnosis.

The paper by Suami et al (1) reports on a protocol developed to image superficial lymph pathways in post-mastectomy arms. Each time something like is is published I see excited posts in social media suggesting this will change the way we do MLD.

But how these findings will change the way we deliver MLD still escapes me. In fact every result reported in this article supports our current unilateral BCRL protocol.

The original article is available open access. Click on the image to go to the article.

Let me take you through the article and show you how. I'll begin with the stated assumption that "Conventionally, BCRL was thought to be caused by the complete obstruction of the lymphatic drainage to the ipsilateral axilla secondary to surgical and/or radiation intervention. Our results contradict this notion..."

I don't think I have ever made this assumption - there is no reference for it in the article and I don't know of any therapist that works on the assumption that there is no drainage whatsoever through the affected axilla. We redirect around the axilla to off load as much as possible to more open pathways, but this is not because we think there is no flow through the axilla at all, it is just to reduce the load that is dependent on that axillary lymph node basin.

So the reported finding that in 67% of arms that were imaged, there is lymph flow through the axilla, does not surprises me at all. Rather it confirms that what I have been telling my clients for many years is correct - there will be some lymph going through your arm pit, but we are going to try and offload whatever we can to other open pathways anyway, to make sure the axilla does not become overloaded. So in my view this finding doesn't change what we are doing to redirect around the axilla.

The study also found that a higher stage of lymphoedema - as defined by the proposed ICG based staging criterion - is associated with less lymph drainage through the axilla and that there was more reliance on dermal movement toward adjacent open drainage areas in these arms. Which is also a nice confirmation of what we already know. The first step in any treatment is to assess our client and find out as much as we can about the cancer treatment. We do this because we know that the more extensive and invasive the interventions in the axilla, the higher the risk of developing arm lymphoedema. So we want to know where the tumour was removed, where and how many lymph nodes were removed, what was the area of radiotherapy, and more recently we also want to know if Taxanes were used during chemotherapy. We also assess other factors that might impact on lymph flow such as BMI, level and type of usual activity, history of other surgeries, co-morbidities, medications, tight underwear etc. We then use this information to determine where the most likely open areas of drainage will be, so the finding that ...'drainage to the ipsilateral axilla decreased by stage... simply confirms our current working assumption that the more damage in the deep axilla, the less we can rely on lymph escaping the arm that way.

The study also found tha higher the stage of lymphoedema the more likelihood that there was drainage to the contralateral axilla via contralateral lymph vessels in the breast. So again, nothing new here I think. Unfortunately the article does not report on the number or location of lymph nodes removed, or the area of XRT so we can't directly correlate the low level of axillary flow to the extent of the ALND or axillary XRT.

When no patent vessels remained in the axilla, ICG imaging showed that dermal flow progressed toward another lymph node basin. This again supports our treatment techniques that are aimed at promoting dermal movement towards open drainage areas. So this is a nice confirmation that the body is already trying to do this itself, and that we are on the right track in supporting that direction of movement with our MLD techniques.

Another finding that confirms what we already know is the observation that 'Patients with BCRL often complain, [..] of discomfort in specific areas of their upper limb instead of uniform changes or swelling in the whole limb. In this study, we introduced a new ICG lymphography protocol for the upper limb to help to identify areas with underlying anatomical changes that occur in lymphoedema.' We already do this when we take time to listen to our clients and pay attention to what they tell us about the way their arm feels and by using this information to guide our treatment. It would have been great if the researchers had added some report on how the ICG imaging matched the client's self reported symptoms.

The stated purpose of this paper was to show that the proposed protocol to image the superficial lymphatics with ICG is valid, and it is great that publications like this are coming out as we need a standardised method of performing this procedure. My issue with the proposed protocol is that they use a manual technique to '..facilitate ICG transit via the lymphatics.' One problem with this is that they have not described the technique used, and we know that not all MLD is the same (see my post on this topic). Additionally the MLD was performed using real time imaging to adjust the direction, speed and pressure applied. If the diagnostic procedure is to be reproducible, then there needs to be fewer variables in what is done to promotr the uptake of the dye. A more standardised method might have been to use a skeletal muscle exercise such as the Tai Chi deep breathing that we teach our clients. To use MLD within the diagnostic procedure seems to be confusing diagnostic imaging with image guided treatment. If we want a procedure that will tell us what the lymphatic system is doing to inform our MLD treatment, then leave the MLD out of it at this stage. The paper does attempt to address this by stating that 'We found that MLD facilitated dye movement more efficiently compared to post-injection exercise and delayed scanning although this was not formally evaluated.' Which is another unsubstantiated claim.

This paper is a valuable addition to our understanding of the lymph system and what happens when lymph drainage is inhibited, but I do feel there are a few issues with the proposed guideline for performing the ICG imaging. This is not a major concern and I am sure that we will soon see widely accepted standardised procedures for this purpose.

My bigger issue is with the way that therapists and clients pick up on studies like this and start thinking that it means we should be doing something different.

Nothing in this paper will tell you what open drainage pathways are present in the client on your table, and the conclusion should be read carefully - 'We developed a new ICG lymphography protocol for diagnosing BCRL focusing on identification of an individual patient’s lymphatic drainage pathway after lymph node surgery to guide MLD and to assist with selection criteria for lymphatic microsurgery. ICG imaging combined with MLD will allow a personalised approach to lymphoedema care.' This does not suggest that we need change anything in our current treatment of clients with BCRL of the arm.

One day ICG may be approved for general use in clinical diagnosis and management of lymphoedema, and when it is that will be a real asset in problem solving for clients who do not respond to current best practice therapies. In the meantime, and for future clients who respond well to treatment, this paper supports our current approach to unilateral BCRL of the arm.

1. Suami H, Heydon-White A, Mackie H, Czerniec S, Koelmeyer L, Boyages J. A new indocyanine green fluorescence lymphography protocol for identification of the lymphatic drainage pathway for patients with breast cancer-related lymphoedema. BMC Cancer. 2019;19(1):1-7.