Gadolinium Storage Condition (GSC) is the term that I use to describe patients who have received a prior GBCA injection and are not sick from it. Essentially everyone who has received a GBCA has some Gd retained in their body, with the bone and skin being the sites with the most Gd retained. So if you received 1 GBCA or 100, there will be some Gd left in your body. Meaningful amount of Gd retained may require atleast 2 administrations of GBCA.
So if my present estimate is there is 10,000 - 100,000 individuals with GDD, one could consider the total number of individuals who have received GBCA and are not sick from it represents 300 million people - 100,000 (the GDD group) individuals. With meaningful Gd probably in the range of 10-50 million people with GSC.
Before you panic thinking about that, remember that unfortunately all of us are exposed to various harmful heavy metals. Everyone living in old cities with lead pipes involved in water supply to their houses will have lead in their body. So 8 million people in NYC and 5 million in Chicago, to name 2 of hundreds of cities, will have lead in their body.
With normal functioning kidneys we also continuously eliminate Gd. I have now written a few blogs related to this topic.
What it seems I need to clarify is the observation of Gd retained in the brain on T1-weighted noncontrast MR images. Many papers have been written on this topic, also by my team. Gd visible in the brain on MRI has little to do with GDD (except that in both cases they have received GBCA), and also represents a very small subset of GSC patients. Basically if you have received at least 5 GBCA enhanced MRIs with Omniscan or Optimark (probably within the last 2-4 years) Gd will be visible in the brain; if you received 10 GBCA enhanced studies with Magnevist over the same time frame you may see this finding; and If you received 20 GBCA enhanced studies with Multihance over that time frame, you may see it. You may never see it with Gadavist, Prohance or Dotarem (the macrocyclics) > by which I do mean never, but possibly after 100 injections. Yet you can receive just one of these macrocyclic agents (or the linear agents) and be devastated by GDD.
So Gd seen on MRI in the brain to me is relatively uninteresting, because it does not correlate with disease, and is just a function of how many and what type of GBCA you received.
The problem comes in, some people do not become sick with GDD after the first GBCA administration but after a subsequent GBCA. So, does the cumulative dose of GBCA and cumulative retained Gd in the body correlate with some cases of GDD (perhaps about half of them, as about half of sufferers get GDD after a repeat GBCA). The answer is possibly and perhaps even probably. The correlation between dose and NSF, certainly severity of NSF is quite clear. The correlation between dose and origination of GDD is not as clear. The correlation between repeat GBCA injections and increasing severity of GDD is however extremely clear.
So, if the question is, since I have received multiple GBCA injections and am not sick from it, should I do anything about it? My answer, for the great majority of patients, probably they do not need to worry about it and do not need to do anything about it. However it is not clear if this advice is true for atleast the highest risk group: white women with central/northern European ancestry and a strong personal or family history of autoimmune disease. Should they do anything about the Gd left in their body? My answer is: I don't know. Certainly it may be not unreasonable to consider chelation with DTPA. At least if they currently just have GSC, and not GDD, they should not experience the devastating effects of Flare with chelation, and possibly it may prevent GDD in their future.