Radiology Contrast Agents: Who's Minding the Contrast Mint?

July 9, 2018

 

It was something like 15 years ago that the Radiology community had imposed upon them, by some combination of hospital administration, hospital pharmacy, and maybe initiated by the FDA, that radiology contrast agents were actually drugs, and as such had to be prescribed by physicians. I am speaking for myself, but I think my views in this piece reflected the general views of radiologists. Drugs.... we thought they were just one time use contrast agents to allow us to see diseases better on images.

 

     It was also decided at the time, that since they had to prescribed, that the ordering physician was to decide if the imaging study required contrast or not. So, radiologists, who knew imaging and the contrast agents the best, had to defer to ordering physicians whether contrast was needed or not. The consequence of this was at times radiologists (most of the time radiologists-in-training, radiology residents) had to spend hours to try to track down an ordering physician to change the order from no contrast to with contrast, or vice versa. Beyond that, most ordering physicians would know very little about contrast agents and their safety, and extremely few would know differences between agents in the same class (for example, when Multihance or Prohance would be indicated).

   

The net result, the physicians who knew the most about the images and about the contrast agents did not make the primary decision when to order contrast, or not, or what type. This has been a subject of irritation to radiologists from when this started, 15 years or so ago, to the present.   At the same time ordering physicians have likely been most often annoyed that they had to make this decision, on top of it because they would have had no specific eduction about this.

   

 As the ordering physicians have no specific knowledge about contrast agents, and they put in the order for contrast agents because they have to, it would not occur to them to have specific followup regarding the contrast agent. Radiologists are not ordering the agents and not following patients in any event. The result of this is: this is the only situation in Medicine and the ordering of drugs that no one is actually specifically following up to see how patients are doing after they have been given a drug.

   

 No one is minding the contast mint of Radiology contrast agents, whether patients are having any adverse reactions beyond immediate hypersensitivity reactions. Any knowledge of subacute or chronic adverse reactions arises from serendipity, and not from the classic physician prescribing drug circumstances: a doctor ordering patients a drug for a condition, seeing them some days later to see how they are doing. This follow-up does not occur with radiology contrast agents.

     

So if we all wonder how it is that NSF went unrecognized for atleast 8 years as being caused by GBCAs, after the condition was described, this is why. This is also why the condition of Gadolinium Deposition Disease is at present only recognized by a minority of orthodox physicians.The obvious question is what else are we missing? 

     

There are two separate changes of practice that should occur.

     

I will start with the most critical problem: no one is following up patients after contrast administration. The simplest, most straight-forward solution was proposed to me by a senior GE medical representative: all patient should receive emails from the imaging facility where they were studied to see how they are doing after the study. With what I have learned from GDD, the minimum contact points should be at 1 and at 4 weeks. Likely, as with surveys in general, most individuals will not respond. It may be not unreasonable to consider no response as a surrogate for no complication. People generally only respond to surveys if there is a problem. Therefore incidence for adverse events can be determined. The numerator being those who complain of an adverse experience, and the denominator the number of emails that have been sent out. There are obvious bias flaws in this, but probably no more and likely less then most other methods of incidence determinations.

     

This way, for example, we could have a more accurate idea of the incidence of GDD amongst all patients who receive GBCAs. Right now we just have my educated guess, that probably 1 in 10,000 experience GDD, and 1 in 100,000 develop severe GDD. But this is in the end just a guess. There is tremendous debate about incidence of acute hypersensitivity reactions with GBCAs. Although meta-analysis (with its limitations) have been reported, most of the information is driven by company marketing and not science. These large scale patient follow-up surveys should be able to answer those debates. This same marketing-driven debate with Iodine contrast agents and induction of contrast media induced acute kidney injury, could also be more objectively answered by this survey.

     

With all the focus on Gadolinium agents, Iodine agents have been largely ignored. Hypothyroidism and delayed skin reactions have been described,  but again purely by serendipity, with no idea of incidence. Who knows what other adverse events occurs with Iodine contrast? Then there are all the nuclear agents, and microbubbles with ultrasound.

     

Surveys emailed out to all patients seems the best strategy. Elderly patients may not use computers but it is almost certain that some family member will.

 

      If Radiology takes over the, to date ignored, responsibility of follow-up of contrast agents (and ofcourse the imaging systems themselves), it would make sense that Radiology also take over the prescribing of the agents. This would save the agony of trying to track down ordering physicians; and then the experts with contrast and imaging are the ones ordering the studies. This would also address one of the issues Radiologists have had to deal with, that somehow they are not full citizens in the pantheon of physicians, because they are not fully responsible for patient care. One of the reasons that had argued against radiologists ordering the contrast agents is that they do not know the patients, but other than a few clear cut contra-indications for contrast, is that of any consequence? Also, it is not uncommon that in hospital settings referral physicians order drugs and they often are not so knowledgeable about patients.

 

   No one is minding the contrast mint of Radiology contrast agents. No one knows what happens to patients after they have left the imaging center, regarding adverse reactions. Surveys sent out by imaging centers to patients would address this huge void.

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