The MRI is a very important tool in the care of patients with multiple sclerosis – especially in monitoring the response to MS therapy. In principle, an annual MRI check-up is desirable. At the beginning of the disease or with changes in MS therapy, however, I also often carry out more frequent MRI checks, e.g. at three or six-month intervals.
For these progress checks, I do not need contrast-enhanced images – I also inform my patients about this and encourage them to enforce this with the radiologist. Often, my patients then encounter a lack of understanding in the radiological practice – sometimes the practice even refuses to carry out the examination, sometimes the patient is eventually examined with contrast media. This behaviour is justified by the argument that “without contrast media, one could not see new lesions at all.”
What is actually achieved by the administration of contrast media (CM)? Gadolinium-containing contrast media accumulates in lesions that are not older than 6 – 8 weeks. So, indeed, it is possible to distinguish very fresh (up to about 6 weeks old) from (still) older lesions. For lesions that are older than 6 weeks, although there is no longer any uptake of contrast medium, the lesions can still be seen in the MRI – they appear as “bright spots” in the so-called T2 weighting (which do not take up contrast medium in the T1 weighting). – A short note: T1 and T2 sequences are different recording techniques with which the brain is each pictured. So, different series of recordings are made of the brain, as if the brain were being photographed once in “colour and once in b/w” – In a follow-up MRI, which I do after 3, 6 or 12 months, I therefore see all “new” lesions when I compare the current T2 series with the T2 series of the previous recordings. The “additional” information provided by the administration of contrast media, namely, that a lesion has only recently – i.e. in the last 6 weeks – occurred, is usually not so relevant. Basically, all new lesions that have occurred in an examination interval are important information for further treatment planning.
Meanwhile, it has also been shown in the medical literature that the administration of gadolinium contrast media for the follow-up examination has only a very low diagnostic added value. We know from these scientific works that by refraining from administering contrast media, at most 1.7% of new lesions are overlooked (for those who want to read up on this: Karimian-Jazi K et al. Gd contrast administration is dispensable in patients with MS without new T2 lesions on follow-up MRI. Neurol Neuroimmunol Neuroinflamm. 2018 Jul 16;5(5):e480). Against the background that gadolinium contrast media can also have side effects and the linear gadolinium contrast media have recently come under discussion due to possible permanent gadolinium deposits in the brain, administration should be avoided if no diagnostic added value is expected.
Much more important for the progress control is a careful repositioning of the patient, so that a good comparability of the current recordings and the previous recordings is ensured. It would also be desirable if radiologists would adhere to the standards prescribed by professional societies when carrying out the recordings, instead of carrying out their own and non-consensual protocols.
However, the administration of contrast media still has a high value for new diagnoses, as here the coexistence of older and fresher lesions can serve to demonstrate the characteristic temporal dissemination of the disease. I also find the administration of contrast media useful if no MRI diagnostics have been carried out for many years and a status survey is to be carried out now after a long time. Here I am indeed interested in which and whether some of the lesions that have occurred in the interval have perhaps only recently occurred. This plays a role especially in secondary chronic progressive MS, in order to identify patients with active disease.
