Maintaining a Consistent Protocol and Scanner for MS
David Li, MD, FRCPC: One of the things that we’re talking about is detecting new lesions, and in many ways, this is really why the meeting was held and why Don Paty, MD, FRCPC came up with the idea of a standardized MR [magnetic resonance]. To be able to see a new lesion, particularly if we’re starting to reduce our use of gadolinium, all we want to know is what happens within the past year. Having 2 scans that are as similar as possible to each other allows you then to detect a new change, because it’s possible that if the patient moves between the scans and the scans have not been performed in exactly the same way—they may be of different thicknesses between 1 scan and the next—that you may not be as certain as a radiologist that this is a new lesion.
June Halper, MSN, APC-C, MSCN, FAAN: Right.
David Li, MD, FRCPC: Being able to identify that new lesion may have consequences in terms of the management of the patient.
Scott D. Newsome, DO, MSCS, FAAN: You bring up a good point. A large part of the meeting and prior meetings is talking about what tesla strength is needed. Is it 1.5T, 3T? I know in our area, based on the payer, sometimes you don’t have a choice. We like to try to get patients in the 3T scanner, but sometimes the payers say, “No, you’re going to go down the road and get her in a 1.5T.” I think the most important thing for me is comparing apples to apples. So if someone is on a 1.5T, then it’s good to keep them consistently on the same scanner.
Frederik Barkhof, MD, PhD: It’s difficult. It’s really difficult. I work both in Amsterdam and in London, and we have between 5 and 7 scanners. It’s really difficult to schedule the patient for the next...on the same scanner. The MAGNIMS [Magnetic Resonance Imaging in Multiple Sclerosis] group did a study comparing head-to-head 3 tesla with 1.5 tesla, so people had a same day scan when they had a clinically isolated syndrome and then the follow-up scans as well. It was quite a tedious study. We had anticipated that we would be more certain or more frequently make the diagnosis of MS [multiple sclerosis] based on the 3T, but in fact it wasn’t true. Although you do see slightly more lesions. If you have good quality FLAIR [fluid-attenuated inversion recovery] scans, they’re quite comparable in picking up the relevant lesions.
Conversely, we had anticipated that there would be issues doing good spinal cord scans on the 3T. The quality is not as nice and crisp as a 1.5T, but in terms of diagnostic quality, it was performing equally well. Progressively these machines are maturing. The 3Ts are getting better at this point. The 1.5Ts are getting better in the brain. I think they are comparable, and it’s important, as David said, to use the same protocol. The 3-D FLAIR is my favorite sequence, and it is very helpful because if you get it at approximately the same resolution, you can re-slice it in multiple directions and always make a fair comparison between time points.
David Li, MD, FRCPC: One of the things that is important besides using the same protocol is making sure as much as possible that the same scanner can be used. Scanners will change over time, there’s no question about it. But during the short period when there is the capacity of being able to return to the same scanner, that’s better than jumping between scanners. This is because there will be some differences between the scanners. If the scans are comparable, then it makes it possible for us as radiologists to be much more confident in saying that there is a new lesion, and for you, as a neurologist, to feel comfortable that you have information to help you guide what you want to do and discuss with the patient.
Scott D. Newsome, DO, MSCS, FAAN: I have a question. In Vancouver, if patients aren’t coming to the medical center and they’re getting scans from the outside, how realistic is getting the patient on the same scanner, even in the same radiology center? I’ve had some challenges doing that. I totally agree. Ideally, we’d like the same scanner, same facility, and the same patient in the tube with the same angle because we have our challenges.
Anthony Traboulsee, MD, FRCPC: We have those challenges as well, and what we’ve been trying to do is work on the state or provincial level to try to harmonize so that the protocols are similar at all the different centers and try to have the patient go to the same center. It brings up another issue, of course, which is people move.
June Halper, MSN, APC-C, MSCN, FAAN: Right.
Anthony Traboulsee, MD, FRCPC: You’d hate to lose all that important information they’ve had from previous scans, and so 1 of the important things is, in order to compare over time if people are moving, they need to bring their data with them. They should bring their MRI [magnetic resonance imaging] studies on a CD or a flash drive, so that when they go to their new center, there can be some attempt to compare studies over time to get a better idea. This will also actually save on getting unnecessary scans and paying for those scans.
Scott D. Newsome, DO, MSCS, FAAN: I have a question for you. Let’s say someone does move, they bring their flash drive, and they establish care with a new provider. Say the quality of their prior MRIs is maybe subpar, but the more current MRI that they’re getting is a bit better quality. The neuroradiologist says, “Well, maybe there’s a new lesion compared to the outside film.” What do you do clinically?
Anthony Traboulsee, MD, FRCPC: In those situations, I’d certainly want a new baseline MRI, and if I don’t have a baseline of the spinal cord, I’d want that baseline too. I’d like to establish a new line in the sand for future comparison. Depending on the patient’s profile, I may or may not request that with gadolinium. It all depends on what stage of the disease they’re in, if they’re on therapy, if I’m concerned that there’s a lot of breakthrough disease activity. But getting a good quality new baseline scan can be invaluable in the future care of that patient.
Scott D. Newsome, DO, MSCS, FAAN: Do you ever do a shorter interval MRI after that, at 6 months versus a year, or do you just go based on that clinical presentation?
Anthony Traboulsee, MD, FRCPC: I’m an old school clinician. It’s really based on the patient’s needs. So, if they’re on stable therapy, well established MS, there have been no changes in their profile, I might get an MRI every 1 to 2 years. If they’ve got longstanding, essentially burned-out MS, they don’t need MRIs as frequently. But if there are a lot of dynamic changes in their clinical profile, and they’re switching therapies, I think we need to image them more frequently just to make sure we’re going down the right pathway in terms of disease control and safety. I think 1 thing we’ve talked about is risk of infections.
Frederik Barkhof, MD, PhD: I agree. I think if patients switch therapy, it’s good to establish a new baseline, preferably not just before they start but 3 to 6 months into the therapy because some therapies take a few months to become fully active. You can reestablish a new baseline after 3 to 6 months and then start your yearly monitoring. As you said, if there are drugs with safety concerns, for example, around PML [progressive multifocal leukoencephalopathy], you could do more frequent monitoring. Especially if people have antibodies against the JC [John Cunningham] virus in the blood, you can go to more frequent scans and then use an abbreviated protocol. Just the FLAIR and the diffusion is sufficient to rule out PML. You don’t have to do the full works including gadolinium in those patients.