Andrew N. Wilner, MD; Daniel Pelletier, MD


September 24, 2014

Editor's Note: While on site at the Joint 2014 Americas Committee for Treatment and Research in Multiple Sclerosis/European Committee for Treatment and Research in Multiple Sclerosis (ACTRIMS/ECTRIMS) conference in Boston, Massachusetts, Medscape correspondent Andrew N. Wilner, MD, spoke with Daniel Pelletier, MD, Professor of Neurology and Diagnostic Radiology, and Chief of the Neuro-Immunology Division at the Yale University Multiple Sclerosis Center at Yale University School of Medicine in New Haven, Connecticut, about standardizing the use of MRI in following the progression of multiple sclerosis (MS).

Dr Wilner: You spoke this evening at a continuing medical education (CME) session[1] and emphasized the need to follow patients with MS with MRI, emphasizing the point that to do that productively, MRI parameters must be standardized. You made some recommendations for this. Can you tell us what these are?

Dr Pelletier: There is no question that if we want to monitor a patient with this disease, and especially if we want to know how the patient is responding to therapy, then imaging is the most sensitive technology. But if you were to do that using imaging and repeating the scans over time, you have to standardize, so that you are comparing apples with apples.

We talked about axial FLAIR or T2-weighted images of the brain, with a resolution of 1 mm × 1 mm × 3 mm. No space, no gaps between two slices. We talked about T1-weighted images before and after gadolinium. Contrast enhancement gives you a sense of whether the lesion is chronic or acute, and that must also be standardized. You need to wait five minutes between the beginning of the injection and obtaining T1-weighted image.[2]

We have a protocol that is now available through the Consortium of Multiple Sclerosis Centers(CMSC). A group of neurologists and radiologists sat down, and we have these sequences ready.

Dr Wilner: Is this what you use at Yale?

Dr Pelletier: We have a different version of it. My main point today was to at least have a common denominator. You can have the lowest common denominator, or you can have a very high common denominator.

At Yale, we are fortunate we have an MS-dedicated scanner. We scan all our patients on the single scanner, and we have a protocol that has been set in stone for the past 18 months. We always repeat the same images. Our technicians are very good at it, so we can compare every six months or every 12 months.

Dr Wilner: Is lack of standardization a problem in the community?

Dr Pelletier: It is a huge frustration. A lesion that you now see because you have a better resolution (1 mm × 1 mm × 3 mm), and you want to go back in time to a year ago, and compare the image, but then there was a gap between two slices—a piece of brain that was not imaged. How do you know whether it is a new lesion?

Dr Wilner: Presumably, there will be improvements in MRI technology as time goes on. How do we take advantage of those improvements? How do we incorporate them into the parameters you are recommending?

Dr Pelletier: When you develop an MRI protocol and you decide to keep it for years to come, some of the sequences are going to be outdated in 3-5 years. There is a price to pay, and you have to accept this price, because by keeping the protocol the same, you provide better care for your patients.

At some point, there is going to be a new MRI scanner and upgrade. You are going to change the hardware, but there are ways to do that. Right before you upgrade, you can measure what your scanner was able to do, and after the upgrade, you can measure again; then you can understand the offset between the two scanners and adapt your software. There are ways to calibrate all these sequences despite the fact that you are going through a significant upgrade.

Dr Wilner: Where are these recommendations published?

Dr Pelletier: The CMSC in North America have published the recommendations.


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