Repositioning consistency is key
Among key suggestions that the expert panel proposed for guideline updates include the use of the subcallosal plane for consistent repositioning, which should allow for more accuracy and consistency in the identification of lesions in MS, Dr. Traboulsee said. “A major change reflecting improvements in MRI technology is the ability to acquire high-resolution 3-D images and that’s particularly helpful with fluid attenuation inversion recovery (FLAIR) sequences, which is what we do to identify lesions,” he explained. “The repositioning along the subcallosal line is important because it allows us to easily compare studies over time. It takes very little time but allows us to prepare studies over time much more easily,” he said.
Central vein sign
Another update is the establishment of a new category of optimum plus sequences allowing for the monitoring of brain atrophy and identifying lesions with a central vein sign, which has gained high interest as a marker on 3T MRI of demyelinating plaques in MS. As described in recent research, the central vein sign shows high accuracy in differentiating between MS and non-MS lesions.
“Many people have a few white spots on neuroimaging, but with MRI so much more available around the world, many of them are being misdiagnosed with MS,” Dr. Traboulsee said. “But the central vein sign, using a very simple MRI technique, can identify lesions with a vein in the center that (distinguishes them as) MS lesions.”
Though the process is still several years from routine clinical use, the proposed update would better implement susceptibility weighted imaging, which has traditionally been used for functional MRI.
PML Surveillance
The updates also include recommendations to help in the detection of the rare but potentially serious complication of some disease-modifying therapies of progressive multifocal leukoencephalopathy (PML). “We need a very quick and comprehensive way to monitor patients for PML before symptoms develop,” Dr. Traboulsee said. “The sequences we recommended were based on expert opinion of people who have worked quite a bit with PML in MS, and if one wants to survey for PML it’s only about a 10-minute scan.”
International protocol
Corey Ford, MD, a professor of neurology and director of the MS Specialty Clinic at the University of New Mexico Health Sciences Center in Albuquerque, commented that, with imaging playing such an important role in MS, the lack of adherence to the protocol can be a significant hindrance. “MRI is the most important imaging tool we have in the diagnosing and management of MS, but ... it’s quite amazing how different the sequences that are used can be when imaging centers are asked to image someone with a diagnosis of MS, so it’s a problem,” he said.
Dr. Ford speculated that part of the problem is simply inertia at some imaging centers. “Practices will have been programmed into their protocol for a long time, so when a patient comes in for imaging regarding MS, they may [turn to] their typical sequence,” he said. “There is an inertial barrier to upgrading that sequence, which can involve testing it out on the machine, training the techs to do it that way, and interpreting it for the physician clients who requested the imaging.”
In addition, there is a lack of exposure of MS imaging guidelines in the radiology literature, Dr. Ford added. “Maybe it’s a matter of giving more presentations at meetings that include radiologists, or getting the information out through the manufacturers. I think at the end of the day it could be a combination of all of those things,” he said.
However, the CMSC collaboration could make a big difference, Dr. Ford noted. “This is where the international protocol could be important in terms of making all of this happen,” he said. “What we’re seeing is the confluence of representatives of the U.S. and European centers hash out a consensus, and if it’s international, I think that adds a lot of weight to an eventual implementation on a wider basis.”
“I think the group has done a stellar job, and we should not try to be too focused on adding everyone’s little tweak,” he noted. “If we can get a good baseline foundational imaging sequence that can be implemented worldwide, we would be much better off.”
The CMSC updated imaging guidelines are expected to be published in coming months. The most recent previous updates are available online.
Dr. Traboulsee disclosed relationships with Biogen, Chugai, Roche, Sanofi, and Teva. Dr. Ford and Dr. Li have disclosed no relevant financial relationships.
A version of this article originally appeared on Medscape.com.