The guideline represents a collaboration between the Consortium of Multiple Sclerosis Centers, the European-based Magnetic Resonance Imaging in Multiple Sclerosis, and North American Imaging in Multiple Sclerosis.
Among its recommendations for improving diagnosis and management of MS is the establishment of much-needed ways to boost protocol adherence. “The key part of these recommendations that we want to emphasize is how important it is for them to be used,” said David Li, MD, University of British Columbia, Vancouver, and cochair of the MRI guideline committee.
Dr. Li noted that there was a widespread lack of adherence among MRI centers to compliance with the 2018 CMSC guidelines in imaging for MS. This potentially compromised clinicians’ ability to identify lesions that allow for earlier and confident diagnoses and to monitor for disease changes that may necessitate the initiation or change of therapy, he said.
“The key to being able to know that brain changes have occurred in patients over time is to have scans that have been performed using standardized protocols – to be certain that the change is truly the result of a change in disease activity and progression and not erroneously due to differences resulting from different MRI scanning procedures,” he said to attendees at the 2021 Annual Meeting of the Consortium of Multiple Sclerosis Centers (CMSC).
The guideline was also published this summer as a position paper in Lancet Neurology.
Key recommendations
The new guideline covers a broad range of imaging topics, with key areas of focus including the use of three-dimensional imaging, when and when not to use gadolinium contrast, and spinal cord imaging.
For example, a 3 Tesla magnet strength is preferred when imaging the brain with MRI because of its increased sensitivity for detecting lesions – but a minimum magnet strength of at least 1.5 T can also be used. For the spinal cord, there is no advantage of 3 T over 1.5 T, the guideline notes.
Other recommendations include:
- Core sequences for the brain should include sagittal and axial T2-weighted 3D fluid-attenuated inversion recovery (FLAIR), along with axial T2-weighted and diffusion-weighted sequences.
- 3D acquisition, which is now available on most scanners, is preferable to 2D acquisitions.
- Use of the subcallosal plane for consistent and reproducible alignment of axial scans is again emphasized, as it allows for easier and more confident comparison of follow-up studies to detect changes over time.
- At least two of three sagittal sequences are recommended for spinal cord MRI.
- The judicious use of macrocyclic gadolinium-based contrast agents (GBCA) is reemphasized because of its invaluable role in specific circumstances.
- However, for routine follow-up monitoring for subclinical disease activity, high-quality nonenhanced scans will allow for identification of new or enlarging T2 lesions without the need for GBCA.
- A new baseline brain MRI scan without gadolinium is recommended at least 3 months after treatment initiation, with annual follow-up scans without gadolinium.