For the diagnosis of MS, imaging of the entire spinal cord, as opposed to only the cervical segments, is recommended for the detection of lesions in the lower thoracic spinal segments and conus. However, 1.5-T scans are acceptable in that imaging, as 3-T scans provide no advantage. For routine follow-up monitoring, spinal cord MRI is optional.
“The current guidelines do not recommend routine follow-up spinal cord MRI, as it remains technically challenging and would disproportionately increase the scanning time, however experienced centers have the option to do so as a small number of asymptomatic spinal cord lesions do develop on follow-up,” the authors noted.
“However, follow up spinal cord MRI is recommended in special circumstances, including unexpected disease worsening and the possibility of a diagnosis other than multiple sclerosis,” they added.
Although the central vein sign has gained significant interest as a potential biomarker of inflammatory demyelination to help distinguish between MS and non-MS lesions, the 2021 protocol does not currently recommend imaging for the feature. However, those recommendations may change in future guidelines, the authors noted.
Low protocol adherence
The ongoing lack of adherence to guidelines that has resulted in frustrating inconsistencies in imaging was documented in no less than four studies presented at the meeting. They showed compliance with standard protocols to be strikingly poor.
Among the studies was one presented by Anthony Traboulsee, MD, professor and research chair of the MS Society of Canada, and from the University of British Columbia in Vancouver. Findings showed that only about half of scans acquired in a real-world dataset satisfied 2018 CMSC Standardized Brain MRI recommendations.
“Of note was that all the scans that were compliant were acquired in 3D while none of the 2D-acquired sequences were adherent,” Dr. Li commented.
Another study assessed use of standardized MRI protocols in a pragmatic, multisite MS clinical trial, the Traditional vs. Early Aggressive Therapy in Multiple Sclerosis (TREAT-MS) trial. Results showed that, upon enrollment, only 10% of scans followed CMSC guidelines for all three structural contrasts.
In that study, when the images provided by Johns Hopkins University Medical School were excluded, that figure dropped to 2.75% of remaining scans that met the criteria.
“Despite the importance of standardization of high-quality MRIs for the monitoring of people with MS, adoption of recommended imaging remains low,” the investigators wrote.
Resistance to change?
Commenting on the research and new guideline, Blake E. Dewey, PhD student, department of electrical and computer engineering at Johns Hopkins University, Baltimore, speculated that the noncompliance is often simply a matter of resistance to change.
“There are a number of reasons that are given for the retention of older, noncompliant MRI scans at different institutions, such as timing and patient throughput; but in my mind the issue is institutional inertia,” he said.
“It is difficult in many instances to get the clinician [radiologist] and institutional buy-in to make these kinds of changes across the board,” Mr. Dewey noted.
“The most common protocol that we see acquired is a set of 2D, low-resolution images with gaps between slices. These are simply not sufficient given modern MRI technology and the needs of MS clinicians,” he added.
Importantly, Mr. Dewey noted that, through direct communication with imaging staff and practitioners in the trial, compliance increased substantially – nearly 20-fold, “indicating a real possibility for outreach, including to commonly used outpatient radiology facilities.”
The updated MAGNIMS-CMSC-NAIMS MRI protocol is beneficial in providing “simple, reasonable guidelines that can be easily acquired at almost any imaging location in the U.S., and much of the rest of the world,” he said.
“As imaging researchers, we often reach for more that is needed clinically to properly diagnose and monitor a patient’s disease,” Mr. Dewey added. “This updated protocol has ‘trimmed the fat’ and left some discretion to institutions, which should help with compliance.”
Mr. Dewey said he also encourages imaging professionals to consider performing the sequences described as “optional” as well.
“Some of these are useful in measuring potential biomarkers currently under extensive validation, such as brain volumetrics and the central vein sign, that may help patient populations that are currently underserved by more traditional imaging, such as progressive patients and patients that could be potentially misdiagnosed,” he said.