MS affects approximately one million people in the United States. As family physicians, these guidelines are important to know, because we are often the ones who make the initial diagnosis of MS. Similarly, if we order the wrong imaging study, we can miss making an accurate diagnosis.
Dr. Linda Girgis
The new guidelines (MAGNIMS), which were sponsored by the Consortium of Multiple Sclerosis Centres, were published in August. The documents offers detailed guidance on the use of standardized MRI protocols as well as the use of IV gadolinium contrast agents, including in children and pregnant patients.
It is advised to use 3-D techniques (as opposed to two-dimensional) and it is noted that this is becoming more clinically available. Sagittal 3-D T2-weighted fluid-attenuated inversion recovery (FLAIR) is the core sequence considered for MS diagnosis and monitoring because of its high sensitivity. High-quality 2-D pulse sequences can be used alternatively when 3-D FLAIR is not available.
When 3 T scanners are not available, 1.5 T scanners are sufficient. However, 3 T scanners do have a higher detection rate for MS lesions. In evaluating the imaging, T2 lesion counts, gadolinium lesion counts, and interval changes should be reported.
The use of GBCAs (gadolinium-based contrast agents) is needed to diagnose MS and rule out other diseases. The time between injection of contrast should ideally be 10 minutes but no less than 5. Optic nerve MRI is recommended only in patients with atypical symptoms, such as new visual symptoms. Spinal cord MRI is also not routinely advised unless it is needed for prognosis.
When the initial MRI does not meet the full criteria of MS, brain MRI should be repeated every 6-12 months in suspected cases. The same modality should be used each time. After treatment is started, it is recommended to perform MRI without GBCAs for 3 months and annual follow ups. The use of GBCAs-free MRIs for routine follow up is a new recommendation compared to previous ones. However, if the use of GBCAs would change the management, then they should be utilized for monitoring.
The same imaging standards are recommended in pediatric patients. Spinal cord MRI should be utilized in kids with spinal cord symptoms or inconclusive brain MRI. Similar scan frequency is recommended as in adults. MRI is not contraindicated during pregnancy but should be decided on an individual basis. Standard protocols should be used as well as a magnetic field strength of 1.5 T. GBCAs should not be used during pregnancy. There are no limitations in the postpartum period.
The complete set of guidelines is quite extensive and adds to the previous guidelines published in 2017. They were first published in The Lancet Neurology.
While most of these patients will be referred to neurologists, as the primary care physician it is our responsibility to know all aspects of our patients’ diseases and treatments. While we may not be actively treating MS in these patients, we need to know their medications, how they interact with others, and how their disease is progressing
Additionally, we may be the ones asked to order MRIs for monitoring. It is imperative that we know the guidelines for how to do this.
Dr. Girgis practices family medicine in South River, N.J., and is a clinical assistant professor of family medicine at Robert Wood Johnson Medical School, New Brunswick, N.J. You can contact her at fpnews@mdedge.com.