Revised clinical practice guidelines for MRI in MS incorporate new information and practice recommendations that will help patients, physicians, and care providers, according to an international working group of MS researchers.
ATLANTA—Revised guidelines regarding an MRI protocol for the diagnosis and follow-up of multiple sclerosis (MS) were presented at the 2009 Annual Meeting of the Consortium of MS Centers (CMSC) and the Americas Committee for Treatment and Research in MS (ACTRIMS). “The new guidelines incorporate new information and practice recommendations that will benefit patients and will be useful for physicians and care providers,” stated Anthony Traboulsee, MD, Assistant Professor of Neurology at the University of British Columbia, Vancouver, Canada, and a member of the working group of international neurologists and radiologists who devised the guidelines.
Standardized Protocol Recommendations
No specific recommendations were made for magnet size or strength, although scans should be of good quality, with adequate signal noise ratio and resolution. However, some of the lower field strength magnets or older machines will probably not be able to produce optimal images under these guidelines, noted Lael Stone, MD, Staff Neurologist at Cleveland Clinic’s Mellen Center, and member of the MS working group.
Core brain MRI sequences are listed as sagittal fluid attenuated inversion recovery (FLAIR); axial FLAIR; axial T2; and axial T1 pre- and post-gadolinium. Core spinal cord MRI sequences are listed as sagittal T2, sagittal proton density or short tau invasion recovery, and sagittal T1.
The guidelines also address the requisition, reporting, and storage of MRIs. Physicians should request the standardized brain and/or spinal cord protocol, indicate the clinical question being addressed, and make the radiologist and technologist aware of relevant medical history, physical findings, and MS medications, as well as the date and place of any previous MRIs. Radiologists should report the lesion number, location, size, shape, and character, as well as whether MRI criteria for dissemination in space and time are met. A comparison with previous studies for new lesion activity and atrophy should be performed whenever possible, assuming that the images are of comparable quality and acquisition. Copies of the MRI studies should be kept permanently, and digital media are the most sensible manner for archiving.
Clinical Indications
For patients with a clinically isolated syndrome (CIS) and suspected MS, the researchers recommend a brain MRI with and without a gadolinium contrast agent at baseline evaluation. They also recommend a spinal cord MRI if persisting uncertainty exists about the diagnosis and/or the findings on brain MRI are equivocal, and if presenting symptoms or signs are at the level of the spinal cord. During a follow-up examination, a brain MRI with and without a gadolinium contrast agent is advised to detect new disease activity.
In noting that an initial brain MRI is recommended when available, “We wanted to recognize that there are some areas of the world, and frankly also in the United States, where it’s very difficult to obtain an MRI for a variety of reasons,” said Dr. Stone.
Among patients with definite MS, the guidelines authors recommend a brain MRI with gadolinium at baseline evaluation and during follow-up. “To assess subclinical disease activity, [brain MRI with and without gadolinium contrast] should be considered every one to two years,” reported the authors. “The exact frequency may vary depending on clinical course and other clinical features.”
“You’ve heard over and over again that MS is a clinical diagnosis but with newer criteria,” commented Dr. Stone. “We are emphasizing the fact that clinically silent lesions on an MRI can count toward dissemination of time or space.”
Dr. Stone emphasized that the goal of setting an MRI frequency timeline was to recommend, not dictate. “We want to emphasize the fact that at least it should pass through one’s consciousness, as to the appropriateness,” she pointed out. “The exact frequency may vary depending on clinical course and other clinical features.” The reasons for follow-up with a brain MRI with and without gadolinium contrast—to evaluate an unexpected clinical worsening that causes concern for diagnosis, to reassess the original diagnosis, and to reassess before starting or modifying therapy—also support the new recommendation. “The threshold for defining a response on MRI that is clinically meaningful in the short term and long term, including the potential effects of newer quantitative techniques, is evolving,” Dr. Stone stated.”
—Laura Sassano