Incidental Finding on Brain MRI Seen in 5% of Older Patients

Pauline Anderson

May 11, 2020

New research shows that almost 5% of older British citizens have potentially serious brain abnormalities, including aneurysms, and about a third have blood test abnormalities.

Knowing the expected prevalence of such incidental findings in the older general population is "extremely useful" for both researchers and clinicians, study author Sarah Elisabeth Keuss, MBChB, Dementia Research Centre, UCL Queen Square Institute of Neurology, London, UK, told Medscape Medical News.

"In research, the knowledge helps to inform study protocols regarding how to manage incidental findings and enables study participants to be appropriately informed," said Keuss.

Greater awareness also helps clinicians make decisions about whether or not to scan a patient, she said, adding that imaging is increasingly available to them.

It allows clinicians to counsel patients regarding the probability of an incidental finding and balance that risk against the potential benefits of having a test.

The research is being presented on AAN.com as part of the American Academy of Neurology (AAN) 2020 Science Highlights. Due to the COVID-19 pandemic, the AAN had to cancel the 2020 annual meeting, April 25 to May 1, in Toronto, Canada.

The incidental findings were published last year in BMJ Open.

The new findings are from the first wave of data collection for the Insight 46 study, a neuroimaging substudy of the MRC National Survey of Health and Development (NSHD) 1946 British birth cohort, a broadly representative sample of the population born in mainland Britain during 1946.

The research uses detailed brain imaging, cognitive testing, and blood and other biomarkers to investigate genetic and life-course factors associated with Alzheimer's disease and cerebrovascular disease.

The current study included 502 individuals, aged about 71 years at the time of the analysis, and 49% were women. Almost all (93.8%) participants underwent 1-day MRI scans.

Some 4.5% of these participants had an incidental finding of brain abnormality as per a prespecified standardized protocol.

Suspected vascular malformations were present in 1.9%, and suspected intracranial mass lesions were present in 1.5%. The single most common vascular abnormality was a suspected cerebral aneurysm, which affected 1.1% of participants.

Suspected meningiomas were the most common intracranial lesion, affecting 0.6% of study participants.

Action Plan

Participants and their primary care provider were informed of findings "that were deemed to be potentially serious, or life-threatening, or could have a major impact on quality of life," said Keuss.

Relevant experts "came up with a recommended clinical action plan to help the primary care provider decide what should be the next course of action with regard to investigation or referral to another specialist," said Keuss.

The new results are important for clinical decision-making, said Keuss.

"Clinicians should consider the possibility of detecting an incidental finding whenever they're requesting a brain scan. They should balance that risk against the possible benefits of recommending a test."

The prevalence of incidental findings on MRI reported in the literature varies because of different methods used to review scans. "However, comparing our study with similar studies, the prevalence of the key findings with regard to aneurysms and intracranial mass lesions are very similar," said Keuss.

Keuss and colleagues don't recommend all elderly patients get a brain scan.

"We don't know what the long-term consequences are of being informed you have an incidental finding of an abnormality; we don't know if it improves their outcome, and it potentially could cause anxiety," said Keuss.

Psychological Impact

The researchers have not looked at the psychological impact of negative findings on study participants, but they could do so at a later date.

"It would be very important to look into that given the potential to cause anxiety," said Keuss. "It's important to find out the potential negative consequences to inform researchers in future about how best to manage these findings."

From blood tests, the analysis found that more than a third (34.6%) of participants had at least one related abnormality. The most common of these were kidney impairment (about 9%), thyroid function abnormalities (between 4% and 5%), anemia (about 4%), and low vitamin B12 levels (about 3%).

However, few of these reached the prespecified threshold for urgent action, and Keuss noted these findings were not the focus of her AAN presentation.

A strength of the study was that participants were almost the exact same age.

Important Issue

Commenting on the research for Medscape Medical News, David S. Liebeskind, MD, professor of neurology and director, Neurovascular Imaging Research Core, University of California, Los Angeles, said it raises "a very interesting" and "important" public health issue.

"The question is whether we do things based around individual symptomatic status, or at a larger level in terms of public health, screening the larger population to figure out who is at risk for any particular disease or disorder."

From the standpoint of imaging technologies like MRI that show details about brain structures, experts debate whether the population should be screened "before something occurs," said Liebeskind.

"Imaging has the capacity to tell us a tremendous amount; whether this implies we should therefore image everybody is a larger public health question."

The issue is "fraught with a lot of difficulty and complexity" as treatment paradigms tend to be "built around symptomatic status," he said.

"When we sit in the office or with a patient at the bedside, we usually focus on that individual patient and not necessarily on the larger public."

Liebeskind noted that the question of whether to put the emphasis on the individual patient or the public at large is also being discussed during the current COVID-19 pandemic.

He wasn't surprised that the study uncovered incidental findings in almost 5% of the sample. "If you take an 80-year-old and study their brain, a good chunk, if not half or more, will have some abnormality," he said.

Keuss and Liebeskind have reported no relevant financial relationships.

American Academy of Neurology (AAN) 2020 Science Highlights. Abstract S57.002.

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