The good news is that MRI has shown itself to be an effective way to track COVID-19's lasting neurological effects, according to presenter Dr. Simonetta Gerevini of Azienda Ospedaliera Papa Giovanni XXIII hospital in Bergamo, Italy.

"Neuroimaging can illuminate a spectrum of central nervous system abnormalities, from ischemic lesions and microhemorrhages to meningoencephalitis and white matter lesions," she noted.

Long-term neurological and neuropsychological sequelae are reported in up to 30% to 40% of COVID-19 survivors. Symptoms can include fatigue, myalgia, headache, dysautonomia, and cognitive impairment, according to Gerevini.

"There's growing evidence of neurological manifestations in patients with COVID-19," she told ISMRM session attendees. "Correct estimation of incidence and prevalence is difficult because ... of a lack of data, [but we see these more frequently] in patients with comorbidities ... and those with multiple organ dysfunction."

In her talk, Gerevini reviewed the hypothesis of how the SARS-CoV-2 virus invades the nervous system through the blood-brain barrier or via peripheral nerves. She listed the most commonly reported MRI findings in patients with severe COVID-19 who are on ventilation and in the intensive care unit:

• Leukoencephalopathy, microhemorrhages, and acute/subacute infarcts
• White-matter injury and large, parenchymal hemorrhages
• Acute infarctions and leptomeningeal enhancement
• Posterior reversible encephalopathy syndrome (PRES) and hemorrhagic infarction
• Acute disseminated encephalomyelitis (ADEM)-like white matter lesions and microhemorrhages

Gerevini cited studies that showed an 0.8% to 6% chance of stroke in hospitalized patients with COVID-19, a risk that increases with the severity of the infection. She also cited a study that found concerning rates of various types of thromboembolism in COVID-19 patients, including large infarctions (44.5%), lacunar infarctions (24%), and hemorrhagic stroke (24%).

"Neurological outcomes are variable depending on comorbidities, but stroke and hemorrhage are reported widely and not uncommonly in younger patients, and [subacute and chronic] patients, particularly those on ventilators in the intensive care unit, [can develop] leukoencephalopathy and microhemorrhages," she said.

Yet despite these concerning neurological long-term effects of COVID-19, brain MRI -- particularly advanced techniques such as diffusion-weighted, diffusion-tensor, and functional MRI -- has been shown to be an effective way to track these effects, according to Gerevini.

"Brain MRI is very useful to image the complications of SARS-CoV-2 infection in the brain in acute, subacute, and chronic phases," she concluded.