Dec. 2, 2003 (Chicago) -- Multiple sclerosis is a chronic, unpredictable, and progressive disease that has traditionally defied early diagnosis. Now, however, early diagnosis of MS -- and early treatment -- is a real possibility, thanks to an imaging technology called magnetic resonance spectroscopy.
The key to this new discovery is the ability to track levels of a key chemical, N-acetylaspartate or NAA, deep in the brain using this imaging technique.
"Patients want to know, 'What is going to happen to me?'" says Oded Gonen, professor of radiology at New York University. Now, he says, that question might finally have an answer. He says using magnetic resonance spectroscopy to determine levels of NAA is potentially the way to measure MS progression and, ultimately, MS prognosis.
He presented results of his study at the 89th Scientific Assembly and Annual Meeting of the Radiological Society of North America.
Multiple Sclerosis Tricky to Diagnose Early
There are no laboratory tests or symptoms that can help determine if a person has the disease early on. Because the disease has such a varying course -- episodic attacks can occur weeks, months, or years apart -- doctors usually wait for the second attack before diagnosing a person with MS and starting treatment.
MS has proven to be a challenge for conventional imaging and even for most new high-speed scanners. Standard magnetic resonance imaging is the preferred method for detecting areas of the brain that contain plaques or scarring, which is evidence of damage caused by the disease. But Gonen says this does not help determine disease severity or even confirm the existence of MS. On the other hand, early studies looking at the amount of NAA in the brain gives a good indication of how many brain cells have been lost, he says.
The reason, he says, is that NAA is only found in brain cells -- so by measuring levels of the chemical in the brain with magnetic resonance spectroscopy, doctors have more information to tell their patients about the course of their disease. As the brain cells die, levels of NAA decrease.
This is a whole new way of looking at MS, says David Yousem, MD, MBA, director of neuroradiology and professor of radiology at Johns Hopkins University in Baltimore.
"Another novel aspect of this work is that it attempts to assess disease before [symptoms] occur and predict how the patient will respond," he says.
But he says the work will not immediately change the way MS is diagnosed. "We will still diagnose this disease on the basis of clinical evidence -- the symptoms experienced by the patient," Yousem says. Nonetheless, he predicted that magnetic resonance spectroscopy could find a niche as a way to become an affirming test for the disease.
And NAA is unlikely to play a therapeutic role in MS because replacing it wouldn't control the disease, says Gonen. It is simply a chemical marker of brain cells, and "brain cells cannot be replaced once they die," he says.
Its true usefulness, Gonen says, will be in determining if new drugs are controlling the disease.
Yousem agrees that it could be a factor in evaluating new therapies.