Optical Coherence Tomography May Help Detect MS Disease Processes

Jacquelyn K Beals, PhD

June 12, 2007

June 12, 2007 (Washington, DC) — Use of optical coherence tomography (OCT) to quantify retinal nerve fiber layer thickness (RNFLT) may offer advantages over MRI in detecting MS disease processes, a new study suggests.

Lead investigator Erica Grazioli, DO, a fellow at the Baird Multiple Sclerosis Center, Jacobs Neurological Institute, Buffalo General Hospital, in New York, and currently in the department of medicine, division of neurology, at Hamot Medical Center, in Erie, Pennsylvania, presented the study here in the Whitaker Research Track presentations at the Consortium of Multiple Sclerosis Centers 21st Annual Meeting.

The study included 30 patients with relapsing/remitting MS. Eighteen of these had quantitative magnetic resonance imaging (MRI) measurements of T1- and T2-lesion volumes (T1- and T2-LV) as well as normalized brain, cortical, white-matter, and gray-matter volumes. Twenty-one patients had a history of optic neuritis (ON): 13 unilateral and 8 bilateral.

Dr. Grazioli reported she was surprised to find a significant association between T2-LV and average RNFLT (P = .002). A weaker association of T1-LV and RNFLT (P = .041) was also observed. RNFLT also showed strong, statistically significant associations with normalized brain volume and normalized white-matter volume; a borderline association was seen with normalized gray-matter volume. The correlation between average RNFLT and expanded disability status scale (EDSS) was negative — that is, decreased RNFLT correlated with increased disability scores.

"OCT is much quicker — it takes 5 minutes, as opposed to an hour to do an MRI. It's cheap compared with MRI, which is certainly costly," Dr. Grazioli told Medscape. "And it's looking as though it's going to be more specific for neural degeneration than MRI is." Dr. Grazioli noted that the MS community in general is exploring neural degeneration more than in the past, and that is where this new technique is heading.

The difference between RNFLT in ON-affected and nonaffected eyes was significant, although decreased RNFLT was also seen in nonaffected eyes. Dr. Grazioli observed that this "probably represents subclinical disease activity, in the same way we can see on an MRI that some patients will develop atrophy over time, independent of their T2-LV. The neurodegeneration we see of the optic nerve without a clinical history of ON probably represents the atrophy and neurodegeneration components of the disease that we're not picking up well now."

Michael Racke, MD, chair of the department of neurology of Ohio State University and moderator of this session, told Medscape that a typical MRI takes about an hour and with gadolinium it is a bit longer. "I think OCT is going to be an interesting surrogate, although I'm not sure it's going to replace MRI. The other big advantage is the cost. OCT is around $100 vs $1000 or so for MRI. That's a significant thing."

He also added that Dr. Grazioli had not gone into as much depth on the RNFLT thinning in patients who have not had optic neuritis. "So, is it going to be a helpful outcome measure? It may be a more valuable outcome measure when we start doing trials specifically to look at neuroprotective agents. I think you're going to have to hook OCT up to 1 of the big clinical trials to really validate it. And once it's validated, then it can be another outcome measure that will be used."

Consortium of Multiple Sclerosis Centers 21st Annual Meeting. John Whitaker Research Track. Presented June 1, 2007.

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