New MRI Methods May Improve MS Evaluation - facebook prikbord

New MRI Methods May Improve MS EvaluationSpinal cord lesions imaged with quantitative MRI-based technologies correlated significantly better with clinical disability of multiple sclerosis (MS) patients than did simple lesion counts based on conventional MRI, researchers said.

Irrespective of whether patients had high or low lesion counts on conventional MRI scans, those with greater levels of abnormality in quantitative MRI measures such as diffusivity and anisotropy were significantly more likely to show high levels of clinical disability (P<0.05), according to Jiwon Oh, MD, of Johns Hopkins University, and colleagues. The strong correlation stood in contrast to the near-total lack of association between simple lesion counts and clinical disability historically seen in MS patients, the researchers contended in their report in the Feb. 5 issue of Neurology. "These findings support the concept that microstructural changes undetectable by conventional lesion count contribute substantially to clinical disability in MS, and suggest that quantitative MRI measures have the ability to provide clinically relevant information beyond that which may be gleaned from measures of MRI lesion load alone," Oh and colleagues wrote. Currently, MRI studies in MS patients focus on the number of lesions and their volume, which can be discerned from standard scans. But ever since the introduction of these scans as a tool for evaluating MS disease activity, clinicians have noted "the clinicoradiological paradox," as Oh and colleagues put it, in which patients with high lesion counts may not show marked clinical symptoms. Moreover, substantial clinical disability may occur in patients with relatively few lesions. Noting that newer MRI technology -- including diffusion tensor and magnetization transfer imaging -- allows more detailed, quantitative measurement of lesions, Oh and colleagues sought to evaluate whether additional parameters would correlate more closely with disability. They studied 124 MS patients, about two-thirds of whom were female, with a mean disease duration of 11 years (SD 9). Their median score on the Expanded Disability Status Scale (EDSS) was 3.5, but the range was substantial enough for the researchers to divide them into "low" and "high" disability groups (median EDSS score 2.5 and 6.5, respectively). Patients were also stratified into high and low lesion counts (mean 3.6 and 1.2, respectively), such that there were a total of four groups: low lesion with low disability, low lesion with high disability, and so on. MRI scans of the cervical spine were taken and processed with diffusion tensor and magnetization transfer analyses. In addition to conventional counts of lesions, these analyses provided measures of five other parameters: Fractional anisotropy Mean diffusivity Perpendicular diffusivity Parallel diffusivity Magnetization transfer ratio Mean lesion counts were not significantly associated with EDSS scores in the sample. But most of the five additional MRI parameters measured were significantly different in the high- versus low-disability groups, irrespective of whether lesion counts were high or low. In the low-lesion patients, the three diffusivity parameters were significantly higher (P<0.03) with high versus low disability. The magnetization ratio was significantly lower with high disability (P=0.003), as was fractional anisotropy (P=0.03). The same pattern was seen in the patients with high lesion counts, except that the differences between high- and low-disability patients did not reach statistical significance. Oh and colleagues noted that the EDSS scale is itself an imperfect measure of disability, insofar as it emphasizes walking ability over other functional outcomes such as manual dexterity or bladder continence. Other limitations to the study included the researchers' choice of cutoffs for high versus low disability and lesion counts, certain difficulties they faced in obtaining the spinal cord MRI scans, and their decision not to include lesion volume in their analyses.

The study was funded by the Multiple Sclerosis Society of Canada, the National Multiple Sclerosis Society, and the National Institute of Neurological Disorders and Stroke.

Study authors reported relationships with Teva, MedicalLogix, Diagnosoft, Philips Healthcare, Novartis, Biogen Idec, Versex, Vaccinex, EMD Serono, Bayer, and Abbott.

Primary source: Neurology

Source reference: Oh J, et al "Spinal cord quantitative MRI discriminates between disability levels in multiple sclerosis" Neurology 2013; 80: 540-547.