SHORT REPORT

MRI lesion volume heterogeneity in primary progressive MS in relation with axonal damage and brain atrophy

D Pelletier¹, S J Nelson², J Oh², J P Antel³, M Kita¹, S S Zamvil¹ and D E Goodkin¹

¹ Department of Neurology, University of California at San Francisco, CA, USA
² Department of Radiology, University of California at San Francisco
³ Department of Neurology, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada

Correspondence to:
Correspondence to:
Dr D Pelletier, University of California at San Francisco, Multiple Sclerosis Center, 350 Parnassus Avenue, Suite 908, San Francisco, CA 94117, USA;
danp{at}itsa.ucsf.edu

Objectives: To investigate whether axonal damage in primary progressive (PP) multiple sclerosis (MS), as measured by proton magnetic resonance spectroscopy (HMRS) imaging and brain atrophy, is a function of T2 weighted brain lesion volume.

Methods: 34 PP MS patients were divided into two categories: low (<3 cm³, n = 18) or high (≥3 cm³, n = 16) T2 lesion load (LL). An Index of Brain Atrophy (IBA) was calculated and HMRS metabolite ratios were derived from a central brain area centred at the corpus callosum.

Results: Patient groups did not differ with regard to clinical characteristics and showed lower mean IBA and mean N-acetylaspartate:creatinine (NAA:Cr) ratios compared to healthy controls.

Conclusion: PP patients with low and high brain T2LL have detectable brain atrophy and NAA:Cr reduction compared to healthy controls. In PP MS, T2 lesions alone are insufficient to explain the presence of brain atrophy and decrease in NAA:Cr.

Keywords: N-acetylaspartate; proton nuclear magnetic resonance spectroscopy; brain atrophy; primary progressive multiple sclerosis

Abbreviations: CB, central brain; COV, coefficient of variation; Cr, creatinine; CSG, cerebrospinal fluid; EDSS, Expanded Disability Status Score; HMRS, proton magnetic resonance spectroscopy; IBA, Index of Brain Atrophy; LL, lesion load; MRI, magnetic resonance imaging; MS, multiple sclerosis; NAA, N-acetylaspartate; NAWM, normal appearing white matter; PD, proton density; PP, primary progressive; ROI, region of interest; RR, relapse remitting; SP, secondary progressive

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