Diffusion tensor magnetic resonance imaging (DTI) indices are abnormal in p
atients with established multiple sclerosis (MS). The objective of this stu
dy was to examine the diffusion characteristics of MS lesions, normal appea
ring white matter (NAWM) and normal appearing grey matter (NAGM) in MS pati
ents with early relapsing-remitting disease. A further objective was to inv
estigate the relationship between three DTI parameters (fractional anisotro
py (FA), mean diffusivity (MD) and volume ratio (VR)) and clinical outcome
measures (Kurtzke expanded disability status scale (EDSS) and MS Functional
Composite Measure) in early disease. DTI was performed in 28 patients and
27 controls. Analysis was carried out using a region of interest (ROI) appr
oach. ROIs were placed in 12 NAWM and nine NAGM regions. Significant differ
ences were found in FA, MD and VR between lesions and NAWM (P < 0.001 for a
ll three DTI parameters). No significant differences were found between pat
ients and controls when examining NAWM or NAGM, although there was a trend
for abnormal NAWM FA and VR in some regions, No correlation was found betwe
en DTI parameters in lesions, NAWM or NAGM and the clinical outcome measure
s. The lack of significant DTI abnormality in the NAWM and NAGM may reflect
a lack of pathological change or a limited sensitivity of DTI using ROI me
thodology. Previous studies have shown abnormalities in TI relaxation time,
magnetisation transfer ratio (MTR) and N-Acetyl aspartate (NAA) in this co
hort of patients, and as such, DTI using a region of interest (ROI) approac
h may not be as sensitive as other MR techniques in detecting subtle change
s in normal appearing brain tissue in early disease.