A comparative study of MR diffusion tensor imaging histogram between clinically isolated syndrome and relapsing-remitting multiple sclerosis in normal appearing white matter and grey matter

Abstract

Objective To investigate whether abnormalities can be detected in normal-appearing white matter(NAWM)and normal-appearing white matter(NAGM)in patients with clinically isolated syndrome(CIS)and comparing them to the abnormalities in relapsing-remitting multiple sclerosis(RRMS)by using diffusion tensor imaging(DTI)histogram.To detect the potential relationship between DTI indices of NAWM,NAGM and patient's clinical condition.Methods Nineteen patients with CIS,19 clinically diagnosed RRMS patients and 19 sex-and age-matched healthy volunteers were included in this study.Conventional MRI and DTI images were obtained using Siemens 1.5 T Magnetom sonata scanner.DTI histograms of NAWM and NAGM were obtained after post-processing.The mean value,peak height,peak location of the histogram were used for analysis.All data was statistically processed with SPSS for Windows.Results NAWM average MD was higher and FA was lower in RRMS[MD(0.83±0.04)×10-3mm2/s,FA 0.36±0.03]when compared to CIS[MD(0.79±0.02)×10-3mm2/s,FA 0.40±0.02]and control[MD(0.78±0.02)×10-3mm2/s,FA 0.41±0.01](P＜0.01).But no statistically significant difference was found between CIS and control.The peak height of NAWM average MD histogram was significantly lower in CIS than control(P＜0.05),while the peak location of average FA histogram shifted to the left(P＜0.01).Patients with CIS[(1.08±0.06)×10-3mm2/s]showed significantly higher NAGM average MD than control[(1.03±0.05)×10-3mm2/s](P＜0.05),but,lower than RRMS[(1.18±0.12)×10-3mm2/s](P＞0.01).There were no correlation between DTI indices and EDSS scores in patients with CIS.Moderate correlation between NAGM average MD(r=0.568,P＜0.05)and EDSS scores were found in patient with RRMS.Conclusion NAWM and NAGM abnormalities do occur in CIS which can be detected by DTI.The underlying pathological changes in NAWM and NAGM in CIS may be milder than RRMS as demonstrated by DTI histogram. Key words: Multiple sclerosis; Diffusion magnetic resonance imaging