Fiber density index in the evaluation of the spinal cord in patients with multiple sclerosis.

PURPOSE: The aims of this study were to determine fractional anisotropy (FA) and the fibre density index (FDi) in the cervical spinal cord of patients with multiple sclerosis (MS) by using diffusion-tensor magnetic resonance imaging (DT-MRI) to identify possible differences between MS patients and controls. MATERIALS AND METHODS: We studied 27 patients with MS - nine with primary progressive (PPMS), nine with secondary progressive (SPMS) and nine with relapsing-remitting (RRMS) disease - and 18 healthy individuals as controls. Conventional and DTI sequences with diffusion gradients applied in 32 directions were obtained. The results were compared between healthy controls and patients, between healthy controls and individual forms of MS and between the three forms of MS. Statistical analysis was performed by analysis of variance (ANOVA) and Student's t test. RESULTS: The FDi in the three subgroups of patients and in controls showed a statistically significant difference. Using the t test, we found results from both PPMS and SPMS groups were different from controls. The correlation between FA and FDi was significant both in healthy controls and in MS patients evaluated as a single group. CONSLUCIONS: Despite the small group of patients, these findings suggest that FDi associated with FA is a sensitive parameter for assessing spinal cord damage in patients with MS.

Functional MRI during the execution of a motor task in patients with multiple sclerosis and fatigue.

PURPOSE: This study was undertaken to assess cortical activation during execution of a motor task in patients with multiple sclerosis (MS) and fatigue. MATERIALS AND METHODS: We enrolled 24 right-handed patients affected by relapsing-remitting MS and mild disability (12 with and 12 without fatigue) and 15 healthy volunteers. Magnetic resonance imaging (MRI) examination (1.5 T) was performed with conventional sequences and an echoplanar imaging (EPI) sequence for functional MRI (fMRI). The motor task consisted of sequential finger tapping performed with the right hand. Statistical maps of motor activation were obtained. Comparison between the two subgroups of patients and between patients and controls was performed with analysis of variance (ANOVA) statistical analysis (p<0.05). RESULTS: Compared with controls, patients without fatigue showed greater activation of the primary sensorimotor cortex bilaterally, of the right supplementary motor cortex, of the left premotor cortex, of the left cerebellum and of the superior parietal lobule bilaterally. Compared with patients without fatigue, patients with fatigue demonstrated greater activation of the right premotor area, of the putamen and the dorsolateral prefrontal cortex. CONCLUSIONS: Patients with fatigue have greater activation of the motor-attentional network when performing a simple motor task.