Marieke van Rosmalen

Chapter 6 106 versions. Another limitation might be the registration step in the processing pipeline. Due to an imperfect registration some tracts were not or incompletely found, particularly in nerve root C7 due to strong susceptibility artifacts caused by the lungs. Our healthy control group is small but we think the number of healthy controls is sufficient as standard deviations of the means of the quantitative MRI parameters were small and comparable to the other three study groups, indicating low levels of variation between individuals. Moreover, the diffusion parameters that we observed were similar to those previously reported in literature. 53 We analyzed relatively short segments of the brachial plexus, since analysis of longer tracts resulted in a significant dropout of data due to poor data quality. We therefore decided to only analyze the first centimeter next to the ganglion in order to maximize the number of datasets. Although we could not include the more distal parts of the brachial plexus, the advantage of this approach is a well-powered study that provides information on a large patient population derived with an automated pipeline without subjective bias. In conclusion, our study gives insight into the nerve architecture of the brachial plexus in a relatively large cohort of patients with CIDP, MMN, MND and healthy controls. Our study shows that diffusion parameters differ between CIDP and MMN, which may reflect differences in the underlying pathophysiological mechanisms. Future studies should combine assessments of the brachial plexus and distal nerves and assess correlations between quantitative MRI parameters in roots, fascicles and peripheral nerves and specific clinical deficits. They should also address whether changes occur in disease course or after treatment.