Marieke van Rosmalen

General discussion 145 8 parameters should be compared over time. Asubgroup of the animals should be sacrificed at the same time points to correlate histological findings. This method may induce sample bias but it seems to be the best alternative available. An animal model for MMN does not exist but the rabbit model for acute motor axonal neuropathy is elicited by GM1 antibodies. 87 This triggers complement activation and can potentially disrupt the node of Ranvier, paranodal junctions and presynaptic terminals, in a similar way to that induced by antiganglioside IgG antibodies. 87,88 Histological changes can already been seen one week after injection. 89 Quantitative MRI, NCS and histological analysis should be performed at baseline, after 4 days, 1-2 weeks, and after full development of symptoms. Future studies in these for CIDP and MMN representative animal models could give us better insights in the correlation between quantitative MRI and histology and consequently in underlying pathophysiological mechanisms. Implementation of quantitative MRI in clinical practice Besides its pathophysiological utilities, quantitative MRI can differentiate CIDP from MMN. Quantitative MRI shows differences in its parameters between patients with CIDP andMMN although these neuropathies show similar abnormalities on diagnostic NCS, nerve ultrasound and MRI. Quantitative MRI could be explored as a diagnostic instrument to differentiate focal or asymmetric CIDP fromMMN. However, some practical challenges regarding the processing of quantitative MRI data have to be overcome if we want to implement this technique in clinical practice. Processing of quantitative MRI data occurs after acquisition of the data. These processing steps can be performed manually or automated. To minimize subjective bias, the use an automated pipeline that processes all the data the same way is preferable. We described a custom-build automated processing pipeline in chapter 6 that processes one data set in approximately 60 minutes and requires some technical background and training for proper use. Duration of the pipeline and user-friendliness should be improved if we finally want to implement quantitative MRI in clinical practice. A close cooperation between technical scientists and medical professionals is the key to the solution. Prognosis The last part of this thesis explores the role of MRI as a potential tool for prognosis, e.g. tomonitor disease course and treatment effects, in patients with CIDP and MMN. In current clinical practice, challenges in management of chronic inflammatory neuropathies concern dosing (frequencies) of immunoglobulins and monitoring of treatment response. These challenges mainly rely on the fact that objective markers that predict disease course and treatment response are lacking. As advanced MRI techniques, such as DTI, can provide quantitative parameters on nerve architecture, these techniques are of interest to serve as biomarkers. Longitudinal quantitativeMRI studies in patients with CIDPandMMN are currently lacking. We therefore evaluated quantitative MRI of the brachial plexus in patients with CIDP and MMN in an exploratory longitudinal study, which is described in chapter 7 . We used the data collected in chapter 6 as our baseline data and compared these data with data of quantitative MRI (i.e. diffusion parameters, T2 relaxation times and fat fraction) after one-year follow-up. We found that mean diffusivity, AD, RD