Marieke van Rosmalen

Chapter 6 94 METHODS Study design We performed a cross-sectional study in patients with CIDP, MMN, MND and healthy controls. We performed quantitative MRI in all patients and used an automated processing pipeline to obtain parameters on microstructural integrity. We compared these parameters between groups and explored correlations with clinical data. Participants and clinical data Consecutive patients with CIDP, MMN and MND were included at the outpatient clinic of the University Medical Center Utrecht (UMCU). Alle prevalent and incident patients with an established diagnosis of CIDP or MMN (definite, probable, possible), according to the predefined consensus criteria of the European Federation of Neurological Societies/Peripheral Nerve Society, were eligible for inclusion. 2,24,25 Patients with MND (i.e. amyotrophic lateral sclerosis (ALS) or progressive muscular atrophy (PMA)), according to the Brooks criteria, were enrolled as disease controls. 26 Healthy controls were included if they had no history of neuromuscular disorders, neuropathy, nerve root injuries or other cervical spine disorders. We excluded patients aged < 18 years, patients with atypical forms of CIDP (e.g. Lewis Sumner Syndrome) and patients with MND that had a bulbar onset of symptoms to minimalize heterogeneity in these groups, and participants who met one of the routine contraindications for MRI. We documented demographic and clinical data from all patients, including muscle strength expressed as a Medical Research Council (MRC) sum score. We tested the following 12 muscle groups on both sides: finger flexion, finger extension, finger abduction, wrist flexion, wrist extension, elbow flexion, elbow extension, shoulder abduction, hip flexion, knee flexion, knee extension and foot dorsiflexion. We calculated MRC sum scores of these 24 measurements, ranging from 0 to 120 (normal). The medical ethical committee of the UMCU approved this study (18-349/NL 62866.041.17). This study conforms with the World Medical Association Declaration of Helsinki. Written informed consent was obtained from all study participants. Equipment and MRI protocol All participants underwent an MRI scan of the brachial plexus bilaterally in supine position on a 3.0 Tesla MRI scanner (Philips Healthcare, Best, the Netherlands) using a 24-channel head-neck coil. We performed DTI in a transversal slice orientation to obtain diffusion parameters, T2 mapping in a coronal slice orientation to obtain T2 relaxation times and T1 Dixon in a transverse slice orientation to obtain fat fraction. As an anatomical reference we used a 3D turbo spin-echo (TSE) spectral presaturation with inversion recovery (SPIR) sequence in a coronal slice orientation. The acquisition parameters are shown in Table 6.1 . We performed a data quality check after enrollment of 43 participants that showed a higher-than-expected frequency (> 5%) of insufficient data due to low