Marieke van Rosmalen

Quantitative MRI characteristics of chronic inflammatory neuropathies 99 6 The same applies to patients with ALS and PMA. There were no significant differences in characteristics between patients with ALS and PMA ( p values ranged from 0.075 – 0.999). We therefore present these data as one group of patients (MND) in further analysis. Diffusion parameters The means of all quantitative parameters are summarized in Table 6.3 and visualized in Figure 6.2 . We found a lower mean FA in patients with CIDP (0.27 (standard deviation (SD) 0.05)) compared to healthy controls (0.30 (SD 0.05); p < 0.001), patients with MND (0.28 (SD 0.04); p = 0.010) and MMN (0.30 (SD 0.06); p < 0.001). FA in patients with MMN and healthy controls was higher compared to patients with MND ( p = 0.002 and p = 0.038, respectively). We found a higher mean MD in patients with CIDP (1.40x10 -3 mm 2 /s (SD 0.20)) compared to patients with MND (1.35x10 -3 mm 2 /s (SD 0.20); p = 0.008) and MMN (1.35x10 -3 mm 2 /s (SD 0.23); p = 0.027). Also, the mean RD was higher in patients with CIDP (1.20x10 -3 mm 2 /s (SD 0.19)) compared to healthy controls (1.12 (SD 0.17); p = 0.015), patients with MND (1.14x10 -3 mm 2 /s (SD 0.16); p = 0.001) and MMN (1.13x10 -3 mm 2 /s (SD 0.20); p < 0.001). We did not find any significant differences in AD between groups. T2 relaxation time and fat fraction We found a longer mean T2 relaxation time in patients with CIDP (42.37 ms (SD 5.36)) compared to patients with MND (41.02 ms (SD 4.81); p = 0.023). The fat fraction was lower in patients with CIDP (40.09% (SD 9.61); p < 0.001) and MMN (39.44% (SD 9.07); p < 0.001) compared to patients with MND (43.62% (9.74)). Correlation with clinical data For all four study groups (CIDP, MMN, MND, and healthy controls) we only found weak correlations between the MRI metrics, i.e. diffusion parameters, T2 relaxation time and fat fraction, and the clinical covariates, i.e. age, MRC sum score and disease duration ( Figure 6.3 ). For the correlation with age, r ranged from -0.19 – 0.14 for patients with CIDP, -0.35 – 0.31 for patients with MMN, -0.20 – 0.34 for patients with MND, and -0.18 – 0.24 for healthy controls. For MRC sum score, r ranged from -0.23 – 0.10 for patients with CIDP, -0.08 – 0.24 for patients with MMN, and -0.13 – 0.20 for patients with MND. For disease duration, r ranged from -0.24 – 0.25 for patients with CIDP; -0.21 – 0.23 for patients with MMN, and 0.02 – 0.23 for patients with MND.