14800-DvRappard

132 Chapter 8 In the pyramidal tracts, there were no group differences in AD. Following the TBSS findings, in NAWM and corpus callosum, AD was lower in both patient groups than in controls, whereas in the thalamus AD was higher in patients. Again, these differences were most pronounced between HCT-non-eligible patients and controls. AD within abnormal WM was higher than in NAWM, and lower in non-eligible patients than in eligible patients (not shown). Spearman rank correlations with MLD-GMF were significant for FA (-0.84), MD (0.78) and RD (0.86), all p<0.01. Thus, low FA and high MD and RD of the pyramidal tracts at baseline indicate poor motor function at follow up. Longitudinal evolvement of diffusion measures Figure 3 shows longitudinal diffusion measures in selected ROIs. For each patient with follow-up measurements, symbols are connected by lines. The longitudinal variation indicates the actual course, but also the reproducibility of the measurement, including the effect of examinations at both field strengths for some patients. The effect of field strength can also be appreciated when comparing control subjects at 3T and 1.5T. Overall, measures remained relatively stable, especially for HCT-eligible patients after treatment. In non-eligible patients, values showed a progressively abnormal trend. In NAWM, FA mildly fluctuated for treated eligible patients, while FA further decreased for HCT-non-eligible patients (Fig. 3A). Diffusivities remained relatively stable for all patients. In the corpus callosum, FA tended to decrease in the treated eligible patients, while the reduction in the non-eligible patients was marginal (Fig. 3B). However, MD, AD and RD longitudinally increased especially in non-eligible patients, which meant that AD, which was decreased at baseline, showed a pseudo-normalization (Fig. 3C). In the pyramidal tracts, FA remained constant or slightly increased over time in most treated eligible patients, whereas FA slightly decreased in HCT-non-eligible patients (Fig. 3D). Diffusivities showed some longitudinal variability, but no clear trend was observed. In the thalamus, in which FA did not differ between groups at baseline, FA remained stable in treated eligible patients, and showed a slight decrease in non-eligible patients (Fig. 3E). Diffusivities in treated eligible patients remained stable or showed a mild increase, whereas a larger increase was observed in non-eligible patients (as shown for AD in Fig. 3F).