Marieke van Rosmalen

Chapter 3 50 agreement. Fourth, differences between scanners may partially explain the poor level of agreement. However, despite small groups, our results showed similar agreement with overlapping confidence intervals for assessment of images performed on 1.5T and 3.0T scanners. Earlier studies in chronic inflammatory neuropathies and plexus MRI focused on characteristics, distribution and prevalence of abnormalities. 3–5 This study addresses the reproducibility of assessment of such abnormalities. Quantification of these abnormalities represents an obvious approach to improve reproducibility and reliability of assessment. Quantification of nerve size allows the identification of patients with CIDP or MMN with high sensitivity and reasonable specificity as shown in ultrasound studies. 10 Few studies that have explored the use of quantitative MRI in chronic inflammatory neuropathies. One study reported cutoff values of 5.0 mm for roots C6, C7 and C8 to distinguish patients with CIDP (n = 14) from controls (n = 10). 11 Sensitivity and specificity were not reported, probably due to the small sample size. Another recent study used the diameter of the ganglia and nerve roots of C5 to T1 and found these to be significantly larger in patients with CIDP (n = 14) than in controls (n = 9), providing evidence to support the feasibility of this approach. However, sensitivity of ganglia measurements was only 48%, despite a specificity of 92%. 12 Sensitivity of root measurements was slightly better at 62%, with 82% specificity. Interrater agreement was good for both ganglia and root measurements. One study did not find any differences in cervical nerve root diameter between patients with CIDP (n = 15) and controls (n = 29). 13 Three-dimensional volume measurements may be another approach. A recent study showed increased volume of peripheral nerves in patients with CIDP (n = 13) compared to controls (n = 12) using MRI with diffusion- weighted whole-body imaging with background body signal suppression. 14 Combined, these studies suggest the potential of a quantitative approach to improve diagnostic reliability. The potential of imaging techniques for diagnosis of CIDP and MMN has been demonstrated by several recent studies. 15–18 In one of these studies MRI was abnormal in 22 of 38 (58%) patients with CIDP without definite electrodiagnostic criteria, which led to an adjustment of final diagnosis to definite CIDP in 7 patients. 15 Additional studies are required to determine reproducible and reliable quantification techniques with optimal sensitivity and specificity in order to ensure proper diagnosis of treatment-responsive polyneuropathies.