Table 2.
Axon diameter index values reported in the literature from in vivo human diffusion MRI studies
| Condition | Demographics | Regions of Interest | Effect Size (Δμ/ μ) | References |
|---|---|---|---|---|
| MS | 6 patients (30.7 ± 9.0 y, 2 F) | Corpus Callosum (lesion vs. NAWM) | Genu: 30.4% Body: 13.0% Splenium: 29.3% |
(Huang et al., 2016) |
| MS | 9 patients (27–59 y, 6 F) 6 HC (22–53 y, 4 F) |
Whole brain tissue (MS vs. HC) | 12.81 % | (De Santis et al., 2019) |
| MS | 23 HC (40.2 ± 11.9 y, 14 F) 7 Progressive MS (48.1 ± 12.8 y, 5 F) 30 MS in total (43.9 ± 11.2 y, 24 F) |
Corpus Callosum | Lesion vs. NAWM: 20.7% NAWM in progress MS vs. HC: 11.7% NAWM in total MS vs. HC: 5.6% |
(Huang et al., 2019) |
| Healthy | 9 HC (29 ± 5 y) | Corpus Callosum | 0.5–1.1 μm spanning from anterior to posterior tips of mid-sagittal corpus callosum (range/ μ≈ 71.2%) | (De Santis et al., 2016) |
| Healthy | 9 HC (23–66 y, 9 M) | Corpus Callosum | 3.1–4.6 μm between five segments of the corpus callosum projecting to various cortical regions (range/ μ≈ 38.9%) | (Yu et al., 2017) |
| Healthy | 36 HC (22–72 y, 23 F) | Corpus Callosum | ~4.5–4.9 μm spanning from 20–72 years old (range/ μ≈ 8.9%) | (Fan et al., 2019) |
| Healthy | 4 HC (22–45 y, 1 F) | Corpus Callosum Cerebral WM |
5.7–6.5 μm spanning from anterior to posterior tips of mid-sagittal corpus callosum (range/ μ≈ 12.5%) 5.7–6.2 μm between 6 major cerebral white matter tracts (range/ μ≈ 8.2%) |
(Veraart et al., 2020) |
| Healthy | 6 HC (29 ± 12 y, 6 F) | Cerebral WM | CST vs. Forceps Major: ~20% Forceps Major vs. Forceps Minor: ~12% |
(Fan et al., 2020) |
Abbreviations: MS: Multiple Sclerosis, HC: Healthy Control, y: years old, F: Female, M: Male, NAWM: Normal Appearing White Matter, CST: Corticospinal Tract