Article Figures & Data
Figures
- Fig 1.
Echo-planar imaging image (A) and FA mapping (B) ROIs were placed on bilateral roots and FA values were calculated (B).
- Fig 2.
Coronal tractogram of lumbar nerve roots in a healthy volunteer. L3, L4, L5, and S1 indicate the third, fourth, and fifth lumbar root, and the first sacral root.
- Fig 3.
Tractograms of lumbar nerve roots in a 75-year-old man with right L5–S1 foraminal stenosis (referenced as patient 1 in Table 3) by ROI placement on bilateral L5 roots at the stenotic level. ROIs were placed both proximally and distally to the foraminal zone at the nonstenotic level of L3, L4, and S1 roots. On the entrapped side of the right L5 root, by placing the region of interest on the proximal side (A), nerve tracts were seen to be disrupted and no tracts were seen distal to the foramen (arrow). However, by placing the secondary region of interest on the distal side (B), though the nerve tracts were traced on the distal side, a deficit is seen in the foramen (arrow). In contrast, on the intact side of the left L5 root, there was no difference whether the ROI was proximal or distal.
- Fig 4.
Tractograms of 8 patients by placing the ROI on the proximal side of the foramen. In all patients, tracts show disruption of nerve fibers in the foramen (arrows).
- Fig 5.
Tractograms of 8 patients by placing secondary ROI on the distal side of the foramen. Nerve traces show abnormalities (white arrows) such as tract disruption (case 1), nerve narrowing (cases 2–6), and indentation (cases 7 and 8) in their course through the foramen.
- Fig 6.
Sagittal T1-weighted MR images (A; right side, B; left side) and a diffusion tensor image (C) of a 62-year-old man with right L5–S1 foraminal stenosis (referenced as patient 4 in Table 3). Although asymptomatic foraminal stenosis on the left L4 and left L5 foramina (arrowheads in B) were found by MR imaging, abnormalities such as disruption of nerve fibers were only accurately detected at the symptomatic root by DTI (arrow in C).
- Fig 7.
Mean FA values at the proximal nerve root and distal spinal nerve in patients with foraminal stenosis. The mean FA of proximal nerve roots on the side of entrapment was 0.155 ± 0.049 and is significantly lower than the 0.208 ± 0.036 on the intact side. The mean FA of distal spinal nerve roots on the side of entrapment was 0.131 ± 0.016 and significantly lower than the 0.240 ± 0.035 seen on the intact side (P < .001).
- Fig 8.
Bland-Altman plots of comparisons of FA values. Most observed differences are within mean ± 1.96 SD. Horizontal dashed lines indicate mean difference (middle line) and limits of agreement, defined as mean difference plus (top line) and minus (bottom line) 1.96 × SD of differences. A, Relationship between differences in the first analysis and second analysis (y-axis) and means of the first analysis and second analysis (x-axis). B, Relationship between differences in observer 1 and observer 2 (y-axis) and means of observer 1 and observer 2 (x-axis).
Tables
Root FA (Proximal) FA (Distal) Right Left Right Left L3 0.157 ± 0.028 0.161 ± 0.032 0.172 ± 0.022 0.196 ± 0.047 L4 0.183 ± 0.017 0.190 ± 0.027 0.188 ± 0.031 0.185 ± 0.029 L5 0.196 ± 0.020 0.192 ± 0.020 0.220 ± 0.030 0.214 ± 0.037 S1 0.195 ± 0.030 0.192 ± 0.040 0.212 ± 0.032 0.205 ± 0.040 L4 L5 Total MR imaging Asymptomatic foramina (n = 24) 5/16 6/8 11/24 Symptomatic foramina (n = 8) 0/0 8/8 8/8 False-positive rate (%) 45.80 DTI L4 L5 Total Asymptomatic foramina (n = 24) 0/16 0/8 0/24 Symptomatic foramina (n = 8) 0/0 8/8 8/8 False-positive rate (%) 0.00 No. Age (yr) Sex Symptomatic Root Disease Duration (mo) VAS (Leg Pain) DTI Findings FA Proximal Distal Entrapped Intact Entrapped Intact 1 75 M L5 (Right) 15 60 Tract disruption 0.0698 0.162 0.117 0.195 2 64 F L5 (Left) 18 90 Tract disruption 0.086 0.185 0.148 0.278 3 66 M L5 (Right) 8 70 Tract disruption 0.112 0.271 0.130 0.252 4 62 M L5 (Right) 14 90 Tract disruption 0.165 0.238 0.124 0.223 5 47 M L5 (Right) 24 80 Tract disruption 0.135 0.174 0.106 0.238 6 44 M L5 (Left) 7 60 Tract disruption 0.128 0.200 0.138 0.242 7 64 F L5 (Right) 24 100 Tract disruption 0.16 0.271 0.141 0.292 8 68 F L5 (Right) 12 60 Tract disruption 0.166 0.203 0.143 0.214 Mean 61 15.2 76.3 0.128 0.213 0.131 0.242
