Table 3. Associated variables with High Intensity Zones at affected lumbar levels.
| Variables | HIZ | No HIZ | p- value | Posterior HIZ | Anterior HIZ | p- value | T1W low-intensity type of HIZ | T1W high-intensity type of HIZ | T1W iso-intensity type of HIZ | p- value |
|---|---|---|---|---|---|---|---|---|---|---|
| Total discs; 4070 | 438 | 3632 | 223 | 215 | 22 | 80 | 339 | |||
| HIZ affected disc level | ||||||||||
| Disc bulges/protrusions, n (%) | 166 (37.9) | 1065 (29.3) | <0.01 | 96 (43.0) | 70 (32.6) | <0.001 | 9 (41.0) | 36 (45.0) | 123 (36.3) | <0.01 |
| Extrusions, n (%) | 5 (1.1) | 48 (1.3) | 0.97 | 4 (1.8) | 1(0.5) | 0.33 | 0 (0) | 2 (2.6) | 3 (0.9) | 0.52 |
| Disc degeneration (mean ±SD) | 3.8± 0.7 | 3.7±0.7 | <0.001 | 3.8±0.7 | 3.6 ± 0.7 | <0.001 | 3.7±0.8 | 3.9±0.7 | 3.8±0.6 | <0.01 |
| HIZ affected vertebral body adjacent to the end plate (total endplates;4070) | ||||||||||
| Modic type I, n (%) | 24 (5.5) | 176 (4.9) | 0.29 | 13 (5.8) | 11 (5.1) | 0.32 | 0 (0) | 7 (8.8) | 17 (5.0) | 0.18 |
| Modic type II, n (%) | 122 (27.9) | 779 (21.4) | <0.01 | 75 (33.6) | 47 (21.9) | <0.001 | 7 (31.8) | 22 (27.5) | 94 (27.7) | <0.05 |
| Modic type III, n (%) | 14 (3.2) | 88 (2.4) | 0.18 | 13 (5.8) | 1 (0.5) | <0.0001 | 0 (0) | 3 (3.8) | 11 (3.2) | 0.4 |
| Schmorl's node, n (%) | 101 (23.1) | 707 (19.5) | 0.075 | 50 (22.4) | 51 (23.7) | 0.19 | 3 (13.6) | 21 (26.3) | 74 (21.8) | 0.75 |
Pearson χ² test and ANOVA (analysis of variance) with within group Tukey post-hoc tests were used to assess the association between HIZ and no HIZ, between posterior HIZ and anterior HIZ, and among T1W low-, high-, and iso- intensity type of HIZ where applicable. Non-paired student t-test was performed to compare continuous Pfirrmann grade at HIZ affected disc level. High-intensity zones (HIZ), T1W: T1-weighted, SD: standard deviation, %: percentage, n: number of subjects.