Abstract
Introduction
The high intensity zone (HIZ) represents a high signal change on lumbar spine T2 MRI images. HIZ has been involved in disc degeneration and its presence was associated with inflammation and vascular granular tissue within the annulus fibrosus. Aim of our study was to investigate the HIZ prevalence, its relationship with disc degeneration and the effect on lumbar segmental motion using kinetic magnetic resonance imaging (kMRI).
Material and Methods
kMRI images of 353 symptomatic patients were analyzed. Data including age, gender, and radiologic assessments based on neutral images including disc degeneration grade of all lumbar spine units from L1/2 to L5/S1 and the presence of HIZ were recorded for all the patients. Demographics and disc degeneration were used for calculating HIZ prevalence. Dynamic flexion and extension images from 168 patients were used for segmental motion comparison between the discs with HIZ and without HIZ. Patients with isthmic or degenerative spondylolisthesis grade 2 or higher, Modic disc or Schmorl's node were excluded due to the potential effect on lumbar kinematics. We used chi-square test and multivariate logistic regression for our statistical analysis.
Results
Among 353 patients, 107 had HIZ in at least one lumbar disc. The overall HIZ prevalence was the highest in age group 40–49 years of age, followed by 50–59 years irrespectively of disc level. The HIZ prevalence was the highest in grade IV degenerative discs, followed by grade III degenerative discs. For L4/5 segment, HIZ prevalence was the highest in age group 50–59 years and disc degeneration grade IV. For L5/S1 segment, HIZ prevalence was the highest in age group 40–49 years and disc degeneration grade III. The multivariate logistic regression model indicated that the age groups (30–39 and 40–49 years), levels (L4/5 and L5/S1) and disc degeneration grades (III and V) were risk factors for HIZ. The segmental angular motion was signicantly greater in discs with HIZ than those without HIZ on L4/5 and L5/S1. However, the differences were reduced to insignificant when adjusted for disc degeneration grade.
Conclusion
HIZ prevalence was the highest in the middle age patients (30–39 and 40–49 years) and in the moderately degenerated discs (III and IV). The lower prevalence was observed in the older patients and grade V degenerative discs. The possible reason of increased segmental angular motion at L4/5 and L5/S1 discs with HIZ may be due to the moderate disc degeneration than HIZ itself.