Introduction
Low back pain (LBP) is the largest cause of disease burden from disability worldwide. Intervertebral disk (IVD) degeneration characterised by disk bulging, annular tears and loss of hydration represent a putative cause of LBP. A novel post-processing technique for a T2* gradient echo mapping sequence MRI image known as Decay Variance (DeVa) was developed to measure level of degeneration. This study aimed to assess whether the DeVa technique can distinguish between patients suffering from chronic LBP with less advanced IVD degeneraetion and asymptomatic controls.
Methods
A single centre cross-sectional case-control study was conducted between a cohort of adult patients (>18yrs) who presented to a tertiary spine clinic with chronic LBP and asymptomatic controls. Patients were included if they were not recommended for spine surgery by treating clinician and excluded if they had a history of spine surgery, radiculopathy, severe neural stenosis, degenerative listhesis, degenerative scoliosis, severe disk collapse, or severe fact arthropathy.
Results
A total of 62 patients with chronic LBP and 7 controls were recruited. There was no statistically significant difference in age (47.22 16.17 vs. 44.8614.64, p=0.713), sex (M/F: 29/33 vs. 2/5, p=0.713) and pfirmann grade (U=300, p=0.081) between the groups. The mean DeVa score for the worst disk in patients with LBP was 0.88 times above asymptomatic controls (Cohen’s d=0.878, 95%CI [0.537, 1.22], p=0.035). The mean DeVa score for the sum of all disks in patients with LBP was 0.84 times above asymptomatic controls (Cohen’s d=0.837, 95%CI [0.452, 1.19], p=0.037). A positive relationship was also observed between Pfirmann grade and DeVa score (=0.615, p<0.001).
Discussion
DeVa works as a technique to separate patients with chronic LBP without severe degenerative changes to asymptomatic controls. It is effective both as a measure of global degeneration (sum of all disk score) and to find the culprit disk (worst disk score). Ultimately it allows clinicians to diagnose the problematic disk without invasive methods like discography and opens the field of spine management to regenerative biologics targeting the IVD.