Catching the circadian rhythm of intervertebral disc and association with clinical outcomes by twice-a-day magnetic resonance imaging

We conducted a prospective magnetic resonance imaging(MRI) surveillance program of the whole spine twice a day to aim at investigating the diurnal prevalence of MRI parameters of intervertebral discs and their associations with relevant symptoms.Sixty-four young volunteers underwent MRI of the whole spine twice on the same day (in the morning and evening). Sagittal T2-weighted MRIs of the whole spine were compared and analyzed. Two independent observers assessed the images for the disc height, anterior-posterior distance, and T2 values. Subject demographics and clinical findings were assessed by standardized questionnaires.There was a statistically significant diurnal disc height change in all the disc level groups. Except four lumbar levels, there was no statistically significant diurnal disc AP distance change seen in other levels. There were statistically significant diurnal T2 value changes in all intervertebral discs except T3/4 levels. The multivariate linear regression analysis showed a positive linear trend association between BMI and the diurnal variations of T1/2 T2 value, T12/L1, L1/2, L2/3, L3/4,L4/5 and L5/S1 disc heights (p < 0.05) . Smoking and passive smoking affected cervical levels of T2 value changes. Interestingly, a reverse trend was observed in all disc changes in the case of more than ten years shift work history.Smoking and passive smoking are associated with cervical disc T2 value diurnal changes and BMI is associated with lumbar disc height changes. Long time disruption of circadian clock may cause reverse changes of discs, however not in short or medium-time shift workers.