Research Article

Modic Changes and Disc Degeneration Caused by Inoculation of Propionibacterium acnes inside Intervertebral Discs of Rabbits: A Pilot Study

Figure 2

Signal changes were observed after the inoculation of the isolated wild-type strain of P. acnes and S. aureus. (a)~(b) Before the surgery, there was not any abnormality at T1WI and T2WI. (c)~(d) Since the second week, an obvious hypointense signal was observed on T1WI (c) and the hyperintense signal was found on T2WI (d) at the P. acnes-inoculated segment (L6~L7, indicated by a white arrow). Meantime, hyperintense signals of nucleus pulposus in T2WI disappeared, suggesting disc degeneration. (e)~(f) The signal changes remained constant until the eighth week at the end of follow-up. The volume of signal changes had increased from the second week to the eighth week. (g)~(h) The hyperintense signal changes were also observed in the S. aureus-inoculated segment (L6~L7, indicated by a white filled arrow) on T1WI (g) and T2WI (h); however, the definition of the endplates and vertebral body was less intact and more severe inflammatory signal changes were found. No significant signal changes were observed at the internal control segment of L5~L6 in all groups (indicated by a white triangle).