Application of molybdenum target X-ray photography in imaging analysis of caudal intervertebral disc degeneration in rats

Abstract

BACKGROUND Conventional plain X-ray images of rats, the most common animals used as degeneration models, exhibit unclear vertebral structure and blurry intervertebral disc spaces due to their small size, slender vertebral bodies. AIM To apply molybdenum target X-ray photography in the evaluation of caudal intervertebral disc (IVD) degeneration in rat models. METHODS Two types of rat caudal IVD degeneration models (needle-punctured model and endplate-destructed model) were established, and their effectiveness was verified using nuclear magnetic resonance imaging. Molybdenum target inspection and routine plain X-ray were then performed on these models. Additionally, four observers were assigned to measure the intervertebral height of degenerated segments on molybdenum target plain X-ray images and routine plain X-ray images, respectively. The degeneration was evaluated and statistical analysis was subsequently conducted. RESULTS Nine rats in the needle-punctured model and 10 rats in the endplate-destructed model were effective. Compared with routine plain X-ray images, molybdenum target plain X-ray images showed higher clarity, stronger contrast, as well as clearer and more accurate structural development. The McNemar test confirmed that the difference was statistically significant ( P = 0.031). In the two models, the reliability of the intervertebral height measured by the four observers on routine plain X-ray images was poor (ICC < 0.4), while the data obtained from the molybdenum target plain X-ray images were more reliable. CONCLUSION Molybdenum target inspection can obtain clearer images and display fine calcification in the imaging evaluation of caudal IVD degeneration in rats, thus ensuring a more accurate evaluation of degeneration.

A novel rat model of vertebral inflammation–induced intervertebral disc degeneration mediated by activating cGAS/STING molecular pathway

“… 8 , 15 However, irreversible damage to IVD structure is main limitation of these models. In fact, according to previous and our observations, 8 , 22 once the IVD structure is damaged, degeneration rapidly and irreversibly progresses. Animal models in which IVD structure is compromised cannot simulate natural IVDD human condition, such as age‐related IVDD.…”

“… 13 , 19 , 20 These models are easily handled and can also be employed to evaluate surgical procedures. 8 , 15 , 22 , 23 Although the stress model recapitulates many features of IVDD, it requires long modelling time and high costs, as well as shows low success rate. On the contrary, the damage model can be realized with a high success rate and at low cost, and more importantly is easily operable, so that it is one of the most favourite animal model in many studies on IVDD.…”

“… 8 According to our previous studies, the molybdenum‐target plain X‐ray is more powerful than common plain X‐ray, in terms of image contrast and resolution of microstructures, such as caudal intervertebral space in rats. 22 Molybdenum‐target plain X‐ray also permitted a better localization of the drilled hole and the trigger point of inflammation in the vertebral body, thus providing a support guaranteeing accuracy of analysis of modelling operation. The VI‐IVDD model (Mid and NIVD groups) showed signs of degeneration of IVD adjacent to the vertebral body (decreased DHI and weakened MRI T2 signal).…”

“…According to our previous research, molybdenum‐target plain X‐ray image is superior to plain X‐ray in assessing intervertebral space in rats. 22 Hence, molybdenum‐target plain X‐ray system (Mammomat Inspiration, Siemens) was adopted to obtain images of vertebral bodies and intervertebral space. Disc height index (DHI) was measured to evaluate the change in intervertebral space height and calculated as follows: DHI = 2 × (D1 + D2 + D3)/[(PV1 + PV2 + PV3) + (DV1 + DV2 + DV3)] (Figure S1 ).…”

“…Disc height index (DHI) was measured to evaluate the change in intervertebral space height and calculated as follows: DHI = 2 × (D1 + D2 + D3)/[(PV1 + PV2 + PV3) + (DV1 + DV2 + DV3)] (Figure S1 ). 8 , 22 , 27 Magnetic resonance imaging (MRI) (uMR770; Shanghai United Imaging Intelligence Healthcare Co., Ltd.) was performed on the tail of rats, and Adobe Photoshop software (CC 2018, Adobe Systems Incorporated) was used to measure the total greyscale value of IVD adjacent to the operating vertebral body (a smaller value indicated severer degeneration), 28 and thus to quantitatively analyse the severity of IVDD.…”