DISC PENETRATION SIGN: A DISTINCTIVE MRI SIGN INDICATING THE SEVERITY OF PYOGENIC SPONDYLITIS

Aim This study seeks to outline the clinical, laboratory, and imaging features of patients with pyogenic spondylitis. It aims to define a novel imaging sign that could indicate the severity of suppurative spondylitis, aiding in its early diagnosis and treatment. Method This retrospective study included 137 patients from 2013 to 2023. Through the analysis and summary of imaging characteristics among all patients, we identified a distinct MRI sign known as ‘the Disc Penetration sign’ (DP). This sign is defined as an image finding on sagittal MRI depicting the anterior and posterior penetration of an abscess through the intervertebral disc space, affecting both the anterior margin of the vertebrae and the structures within the spinal canal. Observational parameters included WBC, ESR, CRP, hemoglobin, and albumin levels. Documentation of the study included location and segment of the lesion, presence or absence of spinal cord compression, and paravertebral abscesses. Results 56 patients presented with the Disc Penetration sign(DP) and 81 did not. In both groups, there were no significant differences in gender ratio or age (P > 0.05). However, significant differences were observed in the presence of comorbid diabetes and chronic kidney disease (p < 0.05). The DP group had a significantly greater ESR level (74.30±33.79 mm/h vs. 51.46±30.46 mm/h, P < 0.001) and CRP level (47.28 mg/L vs. 26.18 mg/L, P = 0.003). Additionally, the DP group had a significantly lower Hb (100.66±19.82 g/L vs. 116.99±19.99g/L,P < 0.001) and the serum albumin level (28.81±6.59 g/L vs. 34.09±6.17 g/L,P < 0.001). Imaging results showed no significant differences in affected spinal segments or parts (p>0.05). Patients in the DP group showed a higher likelihood of developing paravertebral abscesses compared to those in the non-DP group (n = 54 [96.4%] vs. n = 33 [40.7%], P < 0.001), and also exhibited a higher incidence of spinal cord compression(n = 32 [57.1%] vs. n = 17 [21.0%], P < 0.001). Conclusions The study suggests that the Disc Penetration sign in pyogenic spondylitis patients correlates with more severe inflammation and higher incidence of paraspinal abscess, pointing to worse stability of the spine, longer bone restructuring time, and potentially poorer prognosis. These findings enable clinicians to rapidly assess the severity of the disease and prognosticate outcomes more effectively We emphasize the need for early, pathogen-specific diagnosis and treatment, particularly considering surgical intervention for patients demonstrating substantial paraspinal abscesses or spinal instability.