205. Can imaging characteristics on MRI predict the acuity of a lumbar disc herniation

BACKGROUND CONTEXT Magnetic resonance imaging (MRI) is routinely obtained for patients with lumbar disc herniations. However, the correlation between radiographic findings and the timing of patient symptoms is still controversial. PURPOSE To determine whether the MRI signal characteristics at the level of disc herniation are predictive of acuity or chronicity of symptoms. STUDY DESIGN/SETTING Retrospective cohort study. PATIENT SAMPLE Ninety-four patients treated at a high-volume academic center for a lumbar disc herniation between January 2015 and August 2018 were retrospectively identified. Patients were divided into two groups based on symptom duration (acute, less than or equal to 6 months, or chronic, greater than 6 months). OUTCOME MEASURES Disc height, central T2 signal, herniation T2 signal, central T1 signal, herniation T1 signal, Pfirrmann Grade, nerve root compression, Modic changes, facet degeneration, vertebral body spurring, and ligamentum flavum hypertrophy. METHODS MRIs for patients in both groups were reviewed and radiographic characteristics measured. T1/2 central signal and herniation signals were determined from the central 80% and the peripheral 20%, respectively. All variables were recorded as either normal or abnormal, except for Pfirrmann grade, Modic changes, and vertebral body spurring. Univariate analysis was used to compare differences between nonoperative and operative groups. Multiple binary logistic regression was used to determine significant predictors of chronicity, controlling for age, sex, and disc herniation level. RESULTS There were no significant baseline differences on univariate analysis. Time to surgery in the acute and chronic groups was 2.30 [1.28, 3.33] vs 2.33 [1.39, 3.26] months, respectively (p = 0.826). There were no significant differences in disc height, T2/T1 central, and T2/T1 herniation signal characteristics between the two groups (p > 0.05). There was a significant difference in Pfirrmann grade, with the chronic group having a higher proportion of grade 5 (37.0% vs 8.3%, p=0.007). Presence of vertebral body spurring was also significantly different between groups, with the chronic group having a higher proportion of posterior marginal and anterior/posterior spurring (p = 0.006). Multiple logistic regression analysis showed lower odds of predicting acute disc herniation with Pfirrmann grade 5 (OR 0.12 [0.02, 0.74], p = 0.022) or the presence of anterior/posterior spurring (OR 0.053 [0.02, 0.74], p = 0.023). CONCLUSIONS This is one of the first studies to assess acuity of symptoms and MRI signal characteristics. Outside of advanced degenerative findings such as Pfirrmann grade 5 or anterior and posterior vertebral body spurring, no other MRI characteristics could be identified that correlate with acuity of symptoms. Therefore, close clinical correlation is important in combination with imaging in treating patients with lumbar disc herniation. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.