A Preliminary Study of Spectral CT in Predicting Pfirrmann Grading of Lumbar Intervertebral Disc

Objective: To investigate the predictive value of material separation technology of spectral CT in Pfirrmann grading of lumbar intervertebral disc degeneration. Methods: Retrospective analysis was performed on 30 patients with lumbar disc herniation in our hospital from October 2020 to February 2021. Spectral CT scan and MRI scan were performed respectively. Grade 1-3 of Pfirrmann grading was classified into low grade group, while grade 4-5 was classified into high grade group. Water (calcium) concentration, water (HAP) concentration, calcium (water) concentration, HAP (water) concentration and Eff-Z of intervertebral disc were measured by spectral post-processing analysis software in the same ROI. Independent sample t est was used to compare the differences among parameters, furthermore, the ROC curve was drawn. The area under the curve was used to evaluate the diagnostic efficiency and select the optimal diagnostic threshold. Results: The concentrations of water (calcium) and water (HAP) in low-grade intervertebral discs were higher than those in high-grade intervertebral discs, while the concentrations of water (calcium), water (HAP) and Eff-Z in low-grade intervertebral discs, were lower than those in high-grade intervertebral discs, which held statistical significance. The ROC curve showed that water (calcium) concentration and water (HAP) concentration were less effective in diagnosing the difference between low-grade and high-grade discs. Calcium concentration holds certain diagnostic efficacy. HAP and Eff-Z hold high diagnostic efficacy. while Eff-Z shows better diagnostic efficacy with AUC of 0.97. Taking 7.69 as the standard, the sensitivity and specificity of differentiating low-grade and high-grade intervertebral discs are respectively 96.25% and 96.00%. Conclusion: Spectral CT with multi-parameters quantitative analysis holds certain value in distinguishing low grade and high grade intervertebral discs.