Diagnostic Accuracy of Digital Radiography in Evaluation of Lumbar Disc Degeneration

Abstract

Background: Lumbar disc degeneration is a common structural cause of low back pain. Digital radiography is still a primary imaging modality for evaluation of structural changes in the intervertebral disc because of its easy availability and low radiation dose; however, the quantified data regarding its diagnostic accuracy compared with Magnetic Resonance Imaging (MRI) is limited. Methods: This cross-sectional study included 120 patients aged 18-50 years with chronic low back pain who were subjected to weight-bearing PA and lateral digital radiography and MRI at Nishtar Medical University Hospital, Multan, Pakistan. Radiographic features (disc space narrowing, disc height, osteophytes, endplate sclerosis) were assessed and MRI findings were graded according to the Pfirrmann classification. Diagnostic performance measures were computed. The reporting was organized based on the STARD 2015 guidelines for diagnostic accuracy studies. Results: Digital radiography demonstrated sensitivity of 78.41% (95% CI: 68.36–86.47%), specificity of 87.50% (95% CI: 71.01–96.49%), positive predictive value of 94.95%, negative predictive value of 57.46%, and overall diagnostic accuracy of 80.68% (Youden index 0.659; LR+ 6.27, LR− 0.25). ROC (receiver operating characteristic) analysis showed an AUC (area under curve) of 0.830 (95% CI: 0.750–0.892). The disc height on digital radiography were measured at three different levels: anterior, central and posterior. The highest diagnostic performance (AUC 0.850; 95% CI: 0.761–0.939) was obtained for posterior disc height with an optimal cut-off of ≤8.25 mm (sensitivity 86.4%, specificity 78.1%). Conclusion: Digital radiography aids initial assessment of lumbar disc degeneration, while MRI detects occult pathology in symptomatic patients with normal radiographs, emphasizing its complementary diagnostic role.