Time-Dependent Quantitative Magnetic Resonance Imaging Staging of Lumbar Disc Herniation Using T2 Signal-Intensity...

Low back pain is the leading cause of musculoskeletal disability worldwide. Lumbar disc herniation (LDH) commonly causes radiculopathy, yet conventional magnetic resonance imaging may conflate symptomatic pathology with age-related change. We assessed quantitative T2-weighted signal intensity ratios (SIRs) of herniated nucleus pulposus (NP) as an objective biomarker to stage LDH beyond morphology, using internal references (e.g., cerebrospinal fluid) for normalized, comparable measurements.

This retrospective cross-sectional study analyzed 157 patients (64% male) with magnetic resonance imaging-confirmed LDH and radicular symptoms at a tertiary center (2021). Exclusions included prior surgery, infection, tumor, fracture, or suboptimal imaging. SIRs were calculated for herniated NP relative to cerebrospinal fluid (SIR-NP/CSF), anterior annulus fibrosus (SIR-NP/AF), and adjacent uninvolved NP (SIR-NP/adjNP). Symptom duration groups were acute (<2 weeks), subacute (2-4 weeks), and chronic (>4 weeks). Group differences were tested with analysis of variance and Tukey post hoc analyses, adjusting for phenotype (protrusion/extrusion), disc level, age, and sex.

SIRs decreased significantly with longer symptom duration (P < 0.001). Mean SIR-NP/CSF declined from 0.30 (acute) to 0.23 (subacute) to 0.12 (chronic) and was the most robust temporal marker. Posterior NP signal intensity decreased from 194 (acute) to 75 (chronic; F = 136.9, P < 0.001). Trends were consistent across ratios and were not explained by phenotype, level, age, or sex. An SIR-NP/CSF threshold <0.20 suggested subacute/chronic stages.

Quantitative T2 SIRs track NP dehydration and may support reproducible LDH staging; however, clinical applicability is limited without outcome correlation. Prospective multicenter validation with follow-up, including resorption assessment, is needed.