Multimodal MRI Characterization of Structural and Resting-State Functional Brain Alterations in Patients with Low Back Pain: A Retrospective Study
Background/Objectives: Low back pain (LBP) is associated with central alterations, but convergence across structural, functional, and network measures remains unclear. We characterized multimodal differences. Methods: Resting-state fMRI included 69 participants (37 patients, 32 controls); VBM retained 23 patients and 32 controls after structural-image quality control. Structural, local functional, and thalamic-connectivity measures were assessed. Motion control used realignment-based exclusion and Friston-24 nuisance regression. Mean Power framewise displacement was additionally calculated for all participants and compared between groups, and VBM-retained and excluded patients were compared. Models adjusted for age and sex, plus total intracranial volume for VBM. Directional maps underwent one-tailed Gaussian random field correction (voxel p < 0.001; cluster p < 0.05), without cross-direction or cross-family correction. Extracted-value and imaging–clinical analyses were exploratory. Results: Mean framewise displacement did not differ between groups. Patients showed lower gray matter volume in thalamic–hippocampal regions and right cerebellar lobule VIII and lower local functional measures in thalamic, orbitofrontal–striatal, and right temporal regions. Thalamic connectivity with sensorimotor, parietal, supplementary motor, and middle cingulate regions was higher. Nominal analyses showed positive left thalamic connectivity cluster 1–VAS and negative left cluster 1–JOA and right clusters 1/2–JOA; none survived false-discovery-rate correction. Conclusions: Multimodal MRI delineated lower thalamic structural and local functional measures alongside higher thalamo-sensorimotor and thalamo-parietal connectivity. Nominal, directionally coherent clinical associations remain hypothesis-generating. This thalamus-centered pattern warrants replication in prospectively matched, clinically stratified cohorts.