Cranial MRI Findings in Rheumatoid Arthritis Patients Treated with Rituximab: Prevalence, Patterns, and Clinical Correlates

Background/Objectives: Neurological manifestations in rheumatoid arthritis (RA) are common, yet the clinical relevance of central nervous system (CNS) abnormalities detected on neuroimaging remains uncertain. We aimed to determine the prevalence and patterns of cranial magnetic resonance imaging (MRI) findings in RA patients treated with rituximab (RTX) and to assess whether these abnormalities are associated with disease-specific mechanisms or with age- and comorbidity-related factors. Methods: In this retrospective observational study, 84 RA patients who received RTX and had available pre-treatment cranial MRI underwent systematic evaluation. Imaging findings were classified by an experienced neuroradiologist blinded to clinical data and dichotomized as normal or abnormal, and white matter hyperintensities were graded semiquantitatively using a Fazekas-type scale. Factors independently associated with abnormal MRI were assessed by multivariable logistic regression. Results: Cranial MRI abnormalities were identified in 60 patients (71.5%), predominantly as nonspecific white matter hyperintensities (48 patients, 57.1%). In multivariable analysis, older age (adjusted odds ratio [aOR] 1.16 per year, 95% CI 1.08–1.25) and the presence of comorbidities (aOR 5.36, 95% CI 1.49–19.23) were independently associated with abnormal imaging (p < 0.001 and p = 0.010, respectively), whereas no association was found with disease duration, seropositivity, or extra-articular involvement. Imaging findings remained stable over time in the majority of the 39 patients (46.4%) who underwent follow-up imaging. Conclusions: Cranial MRI abnormalities are highly prevalent in RA and were associated primarily with age and comorbidity burden rather than with RA-specific inflammation; however, in the absence of a control group, we cannot determine whether their prevalence exceeds that of a comparable non-RA population. No treatment-related demyelinating disease or progressive multifocal leukoencephalopathy was observed, but the study was not designed to assess drug safety, and these findings should be interpreted as the absence of an observed imaging signal rather than as evidence of the neurological safety of rituximab. Cranial neuroimaging in RA should therefore be interpreted cautiously and in clinical context.