The utility of MRI radiological biomarkers in determining intracranial pressure

Abstract Background Intracranial pressure (ICP) is a physiological parameter that conventionally requires invasive monitoring for accurate measurement. Utilising multivariate predictive models, we sought to evaluate the utility of non-invasive, accessible MRI biomarkers in predicting ICP and their reversibility following cerebrospinal fluid (CSF) diversion. Methods The retrospective study included 325 adult patients with suspected CSF dynamic disorders who underwent brain MRI scans within three months of elective 24-hour ICP monitoring. Five MRI biomarkers were assessed: Yuh sella grade, optic nerve vertical tortuosity (VT), optic nerve sheath distension (ONSD), posterior globe flattening (PGF) and optic disc protrusion (ODP). The association between MRI biomarkers and 24-hour ICP was examined and reversibility of each following CSF diversion was assessed using uni- and multivariate techniques. Results All five biomarkers were significantly associated with median 24-hour ICP (p<0.0001). Using a pair-wise approach, the presence of each abnormal biomarker was significantly associated with higher median 24- hour ICP (p<0.0001). On multivariate analysis, ICP was significantly and positively associated with Yuh grade (p<0.0001), VT (p<0.0001) and ODP (p=0.003), after accounting for age and suspected diagnosis. Bayesian multiple linear regression predicted 24-hour median ICP with a mean absolute error of 2.71 mmHg. Following CSF diversion, we found Yuh grade to show significant pairwise reversibility (p<0.001). Conclusions ICP was predicted with clinically useful precision utilising a compact Bayesian model, offering an easily interpretable tool that utilised non-invasive imaging data. MRI biomarkers are anticipated to play a more significant role in the screening, triaging, and referral of patients with suspected CSF dynamic disorders. Key messages Brain MRI biomarkers have been found to be correlated with cerebrospinal fluid (CSF) pressures. However, previous studies have not examined these imaging features with continuous intracranial pressure (ICP) measurements, or in patient cohorts with sizable numbers or different CSF dynamic disorders than idiopathic intracranial hypertension. In this retrospective cohort study, patients with abnormal neuroradiological markers (optic nerve sheath diameter, pituitary: sella grade, optic nerve vertical tortuosity, posterior globe flattening or optic disc protrusion) had significantly higher median 24-hour ICP readings. After adjusting for age and diagnosis, Yuh sella grade, vertical tortuosity and optic disc protrusion were significantly associated with ICP. Our multiple linear regression model was able to predict 24-hour median ICP using routine MR-imaging in those with chronic CSF disorders. Pituitary deformation resolved following CSF diversion, suggesting reversibility of certain radiological biomarkers. Brain MRIs are widely accessible and non-invasive, and are commonly used in elective patients with suspected raised ICP. Our study provides a tool incorporating simple clinico-radiological parameters for the screening, triaging, and referral of patients with suspected abnormal ICP, and our results have important implications for the diagnostic routine of patients with suspected intracranial hypertension.