Characterizing Cardioballistic Brain Dynamics and Vascular Hemodynamics in Patients with Chiari Malformation Using Advanced MRI

Moss Zhao^1*Rui Duarte²Elizabeth Tong¹Laura M Prolo¹Gerald A Grant³Michael E Moseley¹Kristen Yeom¹

• ¹Stanford University, Stanford, United States
• ²Department of Neuroradiology, Western Lisbon Local Health Unit, Lisbon, Portugal
• ³Duke University, Durham, United States

Chiari Malformation Type I is a neurological disorder involving cerebellar tonsillar herniation, affecting cerebrospinal fluid dynamics and brain biomechanics. Advanced neuroimaging techniques are critical for understanding the pathophysiology of these anatomical abnormalities to guide clinical decision-making. Cardioballistic brain motion, the displacement of brain tissue driven by cardiac pulsation, can be visualized using cardiac-gated balanced steady-state free precession (bSSFP) cine MRI. Cerebellar hemodynamics can be measured using arterial spin labeling (ASL) MRI. Here, we present cerebellar cardioballistic dynamics and cerebellar hemodynamics in a retrospective cohort of 10 pediatric Chiari patients and 10 normal subjects. Cardioballistic brain motion was measured using a phase-based motion amplification algorithm applied to bSSFP cine MRI, yielding a novel scalar metric-the Cerebellar Dynamic Index (CDI). Cerebral blood flow (CBF) was quantified using ASL. CDI was significantly higher in Chiari patients compared to controls (by 39%±26%, p<0.01), indicating greater arterial-driven brain motion. Cerebellar CBF values, however, did not differ significantly between groups (median: 55.5 vs. 51.5 ml/100g/min, p=0.48). These findings suggest that cardioballistic brain dynamics may serve as a sensitive biomechanical biomarker for Chiari Malformation and support the integration of motion and perfusion imaging into a multimodal framework for diagnosis and monitoring.