OBJECTIVES: To evaluate the applicability of 4D phase contrast (4D PC) MR imaging in the assessment of cerebrospinal fluid dynamics in healthy volunteers and patients with lesions at the craniocervical junction or the cervical spinal canal. METHODS: Ten healthy volunteers and four patients with lesions including Chiari I malformation and cervical canal stenoses were examined by a cardiac-gated 4D PC imaging sequence on 1.5T MRI. Phase contrast images were postprocessed allowing for flow quantification and flow pathline visualisation. Velocity data were compared with conventional axial 2D phase contrast images. RESULTS: The 4D PC sequence allowed for flow quantification and visualisation in all individuals. Bland-Altman analysis showed good agreement of 2D and 4D PC velocity data. In healthy volunteers, CSF flow was homogeneously distributed in the anterior and anterolateral subarachnoid space with the flow directed caudally during systole and cranially during diastole. Flow velocities were closely related to the width of the subarachnoid space. Patients showed grossly altered CSF flow patterns with formation of flow jets with increased flow velocities. CONCLUSIONS: 4D PC MR imaging allows for a detailed assessment of CSF flow dynamics helping to distinguish physiological from complex pathological flow patterns at the craniocervical junction and the cervical spine.