HEMODYNAMICALLY INDEPENDENT ANALYSIS OF CEREBROSPINAL-FLUID AND BRAINMOTION OBSERVED WITH DYNAMIC PHASE-CONTRAST MRI

Brain and cerebrospinal fluid (CSF) movements are influenced by the an atomy and mechanical properties of intracranial tissues, as well as by the waveforms of driving vascular pulsations. The authors analyze the se movements so that the purely hemodynamic factors are removed and th e underlying mechanical couplings between brain, CSF, and the vasculat ure are characterized in global fashion, These measurements were used to calculate a set of impulse response functions or modulation transfe r functions, characterizing global aspects of the vasculature's mechan ical coupling to the intracranial tissues, the cervical CSF, and the c ervical spinal cord, These functions showed that a sudden influx of bl ood into the head was rapidly accommodated by some type of intracrania l reserve or capacity. After this initial response, an equal volume of CSF was driven through the foramen magnum over the next 200-300 ms as the intracranial reserve relaxed to its base-line state.