Assessing pulsatile waveforms of paravascular cerebrospinal fluid dynamics within the glymphatic pathways using dynamic diffusion-weighted imaging (dDWI)

Cerebrospinal fluid (CSF) in the paravascular spaces of the surface arteries (sPVS) is a vital pathway in brain waste clearance. Arterial pulsations may be the driving force of the paravascular flow, but its pulsatile pattern remains poorly characterized, and no clinically practical method for measuring its dynamics in the human brain is available. In this work, we introduce an imaging and quantification framework for in-vivo non-invasive assessment of pulsatile fluid dynamics in the sPVS. It used dynamic Diffusion-Weighted Imaging (dDWI) at a lower b-values of 150s/mm2 and retrospective gating to detect the slow flow of CSF while suppressing the fast flow of adjacent arterial blood. The waveform of CSF flow over a cardiac cycle was revealed by synchronizing the measurements with the heartbeat. A data-driven approach was developed to identify sPVS and allow automatic quantification of the whole-brain fluid waveforms. We applied dDWI to twenty-five participants aged 18-82 y/o. Results demonstrated that the fluid waveforms across the brain showed an explicit cardiac-cycle dependency, in good agreement with the vascular pumping hypothesis. Furthermore, the shape of the CSF waveforms closely resembled the pressure waveforms of the artery wall, suggesting that CSF dynamics is tightly related to artery wall mechanics. Finally, the CSF waveforms in aging participants revealed a strong age effect, with a significantly wider systolic peak observed in the older relative to younger participants. The peak widening may be associated with compromised vascular compliance and vessel wall stiffening in the older brain. Overall, the results demonstrate the feasibility, reproducibility, and sensitivity of dDWI for detecting sPVS fluid dynamics of the human brain. Our preliminary data suggest age-related alterations of the paravascular pumping. With an acquisition time of under six minutes, dDWI can be readily applied to study fluid dynamics in normal physiological conditions and cerebrovascular/neurodegenerative diseases.

Intracranial Masson tumor: case report and literature review.

Intravascular papillary endothelial hyperplasia (IPEH) or Masson tumor has only been reported intracranially in 20 cases and can present as a congenital finding. This pathologic entity is an important diagnostic consideration when evaluating an infant with a congenital intracranial mass. We report a third case of a neonate who presented with the appearance of a metastatic brain tumor involving the orbit, sella, and cerebellum that was ultimately proven to be IPEH. A thorough literature review of IPEH is presented and we discuss this clinical entity and its management.

Multichannel computed tomography angiography and its role in the evaluation of rotational vertebrobasilar insufficiency.

We present a case of rotational vertebrobasilar insufficiency diagnosed and followed by computed tomography angiography. Diagnosis of this entity provides a unique challenge in that the patient must be positioned properly to avoid a false-negative result without causing ischemic brain injury. The evaluation of rotational vertebrobasilar insufficiency with computed tomography angiography has never been described in the literature to the best of our knowledge. We highlight the advantages of using this technique in the diagnosis and follow-up of this uncommon entity.