3/30/2023 0 Comments Cerebrospinal fluid image![]() ![]() The 4D-VM images of the cardiac-driven CSF motion of a healthy volunteer and iNPH patient are shown in Figure 4, demonstrating the difference in the velocity distribution between the healthy volunteer and the iNPH patient. Since this value was less than 2000, the CSF motion inside the aqueduct was regarded to be a laminar flow when moving toward one direction. The Reynolds number in the aqueduct was calculated to be around 136 when the velocity was 2.47 cm/s. CSF motion visualization based on cardiac-gated PC imaging To quantify the P-map, regions of interest (ROIs) were placed, as shown in Figure 3.ģ.1. The brightness of the F-map was weighted with that averages the maximum values of PSD in intracranial space. The frequencies of the maximum peak in the PSD were depicted at all the voxels to form a frequency map (F-map). Such calculations were performed for all the voxels including CSF to create a power map (P-map). The energy of the cardiac and respiratory component was calculated by integrating the power spectral density of these components in each voxel and then normalized by the entire energy in the 0–2.0-Hz range. Monitoring an ECG signal as well as a respiratory signal, which is obtained by a bellows-type pressure sensor, the cardiac- and respiratory-driven CSF velocity components were separately extracted in the frequency domain. Since cardiac- and respiratory-driven CSF motions have different frequency ranges corresponding to cardiac pulsation and respiration, these motions should appear as different spectral peaks in the frequency domain. This chapter presents the techniques for the visualization and characterization of CSF motion in intracranial space based on the cardiac-gated PC and asynchronous PC technique of MRI. Thus, the characterization of the CSF dynamics may lead to the key for clarifying the status and the symptom of the abovementioned diseases. It is also known that the development of Alzheimer’s disease (AD) relates to the accumulation of amyloid beta protein and thus to the malfunction of the glymphatic system, which in turn the bulk flow. Therefore, the investigation of the relationship between hydrocephalus and CSF motion is essential. Even in such a case there might be abnormality in the CSF dynamics. Although hydrocephalus increases intracranial pressure (ICP) in some cases, normal pressure hydrocephalus (NPH), including idiopathic NPH (iNPH), does not increase ICP, and thus, it is difficult to know the exact status of the disease using invasive pressure measurement, as in a lumber puncture (LP) procedure. Hydrocephalus is the most commonly known disease relating to the alternation of CSF dynamics through, for example, a velocity increase in the aqueduct. Bulk flow is a slow motion relating to CSF production and absorption, thus playing a role to washout wastes from the brain through the glymphatic system. A change in intrathoracic pressure caused by respiration induces the modulation of venous blood pressure, resulting in respiratory-driven motion. Cardiac-driven motion is primarily induced by arterial blood vessel pulsation and relates to the regulation of intracranial pressure (ICP). CSF motion is thought to be composed of three components: cardiac-driven motion, respiratory-driven motion, and bulk flow. Investigations of CSF motion based on MRI have been actively performed. ![]()
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