Figure 1.
Anatomical data of the model cistern.
Three orthogonal slices of the MRI data with cerebrospinal fluid in the cerebral sulci, ventricles, and basal cisterns indicated in pink. The three-dimensionally reconstructed basal cistern (red) and the ventricular system (blue) are shown for a better space orientation.
Figure 2.
Surface of the reconstructed basal cistern in a lateral (A) and frontal (B) view. The g-arrow indicates the longitudinal axis of the human body which is aligned with the gravitational force for a sitting patient. Photo (C) shows the corresponding wax model and photo (D) the fabricated silicone model. Arrows indicate the sites of the inflow of the blood model as well as the inflow and outflow of the CSF model.
Figure 3.
Left: Photo of the experimental setup mounted on the optical table: (1) CCD camera; (2) rigid frame mounting the basal cistern model (5), light source (6) and camera (1) on two pylons (4) allowing x-axis rotation; (3) syringe pump; (7) and (8) step motor with programmable controller; (9) pulse generator. Right: Schematic drawing of the experimental setup.
Table 1.
Experimental parameters.
Figure 4.
Standard deviation (n = 6) for normalized gray value and time to achieve a normalized gray value of Exp. 1 (see Table 1). The horizontal lines labeled with 100%, 50%, 25% and 12.5% represent the normalized gray values from a calibration experiment with according blood model concentrations.
Figure 5.
Examples of washout images at different time steps.
Five in vivo time step images of four dye washout experiments. Settings of experiments are shown in Table 1.
Figure 6.
Normalized gray value curves quantifying the washout process of six of the eight washout experiments, of both reference experiments and of the experiment with pulsatile conditions. For a better clearness graphs were displayed in two groups (A and B) with identical scales. The horizontal lines labeled with 100%, 50%, 25% and 12.5% represent the normalized gray values from a calibration experiment with according blood model concentrations.
Table 2.
Mixing and clearance times.
Figure 7.
Scheme of the influence of gravitational alignment and shaking angle.
Blood model distribution images (A) and schematic drawings (B) after injection (φ = 0°, T = 0 min). The g-arrows indicate the direction of the gravitational force, blue regions correspond to experimental blood, whereas white regions to experimental CSF. Different cistern orientations (α = 0°, 30°, 90°) cause different CSF-blood layers. (C) Schematic drawings of different shaking angles for a given cistern position (α = 0°). The complex shape of the basal cistern hampers extensive movement of cisternal blood if the shaking angle is too small.