Flow Quantification

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Algorithm Description

Calculates and plots the following flow parameters from a phase contrast study: average velocity (cm/s), max positive velocity (cm/s), max negative velocity (cm/s), average positive velocity (cm/s), average negative velocity (cm/s), flow (ml/s), net flow (ml), area (mm2). A simple phase unwrapping algorithm is used for compensate for phase aliasing. A simple average is calculated for each vessel at each time point, if any voxels are 1.2*π above or below the mean they are assumed to have aliased at 2π is added or subtracted from them.

Clicking on the plot lines will display the precise value of that location below the graph.

Double clicking on a time point will advance the magnitude images that the vessels are marked on to that time point.

Flow Quantification Input

Venc Scale - Unknown
Venc Value - Sets scale from image units of radians to flow units of cm/s. For example a value of 50 indicates that +π corresponds to 50 cm/s. This is read from the header in Siemens scans and set to a default value of 50 for GE data.
Phase Image - Specifies where the phase image from the phase contrast scan is located.
Plot Lines - Specifies what plots to display.
Plot Options
Independent Scales - Plots all lines with independent Y-axis the maximum value will be at the top of the window and the minimum value at the bottom.
Draw Y grid lines - Displays vertical grid lines
Draw X major grid lines - Displays horizontal major grid lines
Draw X minor grid lines - Displays horizontal minor grid lines
Draw X axis - Draws a horizontal line for the X axis
Object colors - Not functional
Show legend - Displays legend

Flow Quantification Output

Export to Excel - Exports a summary to Excel of the flow and net flow for the internal jugular, common carotid, and left and right subtotals and total for all arteries and veins. Also includes the detailed data for all vessels.
Export Report Plots - Exports five standardized plots of all vessels in PNG format: average velocity, flow, max negative velocity, max positive velocity, and net flow.
Export Displayed Plots - Exports the plot currently displayed exactly as it appears on the screen.