Generate / save statistical output

Once the functional maps have been generated, statistical details as well as dynamic curve information can be obtained.
The Lesion stats tab provides statistical info as well as histogram analysis of the selected output map from either the whole image volume or the lesion mask VOI (selected from the <VOI scope> drop-down. By default, the histogram is coloured according to the selected overlay palette. This can be changed under <Options>. The resulting statistical output as well as histogram can be saved to clipboard / file.

Figure 1: Display of statistical data and histogram for tumor mask in selected output map.

Visualization of dynamic time-intensity data

Dynamic data can be visualized in multiple ways from the <Dynamic ROI analysis> menu tab. If a lesion mask has been defined, pressing the button will show the time-intensity curve (TIC) for the selected lesion mask. Note that the curve shown will depend on the selected output in the <Display>  menu:

1. <Dynamic R2 curves> : Displays time-intensity data converted to delta R2/R2* (using the standard mono-exponential echo time dependence) for the spin echo and gradient echo series. By default, the curve fits (either gamma variate or gaussian) to the dynamic curves will also be shown. In this mode, the baseline (pre-bolus arrival) range can be defined manually by setting the red vertical line at the appropriate time-point prior to bolus arrival, as shown in the figure. The line can also be used to define the last time-point to include in the analysis. By default, all time-points are included. The <Temp upscale factor> defines the factor by which the gamma-variate or gaussian curve fit is resampled to higher temporal resolution for better visualization of the hysteresis curve.

2. <Hysteresis curves>: Displays the plot of R2^(3/2)  (from SE) along the x-axis versus R2* (from GRE). This plot is known as the hysteresis plot in VAI terminology and contains information about the microvascular properties of the tissue in the VOI.  Note that the colouring of the hysteresis curve indicate the direction of the ‘loop’

Figure 2 shows the dynamic curves from the same lesion mask for the two different output options.

Figure 2: Visualization of dynamic change in R2/R2* and corresponding gamma variate (or gaussian) curve fits (left) and the corresponding ‘loop’ representation using the ‘hysteresis’ display option.

Displaying TIC for current cursor position in ‘trace mode’.
When in trace mode, the TIC will be displayed for the current cursor position as long as the ‘show ROI intensity curve’ is active in the ‘Dynamic ROI analysis’ tab (figure 2). Note that TIC curves can only be shown when the cursor is tracing the dynamic perfusion image series.