Inobitec DICOM Viewer

2.16. Perfusion Parameters Estimation

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Functionality is available in the Pro edition
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PIC This function cannot be used for establishing a diagnosis

The following series are suitable for perfusion parameters estimation:

  • multiphase MR series. The minimal recommended phase number for brain perfusion parameters estimation is 40
  • multiphase CT series

2.16.1 Open series in Perfusion Parameters Estimation mode

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Functionality is available in the Pro edition
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PIC This function cannot be used for establishing a diagnosis

To open series in perfusion parameters estimation mode:

  1. Open a series in the View Flat Images window.
  2. Make sure that the series images are sorted by image position and phase (For details on how to sort images see Section 2.1).
  3. select the main menu Image and the Perfusion item.

The perfusion parameters estimation panel will be displayed on the right side of the window (Fig. 2.16)



If the series is not suitable for Perfusion Parameters Estimation, then the The current series don‘t fit in perfusion message will be displayed on the Perfusion Parameters Estimation panel.

2.16.2 Brain Perfusion Parameters Estimation for MR series

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Functionality is available in the Pro edition
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PIC This function cannot be used for establishing a diagnosis

To estimate brain perfusion parameters, go to the Brain perfusion tab. The graph displayed shows the arterial input function (AIF) estimated for the whole scope of the model. This function cannot be deleted. AIF is evaluated by Monte Carlo method.

To add an arterial input function:

  1. Find the image that shows the artery.
  2. Choose the phase you need. The vertical yellow line represents the current phase. To change the phase, move your mouse over the line so that it looks like PIC , and then move the line with the mouse while holding down the left button.
  3. Click the Add AIF button. At the bottom of the Brain Perfusion Parameters Estimation panel you will see the AIF settings panel.
  4. Set the following AIF parameters:
    • Scale factor
    • Appearance time
    • a
    • b
    • Baseline intensity

    To see how the changes in the parameters affect the perfusion parameters estimation, check the Set AIF as selected box.

  5. To create an AIF on the basis of a complete model, click the OK button.
  6. To create an AIF with the help of ROI, activate one of the PIC ROI rectangle, PIC ROI ellipse or PIC ROI polygon on the Perfusion Parameters Estimation panel by clicking the left/right/middle mouse button. The button will look as follows: PIC . To continue work with this tool, use the button with which the tool was activated. To learn more about tool control, see Section 1.14.
  7. Build ROI around the artery. Graphs of artery input fucntion for each ROI pixel will be displayed at the bottom of the Perfusion Parameters Estimation panel.
  8. Set the arterial input function by several ROI pixels, select these pixels by clicking the left mouse button holding down the Ctrl key on the keyboard or else move the mouse while holding down the left button. By default, all the pixels are chosen. When you change ROI, your previous choice of pixels is reset. To create an AIF, click the OK; to cancel ROI creation, click the Cancel button; to see how the new settings will alter the measurements, click the Show Results button.
  9. To limit the phase interval to calculate parameters type the begin and the end phase numbers to the corresponding fields and press Enter on the keyboard or move the interval borders on the graph. To do this, move the cursor to the border so that it looks like PIC and move the border, holding the left mouse button.
  10. If the peak of the intensity graph is directed down select the T2-weighted images item (it is selected by default), otherwise select the T1-weighted images item.

The AIF added will be displayed on the AIF list panel. If the AIF is based on a complete model, its name will start with the word "Simulated", if it is created with the help of ROI, its name will start with "ROI". To choose a name for an AIF, left-click the input box and print the name. The dotted lines show all the arterial input functions. To use an AIF, click the switch for the respective AIF. The graph shows the perfusion parameters estimation for the AIF selected.

To choose different ROI pixels, press the Settings button for the respective AIF.

To build ROI for Signal, Concentration and Response measurement:

  1. Activate one of the PIC Point value, PIC ROI rectangle, PIC ROI ellipse or PIC ROI polygon on the Perfusion Parameters Estimation panel by clicking the left/right/middle mouse button. The button will look as follows: PIC . To continue work with this tool, use the button with which the tool was activated. To learn more about tool control, see Section 1.14.
  2. Build ROI object for the target region.

The built ROIs are displayed on the ROI list panel.

Graphs of these values are shown at the top of the Perfusion Parameters Estimation panel. The solid lines represent the graphs of values.

The DICOM Viewer allows you to perform the following actions with AIFs and ROIs:

  1. Rename.
  2. Change a color. Click the color button to the right of the AIF or ROI name.
  3. Change visibility. To make an AIF or ROI invisible, uncheck the box for the selected AIF or ROI.
  4. Move the phases. If the patient moves while scanning is being performed, the tissues for which AIF and ROI are to be built are displaced, and the phases are changed. The DICOM Viewer provides an opportunity to build AIF and ROI separately for each phase. To move an AIF or ROI for the current phase, hold down the Ctrl key while moving; for the current and all the following phases hold down the Shift key; for the current and all the previous phases hold down the Alt key. When an AIF or ROI is edited or deleted, they are edited or deleted for all the phases.
  5. Move to the next slice. To move an AIF or ROI to the next slice, choose Move ROI to previous slice or Move ROI to next slice in the right-click menu.
  6. Remove. Click the PIC button to the right of the selected AIF or ROI.

To go to image containing AIF or ROI, click the PIC button to the left of the selected AIF or ROI.

The values of the following parameters are shown for ROIs:

  • Time to peak (TTP);
  • Cerebral blood flow (CBF);
  • Cerebral blood volume (CBV);
  • Mean transit time (MTT).

2.16.3 Perfusion Parameters Estimation for CT series

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Functionality is available in the Pro edition
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PIC This function cannot be used for establishing a diagnosis

The DICOM Viewer shows the Time to peak (TTP) parameter values for ROIs.

2.16.4 Map mode

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Functionality is available in the Pro edition
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PIC This function cannot be used for establishing a diagnosis

To activate the map mode, check the Map settings box.

Select one of the following parameters to show map from the Parameter dropdown menu.

For Brain perfusion tab:

  • Time to peak
  • Slope
  • Area
  • Cerebral blood volume
  • Cerebral blood flow
  • Mean transit time

For General tab:

  • Time to peak
  • Slope
  • Area

You can set the following map parameters:

  • CLUT
  • Minimal signal: the map will be built for the tissue with signal level greater than the specified;
  • Opacity.

You can set the values limit on the Range of values panel. If the Automatic selection box is checked, then the limit will be set automatically while viewing images. To set the borders manually, type the values to the Minimal value and the Maximum value fields and press Enter on the keybord.

When the map is activated, in the left-hand side of the window you see a color range (Fig. 2.17).



To hide the range, uncheck the Show color range box on the Range of values panel. This box is checked by default.

To change the range values, move your mouse over the upper or the lower bound, so that it looks like PIC . Then move the bound outwards to enlarge the range or inwards to shrink it. The bound value will be displayed when moved. When you release the mouse button, the range will be adjusted and the range values will be saved.

The range is a separate design element and is not linked to the window. The range can be moved around the screen with the mouse, when the left button is pressed.