The Desktop Viewer
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PACS Desktop Viewer

Image Fusion

 

The image fusion tool is a plug-in module for superimposing PET/CT and SPECT/CT structural and functional images into a single volume. Tools include orthogonal and volume oriented view controls, alpha blending, color spectrum application, and MIP view. The plug-in applies to studies whose largest, contiguous segment of images share complementary spatial resolution characteristics, meaning they were acquired on a single machine as part of a single procedure.

 

The image fusion plug-in module has the following workstation requirements:

Attempts to invoke the fusion plug-in module on a machine with insufficient resources may display one or more warnings or error messages. If so, the plug-in may appear to process the data correctly but performance may be poor and results cannot be guaranteed. Do not use the fusion plug-in until you are able to load the plug-in without receiving any popup notices.

 

When the viewer starts, it searches the server for the fusion plug-in license. If a valid license exists and the user account is configured to use the plug-in module, the viewer prompts the user to download and install it on the workstation. Once downloaded the plug-in installs automatically and is ready to use.

 

To invoke the fusion plug-in module:

  1. Drop a series from the thumbnail panel into an image frame
  2. Select the Extensions menu
  3. Expand the Image Fusion submenu and chose Create

The plug-in is ready to use when:

To fuse the loaded series with another, drag and drop another series into the image frame running the plug-in module. A progress bar pops up while the plug-in module processes the data. When finished, the progress bar disappears and all series loaded into the plug-in frame appear fused together on the screen.

 

 

Fusion Frame Layout

 

The fusion plug-in consists of a viewing area and a toolbar (highlighted area).

 

 

The toolbar defaults to the right side of the image frame. It can be detached and floated anywhere in the image frame.

 

Icon Tool Description

4-up Four image cells containing orthogonal and MIP views

9-up Nine image cells containing each series in orthogonal views

Show/hide structural Show/hide the structural image in individual cells

Show/hide functional Show/hide the functional image in individual cells

Move structural Manually line up the images by manipulating the structural image

Move functional Manually line up the images by manipulating the functional image

Save image Export the highlighted image

Save series Export a series of images from the highlighted cell

Show/Hide hash marks Toggle to show and hide the hash marks

Show/hide SUV values Toggle to show and hide the SUV overlay and SUV ROI annotation

 

Display layouts

 

The two primary layouts display the images in different views:

 

Layout Description
4-up Displays the individual or fused series in all three orthogonal views, plus one MIP view.
9-up Consists of three rows showing the series in all three orthogonal views. The first row shows the structural image. The second row shows the functional image. The final row displays the fused images.

 

MIP Image View

 

A MIP view of an individual or the fused image is available in 4-up display mode.

 

Image Manipulation

 

Image manipulation tools include scrolling, zooming, windowing/leveling, color palette adjustments, alpha blending, rotating and panning. By default, the fusion plug-in renders all loaded series. To display the image in a single series, load only one series into the plug-in frame, or deselect the Show Structural or Show Functional button from the toolbar.

 

Window/Level

 

To adjust the window and level settings for the displayed image:

  1. Position the mouse cursor over any image in the fusion plug-in frame
  2. Adjust the window/level of primary/structural image and secondary/functional image palette range
    1. Primary/structural image - press and hold down the right mouse button
    2. Secondary/ functional image palette range - press and hold the Shift button and the right mouse button.
  3. Drag the mouse left and right or back and forth
    1. Left and right - increases or decreases window width
    2. Back and forth - increases or decreases window center

 

Scrolling

 

To scroll through the image stack:

  1. Position the mouse cursor over any image in the fusion plug-in frame
  2. Press the left mouse button to select it
  3. Scroll the mouse wheel backward to advance and forward to return one frame at a time
  4. Press and hold down both the left and right mouse button, and drag the mouse forward or backward to increase or decrease

 

Zooming

 

To magnify the images:

  1. Position the mouse cursor over any image in the fusion plug-in frame
  2. Press and hold down both the left and right mouse button
  3. Drag the mouse forward to increase the image size and backward to decrease it

 

Orbiting MIP View

 

To rotate the default MIP volume around a center point:

  1. Position the mouse cursor over the MIP image
  2. Press and hold down the left mouse button
  3. Drag it to orbit the image

 

Cross Correlation

 

Cross correlation is the ability to identify the same point in all orthogonal images.

 

There are two modes:

 

After selecting the cursor mode:

  1. Position the cursor over the point in an image
  2. Press and hold down the CTRL button and do either of these two options:
    1. Click the left mouse button to display the intersecting point in all image cells
    2. Hold down the left mouse button and drag the mouse to dynamically refresh the point under the cursor in each of the other cells

     

Color Schemes

 

A number of predefined color schemes are available. The default scheme is red, and can be changed by the user. The other options include blue, red glow, blue glow, hot metal, ice water, rainbow, and none (grayscale).

 

To apply a selected color scheme:

  1. Position the mouse over the fusion plug-in frame

  2. Click the right mouse button

  3. Select Color Scheme to display the submenu

  4. Select the color scheme from the submenu

To adjust the palette range:

  1. Position the mouse cursor over any functional or fused image in the fusion plug-in frame
  2. Press and hold the Shift button and the right mouse button
  3. Drag mouse:
    1. left and right to increase or decrease window width
    2. back and forth to increase or decrease window center

To change the default color scheme:

  1. Drop a function (PET) image in the fusion plug-in frame.
  2. Select the color scheme you want as the default (instructed above)
  3. Position the mouse over the fusion plug-in frame and click the right mouse button
  4. Select Color Scheme to display the submenu
  5. Click Save Current as Default

 

 

Alpha Blending

 

Alpha blending is combining the alpha layer with other layers in an image in order to show translucency. Alpha blending modes include Constant and Linear.

 

To select an alpha blending mode:

  1. Position the cursor over the fusion plug-in frame and click the right mouse button
  2. Click Alpha to display the submenu
  3. Select the alpha blending mode
Mode Description
Constant Alpha blending adjustments alter the alpha constant. The initial alpha constant is 0.5
Linear (Default) Alpha blending adjustments alter the alpha scaling factor. The initial alpha scaling factory is 2.0
Reset Reset the alpha constant and scaling factor to system defaults

 

Constant alpha blending mode - the transparency is independent of the image’s color/intensity value

 

Linear alpha blending mode - the transparency is a linear function of the image’s windowed intensity

 

To alter the alpha constant or scaling factor:

  1. Select the alpha blending mode (described above)

  2. Press and hold down the CTRL key and the right mouse button

  3. Drag the mouse forward or backward to increase or decrease the value

 

Manual Registration

 

The image series are automatically registered if they were acquired on the same device and are encoded with a shared frame of reference identifier. Other series can be manually registered.

 

To register an image series:

  1. Load both series into the fusion plug-in frame
  2. Select the Move Functional or Move Structural icon
    1. Move Functional - keep the structural image fixed and adjust the functional image
    2. Move Structural - keep the functional image fixed and adjust the structural image
  3. Position the cursor over the fusion cell containing the image you want to adjust:
    1. To move the affected image - press and hold down the left mouse button, and drag the mouse
    2. To rotate the affected image around the starting point - press and hold down the right mouse button and drag the mouse
    3. To resize the affected image centered around the starting cursor position - press and hold down the left/right mouse buttons and move the mouse forward and backward

 

Annotations

 

The fusion plug-in module supports a number of annotations and overlays, including hash marks and SUV values.

 

Hash Marks

 

Orthogonal images in the fusion frame include hash lines of the interesting image planes that appear as cross hairs on the images. To show and hide the hash marks press the Show/Hide Hash Marks icon in the fusion toolbar.

 

SUV Values

 

When the functional image contains the standard uptake value (SUV) data, the information is displayed in the image cell by default. The uptake value for the point under the cursor is displayed. If SUV information is available, SUV values are displayed by default. To hide the SUV data overlay, press the Show/Hide SUV Values button in the fusion toolbar. SUV values are only displayed when specific values are present in the PET or SPECT series. Some values depend on the modality vendor and are generally required.

 

The value in parentheses is the DICOM tag value:

 

SUV Values DICOM Tag Value
Injection Dose (0018,1074)
Injection date/time (0018,1078) / (0018,1072)
Acquisition date/time (0008,0022) / (0008,0032)
Half life (0018,1075)
Patient weight (0010,1030)

 

 

SUV Regions of Interest

 

To display the maximum SUV value in a region of interest:

  1. Position the cursor over the center of the SUV ROI sphere you want to draw

  2. Press and hold down the Shift key and the left mouse button

  3. Drag the mouse away from the center point for a circle to appear on the image

  4. Release the mouse and keyboard once the circle defines the region

The maximum SUV value in the sphere will now appear on the image.

 

To remove or redefine an SUV ROI:

  1. Position the cursor within the boundaries of the SUV ROI to highlight the annotation

  2. Press the Delete key

 

Saving Images

 

Images created by the fusion module can be exported to the main viewer and sent to the archive for storage. Exported images can be attached to reports as key images on they are uploaded to the server. Uploading exported images requires Edit or Report permissions. Annotations applied to a fused image when it is exported remain on the image after exporting, but they cannot be modified outside the plug-in frame. To make adjustments to an annotation, reload the exported image into a fusion plug-in frame and edit it.

 

Exporting Fused Images

 

There are two ways to export a single fused image:

 

Exporting Fused Series

 

To export a series of fused images:

  1. Select the fusion cell containing the images to export

  2. Click the Export Series button

  3. In the Export Options window, select the number of slices to include in the series plus the slice spacing (fused images) or incremental rotational angle (MIP)

  4. Click OK

 

Configuration

 

Fusion configuration allows you to define default color schemes, alpha blending mode and associated parameters, a slice space limit and some D3D compatibility parameters. Default color schemes can be different when applied to the fused image, the PET-only image and the MIP image. The fusion module configuration panel is available from the Image Fusion item under the Extensions menu at the top of the viewer. Click on Configure to pop up the configuration window.

 

 

The four main areas of the configure pop-up are:

General

 

Settings Default Description
Maximum slice spacing error 5% Defines the maximum spacing between slices accepted as belonging to the data volume.
Don’t use 32-bit textures Disabled If the data cannot be rendered in 16 bits, the data is expanded to 32 bits to preserve precision. Some D3D drivers and devices do not support this. Checking this box avoids this issue, but may result in rounding errors in the data.

 

Coloring

 

Settings Default Description

Fused coloring

 Red Default color scheme applied to fused images.

Functional only coloring

 Same as Fused Coloring Default color scheme applied to functional (PET) images when rendered non-fused

MIP coloring

 Same as Fused Coloring Default color scheme applied to MIP image

 

Blending

 

Settings Default Description
Blending mode

Linear

 Alpha blending mode which can be Linear or Constant
Blending parameter Scaling factor / Constant - 2.0 / 0.5 When mode is linear, this parameter is the alpha scaling factor. When mode is constant, this parameter is the alpha constant

 

Auto Palette Range

 

Settings Default Description
Fused image 100% Color saturation intensity applied to fused images. The default 100% is full intensity

 

Keyboard Control Summary

 

The following tables summarize the keyboard and mouse commands.

 

There are three modes available:

Normal Mode

 

Key Mouse Action Result
  Right Drag left/right Window structural/primary image
  Right Drag forward/backward Level structural/primary image
Shift Right Drag left/right Change palette range width of functional image
Shift Right Drag forward/backward Change palette range center of functional image
  Middle Scroll forward/backward Scroll through images
  Middle Drag forward/backward Scroll through images
  Left+Right Drag forward/backward Resize image
  Left Drag Orbit MIP image
Shift Middle Drag Tilt the reconstructed planes
Ctrl Left Click or drag Set cross correlation point
Ctrl Right Drag forward/backward Adjust alpha blending setting
Shift Left

Drag

 Define SUV ROI

 

Magic X Cursor Mode

 

Key Mouse Action Result
Ctrl Left Click or drag Apply Magic X

 

Manual Registration Mode

 

Key Mouse Action Result
Shift Left Drag Moves the structural image
Ctrl Left Drag Moves the functional image
Shift Right Drag Rotate the structural image
Ctrl Right Drag Rotate the functional image
Shift Left+Right Drag Resize the structural image
Shift Left+Right Drag Resize the functional image