PET / CT Fusion overview

This feature requires a separate license and may not be available. Contact your system administrator to have this feature licensed and enabled.

If the PET / CT Fusion module is enabled in eUnity, Fusion is available in the Advanced Visualization menu so that you can generate fused PET and CT stacks. Fusion uses slice-based navigation, where possible. When it is not possible, for example, the gantry is tilted relative to the patient, or the patient is rotated relative to the table, it uses volume-based navigation. When slice-based navigation is used, the annotation overlay shows the slice numbers. When volume-based navigation is used, the annotation overlay displays NA in place of slice numbers.

Warning

All reformatted and volume rendered views (PET / CT Fusion) are treated as Lossy and will display a Lossy Indicator in the upper-right corner of the viewport. See Lossy image display for more information.

Turn on PET / CT Fusion

  1. Open a PET / CT study.
  2. Click and click Fusion.
  3. Drag the CT or PET into the viewer from the Series Tray.
  4. On the Fusion toolbar, click the desired Fusion layout.

These layouts will generate slice-based axial, sagittal, and coronal fusion planes from the selected series and display it in the following layout formats. Note that the tiling (i.e. 3x3) is drawn on the icon.

  • 3x3 basic fusion layout with CT(non-fused), PET(non-fused), and fused views
  • 3x1 fused axial, sagittal, coronal views
  • 3x1 fused axial, sagittal, coronal views + 3D MIP
  • 3x1 axial only
  • 3x1 sagittal only
  • 3x1 coronal only

Custom layouts (can be added to the toolbar using the Customize the toolbar editor)

  • 2x2 axial CT, PET, and fused view with 3D MIP PET
  • 3x2 axial CT, PET, and fused view, coronal PET, coronal fused, and 3D MIP PET

PET / CT Fusion Tools

Note

Collaboration is not currently supported for PET / CT Fusion.

Advanced Visualization Parameters

View or change render types, render parameters, or SUV parameters. The tabs / options that are available in the panel depend on the visualization mode (i.e. Fusion vs 3D) and the series type (i.e. PET vs CT ) or series orientation (i.e. same plane as the original series or not) that is selected in the viewer.

Fusion Blending

Left-click and drag the mouse up or down to increase or decrease the PET opacity. Increasing the opacity shows more of the functional (metabolic) data from the PET. Decreasing the PET opacity shows more of the anatomical data from the CT.

Fusion Presets

Apply presets such as Hot Iron to fused PET / CT studies so that the metabolic data of the PET information is assigned a preset pseudo color value from the Color Look Up Table (CLUT).

Point Tool

Measures the value of a specific point. The unit of measure depends on the modality type. For example, in PET images it provides the SUV value, and in CT images it provides the Hounsfield units.

Circle ROI

Draw a circular region of interest.

PET / CT Fusion indicators

Image loading indicator

Shown in the viewport to indicate that data is being loaded.

Caution

When you load an image or zoom further into an image, eUnity will typically need to load more data. Once loaded, the indicator will disappear. If the indicator is visible, you must wait for the full data to be loaded.

Lossy

Lossy compression indicator (reformatted and rendered views)

Warning

All reformatted and volume rendered views (MPR and 3D) are treated as Lossy and will always display a Lossy indicator.

In MPR, 3D , and Fusion modes, hover the cursor over the to display the final JPEG render quality.

Limited Measurements

Limited Measurements indicator

Shown in the viewport to indicate that not all measurement types are available for the series. Click the for more information.

Partial Volume

Partial Volume indicator

Shown in the viewport to indicate that the complete 3D volume cannot be rendered. A partial volume occurs when the original 2D data does not provide contiguous 2D slices.

SUV not available

SUV not available indicator

Shown in the viewport to indicate that there is not sufficient data to perform SUV measurements. Click the for more information.

Interactive view mode in PET / CT Fusion

Caution

The images presented in eUnity PET / CT Fusion Display Layouts are derived from a continuous-space volume which is constructed from the original 2D images. As a result, the user-presented 2D images may not have a direct spatial mapping to the original 2D images. More specifically, navigating in volume space is different from navigating the original 2D slices.

As the user-presented 2D images are derived from a different location and may be rendered with different thickness, the applied pseudo color palette may be different from the intensity values on the original 2D PET images as they are subject to interpolation algorithms used in the rendering process.

If there is ever any doubt concerning the fusion image(s), users should always reference the closest images from the original 2D PET images.

Interactive mode is a special low-latency mode that prioritizes frame-rate and is enabled in fast operations such as adjusting Window Level on the fly, navigating the stack, or adjusting the 3D image render function or volume orientation on volume rendered stacks.

Note: Viewports in Interactive mode will display in the upper-right corner of the viewport to indicate that higher quality images are in progress.

For information on adjusting the quality of interactive or final images, see Advanced Visualization Parameters for Fusion.

Annotations and measurements in Fusion mode

Annotations and measurements that you make in Fusion are available only for your session. That is, they cannot be saved as a Presentation State.

However, if an ROI measurement is made on the original 2D PET stack, it can be saved as a Presentation State. Note that if any of the SUV parameters were changed, they will be saved along with the Presentation State. For information on using ROI tools in Fusion mode, see SUV measurement tools .