Image Viewer > Advanced Viewing > Multiplanar Reconstruction (MPR)

This is a premium feature and may not be available in all installations.

Any supported series in a standard viewer workspace can be directly formatted in-place to another view orientation, allowing you to view the reformatted series without leaving the context of the patient, the parent study and any loaded prior studies.

There are some restrictions on the kind of source images from which MPR can be started:

•	There must be at least three images in the display set.

•	All the images must come from the same study and series.

•	All the images must have the same frame of reference.

•	All the images must have the same image orientation (relative to the patient).

•	The spacing between consecutive images must be consistent.

•	The images may not have a horizontal gantry tilt 1.

Standard Views

You can view the selected series from any of the three standard views by selecting the appropriate Reformat option from the context menu, or from the Reformat drop down on the toolbar. The reformatted series will replace the original series in the layout.

Oblique Views

You can define an oblique view by selecting the Reslice command from the context menu or from the toolbar, and drawing an MPR line directly on the selected series. The reformatted series will replace the original series in the layout as soon as you finish drawing the MPR line.

Draw the MPR line by clicking once to set the start point, and a second time to set the end point.

Adjusting Slice Thickness/Spacing

The slice thickness and spacing is automatically chosen based on the voxel spacing in the original series as well as the chosen image orientation. You can modify these parameters by selecting the Options item from the Reformat context menu or drop down. Thicker slices (also known as "slabbing" or "slab MPR") are computed by aggregating the data across the entire thickness according to the specified Slab Mode.

For your convenience, shortcuts to change slab mode and certain common thicknesses are provided on the Reformat menu.

Technical Notes

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Increasing the slice thickness will result in "slab MPR" where the viewer takes multiple subsamples of the volume and aggregates them together to form an image that is representative of the specified thickness. The method of aggregation can be chosen from the Slab Mode options, and the optimal choice will depend on the type of images being viewed. For example, Average Intensity can be used to reduce noise artifacts in MR images, whereas Maximum and Minimum Intensity can be used to view selected regions of CT images in a manner similar to traditional projection radiographs (e.g. CR, DX).

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Decreasing the slice spacing will result in a series where consecutive images overlap one another. The maximum slice spacing is always exactly the slice thickness, since any spacing greater than the thickness would mean that there a gap in the volume that is not represented by the slices on either side of it.

2D Fast Projection

Fast Projection is a special 2D case of 3D projection where the thickness of the slab is taken to be the entire depth of the stack of images and no reorientation of the volume is performed. The result is an image that cannot be freely rotated in 3D, but is basically an aggregation of all the original images according to the specified Slab Mode.

This function has particular utility for X-ray based tomographic image sets (e.g. CT, 3D X-ray, Breast Tomosynthesis) because it can create 2D views similar to traditional projection radiographs. For example, it can reformat a 3D Breast Tomosynthesis series as a single frame that functions in a similar way to a traditional mammogram.

Reset View

You can reset a reformatted view and go back to the original series at any time by selecting the Reset View option from the Reformat context menu or drop down. Please note that you can also use undo/redo if, for example, you had measurements on the original series.