Basic tutorial to start a Stereotactic pre-surgery plan with MNPS. Includes loading of stereotactic CTs and registration with non-stereotactic MRIs. Does not cover advanced topics like functional maps, DBS simulations, 3D rendering, Radiosurgery o Brachytherapy. Search for other presentations covering advanced topics. This version of the document corresponds to MNPS version 10.33.04 MNPS is an Stereotactic Planning System, for Windows PCs developed by "MEVIS Informática Médica LTDA"l.

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Getting Started with MNPS, version 10.33.04
1. Copy all DICOM images of the patient in a folder in c:MNPSdicom . Example, if the patient has
the name "John Doe", create the C:MNPSdicomJohn_Doe. Creating a subfolder for each kind
of images, CT, MRI, etc.
2. If it is a simple biopsy, without merging with MRI, drag one (1) CT file (stereo-CT) and drop over
the icon (shortcut) of MNPShell on the desktop:
3. Answer if the image belongs to a stereotactic images set.
The DICOM filter will open, which will do the images pre-processing to save them in the internal
format of MNPS (*.IMG).
4. If the images are scattered across several subdirectories, use the third toolbar icon and navigate
through the folders until the base of the subfolders containing all DICOM images. Then click on
"File" and select "Scan Path in Depth".
5. At any time, you can change the number of images on the screen by viewing an image at a time
or a mosaic with several pictures. To do this you can click on the fourth button from the toolbar
or the View option from the main menu. This is a matter of user preference.
6. Sort images on the sequence according to the orientation relative to patient anatomy. Click in
Options from the main menu and select “Sort images”.
Select the sorting criteria according to image orientation.

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Axial (transverse) images must be sorted by Z, coronal by Y and sagittal by X. CT images are
always in axial orientation. The program will sort the images. Next, if the sort is satisfactory, click
"Exit sort".
7. The images are all initially selected to be processed and converted to IMG format. However, you
may need to discard some images for different reasons. In general, it is recommended to
dispose, where possible, images with artifacts caused by frame and some images where the
fiducials are completely united. To deselect a picture, make a click on it and hit the Space key.
Space select or deselect a frame. You can also deselect or select by clicking in a blue small
square on the right upper corner of each image.
8. To adjust the field of view (FOV), click the icon with a square in dotted line (the fifth icon on the
toolbar, shown below). Leave the red frame slightly larger than the fiducials. To accept the FOV,
press ENTER.
The selected FOV applies to all images, therefore, it is recommended to go through the set of
images checking if in all of the fiducials are within the FOV.
9. IMG images files will be created with names derived from the name of the patient. If you need to
change this name, use “Options”, from the main menu and select “Rename”.
10. When finished selecting DICOM images, adjust FOV, etc., click the floppy disk icon, the system
will save the images (*.img) and ask if should call the MNPS to start the search of fiducials: "Call
MNPS with this patient?" Reply YES.
11. The MNPS opens asking how the placement of fiducials was made, the frame type, etc. (only for
stereotactic systems with several fiducials model or fiducials that could be fixed in different

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positions). Reply all and click OK. After that the system ask for confirmation. If it is correct,
confirm with OK.
12. Beginning search of fiducials. The MNPS tries to find them automatically, but the user must
confirm with <ENTER> if it is right or <ESC> if it is wrong. Watch very carefully each image until
complete.
13. The system prompts you to save the data planning. Fill in the fields as required and confirm with
OK.
14. From here each image is properly calibrated and registered to the stereotactic coordinates. The
MNPS goes to the image mosaic. Double-clicking an image.
15. If it is for a biopsy and only needs coordinates of the target, just search the image with the best
point for biopsy and click on the desired place. Cursor coordinates will be in the lower right
corner as X, Y, Z. To navigate through the images using the arrow buttons or the PageUp /
PageDown keys on the keyboard.
16. Create a point of interest (POI) for the biopsy location. Click on the desired place for biopsy and
click the "POI" button on the right side of the toolbar. Give a name for the POI.
17. To view the coordinates of the POIs open the POI table on the icon that is at left side of the POI
icon. To print the POI table click the printer icon that is underneath the icon mentioned above,
select "POI Table".
18. To create a POI at the end of a needle trajectory click the icon that looks like a path, next to the
POI table icon.
19. Save the plan by clicking the icon that looks like a floppy disk.

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How to merge the previous planning CT with an MRI set of the patient. Image registration and
fusion.
20. Drag one (1) DICOM file from MRI and drop on the MNPShell icon.
21. Reply that it is not a stereotactic set of images, as they were made without fiducials. For those
cases you can use “Virtual Fiducials Mode” or plain “Non Stereotactic Image Set”.
22. The system will display the images of the first sequence found. As in MRI can be several
sequences, you should use the File / Open option or click the corresponding button on the
toolbar to display the list of sequences available for the patient and select the one that will be
used for registration and fusion. In the list, click on the desired sequence. Images of that
sequence will be displayed.
23. For MRI sequence is always necessary to order the images using Options / Sort images by
selecting the "Select sort criteria" as according to plane orientation, whether sagittal, coronal or
transverse.
24. Select or deselect images, with space bar. Adjust FOV if necessary.
25. Finish saving changes by clicking the floppy disk icon.
26. If you selected “Virtual Fiducials Mode”, MNPS will continue. If you selected “Non-stereotactic
Image Set” CAT3D program will be called. Answer YES to the question "Call CAT3D with this
patient?" or "Call MNPS with this patient?"
27. CAT3D or MNPS (in Virtual Fiducials Mode) starts.
28. The system prompts you to save the planning. Fill in the fields as required and confirm with OK.
29. The CAT3D or MNPS starts by the mosaic. Double-click an image to enter the main window
where you can select POIs and draw ROIs if necessary. Click the EXIT icon or press <ESC>
key.
30. Go to File menu and select "Export for Fusion."
31. Return to MNPS. Click the icon that looks like a split axial image or <F5> key. You will see the
list of previously imported sequences. Select the sequence that will be used for Registration and
fusion.

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32. MNPS asks if you need “Registrations Points”
Registration Points are very useful in cases with sagittal or coronal MRI sets, because they are
used as initial approximations of the automatic registration process. But let us keep this first
example simple and click in “NO”, to have full automatic registration.
33. Leave MNPS optimize the fusion for a while until it tells that ran up to 8 times without
improvements. Please, keep watching the side window for consistency of the borders between
the two image modalities is satisfactory. To finish optimizing use <ESC> key. An informational
window appears with the results of the fusion Press ESC to close it.
34. To set the area where the MRI is displayed, use <Ctrl-F5>. You will see a red rectangle that
defines the region where the MRI image will be displayed beside CT. This rectangle can be
dragged with the mouse by clicking the circle in the center of it, and resized by dragging the
lower right corner. You can also move the rectangle with arrow keys, and change the size with
numeric key <+> and <->. Press <ENTER> to fix the rectangle position.
35. On the merged image (MRI + CT) you can define POIs and view the coordinates in the manner
already explained above. The coordinates on the registered MRI are transformed into
stereotactic coordinates continuously.
This document shows the very basic operations of MNPS. For in-depth information, please, read the
manuals and other published documents covering the full set of tools that MNPS presents. You can also
contact Mevis about the next available MNPS course.