Skull base tumour
This model will be divided in two parts.
Part one: Tumour
Part two: Skull with arteries
DICOM to STL conversion:
Creating tumour file
Step 1: Import MRI images in the slicer in which tumour is visible.
Step 2: Go to the segment editor module. Click on add and create a new segment named tissue by choosing the preset “tissue”
Step 3: Click on the threshold option and set it according to the tumour so that it covers the whole tumour and nothing else and click on apply. If it covers other areas of the brain as well then we will clean it using scissors and islands options. Click on show 3d option.
Step 4: Now we will clear the remaining areas:
i) Using scissor effect and clicking on the option erase outside to erase all the other selected regions.
ii) using islands effect and clicking on the option “keep only the largest island”
Step 5: Now export the file by clicking on the option export to files in segmentation options.
Creating arteries file
Step 1: Import CT angiography file of the patient in the slicer.
Step 2: Load the CT angio and NCCT head file in the slicer.
Step 3: Now click on the “all modules” option and load general registration(elastix) module.
Step 4: Now choose the following options and click on apply.
Step 5: Now choose the module “Subtract scalar volumes” modules and choose the following options and click apply.
Step 6: Now click on vesselness filtering option and choose following parameters and click on start.
Step 7: Adjust visualization of vesselness image in Volumes module. Set window (W) value to 1.0, set level (L) value to 0.5. Set Threshold to Off.
Step 8: Now go to the segment editor and choose vesselness filtered as master volume and create a new segment for arteries like we did for tumour.
Step 9: Go to the threshold option and set it to 0.15 to 0.97.
Step 10: Click on show 3D option and click on the islands effect and choose to keep only the largest island to remove all the unwanted areas.
Step 11: Final arteries
Thickening arteries(If arteries are too thin to print):
Now you have an artery file. Click on the edit menu and click on make solid button and it will solidify the arteries. You can change the parameters if you want.
Now import skull and combine these two. So now we have 2 files one with a tumour and another with skull and arteries. It will be printed in two colours.
Tumour- Brown (Depending upon the Doctor’s requirement)
Skull and arteries – White
- The skull file can be easily extracted for CT scan like we do for cranioplasty.
Post Processing of prints
After removing the support material we will paint the arteries with red acrylic colour. We will use the white masking tape so that the other parts remain clean as shown below..