@Marco_Festugato Please, try to honor the subject of the thread so that the discussion is kept healthy, and other users can find more easily answers and/or pointers to similar questions.
Now, the question you are asking is again related to image processing tools, such as ITK, so please post your question at the right discussion forum.
For the time being, you may find useful the following ITK examples:
https://itk.org/ITKExamples/src/Filtering/ImageFeature/SegmentBloodVessels/Documentation.html
https://itk.org/ITKExamples/src/Nonunit/Review/SegmentBloodVesselsWithMultiScaleHessianBasedMeasure/Documentation.html
Note that vessel segmentation is a complex task, and usually requires domain or image-specific development. So do not expect the above examples to provide you with a perfectly clean segmentation.