This is an experimental plugin, and I have doubts about its correctness—in particular, the results are strange when the ratio of pixelWidth : pixelHeight : pixelDepth is other than 1:1:1. In addition, the results in any case seem to be different from those from other implementations, such as this [MATLAB](MATLAB) one. I don’t have time to work on this any more (and no longer work in academia at all) so if someone were interested in taking it over, that would be brilliant.
This plugin implements the algorithm for detection of vessel- or tube-like structures in 2D and 3D images described Frangi et al 1998. 
In my experience, this method produces consistently better results than the Tubeness plugin for isotropic image data, although it is significantly slower.
These screenshots show the results on an example file:
Alejandro F. Frangi, Wiro J. Niessen, Koen L. Vinc and Max A. Viergever (1998), “Multiscale Vessel Enhancement Filtering”, Medical Image Computing and Computer-Assisted Interventation — MICCAI’98 Lecture Notes in Computer Science 1496/1998: 130 .