STI is a new MRI”technology in development. It consists on creating images and contrast based on the susceptibility of the tissue to the magnetic field. This susceptibility seems to be based to the anisotropic alignment of the molecules. The tissue is more susceptible when the angle to the magnetic field is smaller. A recent study in mouse, (Chunlei L. et al. 3D fiber tractography with susceptibility tensor imaging. NeuroImage (2012) 59: 1290-1298), shows a similar contrast to Diffusion Tensor Imaging (DTI), although DTI seems to be superior in small and complex fibers.
It would be interesting to compare STI to neuroanatomical tract tracing, since pathology is still the gold standard. This is a new technology that needs more development although the initial results look promising.
Adolfo Cotter, MD