When using MRI, in order to increase spatial resolution we need a longer acquisition time. We also need the same to increase signal to noise ratio (SNR). High tesla MRI, although it increases SNR, it has a problem with deep penetration called the skin effect. Deep structures might be difficult to visualize.
A new post-processing method called TDI seems to be useful to increase spatial resolution and it has a high SNR when imaging the brain white matter. It is also an objective technique and able to be automated. It basically calculates the number of tracts throughout the brain. It seems to help with the crossing fiber problem of fiber tracking by the use of high angular resolution diffusion imaging (HARDI).
A good paper in the topic is the following:
Calamante F, etal. Track-Density imaging (TDI): Super-resolution white matter imaging using whole-brain track-density mapping. NeuroImage, 53 (2010) 1233-1243.
Adolfo Cotter, MD