I fear we are not the best people to ask here. Of course, general imaging principles apply: The better the resolution and signal to noise ratio, the more accurate the results may be.
Maybe you can get some insight here: http://www.ncbi.nlm.nih.gov/pubmed/25113409
In any case, I personally prefer T2 sequences over T1 sequences since they show the STN. If possible, 3D sequences with high resolution are optimal. However, more “clinical” acquisitions with high in-plane resolution and larger slice thicknesses are also okay. Up to three post-op sequences can be used in Lead-DBS in combination, e.g. an axial, coronar and saggital acquisition.
Hope this helps,