This is an article from the January issue of European Radiology by Khan MF et al, where they compared the use of 4-slice and 16-slice CT in the evaluation of bypass grafts. They found that thin MIPs and VRT images are the most useful in assessing grafts, that 16-slice CT depicts grafts better than 4-slice, but that there was no difference in assessing the distal anastomosis.
The latter is a little difficult to understand, though it is likely that the issue is of spatial resolution, not speed and temporal resolution. The 64-slice CT has a far superior spatial resolution of 0.37mm and it is likely that there would be better visualization of the distal anastomosis with this scanner. Our experience so far has been very positive.