Resolution of Definition axial datasets

The following question has been sent by Judy Oltmann, CTA Technologist, USA:

Resolution of Definition Axial Datasets:
My question may have appeared vaque before. My radiology group has had a consistent complaint concerning the mottle or graininess, both terms applied, to the axial datasets acquired during our coronary scans with the Definition scanner. We have applied new kernal and slice thickness, increased flow rates for contrast and a fixed pitch with certain patients. The temporal resolution is too grainy for them at 82 ms, but much sharper than a reconstruction at 165 ms, resembling a 64 slice cardiac acquisition. The comment is that the 82 ms recon makes the diagnosis of a soft plaque difficult due to the mottle on the axial dataset.
I would like the opinion of other groups who are interpreting cardiac studies to give me some insight as too any possible solutions to their complaints. Also understand that in South Texas, our patients population averages 200 LBS and more.

Stephan Achenbach M.D., University of Erlangen-Nuernberg, Germany:

Indeed, image noise can be problematc expecially in very heavy patients. This is not specific to the DSCT scanner but holds true for all scanners. The default reconstruction should be 0.75 mm slice thickness and 0.4 mm increment, and B26 f should be used as standard kernel.
Increasing contrast flow rate is an option to improve image noise (we sometimes go up to 7 ml/s).
The pitch does not really play a role.
The “XXL mode” can be useful especially in patients whose heart rate is not so high.

See another answer to this question by Dr. Suranyi

See another answer to this question by Dr. Nicolaou