Factors related to low contrast resolution in CT scanners.

The concept of "low contrast resolution" in CT scanners is examined. Several questions are raised, not only about limitations to interpretation of figures of merit of low contrast resolution, such as contrast-detail diagrams; but also, interpretation of related CT physical performance parameters, such as: noise, dose, spatial resolution and slice width (or sensitivity profile). Caveats are raised concerning interpretation of contrast-detail studies and the degree to which first-order observer studies are reflective of the actual clinical situation. Particular care is suggested in interpretating contrast-detail diagrams in which sensitivity, specificity and the number of target signals may be varying.