Technical requirements for CT

• Arterial phase, portal venous phase and delayed phase imaging are required.Pre-contrast imaging suggested.
  • Late arterial phase strongly preferred over early arterial phase.
• Multi-planar reformations suggested.
• Arterial, portal venous, and delayed phase are all required for CT per OPTN policy to assign HCC exception points. Pre-contrast imaging not required per OPTN policy.

Background

• Arterial phase and portal venous phase generally are the most useful phases for characterization of LI-RADS major features and hence are required. Delayed phase imaging improves detection and characterization of HCC, particularly in small lesions
• Late arterial phase is strongly preferred. HCC enhancement usually is greater in the late than in the early arterial phase. Some HCCs show hyper-enhancement only in the late arterial phase.
• While pre-contrast CT imaging may contribute to LI-RADS categorization, the incremental benefit often is low, and the addition of these images increases radiation exposure. The risk-benefit of pre-contrast CT imaging is not established. Hence, LI-RADS suggests but does not mandate pre-contrast imaging.
• Multi-planar reformations may be helpful to differentiate mass from non-mass and to identify capsule appearance. They also may be used to measure observation diameter if they depict observation margins more clearly than axial images.