Definition:

• Unequivocal increase in the diameter of an observation, measured on examinations performed on different dates, which is not attributable to artifact, differences in technique between the two examinations, or measurement error.

Synonyms:

• Synonyms: Growth, Increased size

Comments:

• A diameter increase by a minimum of 5mm AND of ≥ 50% over ≤ 6 months or ≥100% over > 6 months is considered threshold growth, which is a major feature of HCC.
  • A diameter increase of ≥ 50% on exams obtained ≤ 6 months apart in combination with diameter 10-19mm and arterial phase hyperenhancement is required to categorize an observation as LR-5g. A new observation cannot be categorized as LR-5g. 
• A diameter increase less than threshold growth is an ancillary feature that favors HCC. LI-RADS does not stipulate a minimum increase in diameter required for use as an ancillary feature.
• Radiologists at their discretion may apply diameter increase less than threshold growth to upgrade category (up to LR-4).
• Radiologists should exercise judgment in the application of this feature, which applies only to an unequivocal increase in the diameter of an observation.
• Diameter increase should be assessed on images in the same plane and, if possible, acquired in the same phase or sequence.