Definition:

• No significant change in diameter of an observation, measured on examinations performed on different dates and in the absence of treatment.

Synonyms:

• Synonyms: Stable size

Comments:

• Applies to observations with
  • No measurable change in diameter or
  • A change in diameter so small that the change is attributable to artifact, differences in imaging technique, or measurement error.
• Diameter stability ≥ 2 years in the absence of treatment is an ancillary feature that favors benignity.
• Radiologists at their discretion may apply diameter stability ≥ 2 years to downgrade category.
• Diameter stability should be assessed on images in the same plane and, if possible, acquired in the same phase or sequence.
• After treatment, diameter stability should not be used as an ancillary feature favoring benignity.