CEUS EXAMINATION

Liver CEUS Lexicon

• Observation: Distinctive area with imaging features that differ from those of adjacent liver parenchyma; may be nodule or pseudolesion
• Nodule: Discrete mass of rounded or irregular shape
  • On CEUS, with exception of focal fatty infiltration and sparing, most liver observations are true nodules
  • CT and MR literature often uses term "observation" to describe focal signal abnormality since many findings detected on CT and MR may not be true nodules but rather contrast enhancement abnormalities
• CEUS exam characterized as adequate when entire observation or nodule can be unequivocally visualized for entirety of exam
  • Observations or nodules that cannot be categorized due to image degradation or omission reported as "not categorizable"
• Location: Liver observation or nodule location using Couinaud liver segment classification
• Size: Largest dimensions of liver observation or nodule
  • No universally accepted guidelines for US measurements
  • Measurements preferably performed on precontrast B-mode imaging
  • If margins indistinct on B-mode imaging, measurements on arterial-phase CEUS could be performed instead
    • CEUS measurements might be affected by contrast blooming artifact or inclusion of hyperenhancing surrounding liver parenchyma in observation or nodule size measurement
• Unequivocal diameter increase: Increase in maximal diameter of observation or nodule, measured on exams performed on different dates, which is not attributable to artifact, differences in technique or modality between exams, or measurement error
  • Often used as ancillary feature to suggest malignancy
• Unequivocal diameter decrease: Decrease in maximal visualized diameter of observation or nodule, measured on exams performed on different dates, which is not attributable to artifact, differences in technique or modality between exams, or measurement error
  • Often used as ancillary feature to suggest benign process
• Diameter stability: No significant change in maximal diameter of observation or nodule, measured on exams performed on different dates over ≥ 2 years, and in absence of treatment
  • Often used as ancillary feature to suggest benign process
• Judgment of US examiner to determine if changes in size unequivocal and not attributable to artifact, differences in technique or modality between exams, or measurement error

Enhancement Phases

Arterial-Phase Enhancement

Arterial-Phase Hyperenhancement

Washout

Tumor-in-Vein

Mosaic Architecture