How should an US-3 observation be managed if there is no correlate on subsequent multiphase contrast-enhanced CT or MRI??
A patient presents for US Surveillance, and the prior US Visualization Score was C. Should the patient undergo a test other than repeat US?
What percentage of US exams are adequate? What factors are associated with poor visualization scores?
Why is short-interval follow-up US recommended, rather than multiphase contrast-enhanced imaging, for observations smaller than 10 mm (e.g., US-2 Subthreshold Category)?


FAQ-126: How should an US-3 observation be managed if there is no correlate on subsequent multiphase contrast-enhanced CT or MRI?

  

More research in this area is needed, and there is no single correct answer to this question. The level of clinical concern, lesion size, serum AFP values, and other patient factors may influence management decisions on a case-by-case basis. Potential next steps include: 

  1. Performing a contrast-enhanced US (CEUS) of the sonographically visible observation. 

  2. Performing an alternative imaging modality, e.g. CT if it was not visible on MRI, or MRI if it was not visible on CT. The time interval between studies will need to be determined based on the level of clinical suspicion. 

  3. Performing short interval follow-up US (in 3-6 months) to assess for stability or growth 

  4. Multidisciplinary discussion with consideration of biopsy of the observation  


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FAQ-127: A patient presents for US Surveillance, and the prior US Visualization Score was C. Should the patient undergo a test other than repeat US?

In general, a patient can undergo a repeat US because the reasons for Visualization B or C can change. Examples: 

  • Bowel gas that obscured the liver on prior imaging can resolve on follow-up US with improved bowel preparation.

  •  A patient’s ability to comply with breathing and positioning instructions may improve, yielding an improved Visualization Score.

  • The degree of hepatic steatosis, if present, can change.

  • A different sonographer or the same sonographer on a different day might achieve a higher quality exam with better liver visualization.


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FAQ-128: What percentage of US exams are adequate? What factors are associated with poor visualization scores?

  

Emerging data shows that the vast majority of US LI-RADS screening/surveillance studies are diagnostically acceptable with Visualization Scores of A or B. Visualization C Scores are uncommon (~5% of exams). Factors associated with a Visualization C Score include high body-mass-index, moderate to severe hepatic steatosis, and Child-Pugh class B and C cirrhosis. Follow-up recommendations in patients with persistent Visualization C should be made on a case-by-case basis. 


Reference List:

Millet JD, Kamaya A, Choi HH et al. ACR Ultrasound Liver Reporting and Data System: Multicenter Assessment of Clinical Performance at One Year. J Am Coll Radiol. 2019 Dec;16(12):1656-1662.


Choi HH, Perez MG, Millet JD, Liang T, Wasnik AP, Maturen KE, Kamaya A. Association of advanced heaptic fibrosis and sonographic visualization score: a dual-center study using ACR US LI-RADS. Abdom Radiol. 2019 Apr;44(4):1415-1422.


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FAQ-129: Why is short-interval follow-up US recommended, rather than multiphase contrast-enhanced imaging, for observations smaller than 10 mm (e.g., US-2 Subthreshold Category)?


Many of these small observations have no CT or MRI correlate and recalling all patients with such lesions would be an inefficient use of imaging resources. Furthermore, the definitive diagnosis of HCC (LR-5) cannot be made in observations < 10 mm in LI-RADS, AASLD, OPTN, etc. Thus the recommendation for US-2 Subthreshold is a short-interval follow-up US in 3-6 months. A multiphase contrast-enhanced study should be performed when the observation meets or exceeds the threshold size of 10 mm.  


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