Letter to the Editor on “LI-RADS-CEUS – Proposal for a Contrast-Enhanced Ultrasound Algorithm for the Diagnosis of Hepatocellular Carcinoma in High-Risk Populations”. Ultraschall in Med 2016; 37: 627–634

Dear Editor,

We designed a CEUS-based diagnostic algorithm (LI-RADS-CEUS) for lesions suspicious for HCC in high-risk patients modelled after CT- and MRI-based LI-RADS. Our work was submitted to UiM on April 13, 2016 and published e-first online on August 3, 2016, DOI: 10.1055/s-0042 – 112 221. Shortly after the publication in PubMed, we received an email (August 28, 2016) from Prof. Claude Sirlin. On behalf of the ACR CEUS LI-RADS working group, Prof. Claude Sirlin expressed concerns about potential confusion caused by the parallel development of a similar, but in several points different, algorithm called ACR CEUS LI-RADS v2016. We would like to clarify that at the time of submission and acceptance of our paper in UiM, no ACR CEUS LI-RADS algorithm was accessible in PubMed or on the ACR homepage. The ACR CEUS LI-RADS algorithm, CEUS LI-RADS v2016, was not available until recently, when it was published online on the ACR homepage in September 2016 [http://www.acr.org/Quality-Safety/Resources/LIRADS] Currently, no data evaluating the ACR CEUS LI-RADS algorithm is available. We agree that confusion caused by misunderstanding and misapplication of the two proposed algorithms should be avoided. We replied to Prof. Claude Sirlin and the ACR working group chaired by Yuko Kono from UC San Diego and co-chaired by Andrej Lyshchik from Thomas Jefferson University with respect to formal and scientific issues in a detailed e-mail on September 6^th (cc editorial board UiM). In Germany, clinical expertise in CEUS diagnosis of focal liver lesions has been growing for about 15 years as expressed by multi-center national studies (DEGUM studies) on CEUS in focal liver lesions [D. Strobel et al. Ultraschall in Med. 2011 Dec;32(6):593 – 597; D. Strobel et al. Ultraschall in Med. 2009 Aug;30(4):376 – 382; K. Seitz et al. Ultraschall in Med. 2009 Aug;30(4):383 – 389.] including data on hepatocellular carcinoma (HCC). Results from these national studies influenced the German national HCC guidelines [http://www.awmf.org/leitlinien/detail/ll/032–053OL.html]. The ready acceptance of CEUS in Germany in the clinical routine and the model of an algorithm for standardized assessment and documentation of cross-sectional imaging (LI-RADS, BI-RADS, TI-RADS) have prompted us to test a similar concept in a clinical setting, which we named LI-RADS-CEUS. For LI-RADS-CEUS as presented in our paper, a high-risk population was defined according to the national German HCC guidelines. In our LI-RADS-CEUS algorithm, categories were named “LR-CEUS”, not “LR” as in original ACR LI-RADS for CT and MRI. With recent meta-analyses showing better sensitivity with unchanged specificity for the combination of LR-4 and LR-5 in MRI LI-RADS [A Darnell et al. Radiology. 2015 Jun;275(3):698 – 707], our algorithm LI-RADS-CEUS was designed from the outset to distinguish four categories only and contains a clearly defined category of LR-CEUS-C to designate intrahepatic cholangiocellular carcinoma (ICC). Difficulties in the differential diagnosis between intrahepatic cholangiocellular carcinoma (ICC) and HCC led to the exclusion of CEUS as a first-line imaging modality equivalent to CE-CT and CE-MRI from the AASLD and EASL guidelines. This remains a controversial issue [D Wildner et al. Ultraschall in Med. 2015 Apr;36(2):132 – 139]. We hope this has clarified the timing and differences between LI-RADS-CEUS as suggested by our group and the ACR CEUS LI-RADS algorithm published on the ACR homepage. We also look forward to the scientific evaluation of both algorithms in patients at risk for HCC in order to directly compare diagnostic accuracy and clinical applicability.

Sincerely