Diagnosis of Hepatocellular Carcinoma with Non-Invasive Imaging: a Plea for Worldwide Adoption of Standard and Precise Terminology for Describing Enhancement Criteria Diagnose des hepatozellulären Karzinoms mittels nicht-invasiver Bildgebung: Ein Plädoyer für die weltweite Umsetzung einer standar

Hepatocellular carcinoma in cirrhosis is unique in oncology since a definitive diagnosis based on non-invasive imaging can be used without biopsy confirmation to determine even the most radical therapies such as liver transplantation. Given the enormous responsbility assigned to non-invasive imaging in guiding HCCmanagement one would expect that there would be standardized terminology in use throughout the world for describing the diagnostic imaging criteria. Surprisingly, this is not the case. Different guidelines have adopted different terminology for assessing the temporal enhancement characteristics of HCC. The adoption of different terminology by different guidelines, even if intended to have similar meaning, contributes to inconsistency in clinical care, causes confusion in research, and is a barrier to progress in the field. It is time to standardize the terminology for describing temporal enhancement criteria, which will be suggested at the end of the present editorial in line with recently published relevant documents in this field. A summary of the current guidelines and of the variance of the terminology is useful to understand the potential causes of variability and misunderstandings. Guidelines released by the AASLD in 2005 [1] recognized the need to incorporate imaging features from both the arterial phase and the subsequent venous/delayed phase. This was done to help avoid false-positive diagnosis of perfusion disturbances caused by arterioportal shunting which also can manifest with hyperenhancement in the arterial phase. The criteria for the diagnosis of HCC was a lesion showing “arterial hypervascularity that washes out in the early or delayed venous phase” [1]. The update of these guidelines in 2011 adopted the wording of “intense arterial uptake followed by wash out in the venous-delayed phases” [2]. Although the AASLD guidelines should be lauded for recognizing the importance of “washout”, the terminology advocated by the AASLD is suboptimal. The term “hypervascularity” is ambiguous as it encompasses multiple different pathophysiological alterations – including number and size of vessels, type of vessels, quality of their walls (fenestrated or not fenestrated sinusoids, capillarization), degree of vascular tone, etc. – most of which cannot be assessed reliably by imaging. A descriptive term would be more appropriate. In this sense, the usage of “intense arterial uptake” in the 2011 update is an improvement [2], but remains suboptimal for several reasons. In a liver with only arterial inflow and no portal perfusion (e. g. a patient with reversal of portal flow due to portal hypertension or TIPS), any part of the liver, including benign parenchyma, has intense arterial “uptake”. Moreover, no cancer and no part of the liver, literally takes up contrast agents in the arterial phase. Even contrast agents that eventually are transported into liver cells via membrane transporters do not enter cells in any meaningful concentration during the arteial phase. Thus the wording, “intense arterial uptake”, is pathophysiolgicaly incorrect and cannot be considered appropriate. The EASL 2012 guidelines [3] as well as the Spanish guidelines [4] utilized similar imperfect terminology as the AASLD guidelines Fabio Piscaglia Masatoshi Kudo Kwang-Hyub Han Claude Sirlin Editorial