Hepatobiliary agents and their role in LI-RADS

Abstract

The Liver Imaging Reporting and Data System (LI-RADS) was introduced with the goal of standardizing the diagnosis of hepatocellular carcinoma. The 2014 version of LI-RADS incorporates the use of hepatobiliary contrast agents (HBAs) into the diagnostic algorithm, including gadoxetate disodium and gadobenate dimeglumine. Three new ancillary features are introduced: hepatobiliary phase (HBP) hypointensity and HBP hypointense rim favor malignancy, while HBP isointensity favors benignity. HBP hyperintensity favors neither malignancy nor benignity. In this review, we describe how to use these new features as well as numerous pitfalls associated with the use ofHBAs, including hemangiomas, cholangiocarcinomas, and focal confluent fibrosis. Importantly, findings on the HBP are not included as major criteria and therefore the criteria for the diagnosis of LI-RADS 5 observations remain unchanged, and so congruence with the Organ Procurement Transplant Network system remains intact. Additionally, we review how the major features in LI-RADS, arterial phase hyperenhancement, threshold growth, and washout and capsule appearance, may be affected with HBAs. Notably with HBAs, hypointensity on the delayed phase, termed the transitional phase, does not qualify as washout appearance due to the possibility of early parenchymal enhancement. It is hoped that the incorporation of HBAs into LI-RADS will help create consistency when interpreting HBA enhanced MRIs.

Added Value of a Gadoxetic Acid-enhanced Hepatocyte-phase Image to the LI-RADS System for Diagnosing Hepatocellular Carcinoma

“…Adding an HP might help to downgrade such an AP shunt to LR2 or LR1. 17,27 In our series, 15 benign lesions showed hypervascularity without washout on CECT or the late phase of dynamic MR imaging. Among them, 2 lesions were categorized as LR3.…”

“…Apart from inter-reader variability, we may have further improved the sensitivity for MR imaging with HP by taking into account these features in the modified LI-RADS guidelines. 27 High signal intensity even in precontrast T 1 WI can be another confounder. Even if the uptake of gadoxetic acid is reduced in the nodule, the high signal of the nodule on precontrast T 1 WI could mask the feature of hypointensity in HP images.…”

Recent Advances in the Imaging Diagnosis of Hepatocellular Carcinoma: Value of Gadoxetic Acid-Enhanced MRI

“…Finally, the latest 2014 LI-RADS guidelines also introduced its recommendation for the use of Gd-EOB-MRI to evaluate the dynamic enhancement pattern of hepatic nodules for the diagnosis of HCCs. It has differences from the JSH or KLCSG-NCC guidelines, including 1) "washout" appearance should be described on the PVP and 2) hypointensity on the HBP is regarded as one of the ancillary features favoring malignancy [13]. These differences in the included phase(s) for assessing "washout" between guidelines may have been derived from the different preferences for either higher sensitivity or higher specificity of a Gd-EOB-MRI diagnosis of HCC.…”

“…This is based on the typical dynamic enhancement pattern of arterial enhancement and washout on the portal/delayed phase in patients with liver cirrhosis or chronic liver disease [7,25]. However, the latest guidelines including those of the Japan Society of Hepatology (JSH) [10], the Korean Liver Cancer Study Group (KLCSG) and the National Cancer Center (NCC) [11], and the Liver Imaging-Reporting and Data System (LI-RADS) [12,13] have incorporated Gd-EOB-MRI into their diagnostic algorithms for HCC. According to the updated 2014 JSH guidelines, a noninvasive diagnosis of HCC can be made using Gd-EOB-MRI if a mass shows: 1) arterial hypervascularity and venous washout, or 2) arterial hypervascularity without venous washout, but with hypointensity on the HBP.…”

“…Although several previous guidelines have recommended that the enhancement pattern should be assessed using extracellular contrast media (ECCM)-enhanced multiphasic computed tomography (CT) and MRI [7,9], other recent guidelines have suggested Gd-EOB-MRI as one of the diagnostic tests for the noninvasive diagnosis of HCC [10][11][12][13]. Indeed, there is cumulative evidence of the value of Gd-EOB-MRI for the detection of small HCCs [14], and for the differentiation between HCCs and other hepatic lesions or hypervascular pseudolesions [15][16][17].…”