How reader perception of capsule affects interpretation of washout in hypervascular liver nodules in patients at risk for hepatocellular carcinoma

Multimodality imaging of hepatocellular carcinoma and intrahepatic cholangiocarcinoma

Hepatocellular carcinoma and intrahepatic cholangiocarcinoma are the two most common primary malignant tumors of the liver. The similarities and variations in imaging characteristics that may aid in distinguishing between these two primary tumors will be discussed and outlined in this review. Knowledge of imaging techniques that are currently available would assist in the differentiation between these primary malignancies.

The role of enhancing capsule and modified capsule appearances in LI-RADS for diagnosing HCC ≤ 3.0 cm on gadoxetate disodium-enhanced MRI

OBJECTIVES

To evaluate the value of using enhancing capsule (EC) or modified capsule appearance as a major feature in LI-RADS for diagnosing HCC ≤ 3.0 cm on gadoxetate disodium-enhanced MRI (Gd-EOB-MRI), and to explore the relationship between the imaging features and the histological fibrous capsule.

METHODS

This retrospective study enrolled 342 hepatic lesions ≤ 3.0 cm in 319 patients that underwent Gd-EOB-MRIs from January 2018 to March 2021. During dynamic phases and hepatobiliary phase, the modified capsule appearance added the nonenhancing capsule (NEC) (modified LI-RADS + NEC) or corona enhancement (CoE) (modified LI-RADS + CoE) to EC as an alternative capsule appearance. Inter-reader agreement of imaging features was assessed. The diagnostic performances of LI-RADS, LI-RADS with EC ignored, and two modified LI-RADS were compared, followed by Bonferroni correction. Multivariable regression analysis was performed to identify the independent features associated with the histological fibrous capsule.

RESULTS

The inter-reader agreement on EC (0.64) was lower than that on the NEC alternative (0.71) but better than that on CoE alternative (0.58). For HCC diagnosis, compared to LI-RADS, LI-RADS with EC ignored showed significantly lower sensitivity (72.7% vs. 67.4%, p < 0.001) with comparable specificity (89.3% vs. 90.7%, p = 1.000). Two modified LI-RADS showed slightly higher sensitivity and lower specificity than LI-RADS, without statistical significance (all p ≥ 0.006). The AUC was highest with modified LI-RADS + NEC (0.82). Both EC and NEC were significantly associated with the fibrous capsule (p < 0.05).

CONCLUSION

EC appearance improved the diagnostic sensitivity of LI-RADS for HCC ≤ 3.0 cm on Gd-EOB-MRI. Considering NEC as an alternative capsule appearance allowed for better inter-reader reliability and comparable diagnostic ability.

KEY POINTS

• Using the enhancing capsule as a major feature in LI-RADS significantly improved the sensitivity of diagnosing HCC ≤ 3.0 cm without reducing specificity on gadoxetate disodium-enhanced MRI. • Compared to the corona enhancement, the nonenhancing capsule might be a preferable alternative capsule appearance for diagnosing HCC ≤ 3.0 cm. • Capsule appearance should be considered a major feature in LI-RADS for diagnosing HCC ≤ 3.0 cm, regardless whether the capsule appears to be enhancing or nonenhancing.

Improved diagnosis of histological capsule in hepatocallular carcinoma by using nonenhancing capsule appearance in addition to enhancing capsule appearance in gadoxetic acid-enhanced MRI

To assess the value of nonenhancing capsule by adding to enhancing capsule in gadoxetic acid-enhanced MRI (EOB-MRI) in comparison with contrast-enhanced CT (CE-CT) for diagnosing histological capsule in hepatocellular carcinoma (HCC). One-hundred fifty-one patients with HCC who underwent both CE-CT and EOB-MRI were retrospectively reviewed. Liver Imaging-Reporting and Data System (LI-RADS) v2018 imaging features, including enhancing and nonenhancing capsule were evaluated by two readers in CE-CT and EOB-MRI. Frequencies of each imaging feature were compared between CE-CT and EOB-MRI. The area under the receiver operating characteristic (AUC) curve for the diagnosis of histological capsule was compared across the following three imaging criteria: (1) enhancing capsule in CE-CT, (2) enhancing capsule in EOB-MRI, and (3) enhancing/nonenhancing capsule in EOB-MRI. Enhancing capsule in EOB-MRI was significantly less frequently depicted than that in CE-CT (p < 0.001 and = 0.016 for reader 1 and 2). Enhancing/nonenhancing capsule in EOB-MRI achieved a similar frequency of enhancing in CE-CT (p = 0.590 and 0.465 for reader 1 and 2). Adding nonenhancing capsule to enhancing capsule in EOB-MRI significantly increased AUCs (p < 0.001 for both readers) and achieved similar AUCs compared with enhancing capsule in CE-CT (p = 0.470 and 0.666 for reader 1 and 2). Adding nonenhancing capsule to the definition of capsule appearance can improve the diagnosis of capsule in EOB-MRI for the diagnosis of histological capsule in HCC and decrease discordance of capsule appearance between EOB-MRI and CE-CT.

LiSNet: An artificial intelligence -based tool for liver imaging staging of hepatocellular carcinoma aggressiveness

BACKGROUND

Presurgical assessment of hepatocellular carcinoma (HCC) aggressiveness can benefit patients' treatment options and prognosis.

PURPOSE

To develop an artificial intelligence (AI) tool, namely, LiSNet, in the task of scoring and interpreting HCC aggressiveness with computed tomography (CT) imaging.

METHODS

A total of 358 patients with HCC undergoing curative liver resection were retrospectively included. Three subspecialists were recruited to pixel-wise annotate and grade tumor aggressiveness based on CT imaging. LiSNet was trained and validated in 193 and 61 patients with a deep neural network to emulate the diagnostic acumen of subspecialists for staging HCC. The test set comprised 104 independent patients. We subsequently compared LiSNet with an experience-based binary diagnosis scheme and human-AI partnership that combined binary diagnosis and LiSNet for assessing tumor aggressiveness. We also assessed the efficiency of LiSNet for predicting survival outcomes.

RESULTS

At the pixel-wise level, the agreement rate of LiSNet with subspecialists was 0.658 (95% confidence interval [CI]: 0.490-0.779), 0.595 (95% CI: 0.406-0.734), and 0.369 (95% CI: 0.134-0.566), for scoring HCC aggressiveness grades I, II, and III, respectively. Additionally, LiSNet was comparable to subspecialists for predicting histopathological microvascular invasion (area under the curve: LiSNet: 0.668 [95% CI: 0.559-0.776] versus subspecialists: 0.699 [95% CI: 0.591-0.806], p > 0.05). In a human-AI partnered diagnosis, combining LiSNet and experience-based binary diagnosis can achieve the best predictive ability for microvascular invasion (area under the curve: 0.705 [95% CI: 0.589-0.820]). Furthermore, LiSNet was able to indicate overall survival after surgery.

CONCLUSION

The designed LiSNet tool warrants evaluation as an alternative tool for radiologists to conduct automatic staging of HCC aggressiveness at the pixel-wise level with CT imaging. Its prognostic value might benefit patients' treatment options and survival prediction.

What is the "washout" of hepatocellular carcinoma as observed on the equilibrium phase CT?: consideration based on the concept of extracellular volume fraction

PURPOSE

To verify the hypothesis that extracellular volume fraction (ECV) and precontrast CT density are the main determinants of washout of hepatocellular carcinoma (HCC) at the equilibrium phase CT.

MATERIALS AND METHODS

Between 2018 and 2020, patients with surgically resected HCC were recruited who had undergone preoperative 4-phase CT. Those larger than 6 cm were excluded to minimize the possibility of intratumoral hemorrhage or degeneration. Two radiologists reviewed the whole images in consensus and divided cases into washout positive and negative groups. Washout positive group at the equilibrium phase was defined as "HCC showing relatively low density as compared to the surrounding background liver (BGL), irrespective of the presence of early enhancement or fibrous capsule". Several clinico-pathological and radiological features, including ECV and precontrast CT density, were correlated to the presence of washout, using uni- and multi-variable analyses.

RESULTS

27 HCC in 24 patients met the inclusion criteria. 22 (82%) and five HCC belonged to washout positive and negative groups, respectively. Univariable analysis revealed ECV of HCC and BGL, ECV difference between HCC and BGL, and presence of fibrous capsule on the equilibrium phase CT were the significant factors. Multivariable analysis showed ECV of HCC and BGL, and precontrast CT density of BGL, were the independently significant factors related to washout, suggesting washout is more likely observed with lower HCC ECV, higher BGL ECV, and higher BGL precontrast CT density.

CONCLUSION

Major determinants of washout of HCC may be ECV of HCC and BGL, and precontrast CT density of BGL.

Detection of hepatocellular carcinoma in a population at risk: iodine-enhanced multidetector CT and/or gadoxetic acid-enhanced 3.0 T MRI

OBJECTIVE

To evaluate the diagnostic performance of iodine-enhanced multidetector CT and gadoxetic acid-enhanced 3.0 Tesla (T) MRI for detection of hepatocellular carcinoma of patients.

DESIGN

Retrospective, multicentre cohort study.

SETTING

The Gong'an County People's Hospital, Gong'an County, China and the First People's Hospital of Jingzhou City, China.

PARTICIPANTS

Reports of CT, MRI and liver biopsies/histopathology data of a total of 815 patients who at risk were reviewed.

PRIMARY AND SECONDARY OUTCOME MEASURES

The lesions that possessed detection in the plain scan phase, enhanced arterial phase and/or enhanced portal phase of CT images and the lesions that possessed enhancements in the plain scan phase, enhanced arterial phase, enhanced portal phase and/or hepatobiliary phases of MRI were considered hepatocellular carcinoma. The decision of hepatocellular carcinoma was made based on the current Liver Imaging and Data Reporting System for diagnosing hepatocellular carcinoma.

RESULTS

True positive hepatocellular carcinoma (563 vs 521, p=0.0314), true negative hepatocellular carcinoma (122 vs 91, p=0.0275), false positive hepatocellular carcinoma (88 vs 123, p=0.0121), false negative hepatocellular carcinoma (42 vs 80, p=0.0005), specificity (58.10 vs 42.52, p=0.0478) and negative clinical utility (0.1 vs 0.073, p=0.0386) were superior for gadoxetic acid-enhanced 3.0 T MRI than those of iodine-enhanced multidetector CT. Sensitivity and accuracy for gadoxetic acid-enhanced 3.0 T MRI were 93.06% and 77.40 %, respectively, and those for iodine-enhanced multidetector CT were 86.69% and 75.09 %, respectively. Likelihood to detect hepatocellular carcinoma for gadoxetic acid-enhanced 3.0 T MRI was 0-0.894 diagnostic confidence/lesion, and that for iodine-enhanced multidetector CT was 0-0.887 diagnostic confidence/lesion.

CONCLUSION

Gadoxetic acid-enhanced 3.0 T MRI facilitates the confidence of initiation of treatment of hepatocellular carcinoma.

LEVEL OF EVIDENCE

III.

TECHNICAL EFFICACY STAGE

4.

Does Training in LI-RADS Version 2018 Improve Readers' Agreement with the Expert Consensus and Inter-reader Agreement in MRI Interpretation?

BACKGROUND

The Liver Imaging Reporting and Data System (LI-RADS) was established for noninvasive diagnosis for hepatocellular carcinoma (HCC). However, whether training can improve readers' agreement with the expert consensus and inter-reader agreement for final categories is still unclear.

PURPOSE

To explore training effectiveness on readers' agreement with the expert consensus and inter-reader agreement.

STUDY TYPE

Prospective.

SUBJECTS

Seventy lesions in 61 patients at risk of HCC undergoing liver MRI; 20 visiting scholars.

FIELD STRENGTH/SEQUENCE

1.5 T or 3 T, Dual-echo T₁ WI, Fast spin-echo T₂ WI, SE-EPI DWI, and Dynamic multiphase fast gradient-echo T₁ WI.

ASSESSMENT

Seventy lesions assigned LI-RADS categories of LR1-LR5, LR-M, and LR-TIV by three radiologists in consensus were randomly selected, with 10 cases for each category. The consensus opinion was the standard reference. The third radiologist delivered the training. Twenty readers reviewed images independently and assigned each an LI-RADS category both before and after the training.

STATISTICAL TESTS

Accuracy, sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, negative likelihood ratio, receiver operating characteristic (ROC) analysis, simple and weighted kappa statistics, and Fleiss kappa statistics.

RESULTS

Before and after training: readers' AUC (areas under ROC) for LR-1-LR-5, LR-M, and LR-TIV were 0.898 vs. 0.913, 0.711 vs. 0.876, 0.747 vs. 0.860, 0.724 vs. 0.815, 0.844 vs. 0.895, 0.688 vs. 0.873, and 0.720 vs. 0.948, respectively, and all improved significantly (P < 0.05), except LR-1(P = 0.25). Inter-reader agreement between readers for LR-1-LR-5, LR-M, LR-TIV were 0.725 vs. 0.751, 0.325 vs. 0.607, 0.330 vs. 0.559, 0.284 vs. 0.488, 0.447 vs. 0.648, 0.229 vs. 0.589, and 0.362 vs. 0.852, respectively, and all increased significantly (P < 0.05). For training effectiveness on both AUC and inter-reader agreement, LR-TIV, LR-M, and LR-2 improved most, and LR-1 made the least.

DATA CONCLUSION

This study shows LI-RADS training could improve reader agreement with the expert consensus and inter-reader agreement for final categories.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY STAGE: 2.

Assessment of factors affecting washout appearance of hepatocellular carcinoma on CT

OBJECTIVES

To identify independent imaging and histopathologic factors that affect washout appearance of hepatocellular carcinoma (HCC) in CT images.

METHODS

This retrospective study included 264 patients who had undergone surgical resection for treatment-naïve single HCC between January 2014 and December 2015 and had available preoperative multiphasic CT images. Two reviewers evaluated the CT imaging features of HCC using LI-RADS v2018. The "washout" was visually assessed in portal venous or equilibrium phases. Depending on the presence of washout appearance of HCC, all patients were divided into "washout" (n = 228) and "no washout" (n = 36) groups. Multivariable logistic regression analysis was used to identify factors associated with the absence of washout appearance of HCC.

RESULTS

A total of 264 HCCs (median size, 2.6 cm) were analyzed. Histologically proven hepatic steatosis (macrovesicular steatosis ≥ 5%) (odds ratio [OR], 2.65; 95% confidence interval [CI], 1.05-6.74; p = 0.040), tumor capsule on histopathology (OR, 0.17; 95% CI, 0.06-0.50; p = 0.001), and mosaic appearance on CT image (OR, 0.34; 95% CI, 0.14-0.85; p = 0.021) were independent factors associated with the absence of washout appearance of HCC. In 189 patients with available unenhanced CT images, CT-diagnosed hepatic steatosis was also an independent factor for the absence of washout appearance of HCC (OR, 9.26; 95% CI, 3.06-28.02; p < 0.001).

CONCLUSIONS

Washout appearance of HCC in CT images could be obscured in both histologically proven hepatic steatosis and CT-diagnosed hepatic steatosis, and could be enhanced with tumor capsule on histopathology and mosaic appearance on CT image.

KEY POINTS

• Hepatic steatosis is an independent factor related to the absence of washout appearance of hepatocellular carcinoma in CT images, in both histologically proven hepatic steatosis and CT-diagnosed hepatic steatosis. • Both histologically proven hepatic steatosis and CT-diagnosed hepatic steatosis have higher odds of absence of washout appearance of hepatocellular carcinoma compared to non-steatotic liver. • Tumor capsule on histopathology and mosaic appearance on CT image are independent factors that enhance the probability that washout appearance of hepatocellular carcinoma is visible.

The role of lesion hypointensity on gadobenate dimeglumine-enhanced hepatobiliary phase MRI as an additional major imaging feature for HCC classification using LI-RADS v2018 criteria

OBJECTIVES

To determine the value of lesion hypointensity in the hepatobiliary phase (HBP) on gadobenate dimeglumine-enhanced MRI as an additional major imaging feature for diagnosis of hepatocellular carcinoma (HCC) using LI-RADS v2018 criteria.

METHODS

Between March 2016 and August 2018, 235 patients with 250 hepatic nodules at high risk of HCC underwent gadobenate dimeglumine-enhanced MRI. Two radiologists independently evaluated the imaging features and classified the nodules based on LI-RADS v2018 criteria, and their consensus data were used to calculate the diagnostic performance of LI-RADS categories. Two modified LI-RADS definitions were as follows: (1) LI-RADS-m1: HBP hypointensity as an additional major feature; (2) LI-RADS-m2: HBP hypointensity as an alternative to "enhancing capsule" as an additional major feature. The diagnostic performance of LR-5 categories was compared using McNemar's test.

RESULTS

The sensitivity and specificity for LR-5 classification using original LI-RADS v2018 criteria were 78.1% and 96.3%, respectively. Significantly improved sensitivity (82.7%; p = 0.004) with unchanged specificity (96.3%; p = 1.00) was seen for LR-5 classification using LI-RADS-m1. Similar sensitivity and specificity (82.7% and 96.3%, respectively) were also seen using LI-RADS-m2. Significantly improved sensitivity (79.5% vs. 64.0%; p = 0.031) with unchanged specificity (96.2% vs. 96.2%, p = 1.00) was seen using both LI-RADS-m1 and LI-RADS-m2 compared to the original LI-RADS v2018 for 39 HCC nodules measuring 10-19 mm.

CONCLUSIONS

Lesion hypointensity on gadobenate dimeglumine-enhanced HBP MRI may improve sensitivity for LR-5 classification beyond that achievable using conventional LI-RADS v2018 criteria. Lesion hypointensity may prove a suitable alternative imaging feature to enhancing capsule for accurate LR-5 classification.

KEY POINTS

• Including lesion hypointensity in the HBP as an additional major feature improved sensitivity for LR-5 classification on gadobenate dimeglumine-enhanced MRI. • Lesion hypointensity in the HBP can replace "enhancing capsule" as an additional major feature for LR-5 classification without impairing specificity.

Intraindividual Comparison of Hepatocellular Carcinoma Washout between MRIs with Hepatobiliary and Extracellular Contrast Agents

Objective

To intraindividually compare hepatocellular carcinoma (HCC) washout between MRIs using hepatobiliary agent (HBA) and extracellular agent (ECA).

Materials and Methods

This study included 114 prospectively enrolled patients with chronic liver disease (mean age, 55 ± 9 years; 94 men) who underwent both HBA-MRI and ECA-MRI before surgical resection for HCC between November 2016 and May 2019. For 114 HCCs, the lesion-to-liver visual signal intensity ratio (SIR) using a 5-point scale (−2 to +2) was evaluated in each phase. Washout was defined as negative visual SIR with temporal reduction of visual SIR from the arterial phase. Illusional washout (IW) was defined as a visual SIR of 0 with an enhancing capsule. The frequency of washout and MRI sensitivity for HCC using LR-5 or its modifications were compared between HBA-MRI and ECA-MRI. Subgroup analysis was performed according to lesion size (< 20 mm or ≥ 20 mm).

Results

The frequency of portal venous phase (PP) washout with HBA-MRI was comparable to that of delayed phase (DP) washout with ECA-MRI (77.2% [88/114] vs. 68.4% [78/114]; p = 0.134). The frequencies were also comparable when IW was allowed (79.8% [91/114] for HBA-MRI vs. 81.6% [93/114] for ECA-MRI; p = 0.845). The sensitivities for HCC of LR-5 (using PP or DP washout) were comparable between HBA-MRI and ECA-MRI (78.1% [89/114] vs. 73.7% [84/114]; p = 0.458). In HCCs < 20 mm, the sensitivity of LR-5 was higher on HBA-MRI than on ECA-MRI (70.8% [34/48] vs. 50.0% [24/48]; p = 0.034). The sensitivity was similar to each other if IW was added to LR-5 (72.9% [35/48] for HBA-MRI vs. 70.8% [34/48] for ECA-MRI; p > 0.999).

Conclusion

Extracellular phase washout for HCC diagnosis was comparable between MRIs with both contrast agents, except for tumors < 20 mm. Adding IW could improve the sensitivity for HCC on ECA-MRI in tumors < 20 mm.

Vanishing washout of hepatocellular carcinoma according to the presence of hepatic steatosis: diagnostic performance of CT and MRI

OBJECTIVES

To compare the presence of washout and the diagnostic performance of computed tomography (CT) and magnetic resonance imaging (MRI) for hepatocellular carcinoma (HCC) according to the presence of hepatic steatosis.

METHODS

This retrospective study included 566 patients with chronic liver disease who had undergone hepatic resection for hepatic tumors (482 HCCs and 84 non-HCCs) between January 2016 and June 2018 and had available multiphasic CT and MR images. Patients were allocated in the fatty liver (n = 141) or non-fatty liver (n = 425) group according to the presence of hepatic steatosis, defined as lipid droplets in at least 5% of hepatocytes on pathological examination. The presence of HCC washout and the diagnostic performance of CT and MRI for HCC were compared between the groups.

RESULTS

HCC washout was less frequently seen in the fatty liver group than in the non-fatty liver group on CT (61.5% vs. 88.9%, p < 0.001), whereas it was similarly present on MRI in both groups (77.0% vs. 74.4%, p = 0.565). For diagnosis of HCC, the sensitivity (53.3% vs. 80.0%, p < 0.001) and accuracy (53.9% vs. 80.9%, p < 0.001) of CT were lower in the fatty liver group than in the non-fatty liver group. However, for MRI, these values were not significantly different between the groups (p > 0.05).

CONCLUSIONS

Hepatic steatosis significantly decreased the performance of CT for the diagnosis of HCC, whereas it did not significantly alter the performance of MRI.

KEY POINTS

• Unlike MRI, there is vanishing HCC washout on CT caused by the background hepatic steatosis. • The diagnostic performance of CT for the diagnosis of HCC was significantly altered by hepatic steatosis. • The optimal cutoff HU value of the liver parenchyma for the vanishing washout of HCC was < 50 HU on unenhanced CT images.

Evaluation of Primary Liver Cancers Using Hepatocyte-Specific Contrast-Enhanced MRI: Pitfalls and Potential Tips

When radiologists interpret hepatic focal lesions seen on dynamic magnetic resonance imaging (MRI) scans, it is important not only to distinguish malignant lesions from benign ones but also to distinguish nonhepatocellular carcinoma (HCC) malignancies from HCCs. In addition, most major guidelines, including those of the American Association for the Study of Liver Disease, European Association for the Study of the Liver, and Korean Liver Cancer Association and National Cancer Center, allow for the noninvasive imaging diagnosis of HCC in at-risk patients. However, ~40% of HCC cases show atypical imaging features mimicking non-HCC malignancies. Furthermore, several benign and malignant lesions, such as flash-filling hemangioma and intrahepatic mass-forming cholangiocarcinoma, frequently look like HCC. In contrast, although multiparametric MRI options, including hepatobiliary phase and diffusion-weighted imaging, provide useful information that could help address these challenges, there remain several unresolved issues with regard to the noninvasive diagnostic criteria characterizing HCC. In this article, we discuss the typical imaging features and challenging situations related to primary liver cancers in MRI, while considering how to make a correct diagnosis. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY STAGE: 3.

Prospective Intraindividual Comparison of Magnetic Resonance Imaging With Gadoxetic Acid and Extracellular Contrast for Diagnosis of Hepatocellular Carcinomas Using the Liver Imaging Reporting and Data System

We intraindividually compared the efficacy of magnetic resonance imaging (MRI) with extracellular contrast agents (ECA-MRI) and MRI with hepatobiliary agents (HBA-MRI) for the diagnosis of hepatocellular carcinoma (HCC) using the Liver Imaging Reporting and Data System (LI-RADS). Between November 2016 and November 2017, we enrolled 91 patients with chronic liver disease who underwent both ECA-MRI and HBA-MRI within a 1-month interval for a first detected hepatic nodule on ultrasound. In total, 117 observations (95 HCCs, 19 benign lesions, and 3 other malignancies; median size, 18 mm) were identified with surgical resection. Two observers assessed two MRIs based on LI-RADS v2017, with consensus by a third observer. We then compared the diagnostic performance of LR-5 according to LI-RADS and modified LI-RADS. ECA-MRI had higher sensitivity (77.9% versus 66.3%) and accuracy (82.1% versus 72.6%) than HBA-MRI in the LR-5 category (P < 0.001). When applying either modified washout on the portal venous phase (PVP)/transitional phase (TP) of HBA-MRI or isointensity with a capsule during the PVP/delayed phase of ECA-MRI (illusional washout), 13 HCCs on HBA-MRI and 11 HCCs on ECA-MRI were correctly classified as HCC, while achieving 100% specificity. One cholangiocarcinoma was accurately classified only with HBA-MRI due to its targetoid appearance in the TP and hepatobiliary phase. Conclusion: ECA-MRI showed better sensitivity and accuracy than HBA-MRI for the diagnosis of HCC with LI-RADS. We achieved better diagnostic performance when applying a modified washout on PVP/TP HBA-MRI and an illusional washout on ECA-MRI than we did with conventional criteria.

Liver Imaging Reporting and Data System (LI-RADS) Version 2018: Imaging of Hepatocellular Carcinoma in At-Risk Patients

The Liver Imaging Reporting and Data System (LI-RADS) is composed of four individual algorithms intended to standardize the lexicon, as well as reporting and care, in patients with or at risk for hepatocellular carcinoma in the context of surveillance with US; diagnosis with CT, MRI, or contrast material-enhanced US; and assessment of treatment response with CT or MRI. This report provides a broad overview of LI-RADS, including its historic development, relationship to other imaging guidelines, composition, aims, and future directions. In addition, readers will understand the motivation for and key components of the 2018 update.

Pitfalls and problems to be solved in the diagnostic CT/MRI Liver Imaging Reporting and Data System (LI-RADS)

The 2017 Core of the computed tomography (CT)/magnetic resonance imaging (MRI) Liver Imaging Reporting and Data System (LI-RADS) provides clear definitions and concise explanations of the CT/MRI diagnostic algorithm. Nevertheless, there remain some practical and controversial issues that radiologists should be aware of when using the system. This article discusses pitfalls and problems which may be encountered when the version 2017 diagnostic algorithm is used for CT and MRI. The pitfalls include challenges in applying major features and assigning the LR-M category, as well as categorisation discrepancy between CT and MRI. The problems include imprecision of category codes, application of ancillary features, and regional practice variations in hepatocellular carcinoma (HCC) diagnosis. Potential solutions are presented along with these pitfalls and problems. KEY POINTS: • Although the diagnostic algorithm provides clear and detailed explanations, major feature evaluation can be subject to pitfalls and differentiation of HCC and non-HCC malignancy remains challenging. • Ancillary features are optional and equally weighted. However, features such as hepatobiliary phase hypointensity and restricted diffusion have greater impact on HCC diagnosis than other ancillary features and may merit greater emphasis or weighting. • LI-RADS was initially developed from a Western paradigm, which may limit its applicability in the East due to regional practice variations. In Eastern Asia, high sensitivity is prioritised over near-perfect specificity for HCC diagnosis in order to detect tumours at early stages.

The capsule appearance of hepatocellular carcinoma in gadoxetic acid-enhanced MR imaging: Correlation with pathology and dynamic CT

This study aimed to evaluate the capability of gadoxetic acid-enhanced MR (GAeMR) to detect presence of capsule appearance in hepatocellular carcinoma (HCC), and to correlate it with dynamic computed tomography (CT) and pathological features.Sixty-three patients (54: 9 = M: F, mean age 55.8) surgically confirmed HCCs with preoperative CT and GAeMR were included in this retrospective study. Two readers evaluated presence of capsule appearances on CT and GAeMR images in each phase including precontrast (Pre), portal phase (PP), delayed phase (DP), transitional phase (TP), and hepatobiliary phase (HBP). Histologic capsule was compared with CT and GAeMR. Diagnostic performance of CT and GAeMR of each phase for histologic capsule was evaluated and compared by receiver operating characteristic curve. Interobserver agreement was assessed with kappa statistics.Histologically the capsule was complete in 12.7% (8/63) and incomplete in 60.3% (38/63). Four cases (6.3%) were pseudocapsule. Interobserver agreement for capsule appearance on GAeMR was good in Pre (κ = 0.684), moderate in PP (κ = 0.434), poor in TP (κ = 0.187), fair in HBP (κ = 0.395), and moderate on CT in PP (κ = 0.476) and DP (κ = 0.485). Diagnostic performance and sensitivity for the histologic capsule in DP on CT was highest among PP on CT and other phases on GAeMR. DP on CT images showed a higher Az value than PP on CT images with statistical significance (P < .001). PP on MR images revealed higher Az value than PP on CT images.The capsule appearance was most frequently observed in the DP on CT with highest diagnostic performance, and so DP images should be obtained on CT study for liver mass categorization. GAeMR yielded comparable capsule appearance to CT with moderate interobserver agreement. Considering hypointense rim on the HBP as fibrous capsule on pathology should be refrained, and so further study is warranted to correlate HBP hypointense rim with pathologic findings.

Intra-individual comparison of hepatocellular carcinoma imaging features on contrast-enhanced computed tomography, gadopentetate dimeglumine-enhanced MRI, and gadoxetic acid-enhanced MRI

Background Gadoxetic acid is being widely used for detection and characterization of hepatic nodules. However, there are no data regarding intra-individual comparison of imaging features of hepatocellular carcinoma (HCC) on dynamic computed tomography (CT), gadopentetate dimeglumine-enhanced magnetic resonance imaging (Gd-DTPA-MRI), and gadoxetic acid-enhanced MRI (Gd-EOB-MRI). Purpose To evaluate typical imaging features of HCC and capsule appearance with dynamic CT, Gd-DTPA-MRI, and Gd-EOB-MRI. Material and Methods We retrospectively reviewed 56 HCCs in 49 patients. Lesion attenuation/signal intensity was graded using a five-point scale based on dynamic phase and hepatobiliary phase (HBP) imaging. Subjective washout and capsule appearance were evaluated on portal venous phase (PVP) or delayed/transitional phase (DP/TP) imaging. The tumor-to-liver contrast ratio (TLCR) was calculated. Results Gd-DTPA-MRI and Gd-EOB-MRI was graded higher than CT on arterial phase ( P < 0.001). Gd-EOB-MRI was graded lower than Gd-DTPA-MRI on PVP and DP/TP ( P < 0.05). The detection rate of subjective washout and capsule appearance did not differ among the three imaging studies on either PVP or DP/TP. TLCR of Gd-EOB-MRI was lower than CT on PVP ( P = 0.004) and was lower than Gd-DTPA-MRI on DP/TP ( P = 0.001). Conclusion Arterial phase hyperenhancement and washout appearance of HCC were well demonstrated in Gd-EOB-MRI. The detection of capsule appearance using Gd-EOB-MRI was not inferior to Gd-DTPA-MRI or CT.

LI-RADS v2017 for liver nodules: how we read and report

The Liver Imaging Reporting and Data System (LI-RADS) standardizes the interpretation and reporting of imaging examinations in patients at risk for hepatocellular carcinoma (HCC). For focal liver observations it assigns categories (LR-1 to 5, LR-M, LR-TIV), which reflect the relative probability of benignity or malignancy of the respective observation. The categories assigned are based on major and ancillary image features, which have been developed by the American College of Radiology (ACR) and validated in many studies. This review summarizes the relevant CT and MRI features and presents an image-guided approach for readers not familiar with LI-RADS on how to use the system. The widespread adoption of LI-RADS for reporting would help reduce inter-reader variability and improve communication among radiologists, hepatologists, hepatic surgeons and oncologists, thus leading to improved patient management.

Comparison of Visualization Rates of LI-RADS Version 2014 Major Features With IV Gadobenate Dimeglumine or Gadoxetate Disodium in Patients at Risk for Hepatocellular Carcinoma

OBJECTIVE

The purpose of this study is to compare visualization rates of the major features covered by Liver Imaging Reporting and Data System (LI-RADS) version 2014 in patients at risk for hepatocellular carcinoma using either gadobenate dimeglumine or gadoxetate disodium IV contrast agent.

MATERIALS AND METHODS

This retrospective study included liver MRI examinations performed with either gadobenate dimeglumine or gadoxetate disodium contrast enhancement. Using age, sex, underlying liver disease, and presence of cirrhosis, patients were placed into matched cohorts. All hepatic nodules 1 cm or larger (up to five per subject) were included, resulting in 63 subjects with 130 nodules (median nodule size, 1.9 cm) imaged with gadobenate and 64 subjects with 117 nodules (median nodule size, 2.0 cm) imaged with gadoxetate. Three radiologists reviewed the studies for LI-RADS major features independently. Bootstrap resampling with 10,000 repetitions was used to compare feature detection rates.

RESULTS

Arterial phase hyperenhancement was seen in a similar number of nodules with gadobenate dimeglumine (mean, 91.5% [119/130]) and gadoxetate disodium (mean, 88.0% [103/117]) (p = 0.173). Dynamic phase washout was more commonly seen with gadobenate dimeglumine (mean, 60.2% [78.3/130]) than with gadoxetate disodium (mean, 45.3% [53/117]) (p = 0.006). The capsule feature was more often visualized with gadobenate dimeglumine (mean, 50.2% [65.3/130]) than with gadoxetate disodium (mean, 33.3% [39/117]) (p < 0.001). Interreader agreement for arterial phase enhancement and dynamic phase washout was almost perfect for both contrast agents (κ > 0.83). Agreement for the capsule feature was moderate for gadobenate dimeglumine (κ = 0.52) and substantial for gadoxetate disodium (κ = 0.67).

CONCLUSION

The rates of visualization of arterial phase hyperenhancement are similar in studies performed with gadobenate dimeglumine and gadoxetate disodium, but dynamic phase washout and capsule appearance are more commonly visualized with gadobenate dimeglumine.

Evidence Supporting LI-RADS Major Features for CT- and MR Imaging-based Diagnosis of Hepatocellular Carcinoma: A Systematic Review

The Liver Imaging Reporting and Data System (LI-RADS) standardizes the interpretation, reporting, and data collection for imaging examinations in patients at risk for hepatocellular carcinoma (HCC). It assigns category codes reflecting relative probability of HCC to imaging-detected liver observations based on major and ancillary imaging features. LI-RADS also includes imaging features suggesting malignancy other than HCC. Supported and endorsed by the American College of Radiology (ACR), the system has been developed by a committee of radiologists, hepatologists, pathologists, surgeons, lexicon experts, and ACR staff, with input from the American Association for the Study of Liver Diseases and the Organ Procurement Transplantation Network/United Network for Organ Sharing. Development of LI-RADS has been based on literature review, expert opinion, rounds of testing and iteration, and feedback from users. This article summarizes and assesses the quality of evidence supporting each LI-RADS major feature for diagnosis of HCC, as well as of the LI-RADS imaging features suggesting malignancy other than HCC. Based on the evidence, recommendations are provided for or against their continued inclusion in LI-RADS. © RSNA, 2017 Online supplemental material is available for this article.

Hepatocellular carcinoma imaging systems: why they exist, how they have evolved, and how they differ

Over the past 16 years, several scientific organizations have proposed systems that incorporate imaging for surveillance, diagnosis, staging, treatment, and monitoring of treatment response of hepatocellular carcinoma (HCC). These systems are needed to standardize the acquisition, interpretation, and reporting of liver imaging examinations; help differentiate benign from malignant observations; improve consistency between radiologists; and provide guidance for management of HCC. This review article discusses the historical evolution of HCC imaging systems. We indicate the features differentiating these systems, including target population, screening and surveillance algorithm, diagnostic imaging modalities, diagnostic scope, expertise and technical requirements, terminology, major and ancillary imaging features, staging and transplant eligibility, and assessment of treatment response. We highlight the potential benefits of unifying the systems, which we anticipate will enable sharing, pooling, and meta-analysis of data; facilitate multi-center trials; and accelerate dissemination of knowledge.

Interreader Reliability of LI-RADS Version 2014 Algorithm and Imaging Features for Diagnosis of Hepatocellular Carcinoma: A Large International Multireader Study

Purpose To determine in a large multicenter multireader setting the interreader reliability of Liver Imaging Reporting and Data System (LI-RADS) version 2014 categories, the major imaging features seen with computed tomography (CT) and magnetic resonance (MR) imaging, and the potential effect of reader demographics on agreement with a preselected nonconsecutive image set. Materials and Methods Institutional review board approval was obtained, and patient consent was waived for this retrospective study. Ten image sets, comprising 38-40 unique studies (equal number of CT and MR imaging studies, uniformly distributed LI-RADS categories), were randomly allocated to readers. Images were acquired in unenhanced and standard contrast material-enhanced phases, with observation diameter and growth data provided. Readers completed a demographic survey, assigned LI-RADS version 2014 categories, and assessed major features. Intraclass correlation coefficient (ICC) assessed with mixed-model regression analyses was the metric for interreader reliability of assigning categories and major features. Results A total of 113 readers evaluated 380 image sets. ICC of final LI-RADS category assignment was 0.67 (95% confidence interval [CI]: 0.61, 0.71) for CT and 0.73 (95% CI: 0.68, 0.77) for MR imaging. ICC was 0.87 (95% CI: 0.84, 0.90) for arterial phase hyperenhancement, 0.85 (95% CI: 0.81, 0.88) for washout appearance, and 0.84 (95% CI: 0.80, 0.87) for capsule appearance. ICC was not significantly affected by liver expertise, LI-RADS familiarity, or years of postresidency practice (ICC range, 0.69-0.70; ICC difference, 0.003-0.01 [95% CI: -0.003 to -0.01, 0.004-0.02]. ICC was borderline higher for private practice readers than for academic readers (ICC difference, 0.009; 95% CI: 0.000, 0.021). Conclusion ICC is good for final LI-RADS categorization and high for major feature characterization, with minimal reader demographic effect. Of note, our results using selected image sets from nonconsecutive examinations are not necessarily comparable with those of prior studies that used consecutive examination series. ^© RSNA, 2017.

EASL and AASLD recommendations for the diagnosis of HCC to the test of daily practice

AIMS

To evaluate the diagnostic performance of CT, MRI and CEUS alone and in combination, for the diagnosis of HCC between 10 and 30 mm, in a large population of cirrhotic patients.

PATIENTS AND METHODS

In a multicentre prospective trial, 442 patients have been enrolled. Within a month, CEUS, CT and MRI were performed for all patients. A composite algorithm was defined to obtain the more accurate gold standard.

RESULTS

A total of 544 nodules in 381 patients have been retained for the performance analysis. Eighty-two percent of the patients were male, mean age was 62 years. For the 10-20 mm nodules (n=342), the sensitivity (Se) and specificity (Sp) for the diagnosis of HCC were, respectively, 70.6% and 83.2% for MRI, 67.9% and 76.8% for CT and 39.6% and 92.9% for CEUS. For the 20-30 mm nodules (n=202), the Se and Sp were, respectively, 72.3% and 89.4% for MRI, 71.6% and 93.6% for CT and 52.9% and 91.5% for CEUS. THE BEST COMBINATION FOR THE 10-20 MM NODULES WAS MRI + CT (SE: 55.1%, SP: 100.0%).: After a first inconclusive technique, CEUS as second image technique allowed the highest specificity with only a slight drop of sensitivity for 10-20 mm nodules and the highest sensitivity and specificity for 20-30 mm nodules.

CONCLUSION

This large multicentre study validates the EASL/AASLD recommendations in daily practice. Specificity using CT or MRI in 10-20 mm HCC was low, but we do not recommend combined imaging at first as sensitivity would be very low. The best sequential approach combined MRI and CEUS.

Effect of threshold growth as a major feature on LI-RADS categorization

PURPOSE

Liver Imaging Reporting and Data System (LI-RADS) uses major features (arterial phase hyperenhancement [APHE], "washout" [WO], "capsule," diameter, threshold growth [TG]) to codify probability of hepatocellular carcinoma for each observation. This study assessed the effect of removing TG as a major feature on LI-RADS categorization.

MATERIALS AND METHODS

In this HIPAA-compliant, IRB-approved study, all MR and CT clinical reports containing a standardized LI-RADS v2014 template between 4/15-1/17 were retrospectively reviewed for each LR-3, LR-4, and LR-5 reported observation. Two LI-RADS categories were then assigned: one using all LI-RADS major features and one after removing TG as a major feature. The two categories were compared descriptively.

RESULTS

The study included 265 patients (172 [65%] male, mean age 63 [±10] years) with 489 observations (median diameter 14 mm, IQR 10-20 mm), of which 345 (71%) had APHE, 307 (63%) had WO, 86 (18%) had "capsule," and 72 (15%) had TG. Of 86 observations with TG, 47 (65%) were new observations ≥10 mm, 14 (19%) had diameter increase ≥50% in ≤6 months, and 11 (15%) had diameter increase ≥100% in >6 months. Using all major features, 214/489 (44%) observations were LR-3, 129/489 (26%) were LR-4, and 146/489 (30%) were LR-5. After removing TG, 237/489 (48%) were LR-3, 119/489 (24%) were LR-4, and 133 (27%) were LR-5. Removing TG caused a category downgrade for 35/489 (7%, 95% CI 5-10) observations, including 13/146 (9%, 95% CI 3-14) LR-5 observations.

CONCLUSION

9% of LR-5 observations would be downgraded without TG.

Computer-aided diagnosis program for classifying the risk of hepatocellular carcinoma on MR images following liver imaging reporting and data system (LI-RADS)

PURPOSE

To develop and evaluate a computer-aided diagnosis (CAD) program for liver lesions on magnetic resonance (MR) images for classification of the risk of hepatocellular carcinoma (HCC) following the liver imaging reporting and data system (LI-RADS).

MATERIALS AND METHODS

Liver MR images from 41 patients with hyperenhancing liver lesions categorized as LR 3, 4, and 5 were evaluated by two radiologists. The major LI-RADS features of each index liver lesion were recorded, including size (maximum transverse diameter), presence of hyperenhancement, washout appearance, and capsule appearance. A CAD program was implemented to register MR images at different contrast-enhancement phases, segment liver lesions, extract lesion features, and classify lesions according to LI-RADS. The LI-RADS features quantified by CAD were compared with those assessed by radiologists using the intraclass correlation coefficient (ICC) and receiver operator curve (ROC) analyses. The LI-RADS categorization between CAD and radiologists was evaluated using the weighted Cohen's kappa coefficient.

RESULTS

The mean and standard deviation of the lesion diameters were 21 ± 11 mm (range, 7-70 mm) by radiologists and 22 ± 11 mm (range, 8-72 mm) by CAD (ICC, 0.96-0.97). The area under the curve (AUC) for the washout assessment by CAD was 0.79-0.93 with sensitivity 0.69-0.82 and specificity 0.79-1. The AUC for the capsule assessment by CAD was 0.79-0.9 with sensitivity 0.75-0.9 and specificity 0.82-0.96. The classifications by the radiologists and CAD coincided in 76-83% lesions (k = 0.57-0.71), while the agreements between radiologists were in 78% lesions (k = 0.59).

CONCLUSION

We developed a CAD program for liver lesions on MR images and showed a substantial agreement in the LI-RADS-based classification of the risk of HCCs between the CAD and radiologists.

LEVEL OF EVIDENCE

1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;47:710-722.

Hepatic Lesions in a Cirrhotic Liver: Primary or Metastases?

Although prior studies showed that patients with cirrhosis have a lower risk of developing liver metastases, appropriate workup of incidental liver masses in cirrhotic liver is important for a correct diagnosis. Here we present a case of newly diagnosed liver cirrhosis with multifocal hepatic lesions, which was initially categorized as a LI-RADS (Liver Imaging Reporting and Data System) 5 lesions. Scintigraphy with ¹¹¹In-pentetreotide (Octreoscan) indicated a suspected thyroid nodule, later confirmed to represent medullary thyroid carcinoma lesion. The most relevant imaging finding of this rare form of thyroid malignancy is reviewed in this presentation.

Added value of smooth hypointense rim in the hepatobiliary phase of gadoxetic acid-enhanced MRI in identifying tumour capsule and diagnosing hepatocellular carcinoma

OBJECTIVES

To examine the added value of considering smooth hypointense rim in the hepatobiliary phase (HBP) of gadoxetic acid-enhanced MRI as capsule appearance for diagnosing tumour capsules and hepatocellular carcinoma (HCC).

METHODS

A total of 377 hepatic lesions (330 HCCs, 35 non-HCC malignancies and 12 benign) were included from 345 patients who underwent resection after MRI between January 2008 and December 2011. Two radiologists assessed the presence or absence of conventional capsule appearance and smooth hypointense rim in the HBP, and categorized each hepatic lesion according to the Liver Imaging Reporting and Data System. Difference in diagnostic performance was evaluated using the generalized estimating equation method.

RESULTS

For identifying capsule, the sensitivity and accuracy of HBP hypointense rim were significantly higher than those of conventional capsule appearance (81.5 % vs. 57.8 % and 76.1 % vs. 59.4 %, respectively; P < 0.001). For diagnosing HCC, the sensitivity and accuracy of LR-5 or LR-5 V were significantly higher when the HBP hypointense rim was also considered capsule appearance (83 % vs. 72.7 % and 84.1 % vs. 75.1 %, respectively; P < 0.001), with the same specificity (91.5 %).

CONCLUSIONS

Regarding smooth hypointense rim in the HBP as capsule appearance could improve the detection of tumour capsule and the diagnosis of HCC.

KEY POINTS

• Identifying tumour capsule is important for diagnosis of hepatocellular carcinoma (HCC). • Gadoxetic acid-enhanced MRI provides hepatobiliary phase (HBP) images. • Smooth hypointense rim seen in HBP may represent tumour capsule. • Regarding smooth hypointense rim as capsule appearance may improve HCC diagnosis.