MRI detection of intratumoral fat in hepatocellular carcinoma: potential biomarker for a more favorable prognosis. AJR Am J Roentgenol. 2012;199:1018-1025. [PMID: 23096174 DOI: 10.2214/ajr.12.8632]

An algorithmic approach to MR characterization of focal liver lesions in adults without cirrhosis

Diagnosing both known and incidental liver lesions in the non-cirrhotic liver on MRI can be challenging. The radiologist can often narrow the diagnosis toward a diagnostic category using various sequences. Using an organized framework to guide the reader's differential diagnosis can be helpful. We present a sequential approach to the diagnosis of focal liver lesions, by first assessing background liver parenchymal signal intensity, then comparing the T1-weighted signal intensity of the reference organ(s), followed by comparing the T2-weighted signal intensity characteristics of lesion to fluid/spleen, and finally confirming using additional sequences including dynamic contrast-enhanced imaging, hepatobiliary imaging, diffusion weighted imaging, as well as clinical and laboratory testing and additional modalities. Using this stepwise framework can sequentially guide the reader toward a diagnosis.

Hepatobiliary and Pancreatic Neoplasms: Essential Predictive Imaging Features for Personalized Therapy

Tumor biologic characteristics encompassing histopathologic, immune microenvironmental, genetic, and molecular aspects are becoming indispensable factors to be considered in treatment strategies for patients with cancer. Innovations in oncologic treatment have broadened the range of therapeutic approaches and now hold promise for treatments personalized according to tumor biologic characteristics. Particularly for hepatobiliary and pancreatic neoplasms, the advent of cytostatic agents such as molecularly targeted agents and immune checkpoint inhibitors, which differ markedly from conventional cytotoxic agents, has contributed to advances in clinical practice. These cytostatic agents increase the potential for curative-intent treatment of unresectable cancers by reducing tumor volume. Radiologic examinations are of more interest than ever to noninvasively obtain information about tumor biologic features. Radiomics represents an invaluable research method for elucidating associations between tumor biologic characteristics and radiologic imaging findings, but their applicability in daily clinical practice remains challenging. Various radiologic predictive findings for tumor biologic characteristics have already been proposed for hepatobiliary and pancreatic neoplasms. Radiologists must gain familiarity with these findings and the roles they have in predicting the clinical prognosis and treatment efficacy. In addition, radiologists should explore the potential applications of these imaging findings to current treatment strategies for the coming era of personalized medicine. The authors describe predictive findings using CT and MRI for diagnosis of hepatocellular carcinoma, colorectal liver metastases, intrahepatic cholangiocarcinoma, and pancreatic adenocarcinoma, with correlations to pathologic, immunologic, molecular, and genetic background factors. ©RSNA, 2025 Supplemental material is available for this article. See the invited commentary by Ronot in this issue.

Prediction models for differentiating benign from malignant liver lesions based on multiparametric dual-energy non-contrast CT

OBJECTIVES

To create prediction models (PMs) for distinguishing between benign and malignant liver lesions using quantitative data from dual-energy CT (DECT) without contrast agents.

MATERIALS AND METHODS

This retrospective study included patients with liver lesions who underwent DECT, including non-contrast-enhanced scans. Benign lesions included hepatic hemangioma, whereas malignant lesions included hepatocellular carcinoma, metastatic liver cancer, and intrahepatic cholangiocellular carcinoma. Patients were divided into derivation and validation groups. In the derivation group, two radiologists calculated ten multiparametric data using univariate and multivariate logistic regression to generate PMs. In the validation group, two additional radiologists measured the parameters to assess the diagnostic performance of PMs.

RESULTS

The study included 121 consecutive patients (mean age 67.4 ± 13.8 years, 80 males), with 97 in the derivation group (25 benign and 72 malignant) and 24 in the validation group (7 benign and 17 malignant). Oversampling increased the benign lesion sample to 75, equalizing the malignant group for building PMs. All parameters were statistically significant in univariate analysis (all p < 0.05), leading to the creation of five PMs in multivariate analysis. The area under the curve for the five PMs of two observers was as follows: PM1 (slope K, blood) = 0.76, 0.74; PM2 (slope K, fat) = 0.55, 0.51; PM3 (effective-Z difference, blood) = 0.75, 0.72; PM4 (slope K, blood, fat) = 0.82, 0.78; and PM5 (slope K, effective-Z difference, blood) = 0.90, 0.87. PM5 yielded the best diagnostic performance.

CONCLUSION

Multiparametric non-contrast-enhanced DECT is a highly effective method for distinguishing between liver lesions.

CLINICAL RELEVANCE STATEMENT

The utilization of non-contrast-enhanced DECT is extremely useful for distinguishing between benign and malignant liver lesions. This approach enables physicians to plan better treatment strategies, alleviating concerns associated with contrast allergy, contrast-induced nephropathy, radiation exposure, and excessive medical expenses.

KEY POINTS

Distinguishing benign from malignant liver lesions with non-contrast-enhanced CT would be desirable. This model, incorporating slope K, effective Z, and blood quantification, distinguished benign from malignant liver lesions. Non-contrast-enhanced DECT has benefits, particularly in patients with an iodine allergy, renal failure, or asthma.

Imaging Prognostic Biomarkers in Hepatocellular Carcinoma: A Comprehensive Review

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related mortality worldwide with its incidence on the rise globally. This paper provides a comprehensive review of prognostic imaging markers in HCC, emphasizing their role in risk stratification and clinical decision-making. We explore quantitative and qualitative criteria derived from imaging studies, such as computed tomography (CT) and magnetic resonance imaging (MRI), which can offer valuable insights into the biological behavior of the tumor. While many of these markers are not yet widely integrated into current clinical guidelines, they represent a promising future direction for approaching this highly heterogeneous cancer. However, standardization and validation of these markers remain important challenges. We conclude by emphasizing the importance of ongoing research to enhance clinical practices and improve outcomes for patients with HCC.

Diagnostic performance of hepatic CT and chemical-shift MRI to discriminate lipid-poor adrenal adenomas from hepatocellular carcinoma metastases

PURPOSE

To evaluate the diagnostic performance of multiphase hepatic CT parameters (non-contrast attenuation, absolute and relative washout ratios [APW and RPW, respectively], and relative enhancement ratio [RER]) and chemical-shift MRI (CS-MRI) for discriminating lipid-poor adrenal adenomas (with non-contrast CT attenuation > 10 HU) from metastases in patients with hepatocellular carcinoma (HCC).

METHODS

This retrospective study included HCC patients with lipid-poor adrenal lesions who underwent multiphase hepatic CT between January 2010 and December 2021. For each adrenal lesion, non-contrast attenuation, APW, RPW, RER, and signal-intensity index (SI-index) were measured. Each parameter was compared between adenomas and metastases. The area under the receiver operating characteristic curves (AUCs) and sensitivities to achieve 100% specificity for adenoma diagnoses were determined.

RESULTS

104 HCC patients (78 men; mean age, 71.8 ± 9.6 years) with 63 adenomas and 48 metastases were identified; CS-MRI was performed in 66 patients with 49 adenomas and 21 metastases within one year of CT. Lipid-poor adenomas showed lower non-contrast attenuation (22.9 ± 7.1 vs. 37.9 ± 9.4 HU) and higher APW (40.5% ± 12.8% vs. 23.7% ± 17.4%), RPW (30.0% ± 10.2% vs. 12.4% ± 9.6%), RER (329% ± 152% vs. 111% ± 43.0%), and SI-index (43.3 ± 20.7 vs. 10.8 ± 13.4) than HCC metastases (all p < .001). AUC for non-contrast attenuation, APW, RPW, RER, and SI-index were 0.894, 0.786, 0.904, 0.969, and 0.902, respectively. The sensitivities to achieve 100% specificity were 7.9%, 25.4%, 30.2%, 63.5%, and 24.5%, respectively. Combined RER and APW achieved the highest sensitivity of 73.0%.

CONCLUSION

Multiphase hepatic CT allows for better discrimination between lipid-poor adrenal adenomas and metastases relative to CS-MRI, especially when combined with RER and washout parameters.

The GRAPHS-CRAFITY score: a novel efficacy predictive tool for unresectable hepatocellular carcinoma treated with immunotherapy

OBJECTIVES

To investigate MR features associated with prognosis of unresectable HCC receiving immunotherapy and establish a MR feature-based scoring system to predict efficacy of immunotherapy.

METHODS

This retrospective study included patients with unresectable HCC who received immunotherapy at 2 hospitals between August 2018 and February 2022. The last follow-up was October 2022. Clinical variables and MR features were assessed using univariate and multivariate Cox regression analyses. A new scoring system was constructed based on independent risk factors and the CRAFITY score consisting of AFP (≥ 100 ng/ml) and CRP (≥ 1 mg/dl). And the predictive performance of CRAFITY core and new score were compared by receiver-operating-characteristics curves (ROCs), area under ROCs (AUCs), and calibration curves.

RESULTS

A total of 166 patients (55.6 ± 10.4 years) were included in training cohort and 77 patients (55.4 ± 10.7 years) were included in validation cohort. There were significant differences in BCLC stage, max size, macrovascular invasion, intratumoral artery, and enhancing capsule between the 2 groups. Based on independent risk factors (gross GRowtH type, intratumoral fAt, enhancing tumor caPsule, Sex and CRAFITY score), a novel efficacy predictive tool named the GRAPHS-CRAFITY score was developed to predict OS. The OS was significantly different among the 3 groups according to GRAPHS-CRAFITY score (p value < 0.001). The GRAPHS-CRAFITY score could predict tumor response and disease control (p value < 0.001, p value < 0.001).

CONCLUSIONS

The GRAPHS-CRAFITY score is a reliable and easily applicable tool to predict the efficacy of unresectable HCC receiving immunotherapy.

Simulation of Image-Guided Microwave Ablation Therapy Using a Digital Twin Computational Model

Emerging computational tools such as healthcare digital twin modeling are enabling the creation of patient-specific surgical planning, including microwave ablation to treat primary and secondary liver cancers. Healthcare digital twins (DTs) are anatomically one-to-one biophysical models constructed from structural, functional, and biomarker-based imaging data to simulate patient-specific therapies and guide clinical decision-making. In microwave ablation (MWA), tissue-specific factors including tissue perfusion, hepatic steatosis, and fibrosis affect therapeutic extent, but current thermal dosing guidelines do not account for these parameters. This study establishes an MR imaging framework to construct three-dimensional biophysical digital twins to predict ablation delivery in livers with 5 levels of fat content in the presence of a tumor. Four microwave antenna placement strategies were considered, and simulated microwave ablations were then performed using 915 MHz and 2450 MHz antennae in Tumor Naïve DTs (control), and Tumor Informed DTs at five grades of steatosis. Across the range of fatty liver steatosis grades, fat content was found to significantly increase ablation volumes by approximately 29-l42% in the Tumor Naïve and 55-60% in the Tumor Informed DTs in 915 MHz and 2450 MHz antenna simulations. The presence of tumor did not significantly affect ablation volumes within the same steatosis grade in 915 MHz simulations, but did significantly increase ablation volumes within mild-, moderate-, and high-fat steatosis grades in 2450 MHz simulations. An analysis of signed distance to agreement for placement strategies suggests that accounting for patient-specific tumor tissue properties significantly impacts ablation forecasting for the preoperative evaluation of ablation zone coverage.

MRI proton density fat fraction for estimation of tumor grade in steatotic hepatocellular carcinoma

OBJECTIVES

Image-based detection of intralesional fat in focal liver lesions has been established in diagnostic guidelines as a feature indicative of hepatocellular carcinoma (HCC) and associated with a favorable prognosis. Given recent advances in MRI-based fat quantification techniques, we investigated a possible relationship between intralesional fat content and histologic tumor grade in steatotic HCCs.

METHODS

Patients with histopathologically confirmed HCC and prior MRI with proton density fat fraction (PDFF) mapping were retrospectively identified. Intralesional fat of HCCs was assessed using an ROI-based analysis and the median fat fraction of steatotic HCCs was compared between tumor grades G1-3 with non-parametric testing. ROC analysis was performed in case of statistically significant differences (p < 0.05). Subgroup analyses were conducted for patients with/without liver steatosis and with/without liver cirrhosis.

RESULTS

A total of 57 patients with steatotic HCCs (62 lesions) were eligible for analysis. The median fat fraction was significantly higher for G1 lesions (median [interquartile range], 7.9% [6.0─10.7%]) than for G2 (4.4% [3.2─6.6%]; p = .001) and G3 lesions (4.7% [2.8─7.8%]; p = .036). PDFF was a good discriminator between G1 and G2/3 lesions (AUC .81; cut-off 5.8%, sensitivity 83%, specificity 68%) with comparable results in patients with liver cirrhosis. In patients with liver steatosis, intralesional fat content was higher than in the overall sample, with PDFF performing better in distinguishing between G1 and G2/3 lesions (AUC .92; cut-off 8.8%, sensitivity 83%, specificity 91%).

CONCLUSIONS

Quantification of intralesional fat using MRI PDFF mapping allows distinction between well- and less-differentiated steatotic HCCs.

CLINICAL RELEVANCE

PDFF mapping may help optimize precision medicine as a tool for tumor grade assessment in steatotic HCCs. Further investigation of intratumoral fat content as a potential prognostic indicator of treatment response is encouraged.

KEY POINTS

• MRI proton density fat fraction mapping enables distinction between well- (G1) and less- (G2 and G3) differentiated steatotic hepatocellular carcinomas. • In a retrospective single-center study with 62 histologically proven steatotic hepatocellular carcinomas, G1 tumors showed a higher intralesional fat content than G2 and G3 tumors (7.9% vs. 4.4% and 4.7%; p = .004). • In liver steatosis, MRI proton density fat fraction mapping was an even better discriminator between G1 and G2/G3 steatotic hepatocellular carcinomas.

Clinical and DCE-CT signs in predicting microvascular invasion in cHCC-ICC

BACKGROUND

To predict the microvascular invasion (MVI) in patients with cHCC-ICC.

METHODS

A retrospective analysis was conducted on 119 patients who underwent CT enhancement scanning (from September 2006 to August 2022). They were divided into MVI-positive and MVI-negative groups.

RESULTS

The proportion of patients with CEA elevation was higher in the MVI-positive group than in the MVI-negative group, with a statistically significant difference (P = 0.02). The MVI-positive group had a higher rate of peritumoral enhancement in the arterial phase (P = 0.01) whereas the MVI-negative group had more oval and lobulated masses (P = 0.04). According to the multivariate analysis, the increase in CEA (OR = 10.15, 95% CI: 1.11, 92.48, p = 0.04), hepatic capsular withdrawal (OR = 4.55, 95% CI: 1.44, 14.34, p = 0.01) and peritumoral enhancement (OR = 6.34, 95% CI: 2.18, 18.40, p < 0.01) are independent risk factors for predicting MVI. When these three imaging signs are combined, the specificity of MVI prediction was 70.59% (series connection), and the sensitivity was 100% (parallel connection).

CONCLUSIONS

Our multivariate analysis found that CEA elevation, liver capsule depression, and arterial phase peritumoral enhancement were independent risk factors for predicting MVI in cHCC-ICC.

Radiologic features of hepatocellular carcinoma related to prognosis

The cross-sectional imaging findings play a crucial role in the diagnosis of hepatocellular carcinoma (HCC). Recent studies have shown that imaging findings of HCC are not only relevant for the diagnosis of HCC, but also for identifying genetic and pathologic characteristics and determining prognosis. Imaging findings such as rim arterial phase hyperenhancement, arterial phase peritumoral hyperenhancement, hepatobiliary phase peritumoral hypointensity, non-smooth tumor margin, low apparent diffusion coefficient, and the LR-M category of the Liver Imaging-Reporting and Data System have been reported to be associated with poor prognosis. In contrast, imaging findings such as enhancing capsule appearance, hepatobiliary phase hyperintensity, and fat in mass have been reported to be associated with a favorable prognosis. Most of these imaging findings were examined in retrospective, single-center studies that were not adequately validated. However, the imaging findings can be applied for deciding the treatment strategy for HCC, if their significance can be confirmed by a large multicenter study. In this literature, we would like to review imaging findings related to the prognosis of HCC as well as their associated clinicopathological characteristics.

Prognostic value of baseline imaging and clinical features in patients with advanced hepatocellular carcinoma

Aims

To investigate the prognostic value of baseline imaging features for overall survival (OS) and liver decompensation (LD) in patients with hepatocellular carcinoma (HCC).

Design

Patients with advanced HCC from the SORAMIC trial were evaluated in this post hoc analysis. Several radiological imaging features were collected from baseline computed tomography (CT) and magnetic resonance imaging (MRI) imaging, besides clinical values. The prognostic value of these features for OS and LD (grade 2 bilirubin increase) was quantified with univariate Cox proportional hazard models and multivariate Least Absolute Shrinkage and Selection Operator (LASSO) regression.

Results

Three hundred and seventy-six patients were included in this study. The treatment arm was not correlated with OS. LASSO showed satellite lesions, atypical HCC, peritumoral arterial enhancement, larger tumour size, higher albumin–bilirubin (ALBI) score, liver–spleen ratio <1.5, ascites, pleural effusion and higher bilirubin values were predictors of worse OS, and higher relative liver enhancement, smooth margin and capsule were associated with better OS. LASSO analysis for LD showed satellite lesions, peritumoral hypointensity in hepatobiliary phase, high ALBI score, higher bilirubin values and ascites were predictors of LD, while randomisation to sorafenib arm was associated with lower LD.

Conclusions

Imaging features showing aggressive tumour biology and poor liver function, in addition to clinical parameters, can serve as imaging biomarkers for OS and LD in patients receiving sorafenib and selective internal radiation therapy for HCC.

Hepatocellular Carcinoma with Macroscopic Fat Metamorphosis: A Case Series

Hepatocellular carcinoma (HCC) is the fourth leading cause of cancer-related deaths in the world, with hepatitis B and C as its main causes. HCC can have fat metamorphosis which leads to a better prognosis, though this is more commonly found in lesions smaller than 3 cm in diameter, and usually contains intravoxel fat. In this case series, we present three cases of HCC with macroscopic fat metamorphosis as examined using CT scan and MRI. Macroscopic fat is seen using CT as a hypodense mass with attenuation of −10 to −100 HU, or MRI using fat-saturation technique. Intravoxel fat can be seen on MRI using fat saturation chemical shift technique, appearing as signal loss during opposed phase and increased signal during in-phase. The differential diagnoses of HCC with fat metamorphosis are angiomyolipoma, hepatic adenoma, nodular steatosis, focal nodular hyperplasia, dysplastic nodule, liposarcoma, and hepatic metastasis. Enhancement patterns of the fat and non-fat component; intra-tumoral fat distribution; the presence of cirrhosis; the presence of atoll sign; and history of viral hepatitis are useful clues for differentiation of HCC with other differential diagnoses.

Multimaterial decomposition algorithm for quantification of fat in hepatocellular carcinoma using rapid kilovoltage-switching dual-energy CT: A comparison with chemical-shift MR imaging

Understanding intratumoral fat in hepatocellular carcinoma (HCC) is clinically important to elucidate prognosis. We sought to quantify HCC and liver fat with a multimaterial decomposition (MMD) algorithm with rapid kilovoltage-switching dual-energy computed tomography (DECT) relative to chemical-shift magnetic resonance imaging (CSI).In this retrospective study, 40 consecutive patients with HCC underwent non-contrast-enhanced (non-CE) and four-phases contrast-enhanced (four-CE) DECT (80 and 140 kVp) and abdominal MR imaging (including CSI) between April 2011 and December 2012. Fat volume fraction (FVFDECT) maps were generated by MMD algorithm to quantify HCC and liver fat. Fat fraction measured by CSI (FFCSI) was determined for HCC and liver on dual-echo sequence using 1.5- or 3-Tesla MR systems. The correlation between FVFDECT and FFCSI was evaluated using Pearson correlation test, while non-CE FVFDECT and four-CE FVFDECT were compared by one-way ANOVA and Bland-Altman analysis.Forty patients (mean age, 70.1 years ± 7.8; 25 males) were evaluated. FVFDECT and FFCSI exhibited weak to moderate correlations for HCC in non-CE and four-CE except in equilibrium phase (r = 0.42, 0.44, 0.35, and 0.33; all P < .05), and very strong correlations for liver in all phases (r = 0.86, 0.83, 0.85, 0.87, and 0.84; all P < .05). Those correlation coefficients were significantly higher for liver for each phase (all P < .05). FVFDECT did not differ significantly across scan phases regarding HCC or liver (P = .076 and 0.56). Bland-Altman analysis showed fixed bias in all phases between non- and four-CE FVFDECT in HCC and liver.As compared with liver, correlations between FVF measured by DECT-based MMD and FF measured by CSI were weak in HCC in all phases. FVF is reproducible across all scan phases in HCC and liver. The MMD algorithm requires modification for HCC fat quantification given the heterogeneous components of HCC.

Accuracies of Chemical Shift In/Opposed Phase and Chemical Shift Encoded Magnetic Resonance Imaging to Detect Intratumoral Fat in Hepatocellular Carcinoma

BACKGROUND

Magnetic Resonance Imaging (MRI) being a noninvasive modality may help in preoperative evaluation of intratumoral fat in hepatocellular carcinoma (HCC) using chemical shift encoded (CSE) MRI and in-/opposed-phase (IOP) imaging sequences.

PURPOSE

To compare the diagnostic accuracy of chemical shift encoded fat fraction at three different flip angles (FAs) using quantitative chemical shift encoded MRI (CSE-MRI) with in-/opposed phase (IOP) imaging to evaluate intratumoral fat in HCC.

STUDY TYPE

Retrospective.

POPULATION

Eighty-six patients with 87 pathology proven HCCs.

FIELD STRENGTH/SEQUENCE

IOP (LAVA-Flex) and CSE-MRI (IDEAL IQ) a three-dimensional spoiled gradient-echo pulse sequences acquired at 3 T.

ASSESSMENT

Regions of interest (ROIs) were manually drawn by two observers in the tumors to measure mean fat fractions. Surgical specimens were reassessed for intratumoral fat content. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were assessed for CSE-MRI sequence at FA 3°, 8°, and 9°.

STATISTICAL TESTS

Intraclass correlation coefficient (ICC) was expressed in terms of inter- and intra-observer agreements. Receiver operating characteristic curve analysis was performed for the diagnostic performance followed by combined metric of both. SNR/CNR were analyzed by Kruskal-Wallis test.

RESULTS

Excellent inter- and intra-observer agreements (ICC >0.95, P < 0.001) were observed for both IOP and CSE-MRI. IOP (86.4%) showed higher sensitivity than CSE-MRI at FA 3° (72.5%), FA 8° (76.4%) and FA 9° (76.3%). In contrast, the specificity for CSE-MRI at FA 3° (86%), FA 8° (87%), and FA 9° (87%) were greater than IOP (72%). A combined metric of IOP and CSE-MRI derived fat fractions at FA 8° gave highest AUC of 87% and accuracy of 86%. SNR and CNR for CSE-MRI were significantly higher at FA 8° and FA 9° than FA 3° (P < 0.05).

DATA CONCLUSION

IOP and quantitative CSE-MRI are both feasible methods to detect intratumoral fat in HCC with higher accuracy and SNR for CSE-MRI at FA 8° and 9°.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY: Stage 2.

Steatohepatitic hepatocellular carcinoma: imaging findings with clinicopathological correlation

AIM

To evaluate the clinicopathological and computed tomography (CT) and magnetic resonance imaging (MRI) findings of steatohepatitic hepatocellular carcinoma (SH-HCC).

MATERIALS AND METHODS

Clinicopathological and radiological features were evaluated in 20 patients with SH-HCC. The diagnosis of SH-HCC was made histologically if the tumour had four of the following five characteristics: steatosis (>5% tumour cells), ballooning, Mallory-Denk bodies, interstitial fibrosis, and inflammation. All patients underwent dynamic CT and MRI. CT and MRI images were reviewed for morphological features including tumour size, presence, and distribution of fat, and patterns and degree of contrast enhancement.

RESULTS

Obesity, hypertension, and history of heavy alcohol intake were common clinical findings observed in 10 (50%), 13 (65%), and 11 (55%) of the 20 patients, respectively. Steatosis and steatohepatitis were pronounced in the background liver in 12 (60%) and 10 (50%) patients, respectively. SH-HCC was moderately differentiated in 18 patients (90%) and well differentiated in two (10%). Pathologically, steatohepatitic features were diffuse in 12 (60%) of the 20 tumours and focal in eight (40%). Tumour size and the percentage of intratumoural steatosis were not correlated (r=0.17, p=0.47). On CT, 16 (80%) patients showed arterial phase enhancement and delayed washout. On MRI, 16 (80%) of 20 tumours showed prominent fatty deposition (10 diffusely, six focally) with arterial phase enhancement.

CONCLUSIONS

SH-HCC is likely to show prominent fatty deposits with arterial phase enhancement on CT and MRI. A hypervascular lesion with prominent fatty change should raise the diagnostic suspicion of SH-HCC.

Combined hepatocellular-cholangiocarcinoma: which preoperative clinical data and conventional MRI characteristics have value for the prediction of microvascular invasion and clinical significance?

Objectives

To explore which preoperative clinical data and conventional MRI findings may indicate microvascular invasion (MVI) of combined hepatocellular-cholangiocarcinoma (cHCC-CCA) and have clinical significance.

Methods

The study enrolled 113 patients with histopathologically confirmed cHCC-CCA (MVI-positive group [n = 56], MVI-negative group [n = 57]). Two radiologists retrospectively assessed the preoperative MRI features (qualitative analysis of morphology and dynamic enhancement features), and each lesion was assigned according to the LI-RADS. Preoperative clinical data were also evaluated. Logistic regression analyses were used to assess the relative value of these parameters as potential predictors of MVI. Recurrence-free survival (RFS) rates after hepatectomy in the two groups were estimated using Kaplan–Meier survival curves and compared using the log-rank test.

Results

The majority of cHCC-CCAs were categorized as LR-M. On multivariate analysis, a higher serum AFP level (OR, 0.523; 95% CI, 0.282–0.971; p = 0.040), intratumoral fat deposition (OR, 14.368; 95% CI, 2.749–75.098; p = 0.002), and irregular arterial peritumoral enhancement (OR, 0.322; 95% CI, 0.164–0.631; p = 0.001) were independent variables associated with the MVI of cHCC-CCA. After hepatectomy, patients with MVI of cHCC-CCA showed earlier recurrence than those without MVI (hazard ratio [HR], 0.402; 95% CI, 0.189–0.854, p = 0.013).

Conclusion

A higher serum AFP level and irregular arterial peritumoral enhancement are potential predictive biomarkers for the MVI of cHCC-CCA, while intratumoral fat detected on MRI suggests a low risk of MVI. Furthermore, cHCC-CCAs with MVI may have worse surgical outcomes with regard to early recurrence than those without MVI.

Key Points

• Higher serum levels of AFP combined with irregular arterial peritumoral enhancement are independent risk factors for the MVI of cHCC-CCA, while fat deposition might be a protective factor.

• cHCC-CCA with MVI may have a higher risk of early recurrence after surgery.

• Most cHCC-CCAs were categorized as LR-M in this study, and no significant difference was found in MVI based on LI-RADS category.

Differentiation of hepatocellular carcinoma from non-hepatocellular malignant tumours of liver by chemical-shift MRI at 3 T

AIM

To evaluate the diagnostic performance of chemical shift magnetic resonance imaging (MRI) in distinguishing hepatocellular carcinomas (HCCs) from non-hepatocellular malignant tumours (non-HCCs) of the liver.

MATERIALS AND METHODS

Patients with a diagnosis of malignant liver tumours examined at 3 T MRI were included in this retrospective study. Forty-seven HCCs and 75 non-HCCs that were studied with chemical-shift MRI between January 2012 and October 2016 were retrieved from the radiology database. Two blinded observers measured the signal intensities of the tumours, adjacent normal-looking liver parenchyma, and spleen on chemical-shift MRI. The fat quantification for HCCs, non-HCCs, and adjacent normal-looking liver parenchyma were calculated by using the spleen as a reference standard. The subtraction scores were calculated by subtracting fat percentages in liver parenchyma from those in tumours. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the fat percentage subtraction scores in distinguishing HCCs from non-HCCs were calculated.

RESULTS

According to the optimal cut-off value acquired from both readers, a subtraction score >-0.26 was considered to be a HCC. Fat signal percentage subtraction scores were ≥-0.26 in 45 of 47 HCCs and were <-0.26 in 69 of 75 non-HCCs. The sensitivity, specificity, PPV, and NPV of fat signal percentage subtraction score to differentiate HCCs from non-HCCs were found to be 95.7%, 89.3%, 84.9%, and 97.1%, respectively.

CONCLUSION

Intracytoplasmic lipid in HCCs demonstrated by quantitative chemical-shift MRI may be a potentially powerful imaging biomarker to distinguish HCCs from the other malignant liver tumours.

Liver Imaging Reporting and Data System Category 5: MRI Predictors of Microvascular Invasion and Recurrence After Hepatectomy for Hepatocellular Carcinoma

OBJECTIVE. We investigated in Liver Imaging Reporting and Data System category 5 (LR-5) observations whether imaging features, including LI-RADS imaging features, could predict microvascular invasion (MVI) and posthepatectomy recurrence in high-risk adult patients with hepatocellular carcinoma (HCC). MATERIALS AND METHODS. We retrospectively identified 149 high-risk patients who underwent 3-T MRI within 1 month before hepatectomy for HCC; 81 of 149 patients with no HCC recurrence were followed for more than 1 year. Tumors with clear surgical margins were confirmed in each hepatectomy specimen. MVI was evaluated histologically by a histopathologist. Tumor recurrence was determined by clinical and imaging follow-up. Two independent radiologists reviewed the prehepatectomy MR images and assessed LI-RADS v2018 imaging features as well as some non-LI-RADS features in all LR-5 observations in consensus. Alpha-fetoprotein level, tumor number, and imaging features were analyzed as potential predictors for MVI and posthepatectomy recurrence using multivariate logistic regression and Cox proportional hazards models. RESULTS. One hundred forty-nine patients with pathologically confirmed HCC were included; 64 of 149 (43.0%) patients had MVI, whereas 48 of 129 (37.2%) patients had tumor recurrence within 3 years after hepatectomy. Mosaic architecture (odds ratio, 3.420; p < 0.001) and nonsmooth tumor margin (odds ratio, 2.554; p = 0.011) were independent predictors of MVI. Multifocal tumors (hazard ratio, 2.101; p = 0.034), absence of fat in mass (hazard ratio, 2.109; p = 0.015), and nonsmooth tumor margin (hazard ratio, 2.415; p = 0.005) were independent predictors of posthepatectomy recurrence. CONCLUSION. In high-risk patients with LR-5 HCC, mosaic architecture and non-smooth tumor margin independently predicted MVI. Multifocal tumors, absence of fat in mass, and nonsmooth tumor margin independently predicted recurrence.

Hepatocellular Carcinoma: Current Imaging Modalities for Diagnosis and Prognosis

As opposed to most solid cancers, hepatocellular carcinoma (HCC) does not necessarily require histological confirmation. Noninvasive diagnosis is possible and relies on imaging. In cirrhotic patients, the diagnosis can be obtained in tumors displaying typical features that include non-rim arterial phase hyperenhancement followed by washout during the portal venous and/or delayed phases on CT or MR imaging. This pattern is very specific and, as such, has been endorsed by both Western and Asian diagnostic guidelines and systems. However, its sensitivity is not very high, especially for small lesions. Numerous ancillary features favoring the diagnosis of HCC may be depicted, including appearance after injection of hepatobiliary MR imaging contrast agents. These features increase confidence in diagnosis, but cannot be used as substitutes to liver biopsy. Aside from its diagnostic purpose, imaging also helps to assess tumor biology and patient outcome, by identifying features of local invasiveness. The purpose of this review article is to offer an overview of the role of imaging for the diagnosis and prognostication of HCC.

Current status of imaging biomarkers predicting the biological nature of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is heterogeneous in terms of its biological nature. Various factors related to its biological nature, including size, multifocality, macroscopic morphology, grade of differentiation, macro/microvascular invasion, bile duct invasion, intra-tumoral fat and molecular factors, and their value as prognostic imaging biomarkers have been reported. And recently, genome-based molecular HCC classification correlated with clinical outcome has been elucidated. The imaging biomarkers suggesting a less aggressive nature of HCC are smaller size, solitary tumor, smooth margin suggesting small nodular type with indistinct margin and simple nodular type with distinct margin, capsule, imaging biomarkers predicting early or well-differentiated grade, intra-tumoral fat detection, and low fluorodeoxyglucose (FDG) accumulation. The imaging biomarkers suggesting an aggressive HCC nature are larger size, multifocality, non-smooth margin suggesting simple nodular type with extranodular growth, confluent multinodular, and infiltrative type, imaging biomarkers predicting poor differentiation, macrovascular tumor thrombus, predicting microvascular invasion imaging biomarkers, bile duct dilatation or tumor thrombus, and high FDG accumulation. In the genome-based molecular classification, CTNNB-1 mutated HCC shows a less aggressive nature, while CK19/EpCAM positive HCC and macrotrabecular massive HCC show an aggressive one. Better understanding of these imaging biomarkers can contribute to devising more appropriate treatment plans for HCC.

Imaging features related with prognosis of hepatocellular carcinoma

We discuss various imaging features that have been reported to be associated with the prognosis of hepatocellular carcinoma (HCC) but not included in the current staging systems: findings related with microvascular invasion, tumor encapsulation, intratumoral fat, presence of satellite nodules, peritumoral hypointensity on hepatobiliary phase images of gadoxetic-acid enhanced MRI, restricted diffusion, and irregular rim-like hyperenhancement. Current evidence suggests that larger (> 2 cm) tumor size, presence of satellite nodules, presence of irregular rim-like hyperenhancement of a tumor, peritumoral parenchymal enhancement in the arterial phase, and peritumoral hypointensity observed on hepatobiliary phase images are independent imaging features to portend a worse prognosis in patients with hepatocellular carcinoma.

State of the art in magnetic resonance imaging of hepatocellular carcinoma

Background Liver cancer is the sixth most common cancer worldwide and the second leading cause of cancer mortality. Chronic liver disease caused by viral infection, alcohol abuse, or other factors can lead to cirrhosis. Cirrhosis is the most important clinical risk factor for hepatocellular carcinoma (HCC) whereby the normal hepatic architecture is replaced by fibrous septa and a spectrum of nodules ranging from benign regenerative nodules to HCC, each one of them with different imaging features. Conclusions Furthermore, advanced techniques including the quantification of hepatic and intralesional fat and iron, magnetic resonance elastography, radiomics, radiogenomics, and positron emission tomography (PET)-MRI are highly promising for the extraction of new imaging biomarkers that reflect the tumor microenvironment and, in the future, may add decision-making value in the management of patients with HCC.

Diagnostic value of imaging examinations in patients with primary hepatocellular carcinoma

Primary hepatocellular carcinoma (PHC) includes hepatocellular carcinoma, intrahepatic cholangiocarcinoma and other pathological types and is characterized by rapid progression. Most of the clinical diagnoses are made at late stage or when distant metastasis occurs, increasing the difficulty of treatment and resulting in a poor prognosis. Therefore, the early diagnosis of PHC plays an important role in timely treatment and the improvement of prognosis. The gold standard for the diagnosis of primary liver cancer is liver biopsy, but it has limitations as an invasive examination. Presently, imaging has become the first choice for the diagnosis of liver cancer. We here summarize the new methods and techniques of imaging in diagnosis and evaluation of primary liver cancer in recent years, including ultrasonography, computed tomography perfusion imaging, diffusion-weighted imaging technology-voxel incoherent motion, diffusion tensor imaging, iterative decomposition of water and fat with echo asymmetry and least squares estimation-iron quantification, dynamic enhanced magnetic resonance imaging and hepatocyte-specific contrast medium imaging. Imaging diagnosis can not only evaluate the degree of differentiation, blood supply and perfusion, and invasiveness of the lesion, but also predict the prognosis, evaluate liver function, and provide references for clinical diagnosis and treatment.

CT-MRI LI-RADS v2017: A Comprehensive Guide for Beginners

Hepatocellular carcinoma (HCC) is the most common primary liver malignancy and the second leading cause of cancer-related deceases worldwide. Early diagnosis is essential for correct management and improvement of prognosis. Proposed for the first time in 2011 and updated for the last time in 2017, the Liver Imaging-Reporting and Data System (LI-RADS) is a comprehensive system for standardized interpretation and reporting of computed tomography (CT) and magnetic resonance imaging (MRI) liver examinations, endorsed by the American College of Radiology to achieve congruence with HCC diagnostic criteria in at-risk populations. Understanding its algorithm is fundamental to correctly apply LI-RADS in clinical practice. In this pictorial review, we provide a guide for beginners, explaining LI-RADS indications, describing major and ancillary features and eventually elucidating the diagnostic algorithm with the use of some clinical examples.

Fat-Containing Liver Lesions on Imaging: Detection and Differential Diagnosis

OBJECTIVE

The purpose of this article is to review how fat is detected on imaging and to discuss the differential diagnosis of fat-containing liver lesions.

CONCLUSION

Fat is a highly useful feature in characterizing liver lesions on imaging. Although a variety of liver lesions can show fat on cross-sectional imaging, the presence of fat usually indicates that the lesion is of hepatocellular origin. Less commonly, nonhepatocellular fatty lesions may be distinguished by ancillary clinical and imaging features.

Diagnosis of hepatocellular carcinoma: An update on international guidelines

Imaging is essential for the successful management of patients with or at risk of developing hepatocellular carcinoma (HCC). If ultrasound remains the key screening modality, computed tomography and magnetic resonance imaging (MRI) can play a major role in the characterization and noninvasive diagnosis of nodules in patients at risk of developing HCC. Each technique has succeeded in adapting to the wide histological spectrum of focal liver lesions. In this review, we discuss recent advancements in imaging techniques and evaluation - notably diffusion-weighted imaging, contrast-enhanced ultrasound, and liver-specific MRI contrast agents - as well as their addition to international guidelines and reporting systems such as the Liver imaging reporting and data system (LI-RADS).

Fatty change in moderately and poorly differentiated hepatocellular carcinoma on MRI: a possible mechanism related to decreased arterial flow

AIM

To clarify the frequency of fatty change in moderately and poorly differentiated hepatocellular carcinomas (mHCCs and pHCCs) and its relationship to arterial blood flow.

MATERIALS AND METHODS

One hundred and thirty-six surgically resected HCC lesions were studied. All patients had undergone dynamic magnetic resonance imaging (MRI) with chemical-shift-encoded water-fat imaging (CSI). The presence of fat was identified by a signal drop-off on CSI and confirmed at pathology. Lesions were classified into four groups in the arterial phase; G1, hypointense; G2, isointense; G3, slightly and heterogeneously hyperintense; G4, markedly and homogeneously hyperintense. The number of cumulative arteries (CAs) in the tumours in the pathology examination were counted.

RESULTS

A fat component was observed significantly more frequently in the pHCCs (13/21; 61.9%) compared to the mHCCs (32/101; 31.7%; p=0.013). The numbers of lesions in each group were as follows: (G1, G2, G3, G4) = (18, 9, 23, 4) in the HCCs with fat; (1, 6, 24, 51) in the HCCs without fat (p<0.001); (5, 5, 18, 4) in the mHCCs with fat; (0, 3, 19, 47) in the mHCCs without fat (p<0.001); (11, 0, 2, 0) in the pHCCs with fat; (0, 2, 3, 3) in the pHCCs without fat (p=0.001). The number of CAs in the fat-containing HCCs (5.5±2.9) was significantly lower than that in the HCCs without fat (10.8±5.3; p<0.001).

CONCLUSION

A fat component was more commonly observed in the pHCCs than in the mHCCs. The present results showed a possible mechanism of fatty change in mHCCs and pHCCs in relation to decreased arterial blood supply.

Magnetic resonance imaging with gadoxetic acid for local tumour progression after radiofrequency ablation in patients with hepatocellular carcinoma

OBJECTIVES

To develop and validate a prediction model using magnetic resonance imaging (MRI) for local tumour progression (LTP) after radiofrequency ablation (RFA) in hepatocellular carcinoma (HCC) patients.

METHODS

Two hundred and eleven patients who had received RFA as first-line treatment for HCC were retrospectively analyzed. They had undergone gadoxetic acid-enhanced MRI before treatment, and parameters including tumour size; margins; signal intensities on T1-, T2-, and diffusion-weighted images, and hepatobiliary phase images (HBPI); intratumoral fat or tumoral capsules; and peritumoural hypointensity in the HBPI were used to develop a prediction model for LTP after treatment. This model to discriminate low-risk from high-risk LTP groups was constructed based on Cox regression analysis.

RESULTS

Our analyses produced the following model: 'risk score = 0.617 × tumour size + 0.965 × tumour margin + 0.867 × peritumoural hypointensity on HBPI'. This was able to predict which patients were at high risk for LTP after RFA (p < 0.001). Patients in the low-risk group had a significantly better 5-year LTP-free survival rate compared to the high-risk group (89.6 % vs. 65.1 %; hazard ratio, 3.60; p < 0.001).

CONCLUSION

A predictive model based on MRI before RFA could robustly identify HCC patients at high risk for LTP after treatment.

KEY POINTS

• Tumour size, margin, and peritumoural hypointensity on HBPI were risk factors for LTP. • The risk score model can predict which patients are at high risk for LTP. • This prediction model could be helpful for risk stratification of HCC patients.

Advances in computed tomography and magnetic resonance imaging of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common primary liver cancer. Imaging is important for establishing a diagnosis of HCC and early diagnosis is imperative as several potentially curative treatments are available when HCC is small. Hepatocarcinogenesis occurs in a stepwise manner on a background of chronic liver disease or cirrhosis wherein multiple genes are altered resulting in a range of cirrhosis-associated nodules. This progression is related to increased cellularity, neovascularity and size of the nodule. An understanding of the stepwise progression may aid in early diagnosis. Dynamic and multiphase contrast-enhanced computed tomography and magnetic resonance imaging still form the cornerstone in the diagnosis of HCC. An overview of the current diagnostic standards of HCC in accordance to the more common practicing guidelines and their differences will be reviewed. Ancillary features contribute to diagnostic confidence and has been incorporated into the more recent Liver Imaging Reporting and Data System. The use of hepatocyte-specific contrast agents is increasing and gradually changing the standard of diagnosis of HCC; the most significant benefit being the lack of uptake in the hepatocyte phase in the earlier stages of HCC progression. An outline of supplementary techniques in the imaging of HCC will also be reviewed.

Prognostic role of magnetic resonance imaging vs. computed tomography for hepatocellular carcinoma undergoing chemoembolization

BACKGROUND & AIMS

Computed tomography (CT) and magnetic resonance imaging (MRI) play important roles in diagnosis and staging of hepatocellular carcinoma (HCC). However, prognostic roles of radiological characteristics are not yet determined.

METHODS

Eighty-eight patients treated with chemoembolization were analysed. Radiological parameters at baseline were assessed in all patients using both dynamic CT and MRI. Treatment responses were assessed using modified RECIST 4 weeks after the first chemoembolization.

RESULTS

Gross vascular invasion (GVI), bile duct invasion, irregular tumour margin (ITM), peripheral ragged enhancement (PRE) and satellite nodules on CT or MRI were associated with non-response (stable disease or progression) after chemoembolization respectively (all P ≤ 0.05). GVI, ITM and PRE on CT or MRI were also independently associated with poor overall survival (OS) respectively (all P ≤ 0.05). Using these results, a prognostic scoring system for CT and MRI were developed; 0, absence of all three features (GVI, ITM and PRE); 1, presence of one feature; 2, presence of two features; and 3, presence of three features. After adjusting tumour size, tumour number and alpha-foetoprotein level, both CT and MRI scores were independently associated with OS (both P < 0.001). Patients with CT or MRI score ≥2 had a worse OS than those with score <2 (adjusted hazard ratios, 3.837 and 2.938 respectively). MRI-specific parameters such as signal intensity on T2- or T1-weighted images, fat signal or hyperintensity on diffusion-weighted images did not have prognostic value (all P > 0.05).

CONCLUSIONS

Radiological parameters by CT and MRI may be useful in biological characterization of tumours and prognostification for HCC treated with chemoembolization.

MRI features of hepatocellular carcinoma related to biologic behavior

Imaging studies including magnetic resonance imaging (MRI) play a crucial role in the diagnosis and staging of hepatocellular carcinoma (HCC). Several recent studies reveal a large number of MRI features related to the prognosis of HCC. In this review, we discuss various MRI features of HCC and their implications for the diagnosis and prognosis as imaging biomarkers. As a whole, the favorable MRI findings of HCC are small size, encapsulation, intralesional fat, high apparent diffusion coefficient (ADC) value, and smooth margins or hyperintensity on the hepatobiliary phase of gadoxetic acid-enhanced MRI. Unfavorable findings include large size, multifocality, low ADC value, non-smooth margins or hypointensity on hepatobiliary phase images. MRI findings are potential imaging biomarkers in patients with HCC.

MR characterization of focal liver lesions: pearls and pitfalls

Magnetic resonance (MR) can characterize specific tissue subtypes, thus facilitating focal liver lesion diagnosis. Focal liver lesions that are isointense to hyperintense to liver on T1-weighted images are usually hepatocellular in origin. Chemical shift imaging can narrow the differential diagnosis by detecting the presence of lipid or iron. T2 and heavily T2-weigthed fast spin echo imaging can differentiate solid from nonsolid focal liver lesions. The authors illustrate these MR imaging pearls and the uncommon exceptions (pitfalls). The authors hope that you will find this less traditional contribution to the Magnetic Resonance Clinics of North America helpful in clinical practice.

Prediction of microvascular invasion of hepatocellular carcinomas with gadoxetic acid-enhanced MR imaging: Impact of intra-tumoral fat detected on chemical-shift images

PURPOSE

To investigate the impact of intra-tumoral fat detected by chemical-shift MR imaging in predicting the MVI of HCC.

MATERIALS AND METHODS

Gadoxetic acid-enhanced MR imaging of 365 surgically proven HCCs from 365 patients (306 men, 59 women; mean age, 55.6 years) were evaluated. HCCs were classified into two groups, fat-containing and non-fat-containing, based on the presence of fat on chemical-shift images. Fat-containing HCCs were subdivided into diffuse or focal fatty change groups. Logistic regression analyses were used to identify clinical and MR findings associated with MVI.

RESULTS

Based on MR imaging, 66 tumors were classified as fat-containing HCCs and 299 as non-fat-containing HCCs. Among the 66 fat-containing HCCs, 38 (57.6%) showed diffuse fatty changes and 28 (42.4%) showed focal fatty changes. MVI was present in 18 (27.3%) fat-containing HCCs and in 117 (39.1%) non-fat-containing HCCs (P=0.07). Univariate analysis revealed that serum alpha-fetoprotein (AFP) and tumor size were significantly associated with MVI (P<0.001). A multiple logistic regression analysis showed that log AFP (odds ratio 1.178, P=0.0016), tumor size (odds ratio 1.809, P<0.001), and intra-tumoral fat (odds ratio 0.515, P=0.0387) were independent variables associated with MVI.

CONCLUSION

Intra-tumoral fat detected with MR imaging may suggest lower risk for MVI of HCC and, therefore, a possibly more favorable prognosis, but the clinical value of this finding is uncertain.

Single Hepatocellular Carcinoma: Preoperative MR Imaging to Predict Early Recurrence after Curative Resection

PURPOSE

To identify magnetic resonance (MR) imaging features that enable prediction of early recurrence (<2 years) after curative resection of hepatocellular carcinoma (HCC) and to derive a preoperative prediction model.

MATERIALS AND METHODS

This retrospective study was approved by the institutional review board. The requirement to obtain written informed consent was waived. A total of 268 patients who underwent hepatic resection for a single HCC from January 2008 to August 2011 were divided into two cohorts: a training cohort, which was used to derive a prediction model (n = 187), and a validation cohort (n = 81). All MR images from the training cohort were reviewed by two radiologists. A prediction model was constructed by using MR imaging features that were independently associated with early recurrence with use of multiple logistic regression analysis. The performance of the prediction model in the validation cohort was evaluated with respect to discrimination (ie, whether the relative ranking of individual predictions of subsequent early recurrence is in the correct order).

RESULTS

In the training cohort, four MR imaging features were independently associated with early recurrence: rim enhancement (odds ratio [OR] = 3.83; 95% confidence interval [CI]: 1.39, 10.52), peritumoral parenchymal enhancement in the arterial phase (OR = 2.64; 95% CI: 1.27, 5.46), satellite nodule (OR = 4.07; 95% CI: 1.09, 15.21), and tumor size (OR = 1.66; 95% CI: 1.31, 2.09). A prediction model derived from these variables showed an area under the receiver operating characteristic curve (AUC) of 0.788 in the prediction of the risk of early recurrence in the training cohort. When applied to the validation cohort, this model showed good discrimination (AUC, 0.783).

CONCLUSION

The prediction model derived from rim enhancement, peritumoral parenchymal enhancement, satellite nodule, and tumor size can be used preoperatively to estimate the risk of early recurrence after resection of a single HCC.

CT and MR imaging diagnosis and staging of hepatocellular carcinoma: part II. Extracellular agents, hepatobiliary agents, and ancillary imaging features

Computed tomography (CT) and magnetic resonance (MR) imaging play critical roles in the diagnosis and staging of hepatocellular carcinoma (HCC). The second article of this two-part review discusses basic concepts of diagnosis and staging, reviews the diagnostic performance of CT and MR imaging with extracellular contrast agents and of MR imaging with hepatobiliary contrast agents, and examines in depth the major and ancillary imaging features used in the diagnosis and characterization of HCC.

Hepatocellular carcinoma: diagnostic criteria by imaging techniques

Imaging plays a very important role in the diagnosis of HCC. Indeed, in high-risk patients a noninvasive diagnosis can only be obtained by imaging in presence of typical features. These features include arterial enhancement followed by washout during the portal venous and/or delayed phases on CT scan or MRI. This pattern is quite specific and has been endorsed by both Western and Asian diagnostic guidelines. However, its sensitivity is not very high, especially for small lesions. Therefore ancillary signs may be needed to increase the reliability of the diagnosis. Recent hepatobiliary MRI contrast agents seem to be interesting to improve characterization of small nodules in the cirrhotic liver.

Magnetic resonance imaging in cirrhosis: what's new?

Cirrhosis is the main risk factor for the development of hepatocellular carcinoma (HCC). The major causative factors of cirrhosis in the United States and Europe are chronic hepatitis C infection and excessive alcohol consumption with nonalcoholic steatohepatitis emerging as another important risk factor. Magnetic resonance imaging is the most sensitive imaging technique for the diagnosis of HCC, and the sensitivity can be further improved with the use of diffusion-weighted imaging and hepatocyte-specific contrast agents. The combination of arterial phase hyperenhancement, venous or delayed phase hypointensity "washout feature," and capsular enhancement are features highly specific for HCC with reported specificities of 96% and higher. When these features are present in a mass in the cirrhotic liver, confirmatory biopsy to establish the diagnosis of HCC is not necessary. Other tumors, such as cholangiocarcinoma, sometimes occur in the cirrhotic at a much lower rate than HCC and can mimic HCC, as do other benign lesions such as perfusion abnormalities. In this article, we discuss the imaging features of cirrhosis and HCC, the role of magnetic resonance imaging in the diagnosis of HCC and other benign and malignant lesions that occur in the cirrhotic liver, and the issue of nonspecific arterially hyperenhancing nodules often seen in cirrhosis.