Enhancement patterns and signal-intensity characteristics of small hepatocellular carcinoma in cirrhosis: pathologic basis and diagnostic challenges

LI-RADS v2018 category and imaging features: inter-modality agreement between contrast-enhanced CT, gadoxetate disodium-enhanced MRI, and extracellular contrast-enhanced MRI

PURPOSE

To perform an intra-individual comparison of LI-RADS category and imaging features in patients at high risk of hepatocellular carcinoma (HCC) on contrast-enhanced CT, gadoxetate disodium-enhanced MRI (EOB-MRI), and extracellular agent-enhanced MRI (ECA-MRI) and to analyze the diagnostic performance of each imaging modality.

METHOD

This retrospective study included cirrhotic patients with at least one LR-3, LR-4, LR-5, LR-M or LR-TIV observation imaged with at least two imaging modalities among CT, EOB-MRI, or ECA-MRI. Two radiologists evaluated the observations using the LI-RADS v2018 diagnostic algorithm. Reference standard included pathologic confirmation and imaging criteria according to LI-RADS v2018. Imaging features were compared between different exams using the McNemar test. Inter-modality agreement was calculated by using the weighted Cohen's kappa (k) test.

RESULTS

A total of 144 observations (mean size 34.0 ± 32.4 mm) in 96 patients were included. There were no significant differences in the detection of major and ancillary imaging features between the three imaging modalities. When considering all the observations, inter-modality agreement for category assignment was substantial between CT and EOB-MRI (k 0.60; 95%CI 0.44, 0.75), moderate between CT and ECA-MRI (k 0.46; 95%CI 0.22, 0.69) and substantial between EOB-MRI and ECA-MRI (k 0.72; 95%CI 0.59, 0.85). In observations smaller than 20 mm, inter-modality agreement was fair between CT and EOB-MRI (k 0.26; 95%CI 0.05, 0.47), moderate between CT and ECA-MRI (k 0.42; 95%CI -0.02, 0.88), and substantial between EOB-MRI and ECA-MRI (k 0.65; 95%CI 0.47, 0.82). ECA-MRI demonstrated the highest sensitivity (70%) and specificity (100%) when considering LR-5 as predictor of HCC.

CONCLUSIONS

Inter-modality agreement between CT, ECA-MRI, and EOB-MRI decreases in observations smaller than 20 mm. ECA-MRI has the provided higher sensitivity for the diagnosis of HCC.

Diagnostic performance of gadoxetic acid-enhanced abbreviated magnetic resonance imaging protocol in small hepatocellular carcinoma (≤2 cm) in high-risk patients

BACKGROUND

Biannual Ultrasound showed insufficient sensitivity in detecting small or early-stage hepatocellular carcinoma (HCC). Abbreviated magnetic resonance imaging (A-MRI) protocols with fewer sequences demonstrated higher HCC detection sensitivity than ultrasound with acceptable cost and examination time.

PURPOSE

To compare the diagnostic performance of gadoxetic acid-enhanced A-MRI with a full sequence MRI (F-MRI) protocol for small HCC (≤2 cm) in cirrhotic or hepatitis B virus-infected high-risk patients.

MATERIAL AND METHODS

Two hundred and four consecutive patients with 166 pathologically confirmed small HCC who underwent preoperative gadoxetic acid-enhanced MRI were retrospectively included. A-MRI set comprised T1-weighted hepatobiliary phase imaging, T2-weighted imaging, diffusion-weighted imaging and apparent diffusion coefficient mapping. Two independent radiologists blinded to clinical data assessed the A-MRI set and F-MRI set. Per-patient HCC and per-lesion HCC diagnostic performance were compared.

RESULTS

Per-patient HCC detection sensitivity of A-MRI set was 93.8% and 91.2% for observer 1 and observer 2, and, for the F-MRI set, the per-patient HCC detection sensitivity was 96.6% and 95.2%, respectively. There was no significant difference in per-patient sensitivity, specificity and per-lesion HCC detection sensitivity between the two imaging sets for both readers. (P = 0.06-0.25) The A-MRI set showed higher sensitivity on HCC without arterial phase hyperenhancement, and the F-MRI set demonstrated with higher sensitivity on HCC with arterial phase hyperenhancement (P < 0.05).

CONCLUSION

A-MRI using diagnostic criteria including hypointensity on hepatobiliary phase plus mild to moderate hyperintensity on T2-weighted imaging or restricted diffusion demonstrated comparable sensitivity and specificity for small HCC compared to the F-MRI protocol in high-risk patients.

Multi-phase contrast-enhanced magnetic resonance image-based radiomics-combined machine learning reveals microscopic ultra-early hepatocellular carcinoma lesions

Purpose

This study aimed to investigate whether models built from radiomics features based on multiphase contrast-enhanced MRI can identify microscopic pre-hepatocellular carcinoma lesions.

Methods

We retrospectively studied 54 small hepatocellular carcinoma (SHCC, diameter < 2 cm) patients and 70 patients with hepatocellular cysts or haemangiomas from September 2018 to June 2021. For the former, two MRI scans were collected within 12 months of each other; the 2^nd scan was used to confirm the diagnosis. The volumes of interest (VOIs), including SHCCs and normal liver tissues, were delineated on the 2^nd scans, mapped to the 1^st scans via image registration, and enrolled into the SHCC and internal-control cohorts, respectively, while those of normal liver tissues from patients with hepatocellular cysts or haemangioma were enrolled in the external-control cohort. We extracted 1132 radiomics features from each VOI and analysed their discriminability between the SHCC and internal-control cohorts for intra-group classification and the SHCC and external-control cohorts for inter-group classification. Five radial basis-function, kernel-based support vector machine (SVM) models (four corresponding single-phase models and one integrated from the four-phase MR images) were established.

Results

Among the 124 subjects, the multiphase models yielded better performance on the testing set for intra-group and inter-group classification, with areas under the receiver operating characteristic curves of 0.93 (95% CI, 0.85–1.00) and 0.97 (95% CI, 0.92–1.00), accuracies of 86.67% and 94.12%, sensitivities of 87.50% and 94.12%, and specificities of 85.71% and 94.12%, respectively.

Conclusion

The combined multiphase MRI-based radiomics feature model revealed microscopic pre-hepatocellular carcinoma lesions.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00259-022-05742-8.

[Small hepatocellular carcinoma : Diagnostics according to guidelines and established in the clinical setting]

CLINICAL/METHODICAL ISSUE

The diagnosis of hepatocellular carcinoma (HCC)-especially the characterization of small lesions <2 cm-continues to be a radiological challenge.

STANDARD RADIOLOGICAL METHODS

In the current S3 guideline on diagnosis and therapy of HCC, contrast-enhanced imaging examinations, such as contrast-enhanced ultrasonography (CEUS), computed tomography (CT), and magnetic resonance imaging (MRI), are still the diagnostic standard.

METHODOLOGICAL INNOVATIONS

HCC in the cirrhotic liver should be diagnosed by its typical contrast-enhanced pattern in the MRI. In addition, the use of quality assurance instruments such as LI-RADS (Liver Imaging Reporting and Data System) contributes to the desired consistency of findings, even with small ambiguous findings.

PERFORMANCE

Many studies have shown that the LI-RADS classification reflects the likelihood of HCC and other malignant liver lesions.

ACHIEVEMENTS

Guidelines and quality assurance instruments contribute to a more precise diagnosis in patients with suspected HCC.

PRACTICAL RECOMMENDATIONS

A guideline-compliant diagnostic algorithm and the LI-RADS should be used across the board for accurate HCC diagnostics.

Hepatocarcinogenesis: Radiology-Pathology Correlation

In the background of chronic liver disease, hepatocellular carcinoma develops via a complex, multistep process called hepatocarcinogenesis. This article reviews the causes contributing to the process. Emphasis is made on the imaging manifestations of the pathologic changes seen at many stages of hepatocarcinogenesis, from regenerative nodules to dysplastic nodules and then to hepatocellular carcinoma.

An overview of hepatocellular carcinoma with atypical enhancement pattern: spectrum of magnetic resonance imaging findings with pathologic correlation

BACKGROUND

In the setting of cirrhotic liver, the diagnosis of hepatocellular carcinoma (HCC) is straightforward when typical imaging findings consisting of arterial hypervascularity followed by portal-venous washout are present in nodules larger than 1 cm. However, due to the complexity of hepatocarcinogenesis, not all HCCs present with typical vascular behaviour. Atypical forms such as hypervascular HCC without washout, isovascular or even hypovascular HCC can pose diagnostic dilemmas. In such cases, it is important to consider also the appearance of the nodules on diffusion-weighted imaging and hepatobiliary phase. In this regard, diffusion restriction and hypointensity on hepatobiliary phase are suggestive of malignancy. If both findings are present in hypervascular lesion without washout, or even in iso- or hypovascular lesion in cirrhotic liver, HCC should be considered. Moreover, other ancillary imaging findings such as the presence of the capsule, fat content, signal intensity on T2-weighted image favour the diagnosis of HCC. Another form of atypical HCCs are lesions which show hyperintensity on hepatobiliary phase. Therefore, the aim of the present study was to provide an overview of HCCs with atypical enhancement pattern, and focus on their magnetic resonance imaging (MRI) features.

CONCLUSIONS

In order to correctly characterize atypical HCC lesions in cirrhotic liver it is important to consider not only vascular behaviour of the nodule, but also ancillary MRI features, such as diffusion restriction, hepatobiliary phase hypointensity, and T2-weighted hyperintensity. Fat content, corona enhancement, mosaic architecture are other MRI feautures which favour the diagnosis of HCC even in the absence of typical vascular profile.

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.

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.

Standardisierte Befundung und Dokumentation der Kontrastmittelsonografie der Leber (CEUS LI-RADS)

In der Abklärung von hepatozellulären Karzinomen (HCCs) bei Hochrisikopatienten wurde zur standardisierten Befundung und Dokumentation der Kontrastmittel-Computertomografie (CECT) und Kontrastmittel-Magnetresonanztomografie (CEMRT) vor wenigen Jahren das „Liver Imaging Reporting and Data System” (LI-RADS) durch das American College of Radiology (ACR) erstellt. Die LI-RADS-Kategorisierung wird zur Klassifikation von Leberläsionen in der Leberzirrhose als sicher benigne (LR-1), intermediär (LR2 – 4) bis zu „definitiv HCC“ (LR-5) beurteilt. Seit 2014 wurde die LI-RADS-Klassifikation durch eine Arbeitsgruppe von internationalen Radiologen und Hepatologen auf die Kontrastmittelsonografie erweitert. Zeitgleich mit der Zulassung des Kontrastmittels SonoVue™ (in den USA Lumason™) wurde die Klassifikation 2016 in die LI-RADS Kategorisierung integriert und wird in diesem Artikel erläutert (CEUS-LI-RADS).

Micro-HCCs in rats with liver cirrhosis: paradoxical targeting effects with vascular disrupting agent CA4P

We sought to investigate anticancer efficacy of a vascular disrupting agent (VDA) combretastatin A-4 phosphate (CA4P) in relation to tumor size among hepatocellular carcinomas (HCCs) in rats using magnetic resonance imaging (MRI) and postmortem techniques. Nineteen rats with 43 chemically-induced HCCs of 2.8–20.9 mm in size on liver cirrhosis received CA4P intravenously at 10 mg/kg. Tumor-diameter was measured by T2-weighted imaging (T2WI) to define microcancers (< 5 mm) versus larger HCCs. Vascular responses and tissue necrosis were detected by diffusion-weighted imaging (DWI), contrast-enhanced T1-weighted imaging (CE-T1WI) and dynamic contrast enhanced (DCE-) MRI, which were validated by microangiography and histopathology. MRI revealed nearly complete necrosis in 5 out of 7 micro-HCCs, but diverse therapeutic necrosis in larger HCCs with a positive correlation with tumor size. Necrosis in micro-HCCs was 36.9% more than that in larger HCCs. While increased diffusion coefficient (ADC_diff) suggested tumor necrosis, perfusion coefficient (ADC_perf) indicated sharply decreased blood perfusion in cirrhotic liver together with a reduction in micro-HCCs. DCE revealed lowered tumor blood flow from intravascular into extravascular extracellular space (EES). Microangiography and histopathology revealed hypo- and hypervascularity in 4 and 3 micro-HCCs, massive, partial and minor degrees of tumoral necrosis in 5, 1 and 1 micro-HCCs respectively, and patchy necrotic foci in cirrhotic liver. CD34-PAS staining implicated that poorly vascularized micro-HCCs growing on liver cirrhosis tended to respond better to CA4P treatment. In this study, more complete CA4P-response occurred unexpectedly in micro-HCCs in rats, along with CA4P-induced necrotic foci in cirrhotic liver. These may help to plan clinical applications of VDAs in patients with HCCs and liver cirrhosis.

Radiofrequency Ablation of Hepatocellular Carcinoma with a "Nodule-in-Nodule" Appearance: Long-Term Follow-up and Clinical Implications

PURPOSE

Hepatocellular carcinoma (HCC) with a "nodule-in-nodule" (NIN) appearance has unique histological characteristics as an early HCC. We assessed long-term therapeutic outcomes of radiofrequency ablation (RFA) in HCC patients considering this appearance.

MATERIALS AND METHODS

Our Institutional Review Board approved this retrospective study, and the requirement for written informed consent was waived. Between May 2006 and April 2012, a total of 572 patients underwent RFA for single HCC as a first-line treatment. Patients were divided into a NIN HCC group (n = 22) and a non-NIN HCC group (n = 550), according to the NIN feature on pretreatment imaging studies. Local tumor progression (LTP) and disease-free survival (DFS) were compared. Prognostic factors for LTP and DFS were assessed using a Cox proportional hazards model.

RESULTS

The cumulative LTP rates were 4.6 and 4.6% at 3 and 5 years, respectively, in the NIN HCC group, and 15.9 and 20.5% in the non-NIN HCC group, with borderline statistical significance (p = 0.085). The corresponding DFS rates were 53.8 and 37.7% in the NIN HCC group and 44.0 and 31.7% in the non-NIN HCC group, with no significant difference (p = 0.318). Although on multivariate analysis only tumor size was a significant prognostic factor for LTP, there was a trend bordering on the significance for the NIN feature [hazard ratio (HR) = 0.19; p = 0.099]. However, it was not a significant factor for DFS (HR = 0.18; p = 0.682).

CONCLUSIONS

The NIN appearance, a rare (4%, 22/550) but unique feature of early HCC, may be a favorable prognostic factor for RFA in terms of local tumor control.

Correlation of magnetic resonance signal characteristics and perfusion parameters assessed by volume perfusion computed tomography in hepatocellular carcinoma: Impact on lesion characterization

AIM: To find out if magnetic resonance (MR)-signal characteristics of hepatocellular carcinomas (HCC) correlate with perfusion parameters assessed by volume perfusion computed tomography (VPCT).

METHODS: From October 2009 to January 2014, 26 (mean age, 69.3 years) patients with 36 HCC lesions who underwent both VPCT and MR liver imaging were analysed. We compared signal intensity in the T1w- and T2w-images and wash-in/wash-out kinetics on post-contrast MR images with mean values of blood flow (BF, mL/100 mL per minute), blood volume (BV, mL/100 mL), k-trans (mL/100 mL per minute), arterial liver perfusion (mL/100 mL per minute), portal venous perfusion and hepatic perfusion index (HPI, %) obtained by VPCT. Signal intensity on magnetic resonance imaging (MRI) was classified hyper/iso/hypointense compared with surrounding liver parenchyma.

RESULTS: Signal intensity on native T1w- and T2w-images was hyper/iso/hypo in 4/16/16 and 21/14/1 lesions, respectively. Wash-in and wash-out contrast kinetics were found on MRI in 33 of 36 lesions (91.7%) and 25 of 36 lesions (69.4%), respectively. The latter was observed significantly more often in higher graded lesions (P < 0.005). HPI was 94.7% ± 6.5%. There was no significant relationship between lesion’s MR-signal intensity, MR signal combinations, size and any of the VPCT-perfusion parameters. However HPI was constantly high in all HCC lesions.

CONCLUSION: VPCT parameters add limited value to MR-lesion characterization. However in HCC lesions with atypical MR signal characteristics HPI can add a parameter to ensure HCC diagnosis.

Insights into the diagnosis of hepatocellular carcinomas with hepatobiliary MRI

The incidence of hepatocellular carcinomas (HCCs) has increased worldwide in line with an improved screening by high-resolution imaging of cirrhotic livers. Besides abdominal ultrasonography and computerised tomography, magnetic resonance imaging (MRI) is an important tool to detect HCCs. With commercialisation of MR hepatobiliary contrast agents that cross membrane transporters in hepatocytes or tumour cells, MRI adds new information to detect and characterise HCCs. When tumour cells lose organic anion transporting polypeptides (OATP1B1/B3) in cell membranes facing sinusoidal blood, tumours appear hypointense (decreased contrast agent concentrations) in comparison to surrounding normal or cirrhotic liver that retains OATP1B1/B3 expression. However, expression, regulation, and prognostic significance of transporter evolution along carcinogenesis are not completely known. Moreover, understanding signal intensities in focal lesions also relies on transport functions of cellular efflux transporters. This manuscript reviews all the publications that associate liver imaging with hepatobiliary contrast agents and expression of transporters. The regulation of transporters along carcinogenesis to anticipate the prognosis of focal lesions is also included.

Focal Lesions in Fatty Liver: If Quantitative Analysis Facilitates the Differentiation of Atypical Benign from Malignant Lesions

To evaluate the diagnostic performance of quantitative analysis as an adjunctive diagnostic tool to contrast-enhanced ultrasound (US) for the differentiation of atypical benign focal liver lesions (FLLs) from malignancies in fatty liver. Twenty-seven benign FLLs and fifty-six malignant FLLs that appeared hyper-enhanced during the arterial phase with washout in the portal or late phase in fatty liver were analyzed. Chi-square tests and logistic regression were applied to identify the specific features. Three sets of criteria were assigned: 1) all FLLs subjected to routine contrast-enhanced US; 2) all FLLs subjected to quantification analysis and contrast-enhanced US; and 3) parts of FLLs that could not be diagnosed using contrast-enhanced US (n = 66, 75.9%) but instead were diagnosed using parametric features. The sensitivity, specificity, accuracy and area under the receiver operating characteristic curve (AUC) of the three sets of criteria were analyzed. The AUCs of the criterion set 2 were significantly higher than those of criterion set 1 (0.904 versus 0.792, P = 0.008). Criterion set 3 showed a relatively high sensitivity (90.2%) with a relatively high AUC (0.845). The quantification analysis offers improved diagnostic performance for the differential identification of atypical benign FLLs from malignancies in fatty liver.

Intraobserver and Interobserver Agreement in the Evaluation of Tumor Vascularization With Computed Tomography Perfusion in Cirrhotic Patients With Hepatocellular Carcinoma

OBJECTIVES

To evaluate intrareader and inter-reader agreement in CT perfusion (Perf) measurements in cirrhotic patients with hepatocellular carcinoma (HCC) lesions.

METHODS

Sixteen patients with HCC (9 untreated, 5 recurrence/residual disease after transarterial chemoembolization, and 2 after radiofrequency ablation treatment) underwent standard CT examination and a Perf study; a quantitative map of arterial and portal Perf by means of a color scale was generated. With dedicated Perf software, the following parameters were calculated on untreated and treated HCC lesions and on cirrhotic parenchyma: hepatic Perf, tissue blood volume, hepatic perfusion index, arterial perfusion, and time to peak. Intraobserver and interobserver agreements were assessed for 2 readers with Bland-Altman plots, intraclass correlation coefficients (ICCs), coefficients of variation, and repeatability.

RESULTS

In HCC lesions, agreement analysis demonstrated higher intra-agreement values in comparison with interagreement (range of ICC values, 0.26-0.59 between readers and 0.67-0.94 between readings). Lower interagreement was found for treated HCC lesions in comparison with untreated lesions (range of ICC values, respectively, 0.12-0.54 and 0.31-0.89).

CONCLUSIONS

For all Perf parameters intra-agreement was higher than interagreement, even though a relatively wide range of 95% limits of agreement was found in both cases.

Gadoxetate Disodium-Enhanced MRI to Differentiate Dysplastic Nodules and Grade of Hepatocellular Carcinoma: Correlation With Histopathology

OBJECTIVE

The objective of our study was to determine quantitative differences to differentiate low-grade from high-grade dysplastic nodules (DNs) and low-grade from high-grade hepatocellular carcinomas (HCCs) using gadoxetate disodium-enhanced MRI.

MATERIALS AND METHODS

A retrospective study of 149 hepatic nodules in 127 consecutive patients who underwent gadoxetic acid-enhanced MRI was performed. MRI signal intensities (SIs) of the representative lesion ROI and of ROIs in liver parenchyma adjacent to the lesion were measured on unenhanced T1-weighted imaging and on dynamic contrast-enhanced MRI in the arterial, portal venous, delayed, and hepatobiliary phases. The relative SI of the lesion was calculated for each phase as the relative intensity ratio as follows: [mass SI / liver SI].

RESULTS

Of the 149 liver lesions, nine (6.0%) were low-grade DNs, 21 (14.1%) were high-grade DNs, 83 (55.7%) were low-grade HCCs, and 36 (24.2%) were high-grade HCCs. The optimal cutoffs for differentiating low-grade DNs from high-grade DNs and HCCs were an unenhanced to arterial SI of ≥ 0 or a relative SI on T2-weighted imaging of ≤ 1.5, with a positive predictive value (PPV) of 99.2% and accuracy of 88.6%. The optimal cutoffs for differentiating low-grade HCCs from high-grade HCCs were a relative hepatobiliary SI of ≤ 0.5 or a relative T2 SI of ≥ 1.5, with a PPV of 81.0% and an accuracy of 60.5%.

CONCLUSION

Gadoxetate disodium-enhanced MRI allows quantitative differentiation of low-grade DNs from high-grade DNs and HCCs, but significant overlap was seen between low-grade HCCs and high-grade HCCs.

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.

Characterization of hepatocellular carcinoma (HCC) lesions using a novel CT-based volume perfusion (VPCT) technique

OBJECTIVE

To characterize hepatocellular carcinoma (HCC) in terms of perfusion parameters using volume perfusion CT (VPCT) and two different calculation methods, compare their results, look for interobserver agreement of measurements and correlation between tumor arterialization and lesion size.

MATERIAL AND METHODS

This study was part of a prospective monitoring study in patients with HCC undergoing TACE, which was approved by the local Institutional Review Board. 79 HCC-patients (mean age, 64.7) with liver cirrhosis were enrolled. VPCT was performed for 40s covering the involved liver (80 kV, 100/120 mAs) using 64 mm × 0.6 mm collimation, 26 consecutive volume measurements, 50 mL iodinated contrast IV and 5 mL/s flow rate. Mean/maximum blood flow (BF; ml/100mL/min), blood volume (BV) and k-trans were determined both with the maximum slope+Patlak vs. deconvolution method. Additionally, the portal venous liver perfusion (PVP), the arterial liver perfusion (ALP) and the hepatic perfusion index (HPI) were determined for each tumor including size measurements. Interobserver agreement for all perfusion parameters was calculated using intraclass correlation coefficients (ICC).

RESULTS

The max. slope+Patlak method yielded: BFmean/max=37.8/57 mL/100g-tissue/', BVmean/max=9.8/11.1 mL/100g-tissue, k-trans-mean/max=34.4/44.5 mL/100g-tissue/'. For the deconvolution method BFmean/max, BVmean/max and, k-trans-mean/max were 68.3/106.1 mL/100g-tissue/', 12.6/15.5 mL/100g-tissue and 24/33.8 mL/100g-tissue/'. Mean ALP, PVP, HPI and size were 53.7 mL/100g-tissue/', 2.4 mL/100g-tissue/', 96.4 and 3.5 cm, respectively. Interobserver agreement measured with intraclass coefficient correlation (ICC) was very good for all perfusion parameters (≥ 0.99). Best correlation between calculation methods was achieved for measurements of BF, while BV and k-trans values were less correlated. There was no relationship between HPI and lesion size.

CONCLUSION

VPCT can measure tumor volume perfusion non-invasively and enables quantification of the degree of HCC arterialization. Results are dependent on the technique used with best inter-method correlation for BF. Tumor HPI did not proved size-dependent.

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.

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.

Liver-specific agents for contrast-enhanced MRI: role in oncological imaging

Liver-specific magnetic resonance (MR) contrast agents are increasingly used in evaluation of the liver. They are effective in detection and morphological characterization of lesions, and can be useful for evaluation of biliary tree anatomy and liver function. The typical appearances and imaging pitfalls of various tumours at MR imaging performed with these agents can be understood by the interplay of pharmacokinetics of these contrast agents and transporter expression of the tumour. This review focuses on the applications of these agents in oncological imaging.

Differentiation between dysplastic nodule and early-stage hepatocellular carcinoma: The utility of conventional MR imaging

AIM: To elucidate the variety of ways early-stage hepatocellular carcinoma (HCC) can appear on magnetic resonance (MR) imaging by analyzing T1-weighted, T2-weighted, and gadolinium-enhanced dynamic studies.

METHODS: Seventy-three patients with well-differentiated HCC (wHCC) or dysplastic nodules were retrospectively identified from medical records, and new histological sections were prepared and reviewed. The tumor nodules were categorized into three groups: dysplastic nodule (DN), wHCC compatible with Edmondson-Steiner grade I HCC (w1-HCC), and wHCC compatible with Edmondson-Steiner grade II HCC (w2-HCC). The signal intensity on pre-contrast MR imaging and the enhancing pattern for each tumor were recorded and compared between the three tumor groups.

RESULTS: Among the 73 patients, 14 were diagnosed as having DN, 40 were diagnosed as having w1-HCC, and 19 were diagnosed as having w2-HCC. Hyperintensity measurements on T2-weighted axial images (T2WI) were statistically significant between DNs and wHCC (P = 0.006) and between DN and w1-HCC (P = 0.02). The other imaging features revealed no significant differences between DN and wHCC or between DN and w1-HCC. Hyperintensity on both T1W out-phase imaging (P = 0.007) and arterial enhancement on dynamic study (P = 0.005) showed statistically significant differences between w1-HCC and w2-HCC. The other imaging features revealed no significant differences between w1-HCC and w2-HCC.

CONCLUSION: In the follow-up for a cirrhotic nodule, increased signal intensity on T2WI may be a sign of malignant transformation. Furthermore, a noted loss of hyperintensity on T1WI and the detection of arterial enhancement might indicate further progression of the histological grade.

Quantitative therapy response assessment by volumetric iodine-uptake measurement: initial experience in patients with advanced hepatocellular carcinoma treated with sorafenib

OBJECTIVES

To investigate the volumetric iodine-uptake (VIU) changes by dual-energy CT (DECT) in assessing the response to sorafenib treated hepatocellular carcinoma (HCC) patients, compared with AASLD (American Association for the Study of Liver Diseases) and Choi criteria.

MATERIALS AND METHODS

Fifteen patients with HCC receiving sorafenib, monitored with contrast-enhanced DECT scans at baseline and a minimum of one follow-up (8-12 weeks) were retrospectively evaluated. 30 target lesions in total were analyzed for tumor response according to VIU and adapted Choi criteria and compared with the standard AASLD.

RESULTS

According to AASLD criteria, 67% target lesions showed disease control: partial response (PR) in 3% and stable disease (SD) in 63%. 33% lesions progressed (PD). Disease control rate presented by VIU (60%) was similar to AASLD (67%) and Choi (63%) (P>0.05). For disease control group, change in mean VIU was from 149.5 ± 338.3mg to 108.5 ± 284.1mg (decreased 19.1 ± 42.9%); and for progressive disease group, change in mean VIU was from 163.7 ± 346.7 mg to 263.9 ± 537.2 mg (increased 230.5 ± 253.1%). Compared to AASLD (PR, 3%), VIU and Choi presented more PR (33% and 30%, respectively) in disease control group (P<0.05). VIU has moderate consistency with both AASLD (kappa=0.714; P<0.005) and Choi (kappa=0.648; P<0.005), while VIU showed a better consistency and correlation with AASLD (kappa=0.714; P<0.005; r=0.666, P<0.005) than Choi with AASLD (kappa=0.634, P<0.005; r=0.102, P=0.296).

CONCLUSION

VIU measurements by DECT can evaluate the disease control consistent with the current standard AASLD. Measurements are semi-automatic and therefore easy and robust to apply. As VIU reflects vital tumor burden in HCC, it is likely to be an optimal tumor response biomarker in HCC.

Histological characteristics of small hepatocellular carcinomas showing atypical enhancement patterns on gadoxetic acid-enhanced MR imaging

PURPOSE

To define the histological characteristics of hepatocellular carcinomas (HCCs) showing atypical dynamic enhancement patterns on gadoxetic acid-enhanced dynamic magnetic resonance imaging (EOB-MRI).

MATERIALS AND METHODS

We evaluated a total of 130 small (≤ 3 cm) HCCs from 114 patients that were surgically removed after EOB-MRI. Two radiologists blinded to the histological findings retrospectively classified the HCCs into typical or atypical lesions. Gross morphology, nuclear histological grade, presence of vascular invasion, and capsule formation and infiltration were compared between the two groups using Chi-square or Fisher tests.

RESULTS

Atypical dynamic enhancement patterns were seen in 23 HCCs (17.7%). None of the atypical HCC showed vascular invasion (P < 0.001). Atypical HCCs also showed more frequently smaller size (1.6 ± 0.6 cm versus 2.1 ± 0.6 cm, P = 0.001) with 86.9% (n = 20) of which 2 cm or less in diameter (P = 0.001), vaguely nodular appearance (56.5% vs 3.7%, P < 0.001), and nuclear grade I (69.6% versus 6.5%, P < 0.001), while less frequently showed capsule formation (26.1% versus 77.6%, P < 0.001) or capsular infiltration (16.7% versus 77.1%, P = 0.005).

CONCLUSION

Atypical HCCs on EOB-MRI may be characterized by the absence of vascular invasion, smaller (< 2 cm or less) size, vaguely nodular appearance, and well differentiation, and infrequent capsule formation or capsular infiltration.

Changes in the signal- and contrast-to-noise ratios of hepatocellular carcinomas on gadoxetic acid-enhanced dynamic MR imaging

OBJECTIVE

Our objective was to evaluate whether the enhancement pattern, measured by changes in the signal- (SNRs) and contrast-to-noise ratios (CNRs), of hepatocellular carcinomas (HCCs) on gadoxetic acid-enhanced MRI reflects tumor differentiation.

SUBJECTS AND METHODS

Two hundred eighty-five patients with 286 surgically-confirmed HCCs who underwent gadoxetic acid-enhanced MRI were included (11 grade I, 267 grade II, 7 grade III, and 1 grade IV tumor). Unenhanced and dynamic images with a T1-weighted 3D turbo-field-echo sequence were obtained. Relative signal intensities of the tumors with respect to surrounding liver were evaluated and the SNRs and CNRs were calculated.

RESULTS

SNR measurements demonstrated a fluctuating pattern (an increase in the SNR, followed by a decrease and a subsequent increase [or a decrease in the SNR followed by an increase and a subsequent decrease]) in 282 of 286 (98.6%) tumors. The SNR measurements also showed a single-peak SNR in the arterial phase (1.0% [3/286]) and 3min delayed images (0.3% [1/286]) followed by a decrease in 4 (1.4% [4/286]) grade II tumors. Nearly all tumors (88.1% [252/286]), 9 (81.8% [9/11]) grade I, 236 (88.4% [236/267]) grade II, 6 (85.7% [6/7]) grade III, and 1 (100% [1/1]) grade IV tumor showed maximum absolute CNRs with negative values, which were most commonly found in 20min delayed images (67.5% [170/252]). The remaining 34 of 286 (11.9%) tumors showed maximum absolute CNRs with positive values.

CONCLUSION

Regardless of the tumor grades, the most common manifestation was a SNR with a fluctuating pattern with time and maximum absolute CNRs with negative values, which were most commonly noted in the hepatobiliary phase.

MR imaging of hypervascular lesions in the cirrhotic liver: a diagnostic dilemma

Cirrhosis is characterized by a spectrum of hepatocellular nodules that mark the progression from regenerative nodules to low- and high-grade dysplastic nodules, followed by small and large hepatocellular carcinomas (HCCs). Characterization of small nodules on the basis of imaging and histopathologic findings is complicated by an overlap in findings associated with each type of nodule, a reflection of their multistep transitions. Vascularity patterns change gradually as the nodules evolve, with an increasing shift from predominantly venous to predominantly arterial perfusion. Regenerative and low-grade dysplastic nodules demonstrate predominantly portal perfusion and contrast enhancement similar to that of surrounding parenchyma. Differentiation of high-grade dysplastic nodules and well-differentiated HCCs on the basis of dynamic imaging and histologic findings is challenging, with a high rate of false-negative results. Some small nodules that lack hypervascularity may be early HCCs. Progressed small and large HCCs usually present no diagnostic difficulty because of their characteristic findings. Although characterization of hypervascular lesions in the cirrhotic liver is difficult, it is a key step in disease management and is the radiologist's responsibility.

Noninvasive diagnosis of hepatocellular carcinoma in cirrhotic liver: current guidelines and future prospects for radiological imaging

Noninvasive imaging has become the standard for hepatocellular carcinoma (HCC) diagnosis in cirrhotic patients. Typical imaging features of HCC such as arterial wash-in and venous wash-out deliver very high specificity and acceptable sensitivity even in nodules from 1 to 2 cm in diameter. However, limitations apply specifically in hypovascular HCC, for which the addition of new techniques such as diffusion-weighted magnetic resonance imaging (DW-MRI) or hepatobiliary MRI is helpful. Whereas DW-MRI adds to both the sensitivity and specificity, hepatobiliary MRI additionally contributes valuable information in cirrhotic patients on the histopathology of small lesions, including early HCC and high-grade dysplastic nodules. Biopsy of small, atypical lesions is associated with a high rate of false-negative findings and should be used only after careful consideration in selected patients. Here, we review the current international guidelines on HCC diagnosis as well as the latest developments in imaging that may contribute to safe detection and accurate characterization of suspicious nodules in patients with liver cirrhosis.

Imaging study of early hepatocellular carcinoma: usefulness of gadoxetic acid-enhanced MR imaging

PURPOSE

To describe imaging findings of early hepatocellular carcinoma (HCC) at gadoxetic acid-enhanced magnetic resonance (MR) imaging, dynamic contrast material-enhanced computed tomography (CT), CT during arterial portography (CTAP), and CT during hepatic arteriography (CTHA) and to compare the diagnostic performance of each modality for small (≤ 2 cm) HCC.

MATERIALS AND METHODS

The institute ethics committee deemed study approval unnecessary. One hundred eight resected small lesions in 64 patients were diagnosed as a dysplastic nodule (DN) (n = 12), progressed HCC (n = 66), or early HCC (n = 30). All but two patients underwent all imaging examinations. The imaging characteristics of the lesions with each modality were determined. To evaluate the diagnostic performance of the modalities, two radiologists graded the presence of HCC with use of a five-point confidence scale. The area under the receiver operating characteristic curve (A(z)), sensitivity, and specificity of each modality were compared.

RESULTS

The imaging features that are statistically significant for differentiating an early HCC from a DN include fat-containing lesions at dual-echo T1-weighted MR imaging (seen in 16 of the 30 early HCCs and none of the DNs), low attenuation at unenhanced CT (seen in 13 of the 30 early HCCs and none of the DNs), low attenuation at CTAP (seen in 11 of the 30 early HCCs and none of the DNs), and low signal intensity at hepatocyte phase gadoxetic acid-enhanced MR imaging (seen in 29 of the 30 early HCCs and none of the DNs). The diagnostic performance of gadoxetic acid-enhanced MR imaging (A(z), 0.98 and 0.99) was significantly greater than that of contrast-enhanced CT (A(z), 0.87) and CTHA-CTAP (A(z), 0.85 and 0.86) owing to its significantly higher sensitivity (P < .001).

CONCLUSION

Gadoxetic acid-enhanced MR imaging is the most useful imaging technique for evaluating small HCC, including early HCC.

[Malignant focal liver lesions]

Focal liver lesions are a very common occurrence. The detection and differentiation of such lesions is particularly important for the management of oncology patients and is a core task for radiology. The early and conclusive detection of malignant liver processes in a cost-efficient manner and with a low radiation dose for the patient requires systematic and skillful use of the various radiological methods. This review explains the application of current radiological methods for the detection and differentiation of malignant liver lesions and the typical appearance of the most commonly found liver malignancies.

Outcome of hypovascular hepatic nodules revealing no gadoxetic acid uptake in patients with chronic liver disease

PURPOSE

To elucidate the natural history of hypovascular nodules that appear hypointense on hepatocyte-phase gadoxetic acid-enhanced MR images by focusing on hypervascularization over time.

MATERIALS AND METHODS

In this study, 135 hypovascular nodules revealing no gadoxetic acid uptake in 53 patients were examined. All nodules were retrospectively examined using serial follow-up computed tomography (CT) and MRI examinations until hypervascularity was observed on arterial-phase dynamic CT or gadoxetic acid-enhanced MR images, or on CT during hepatic arteriography. Logistic regression analysis was used to investigate the association between hypervascularization and MR findings including a presence of fat assessed by a signal drop on opposed-phase T1-weighted images.

RESULTS

Of the 135 nodules, 16 underwent hypervascularization. The size of the nodules and the presence of fat in the nodules were independent indicators of hypervascularization. The 1-year cumulative risk of hypervascularization was 15.6%. This risk was significantly increased in the case of nodules >10 mm (37.6%, P < 0.01) and fat-containing nodules (26.5%, P < 0.01).

CONCLUSION

Hypovascular nodules that appear hypointense on hepatocyte-phase gadoxetic acid-enhanced MR images may progress to conventional hypervascular hepatocellular carcinoma. Nodules more than 10 mm in diameter and containing fat are at high risk for developing hypervascularization.

Hepatocellular carcinoma with bile duct tumor thrombus: dynamic computed tomography findings and histopathologic correlation

PURPOSE

This purpose of this study was to analyze the computed tomography (CT) findings of hepatocellular carcinoma (HCC) with bile duct tumor thrombus (BDTT) and explore their correlations with pathological manifestations.

METHODS

The clinical data, CT findings, and pathological manifestations of the 16 HCC patients with BDTT were retrospectively reviewed. All cases were pathologically proven.

RESULTS

Most HCCs showed hyperattenuation at hepatic arterial phase (HAP) (14/16) and hypoattenuation at portal venous phase (PVP) (12/16) and equilibrium phase (9/10), and the presence of rapid washout of contrast material was noted in 11 cases. The BDTT presented as cordlike masses in the dilated bile ducts, and mostly showed hyperattenuation at HAP (12/16) and hypoattenuation at PVP (13/16) and equilibrium phase (10/10), and the presence of rapid washout of contrast material was noted in 10 cases. Four cases of BDTT showed homogeneous enhancement, which were mainly consisted of cancer cells; 9 cases showed heterogeneous enhancement, which were mainly consisted of cancer cells with flakes of necrotic tissues or abundant red blood cells. Bile duct tumor thrombus was composed of 2 different pathological tissues in 3 cases, proximal part of BDTT was composed of tumor tissue, which was uniformly enhanced on dynamic enhanced CT, whereas the distal part was composed of necrotic or debris tissue without enhancement.

CONCLUSIONS

Hepatocellular carcinoma lesion and soft-tissue mass in the bile ducts with bilary dilation are usually depicted on dynamic enhanced CT in HCC patients with BDTT. Early enhancement at HAP and rapid washout of contrast material at PVP are the characteristic findings of HCC and BDTT. Dynamic contrast CT examination is very valuable for diagnosing this disease.

Primary clear cell carcinoma in the liver: CT and MRI findings

AIM: To retrospectively analyze the computed tomography (CT) and magnetic resonance imaging (MRI) appearances of primary clear cell carcinoma of the liver (PCCCL) and compare the imaging appearances of PCCCL and common type hepatocellular carcinoma (CHCC) to determine whether any differences exist between the two groups.

METHODS: Twenty cases with pathologically proven PCCCL and 127 cases with CHCC in the Second Affiliated Hospital of Sun Yat-sen University were included in this study. CT or MRI images from these patients were retrospectively analyzed. The following imaging findings were reviewed: the presence of liver cirrhosis, tumor size, the enhancement pattern on dynamic contrast scanning, the presence of pseudo capsules, tumor rupture, portal vein thrombosis and lymph node metastasis.

RESULTS: Both PCCCL and CHCC were prone to occur in patients with liver cirrhosis, the association rate of liver cirrhosis was 80.0% and 78.7%, respectively (P > 0.05). The mean sizes of PCCCL and CHCC tumors were (7.28 ± 4.25) cm and (6.96 ± 3.98) cm, respectively. Small HCCs were found in 25.0% (5/20) of PCCCL and 19.7% (25/127) of CHCC cases. No significant differences in mean size and ratio of small HCCs were found between the two groups (P = 0.658 and 0.803, respectively). Compared with CHCC patients, PCCCL patients were more prone to form pseudo capsules (49.6% vs 75.0%, P = 0.034). Tumor rupture, typical HCC enhancement patterns and portal vein tumor thrombosis were detected in 15.0% (3/20), 72.2% (13/18) and 20.0% (4/20) of patients with PCCCL and 3.1% (4/127), 83.6% (97/116) and 17.3% (22/127) of patients with CHCC, respectively. There were no significant differences between the two groups (all P > 0.05). No patients with PCCCL and 2.4% (3/127) of patients with CHCC showed signs of lymph node metastasis (P > 0.05).

CONCLUSION: The imaging characteristics of PCCCL are similar to those of CHCC and could be useful for differentiating these from other liver tumors (such as hemangioma and hepatic metastases). PCCCLs are more prone than CHCCs to form pseudo capsules.

Intraoperative ultrasound score to predict recurrent hepatocellular carcinoma after radical treatments

Despite the high complete necrosis rate of radio-frequency ablation (RFA) or the complete removal following curative hepatic resection (HR), recurrent hepatocellular carcinoma (HCC) remains a significant problem. The aim of the study is to identify some intraoperative ultrasound (IOUS) patterns, predicting intrahepatic recurrences. From January 1997 to July 2009, 410 patients with HCC were treated (162 HR and 248 RFA through a surgical access). All patients were submitted to IOUS examination: 148 IOUS were performed during the laparotomic access while 262 IOUS were performed during the laparoscopic access. Primary HCC was classified according to diameter, HCC pattern (nodular or infiltrative), echogenicity (hyper- or hypo-echoic), echotexture (homogeneous or inhomogeneous), capsular invasion, mosaic pattern, nodule in nodule aspect and infiltration of portal vessels. Number of HCC nodules was also considered. Multivariate analysis (Cox model) was performed to determine features associated with recurrent HCC using IOUS patterns that independently predicted recurrent HCC, a IOUS score was developed. The patients were followed for 3-127 months, (median follow-up: 21.5 months). In 220 patients (54%), intrahepatic recurrences occurred. In 155 patients (38%), distant intrahepatic recurrences arose in different segments at the primary tumor site. In 65 HCC cases (16%), local recurrences were found. At multivariate analysis, multiple nodules, HCC diameter (>20 mm), HCC pattern (infiltrative), hyperechoic nodule and portal infiltration were statistically significant for risk factor of intrahepatic recurrences. Therefore, a IOUS scoring system was calculated on the basis of multivariate analysis and identified three risk categories of patients: in group 1 recurrences occurred in 37%, group 2 in 46% and group 3 in 66% (p = 0.0001). IOUS is an accurate staging tool during "surgical" procedures. This study showed an added value of IOUS: it permitted to identify ultrasound patterns, which can predict the risk of HCC recurrences. The calculated IOUS score permits to intraoperatively evaluate the actual surgical choice and to program the best treatment strategies during the follow-up period.

Comparison of different tumor response criteria in patients with hepatocellular carcinoma after systemic therapy with the multikinase inhibitor sorafenib

RATIONALE AND OBJECTIVES

The aim of this study was to compare tumor changes in patients with hepatocellular carcinoma receiving sorafenib using evaluation criteria of the American Association for the Study of Liver Diseases (AASLD) and the European Association for the Study of the Liver (EASL) as opposed to the Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1.

MATERIALS AND METHODS

Twenty-five patients with inoperable hepatocellular carcinoma receiving oral sorafenib underwent magnetic resonance imaging at baseline and follow-up every 8 weeks (range, 2-19 weeks; mean, 7.6 weeks). Data were evaluated retrospectively. Survey time until progression ranged from 5 to 102 weeks (mean, 25.6 weeks), with a total of 54 target lesions being monitored. Additionally, evaluation of serum α-fetoprotein was performed at follow-up.

RESULTS

The best response at follow-up using RECIST resulted in rates of 4% objective response (complete remission or partial remission), 24% (progressive disease), and 72% (stable disease). In contrast, AASLD and EASL criteria identified objective responses in 28% and 48%. Twenty percent of all patients classified as having progressive disease by RECIST were identified as having "pseudo"-progression due to extensive necrosis. Eleven percent of patients classified as having stable disease by RECIST were disclosed as essentially progressive. AASLD area and AASLD diameter disclosed 36% and 40% of patients as having partial remission, respectively, whereas EASL criteria discovered only 24%. There was no significant correlation between serum α-fetoprotein progression and AASLD, EASL, or RECIST evaluation criteria.

CONCLUSIONS

Response monitoring via functional criteria such as AASLD or EASL criteria is likely to more accurately reflect vital tumor burden in hepatocellular carcinoma compared to RECIST.

Intraoperative ultrasound patterns predict recurrences after surgical treatments for hepatocellular carcinoma()

INTRODUCTION

Hepatocellular carcinoma (HCC) is associated with a high incidence of postoperative recurrence, despite high rates of complete necrosis with radiofrequency ablation (RFA) and curative hepatic resections (HR). The aim of this study was to identify intraoperative ultrasound patterns observed during HR or RFA that predicting intrahepatic HCC recurrence.

MATERIALS AND METHODS

From January 1997 through August 2008, we treated 377 patients with HCC (158 with HR and 219 with surgical RFA). All patients underwent intraoperative ultrasound (IOUS) examination. Primary HCCs was classified according to diameter, HCC pattern (nodular or infiltrative), echogenicity (hyper- or hypo-), echotexture (homogeneous or inhomogeneous), capsular invasion, mosaic pattern, nodule-in-nodule appearance, and infiltration of portal vessels. Number of HCC nodules was also considered. Comparisons between the groups of possible factors for intrahepatic recurrence of treated tumors were performed using the Kaplan-Meier method and compared using the log-rank test.

RESULTS

Patients were followed for 9-127 months (median: 18.6 months), and intrahepatic recurrence was observed in 198 (52.5%). In 138 patients (36.5%), recurrences were located in different segments with respect to the primary tumor. In 60 HCC tumors (16%), local recurrences were found in the same segment as the primary tumor. At univariate analysis, primary HCC echogenicity and mosaic pattern were the only factors not significant associated with intrahepatic recurrences.

CONCLUSION

IOUS is an accurate staging tool for use during "surgical" resection or RFA. This study shows that IOUS patterns can also be used to estimate the risk of post-treatment HCC recurrence. In patients at high risk for this outcome, closer follow-up and use of adjuvant therapies could be useful.

Assessment of the diagnostic accuracy of T2*-weighted MR imaging for identifying hepatocellular carcinoma with liver explant correlation

BACKGROUND

T2*-weighted MRI may represent a novel method for identifying hepatocellular carcinoma (HCC). The goal of this study was to assess the diagnostic accuracy of T2*-weighted MRI for HCC with liver explant correlation.

MATERIALS AND METHODS

A retrospective review identified 25 patients who had undergone liver transplantation with pre-operative T2*-weighted MRI. All patients had Child's-Pugh A (9), B (9), or C (7) liver disease with 13 transplanted for liver dysfunction and 12 for HCC. The T2*-weighted images were interpreted by 2 blinded, independent observers and the results compared with the explanted specimens. Sensitivity and specificity of T2*-weighted MRI for the identification of HCC was assessed.

RESULTS

By pathology, 16 HCC (mean largest diameter 2.1 cm; range 0.9-3.6 cm) were identified in 14 patients. Reader 1 had a sensitivity of 69% (95% confidence interval 41-88%) and a specificity of 100% (68-100%). Reader 2 had a sensitivity of 56% (31-79%) and a specificity of 100% (68-100%). There was a very good inter-observer agreement (kappa=0.84).

CONCLUSION

T2*-weighted MRI had a moderate sensitivity for identifying HCC but had an excellent specificity. A T2*-weighted MR sequence may be a useful component of a liver MRI protocol due to its high specificity for HCC, and may be particularly useful in patients unable to undergo gadolinium enhanced MRI.

Value of delayed hypointensity and delayed enhancing rim in magnetic resonance imaging diagnosis of small hepatocellular carcinoma in the cirrhotic liver

PURPOSE

To determine the diagnostic utility of delayed hypointensity and delayed enhancing rim on magnetic resonance imaging (MRI) as indicators of hepatocellular carcinoma (HCC) in arterially enhancing nodules < or =5 cm in the cirrhotic liver and determine the features that best predict HCC.

MATERIALS AND METHODS

Gadolinium-enhanced MRI studies performed from January 2001 to December 2004 in patients with cirrhosis were evaluated for arterially enhancing nodules measuring < or =5 cm. Verification was via explant correlation, biopsy, or imaging follow-up. Sensitivity and specificity of diagnostic features of HCC were calculated. Features predictive of HCC were determined using the Generalized Estimating Equation approach.

RESULTS

In all, 116 arterially enhancing nodules were identified in 80 patients (<2 cm: n = 79, 2-5 cm n = 37). Sensitivity and specificity of delayed hypointensity for HCC measuring < or =5 cm, 2-5 cm, and <2 cm were 0.54 (40 of 74) and 0.86 (36 of 42); 0.72 (23 of 32) and 0.80 (4 of 5); and 0.41 (17 of 42) and 0.87 (32 of 37). For the delayed enhancing rim sensitivity and specificity were 0.64 (47 of 74) and 0.86 (36 of 42); 0.75 (24 of 32) and 1.0 (5 of 5); and 0.55 (23 of 42) and 0.83 (31 of 37), respectively. Lesion size (> or =2 cm) and delayed enhancing rim, as main features and their interaction, were the most significant predictors of HCC.

CONCLUSION

Delayed hypointensity and enhancing rim improve the specificity of diagnosis of HCC of all sizes but are seen less frequently in small (<2 cm) HCC. Nodule size (> or =2 cm) and delayed enhancing rim are the strongest predictors of HCC.

Outcomes of follow-up CT for small (5-10-mm) arterially enhancing nodules in the liver and risk factors for developing hepatocellular carcinoma in a surveillance population

OBJECTIVE

To evaluate the outcomes of small (5-10 mm), arterially enhancing nodules (SAENs) shown exclusively at the hepatic arterial phase of CT in a hepatocellular carcinoma (HCC) surveillance population and to determine risk factors for developing HCC.

METHODS

The study population included 112 patients (male:female = 100:12; aged 36-92 years) with 175 SAENs who were at risk of HCC. We evaluated serial changes during follow-up (1.4-41.8 months, mean 35.7 months) and analysed the initial CT findings of SAENs and the accompanying lesions to elucidate the risk factors for HCC development.

RESULTS

Of 175 SAENs, 101(57.7%) disappeared and 34(19.4%) persisted. Forty SAENs (22.9%) became HCC in 33 patients (29.5%). Presence of HCC treatment history (p = 0.005, risk ratio = 7.429), a larger size of SAEN (p = 0.003, risk ratio = 1.630), presence of coexistent HCC (p = 0.021, risk ratio = 3.777) and absence of coexistent typical arterioportal shunts (p = 0.003, risk ratio = 4.459) turned out to be independently significant risk factors for future development of HCC.

CONCLUSION

SAENs were frequently seen in an HCC surveillance population and have a 22.9% probability of becoming HCC on a per-lesion basis. Risk increased particularly when the lesion was associated with a previous or concurrent HCC, a large size or found without a coexistent typical arterioportal shunt.

Small hepatocellular carcinoma with bile duct tumor thrombi: CT and MRI findings

BACKGROUND

Small hepatocellular carcinoma (sHCC) with bile duct tumor thrombi (BDTT) is rare and easily misdiagnosed as cholangiocarcinoma. This study was to analyze the imaging features of sHCC with BDTT.

PATIENTS AND METHODS

CT and/or MRI examinations were performed on seven patients who had sHCC with BDTT. One patient received CT scan, one received CT and MR scan, and five received MR scan. Magnetic resonance cholangiopancreatography (MRCP) was performed in five patients. The diagnosis of sHCC with BDTT was based on surgical specimens in all patients.

RESULTS

The sHCC lesions and BDTT were presented on CT or MRI scans in all the seven cases. The BDTT is presented as soft tissue mass in the bile duct with biliary dilatation above the obstruction. In the two patients who had received dynamic contrast CT scan, the sHCC lesions showed atypical enhancement pattern of HCC. The BDTT showed similar enhancement pattern as sHCC in one of the two patients. The sHCC and BDTT showed homogenous hypointense signals on T1W images and hyperintense signals on T2W images in all six cases. In the three patients who had received dynamic enhancement MR scan, the enhancement patterns of sHCC lesions and BDTT were similar. Early enhancement of sHCC lesion and BDTT at hepatic arterial phase with hyperintense signals was observed in one patient, while two other patients had no early enhancement. All sHCC lesions and BDTT showed hypointense signals at portal venous phase, equilibrium phase, and delayed phase. Six patients showed hyperintense signal of hemorrhage in the dilated bile ducts on both T1W and T2W images. Five cases of BDTT presented as filling defect in the bile ducts on MRCP. The BDTT were directly connected with sHCC lesions in all the seven patients, without bile duct wall thickening or extra-bile duct invasion.

CONCLUSION

CT or MRI is a safe, reliable, and valuable method for the detection and diagnosis of sHCC with BDTT.

SPIO-enhanced MRI findings of well-differentiated hepatocellular carcinomas: correlation with MDCT findings

Objective

This study was designed to assess superparamagnetic iron oxide (SPIO)-enhanced MRI findings of well-differentiated hepatocellular carcinomas (HCCs) correlated with their multidetector-row CT (MDCT) findings.

Materials and Methods

Seventy-two patients with 84 pathologically proven well-differentiated HCCs underwent triple-phase MDCT and SPIO-enhanced MRI at a magnetic field strength of 1.5 Tesla (n = 49) and 3.0 Tesla (n = 23). Two radiologists in consensus retrospectively reviewed the CT and MR images for attenuation value and the signal intensity of each tumor. The proportion of hyperintense HCCs as depicted on SPIO-enhanced T2- or T2^*-weighted images were compared in terms of tumor size (< 1 cm and > 1 cm), five CT attenuation patterns based on arterial and equilibrium phases and magnetic field strength, by the use of univariate and multivariate analyses.

Results

Seventy-eight (93%) and 71 (85%) HCCs were identified by CT and on SPIO-enhanced T2- and T2^*-weighted images, respectively. For the CT attenuation pattern, one (14%) of seven isodense-isodense, four (67%) of six hypodense-hypodense, four (80%) of five isodense-hypodense, 14 (88%) of 16 hyperdense-isodense and 48 (96%) of 50 hyperdense-hypodense HCCs were hyperintense (Cochran-Armitage test for trend, p < 0.001). Based on the use of multivariate analysis, the CT attenuation pattern was the only factor that affected the proportion of hyperintense HCCs as depicted on SPIO-enhanced T2- or T2^*-weighted images (p < 0.001). Tumor size or magnetic field strength was not a factor that affected the proportion of hyperintense HCCs based on the use of univariate and multivariate analysis (p > 0.05).

Conclusion

Most well-differentiated HCCs show hyperintensity on SPIO-enhanced MRI, although the lesions show various CT attenuation patterns. The CT attenuation pattern is the main factor that affects the proportion of hyperintense well-differentiated HCCs as depicted on SPIO-enhanced MRI.

Detection of hepatocellular carcinoma by ferucarbotran-enhanced magnetic resonance imaging: the efficacy of accumulation phase fat-suppressed T1-weighted imaging

AIM

To evaluate the effectiveness of accumulation phase, fat-suppressed, T1-weighted imaging (FS-T1WI) when detecting hepatocellular carcinoma (HCC) by ferucarbotran-enhanced magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Thirty patients who underwent ferucarbotran-enhanced MRI, which resulted in 35 confirmed HCCs, were included in this prospective study. Two image sets were prepared and two radiologists independently reviewed these in two reading sessions; set A was without contrast-enhanced accumulation phase FS-T1WI and set B included contrast-enhanced accumulation phase FS-T1WI. All HCCs had been confirmed by operation (n=4), by biopsy (n=28), and by follow-up study for at least 1 year (n=3).

RESULTS

The contrast-to-noise ratio significantly increased from -1.2+/-7.5 to 12.7+/-7.3 with contrast-enhanced accumulation phase FS-T1WI, but was only slightly increased from 12.2+/-10.3 to 15.5+/-12.2 with contrast-enhanced T2WI (p<0.001). The signal-to-noise ratio (SNR) was decreased with T1WI and T2WI for liver parenchyma. With T2WI, the SNR for HCCs was decreased; however, it was slightly increased with T1WI (p<0.001). Overall, 29 HCCs were detected using set A, and 35 nodules were identified using set B, which included the contrast-enhanced accumulation phase FS-T1WI. Thus, the detection rate significantly increased using post-contrast medium accumulation phase FS-T1WI (p<0.05).

CONCLUSION

Due to the improved CNR with the post-contrast medium accumulation phase FS-T1WI, which helped to increase HCC detection, accumulation phase FS-T1WI is recommended as one of the routine protocols for inclusion in HCC detection.

Hepatocellular carcinoma: development and early detection

Our eventual aim is to predict, using non-invasive imaging techniques, the biological behaviour of individual cirrhotic nodules. We are some distance away from this, so our current objective is to define imaging features which predict the histologic findings. This short review summarises the current capabilities and limitations of non-invasive imaging in detecting small hepatocellular carcinomas (HCCs) in cirrhosis. Extracellular contrast media used with ultrasound (US), computed tomography (CT) or magnetic resonance imaging (MRI) can characterise nodules according to the predominance of arterial or portal inflow, and most HCCs will be recognised by their arterial hypervascularity. Adding intracellular (liver-specific) MRI contrast agents provides a significant improvement in early detection and in specificity for HCC. Nodules can be classified on dual contrast MRI as clearly malignant, clearly benign, or borderline (needing careful surveillance). Future imaging research needs to establish the histology of small hypervascular nodules, the evolution of hypervascular nodules and of dysplastic nodules, and to seek imaging features which predict microvascular invasion. Currently, cirrhotic patients with either suspicious nodules on screening US or rising AFP should have cross-sectional imaging with multi-phase CT or preferably MRI. Dual-contrast MRI with liver-specific agents should be used to improve diagnostic specificity for small lesions. Borderline nodules should be followed at agreed intervals using the same imaging technique each time. Pre-operative staging in surgical candidates should include CT of thorax, abdomen and pelvis and bone scintigraphy.