Contribution of diffusion-weighted magnetic resonance imaging in the characterization of hepatocellular carcinomas and dysplastic nodules in cirrhotic liver. J Comput Assist Tomogr. 2010;34:506-512. [PMID: 20657216 DOI: 10.1097/rct.0b013e3181da3671]

Histopathological graded liver lesions: what role does the IVIM analysis method have?

PURPOSE

This study aims to investigate three different image processing methods on quantitative parameters of IVIM sequence, as well as apparent diffusion coefficients and simple perfusion fractions, for benign and malignant liver tumors.

MATERIALS AND METHODS

IVIM images with 8 b-values (0-1000 s/mm2) and 1.5 T MRI scanner in 16 patients and 3 healthy people were obtained. Next, the regions of interest were selected for malignant, benign, and healthy liver regions (50, 56, and 12, respectively). Then, the bi-exponential equation of the IVIM technique was fitted with two segmented fitting methods as well as one full fitting method (three methods in total). Using the segmented fitting method, diffusion coefficient (D) is fixed with a mono-exponential equation with b-values that are greater than 200 s/mm2. The perfusion fraction (f) can then be calculated by extrapolating, as the first method, or fitting simultaneously with the pseudo-diffusion coefficient (D*) as the second method. In the full fitting method, as the third method, all IVIM parameters were obtained simultaneously. The mean values of parameters from different methods were compared in different grades of lesions.

RESULTS

Our results indicate that the image processing method can change statistical comparisons between different groups for each parameter. The D value is the only quantity in this technique that does not depend on the fitting process and can be used as an indicator of comparison between studies (P < 0.05). The most effective method to distinguish liver lesions is the extrapolated f method (first method). This method created a significant difference (P < 0.05) between the perfusion parameters between benign and malignant lesions.

CONCLUSION

Using extrapolated f is the most effective method of distinguishing liver lesions using IVIM parameters. The comparison between groups does not depend on the fitting method only for parameter D.

Clinical features and diagnostic and therapeutic strategies of hepatic dysplastic nodules

Hepatic dysplastic nodules (DNs) are a group of neoplastic lesions with a diameter of more than 1 cm that belong to precancerous lesions, with abnormal cytoplasm and cells but without malignant basis in histology. Hepatic DNs lack typical tumor markers and clinical symptoms, and their clinical diagnosis relys mainly on imaging or/and tissue pathological examination. Thanks to the further research on the pathogenesis of hepatic DNs and the development of imaging technology, the combination of medical history, various examinationss, individual tumor markers, and imaging and histopathology techniques can significantly improve the early detection and diagnosis accuracy for hepatic DNs, and reduce the rate of missed and false diagnosis. Due to the potential malignancy risk of hepatic DNs, intervention measures should be carried out on hepatic DNs at all stages, in order to block the transformation process of DNs into hepatocellular carcinoma (HCC), which is of great clinical significance to reduce the incidence and mortality of HCC.

Noncontrast MRI for Hepatocellular Carcinoma Detection: A Systematic Review and Meta-analysis - A Potential Surveillance Tool?

BACKGROUND AND AIMS

This meta-analysis investigates the diagnostic performance of non-contrast magnetic resonance imaging (MRI) for the detection of hepatocellular carcinoma (HCC).

METHODS

A systematic review was performed to May 2020 for studies which examined the diagnostic performance of non-contrast MRI (multi-sequence or diffusion-weighted imaging (DWI)- alone) for HCC detection in high risk patients. The primary outcome was accuracy for the detection of HCC. Random effects models were used to pool outcomes for sensitivity, specificity, positive likelihood ratio (LR) and negative LR. Subgroup analyses for cirrhosis and size of the lesion were performed.

RESULTS

Twenty-two studies were included involving 1685 patients for per-patient analysis and 2128 lesions for per-lesion analysis. Multi-sequence non-contrast MRI (NC-MRI) using T2+DWI±T1 sequences had a pooled per-patient sensitivity of 86.8% (95%CI:83.9-89.4%), specificity of 90.3% (95%CI:87.3-92.7%), and negative LR of 0.17 (95%CI:0.14-0.20). DWI-only MRI (DW-MRI) had a pooled sensitivity of 79.2% (95%CI:71.8-85.4%), specificity of 96.5% (95%CI:94.3-98.1%) and negative LR of 0.24 (95%CI:1.62-0.34). In patients with cirrhosis, NC-MRI had a pooled per-patient sensitivity of 87.3% (95%CI:82.7-91.0%) and specificity of 81.6% (95%CI:75.3-86.8%), whilst DWI-MRI had a pooled sensitivity of 71.4% (95%CI:60.5-80.8%) and specificity of 97.1% (95%CI:91.9-99.4%). For lesions <2 cm, the pooled per-lesion sensitivity was 77.1% (95%CI:73.8-80.2%). For lesions >2 cm, pooled per-lesion sensitivity was 88.5% (95%CI:85.0-91.5%).

CONCLUSION

Non-contrast MRI has a moderate negative LR and high specificity with acceptable sensitivity for the detection of HCC, even in patients with cirrhosis and with lesions <2 cm. Prospective trials to validate if non-contrast MRI can be used for HCC surveillance is warranted.

Overall diagnostic accuracy of different MR imaging sequences for detection of dysplastic nodules: a systematic review and meta-analysis

OBJECTIVE

To assess the overall diagnostic accuracy of different MR imaging sequences in the detection of the dysplastic nodule (DN).

METHODS

PubMed, Cochrane Library, and Web of Science were systematically searched. Study selection and data extraction were conducted by two authors independently. Quality assessment of diagnostic accuracy studies (QUADAS) 2 in RevMan software was used to score the included studies and assess their methodological quality. A random-effects model was used for statistical pooling by Meta-Disc. Subgroup analysis and sensitivity analysis were used to explore potential sources of heterogeneity.

RESULTS

Fourteen studies (335 DN lesions in total) were included in our meta-analysis. The area under the curve (AUC) of summary receiver operating characteristic (SROC) of T₂WI was 0.87. Pooled sensitivity, specificity, positive likelihood ratio (PLR), and negative likelihood ratio (NLR) of DWI were 0.81 (95%CI, 0.73-0.87), 0.90 (95%CI, 0.86-0.93), 7.04 (95%CI, 4.49-11.04), and 0.24 (95%CI, 0.17-0.33) respectively. In the arterial phase, pooled sensitivity, specificity, PLR, and NLR were 0.89 (0.84-0.93), 0.75 (0.72-0.79), 3.72 (2.51-5.51), and 0.17 (0.12-0.25), respectively. Pooled sensitivity, specificity, PLR, and NLR of the delayed phase were 0.78 (0.72-0.83), 0.60 (0.55-0.65), 2.19 (1.55-3.10), and 0.36 (0.23-0.55) separately. Pooled sensitivity, specificity, PLR, and NLR of the hepatobiliary phase were 0.77 (0.71-0.82), 0.92 (0.89-0.94), 8.74 (5.91-12.92), and 0.24 (0.14-0.41) respectively. Pooled sensitivity, specificity, and PLR were higher on DWI and hepatobiliary phase in diagnosing LGDN than HGDN.

CONCLUSION

MR sequences, particularly DWI, arterial phase, and hepatobiliary phase imaging demonstrate high diagnostic accuracy for DN.

KEY POINTS

• MRI has dramatically improved the detection and accurate diagnosis of DNs and their differentiation from hepatocellular carcinoma. • Overall diagnostic accuracy of different MRI sequences in the detection of DN has not been studied before. • Our meta-analysis demonstrates that MRI achieves a high diagnostic value for DN, especially when using DWI, arterial phase imaging, and hepatobiliary phase imaging.

Diagnostic accuracy of apparent diffusion coefficient (ADC) value in differentiating malignant from benign solid liver lesions: a systematic review and meta-analysis

OBJECTIVES

We undertook a systematic review and meta-analysis of the diagnostic performance of mean apparent diffusion coefficient (ADC) values derived by diffusion-weighted (DW)-MRI in the characterization of solid benign and malignant liver lesions, and to assess their value in discriminating these lesions in daily routine practice.

METHODS

A systematic review of PubMed, Embase, Scopus, and Web of Science was conducted to retrieve studies that used ADC values for differentiating solid benign/dysplastic nodules and malignant liver lesions. A bivariate random-effects model with pooled sensitivity and specificity values with 95% CI (confidence interval) was used. This meta-analysis was performed on the per-lesion basis. Summary receiver operating characteristic (SROC) plot and area under curve (AUC) were created.

RESULTS

A total of 14 original articles were retrieved. The combined (95% CI) sensitivity and specificity of mean ADC values for differentiating solid benign from malignant lesions were 78% (67-86%) and 74% (64-81%), respectively. The pooled (95% CI) positive and negative LRs were respectively 3 (2.3-3.8) and 0.3 (0.21-0.43). The DOR (95% CI) was 10 (7-15). The AUC (95% CI) of the SROC plot was 82% (78-85%). Reporting bias was negligible (p value of regression test = 0.36). Mean size of malignant lesions and breathing pattern of MRI were found to be sources of heterogeneity of pooled sensitivity.

CONCLUSION

ADC measurement independently may not be an optimal diagnostic imaging method for differentiating solid malignant from solid benign hepatic lesions. The meta-analysis showed that ADC measurement had moderate diagnostic accuracy for characterizing solid liver lesions. Further prospective and comparative studies with pre-specified ADC thresholds could be performed to investigate the best MRI protocol and ADC threshold for characterizing solid liver lesions.

ADVANCES IN KNOWLEDGE

ADC measurement by DW-MRI does not have a good diagnostic performance to differentiate solid malignant from solid benign lesions. Therefore, we suggest not using ADC values in clinical practice to evaluate solid liver lesions.

ACR Appropriateness Criteria® Liver Lesion-Initial Characterization

Incidental liver masses are commonly identified on imaging performed for other indications. Since the prevalence of benign focal liver lesions in adults is high, even in patients with primary malignancy, accurate characterization of incidentally detected lesions is of paramount clinical importance. This document reviews utilization of various imaging modalities for characterization of incidentally detected liver lesions, discussed in the context of several clinical scenarios. For each clinical scenario, a summary of current evidence supporting the use of a given diagnostic modality is reported. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Diagnosis of Pre-HCC Disease by Hepatobiliary-Specific Contrast-Enhanced Magnetic Resonance Imaging: A Review

We first proposed a new concept, pre-hepatocellular carcinoma (HCC) disease, to describe the precancerous condition of HCC, which has received scant attention from clinicians. Pre-HCC disease is defined as chronic liver injury concurrent with hepatic low- or high-grade dysplastic nodular lesions. Precise diagnosis of pre-HCC disease may prevent or arrest HCC and contribute to relieving the HCC burden worldwide, although noninvasive diagnosis is difficult and biopsy is generally required. Fortunately, recent advances and extensive applications of hepatobiliary-specific contrast-enhanced magnetic resonance imaging will facilitate the noninvasive identification and characterization of pre-HCC disease. This review briefly discusses the new concept of pre-HCC disease and offers an overview of the role of hepatobiliary-specific contrast-enhanced magnetic resonance imaging for the diagnosis of pre-HCC disease.

[Radiological diagnostic workup of liver tumors]

The imaging of focal liver lesions is a common task in daily radiological routine. The objectives of diagnostic imaging are, in addition to lesion detection, the characterization of the lesion as well as the follow-up assessment after surgical or local treatment or under systemic therapy. This article presents the typical morphologies observed in computed tomography and magnetic resonance imaging of hepatocellular carcinomas and intrahepatic cholangiocarcinomas as the most important representatives of primary malignant liver tumors and juxtaposes them with benign primary liver lesions such as adenoma and focal nodular hyperplasia (FNH). In addition, relevant technical aspects of imaging are briefly summarized. Finally, the main and additional criteria of the Liver Imaging Reporting and Data System (LI-RADS®) classification, which are becoming increasingly established clinically for the evaluation of liver lesions in the cirrhotic liver, are presented.

Differentiation of Small Hepatocellular Carcinoma From Dysplastic Nodules in Cirrhotic Liver: Texture Analysis Based on MRI Improved Performance in Comparison Over Gadoxetic Acid-Enhanced MR and Diffusion-Weighted Imaging

Background: Accurate characterization of small (3 cm) hepatocellular carcinoma (sHCC) and dysplastic nodules (DNs) in cirrhotic liver is challenging. We aimed to investigate whether texture analysis (TA) based on T2-weighted images (T2WI) is superior to qualitative diagnosis using gadoxetic acid-enhanced MR imaging (Gd-EOB-MRI) and diffusion-weighted imaging (DWI) for distinguishing sHCC from DNs in cirrhosis.

Materials and methods: Sixty-eight patients with 73 liver nodules (46 HCCs, 27 DNs) pathologically confirmed by operation were included. For imaging diagnosis, three sets of images were reviewed by two experienced radiologists in consensus: a Gd-EOB-MRI set, a DWI set, and a combined set (combination of Gd-EOB-MRI and DWI). For TA, 279 texture features resulting from T2WI were extracted for each lesion. The performance of each approach was evaluated by a receiver operating characteristic analysis. The area under the receiver operating characteristic curve (A_z), sensitivity, specificity, and accuracy were determined.

Results: The performance of TA (A_z = 0.96) was significantly higher than that of imaging diagnosis using Gd-EOB-MRI set (A_z = 0.86) or DWI set (A_z = 0.80) alone in differentiation of sHCC from DNs (P = 0.008 and 0.025, respectively). The combination of Gd-EOB-MRI and DWI showed a greater sensitivity (95.6%) but reduced specificity (66.7%). The specificity of TA (92.6%) was significantly higher than that of the combined set (P < 0.001), but no significant difference was observed in sensitivity (97.8 vs. 95.6%, P = 0.559).

Conclusion: TA-based T2WI showed a better classification performance than that of qualitative diagnosis using Gd-EOB-MRI and DW imaging in differentiation of sHCCs from DNs in cirrhotic liver. TA-based MRI may become a potential imaging biomarker for the early differentiation HCCs from DNs in cirrhosis.

Intravoxel Incoherent Motion Diffusion-Weighted Imaging for Evaluation of the Cell Density and Angiogenesis of Cirrhosis-Related Nodules in an Experimental Rat Model: Comparison and Correlation With Dynamic Contrast-Enhanced MRI

Background

Intravoxel incoherent motion diffusion‐weighted imaging (IVIM‐DWI) and dynamic contrast‐enhanced MRI (DCE‐MRI) are sensitive imaging modalities for detecting liver lesions, but their value in evaluating cirrhosis‐related nodules remains unclear.

Purpose

To investigate whether IVIM‐DWI and DCE‐MRI can differentiate different types of cirrhosis‐related nodules, and whether these modalities can monitor changes in cell density and angiogenesis during the malignant transformation of cirrhosis‐related nodules in a rat model

Study Type

Prospective.

Animal Model

Thirty‐five male Sprague–Dawley rats with 106 cirrhosis‐related nodules (19 regenerative nodules [RNs], 47 dysplastic nodules [DNs], and 40 hepatocellular carcinomas [HCCs]).

Field Strength/Sequence

IVIM‐DWI and DCE sequence at 3.0T MRI.

Assessment

IVIM‐DWI parameters (D, D*, f, and apparent diffusion coefficient [ADC]) and DCE‐MRI parameters (K^trans, K_ep, and V_e) were calculated by two radiologists using postprocessing software. The “cell density” and “unpaired arterial ratio” were analyzed with a microscope by two pathologists.

Statistical Tests

MRI parameters were compared among the different types of nodules by one‐way analysis of variance or the Kruskal–Wallis test. The Pearson correlation test was used to analyze the correlation of MRI parameters with the pathological types of nodules, cell density, and unpaired arterial ratio.

Results

The K^trans, K_ep, and V_e values of HCCs were significantly higher than those of DNs and RNs. D and ADC values were significantly lower in HCCs than in DNs and RNs. There were moderate positive correlations of K^trans with the pathological types of nodules and the unpaired arterial ratio. Moderate negative correlations were observed among D, ADC, and the pathological types of nodules, between D and cell density, and between ADC and cell density.

Data Conclusion

IVIM‐DWI and DCE‐MRI are valuable in differentiating different types of cirrhotic‐related nodules. D and ADC are correlated with changes in cell density during the malignant transformation of cirrhosis‐related nodules, while K^trans is correlated with increased angiogenesis.

Level of Evidence: 1

Technical Efficacy: Stage 1

J. Magn. Reson. Imaging 2020;51:812–823.

The utility of diffusion-weighted imaging in improving the sensitivity of LI-RADS classification of small hepatic observations suspected of malignancy

PURPOSE

We investigated the added value of diffusion-weighted imaging (DWI)/apparent diffusion coefficient (ADC) in the categorization of small hepatic observation (≤ 20 mm) detected in patients with chronic liver disease in reference to LI-RADS (liver imaging reporting and data system) classification system.

METHODS

We prospectively evaluated 165 patients with chronic liver disease with small hepatic observations (≤ 20 mm) which were previously categorized as LI-RADS grade 3-5 on dynamic contrast-enhanced CT (DCE-CT). All patients were submitted to a functional MRI including DCE and DWI. Using LI-RADS v2017, two radiologists independently evaluated the observations and assigned a LI-RADS category to each observation using DCE-MRI alone and combined DCE-MRI and DWI/ADC. In the combined technique, the radiologists assigned a LI-RADS category based on a modified LI-RADS criteria in which restricted diffusion on DWI was considered a major feature of HCC. We evaluated the inter-reader agreement with Kappa statistics and compared the diagnostic performance of the LI-RADS with two imaging techniques by Fisher's exact test using histopathology as the reference standard.

RESULTS

Combined technique in LI-RADS yielded better sensitivities (reader 1, 97% [65/67]; reader 2, 95.5% [64/67]) for HCC diagnosis than DCE-MRI alone (reader 1, 80.6% [54/67], p = 0.005; reader 2, 83.6% [56/67], p = 0.04). The specificities were insignificantly lower in combined technique (reader 1, 88.4% [107/121]; reader 2, 77.7% [94/121]) than in DCE-MRI alone (reader 1, 90.9% [110/121], p = 0.67; reader 2, 79.3% [96/121], p = 0.88). The inter-reader agreement of the LI-RADS scores between combined technique and DCE-MRI was good (κ = 0.765).

CONCLUSION

The use of DWI/ADC as an additional major criterion, improved the sensitivity of LI-RADS in the diagnosis of HCC while keeping high specificity.

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.

Diffusion-weighted MRI as a screening tool for hepatocellular carcinoma in cirrhotic livers: correlation with explant data-a pilot study

OBJECTIVE

The purpose of this study was to compare the sensitivity and specificity of diffusion-weighted liver MRI alone with complete, multiphasic gadoteridol-enhanced MRI for the detection of hepatocellular carcinoma in cirrhotic patients before liver transplant.

MATERIALS AND METHODS

This single institution retrospective study was performed after IRB approval and was HIPAA compliant. MRI scans of 37 patients who underwent liver transplant were evaluated and findings correlated with liver explant (36) or biopsy (1). All MRI scans were obtained within six months of explant. MRI from 17 patients with liver lesions by report at imaging subsequently proven to be HCC at pathology and 20 controls without liver lesions by imaging and pathology were reviewed in random order on the radiology PACS by three independent readers blinded to the MRI reports and pathology reports in two separate sittings. First, only the diffusion-weighted images (DWI) were interpreted. Second, the complete multiphasic MRI exam with DWI was reviewed. A consensus read was obtained by two separate radiologists who had access to the patients' explant data in order to map lesions. Reader-specific and pooled classification was assessed using sensitivity, specificity, positive predictive value, and negative predictive values and corresponding 95% confidence intervals (CI) for both DWI and complete MRI examination readings compared to pathology. McNemar's test and Kappa coefficient were used to assess differences (agreement) in DWI and complete examination readings.

RESULTS

A total of 37 patients have been studied (25M 12F age range 21-70). Averaged results of the three independent readers demonstrated a sensitivity of 78% (95% CI 65-89%) and specificity of 88% (95% CI 77-95%) for DWI alone for detection of liver lesions, with a positive predictive value of 85% (95% CI 72-94%) and a negative predictive value of 83% (95% CI 71-91%). Review of the complete MRI exam showed a sensitivity of 90% (95% CI 76-97%) and a specificity of 82% (95% CI 66-92%) with a positive predictive value of 83% (95% CI 69-93%) and a negative predictive value of 89% (95% CI 74-97%). McNemar's agreement test revealed no significant difference between the DWI and complete multiphasic interpretations (p = 0.3458), with simple Kappa coefficient of 0.6716 (95% CI 0.5332-0.8110). Lesions identified on DWI ranged in size from 1.5 to 5 cm. Detection of lesions was decreased in the presence of artifact from motion, large ascites, and technical issues.

CONCLUSION

Diffusion-weighted MRI has NPV and PPV comparable to complete multiphasic MRI examination for liver lesion detection in cirrhotic patients and may have a role in screening.

ADC similarity predicts microvascular invasion of bifocal hepatocellular carcinoma

PURPOSE

This study aimed to investigate whether ADC similarity can predict microvascular invasion (MVI) in patients with bifocal hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Between January 2015 and September 2015, 51 patients with two HCC lesions were included. All patients underwent conventional magnetic resonance imaging including diffusion-weighted imaging (DWI) before the HCC lesions were surgically resected; the tumor specimens were examined histopathologically. Similarity between two HCC lesions regarding DWI signal intensity (SI) and ADC value was calculated as the difference between the two lesions: Value Similarity = [1-(|value_{large lesion}-value_{small lesion}|)/(value_{large lesion} + value_{small lesion})] × 100%. Univariate and multivariate logistic regression analyses were performed to assess the presence of MVI.

RESULTS

Risk factors significantly related to MVI of bifocal HCC in univariate analysis were cirrhosis (P = 0.010), histological grade (P = 0.040), DWI SI similarity (P = 0.027) and ADC similarity (P = 0.003). In multivariate analysis, cirrhosis (odds ratio 0.068, P = 0.022) and ADC similarity (odds ratio 1.204, P = 0.008) were independent risk factors for MVI of bifocal HCC.

CONCLUSION

In patients with two HCC lesions, highly similar ADC values for the two HCC lesions may be a preoperative predictor of MVI.

Hepatic pseudolymphoma: imaging features on dynamic contrast-enhanced MRI and diffusion-weighted imaging

PURPOSE

To investigate dynamic contrast-enhanced (DCE) MR findings and diffusion-weighted imaging (DWI) characteristics of hepatic pseudolymphoma.

MATERIALS AND METHODS

The MR data of 20 lesions in 14 patients with histopathologically proven hepatic pseudolymphoma were retrospectively analyzed. All patients underwent dynamic gadopentetate dimeglumine-enhanced MR imaging and DWI. Morphologic characteristics and signal features on T1- and T2-weighted images (T1WI, T2WI), and DCE pattern were qualitatively evaluated. The quantitative analysis was performed for the size, the degree of enhancement on arterial phase, signal intensity (SI) of DWI, and apparent diffusion coefficient (ADC) values. The Wilcoxon signed ranks test was used for statistical analysis.

RESULTS

The contour of all lesions was round. The lesion size was 0.7-2.8 cm (mean 1.3 ± 0.5 cm). All lesions manifested as homogeneous hypointensity on T1WI and hyperintensity on T2WI. All lesions were shown as hypervascular with various enhancement patterns on DCE MR imaging. The presence of peripheral enhancement and pseudocapsule was observed in 7 and 4 lesions, respectively. SI of the hepatic pseudolymphoma was significantly lower than that of portal vein on arterial phase (P < 0.001) and the ADC was significantly lower than that of spleen (P = 0.012).

CONCLUSION

A homogeneous nodule with small size (<2 cm), manifestation of hypervascular with lower SI than that of portal vein on arterial phase and lower ADC values than that of spleen are the common MR features of hepatic pseudolymphoma.

LI-RADS® ancillary features on CT and MRI

The Liver Imaging Reporting and Data System (LI-RADS) uses an algorithm to assign categories that reflect the probability of hepatocellular carcinoma (HCC), non-HCC malignancy, or benignity. Unlike other imaging algorithms, LI-RADS utilizes ancillary features (AFs) to refine the final category. AFs in LI-RADS v2017 are divided into those favoring malignancy in general, those favoring HCC specifically, and those favoring benignity. Additionally, LI-RADS v2017 provides new rules regarding application of AFs. The purpose of this review is to discuss ancillary features included in LI-RADS v2017, the rationale for their use, potential pitfalls encountered in their interpretation, and tips on their application.

Comparison of biannual ultrasonography and annual non-contrast liver magnetic resonance imaging as surveillance tools for hepatocellular carcinoma in patients with liver cirrhosis (MAGNUS-HCC): a study protocol

Background

Ultrasonography (US) is recommended as a standard surveillance tool for patients with a high risk of developing hepatocellular carcinoma (HCC). However, the low sensitivity of US for small HCC can lead to surveillance failure, resulting in advanced stage tumor presentations. For the early detection of HCC in high-risk patients and to improve survival and prognosis, a new efficient imaging tool with a high sensitivity for HCC detection is needed. The purpose of this study is to evaluate and compare the feasibility and efficacy of non-contrast magnetic resonance imaging (MRI) with US as a surveillance tool for HCC in patients with liver cirrhosis.

Methods

MAGNUS-HCC is a prospective, multicenter clinical trial with a crossover design for a single arm of patients. This study was approved by six Institutional Review Boards, and informed consent was obtained from all participants. All patients will undergo liver US every 6 months and non-contrast liver MRI every 12 months during a follow-up period of 3 years. If a focal liver lesion suspected of harboring HCC is detected, dynamic liver computed tomography (CT) will be performed to confirm the diagnosis. After the last surveillance round, patients without suspicion of HCC or who are not diagnosed with HCC will be evaluated with a dynamic liver CT to exclude false-negative findings. The primary endpoint is to compare the rate of detection of HCC by US examinations performed at 6-month intervals with that of yearly non-contrast liver MRI studies during a 3-year follow-up. The secondary endpoint is the survival of the patients who developed HCC within the 3-year follow-up period.

Discussion

MAGNUS-HCC is the first study to compare the feasibility of non-contrast MRI with US as a surveillance tool for the detection of HCC in high-risk patients. We anticipate that the evidence presented in this study will establish the efficacy of non-contrast MRI as a surveillance tool for HCC in high-risk patients.

Trial registration

The date of trial registration (NCT02551250) in this study was September 15, 2015, and follow-up is still ongoing.

Diffusion Quantification in Body Imaging

Diffusion-weighted imaging (DWI) is increasingly incorporated into routine body magnetic resonance imaging protocols. DWI can assist with lesion detection and even in characterization. Quantitative DWI has exhibited promise in the discrimination between benign and malignant pathology, in the evaluation of the biologic aggressiveness, and in the assessment of the response to treatment. Unfortunately, inconsistencies in DWI acquisition parameters and analysis have hampered widespread clinical utilization. Focusing primarily on liver applications, this article will review the basic principles of quantitative DWI. In addition to standard mono-exponential fitting, the authors will discuss intravoxel incoherent motion and diffusion kurtosis imaging that involve more sophisticated approaches to diffusion quantification.

Diagnostic Imaging of Hepatocellular Carcinoma - A Pictorial Essay

Hepatocellular carcinoma (HCC) is the most common primary liver cancer, which develops mostly in the setting of chronic liver disease. European Association for the Study of the Liver (EASL) and European Organization for Research and Treatment of Cancer (EORTC) prepared guidelines for screening, follow-up and diagnosis of HCC to facilitate decision making and optimize both diagnostic and therapeutic protocols. The review briefly describes etiology, epidemiology and histopathology of HCC and presents EASL-EORTC guidelines for surveillance and diagnosis of HCC. Target population and screening algorithm is presented in the surveillance section. Ultrasound imaging of HCC and the role of contrast enhanced ultrasound are described as well as the value of laboratory tests in screening. Further, radiological features of HCC in multiphase CT and dynamic contrast enhanced MRI and diagnostic criteria are presented. Additionally, the advantages of advanced techniques in MRI such as diffusion weighed imaging and the use of hepatocyte-specific contrast agents are discussed. Lastly, the EASL-EORTC guidelines are compared with the guidelines of the American Association for the Study of Liver Diseases and the Japan Society of Hepatology. Also LI-RADS and the Barcelona Clinic Liver Cancer classification are mentioned. In the near future, due to the ongoing advances in imaging a revision of the guidelines may be expected.

Major and ancillary magnetic resonance features of LI-RADS to assess HCC: an overview and update

Liver Imaging Reporting and Data System (LI-RADS) is a system for interpreting and reporting of imaging features on multidetector computed tomography (MDCT) and magnetic resonance (MR) studies in patients at risk for hepatocellular carcinoma (HCC). American College of Radiology (ACR) sustained the spread of LI-RADS to homogenizing the interpreting and reporting data of HCC patients. Diagnosis of HCC is due to the presence of major imaging features. Major features are imaging data used to categorize LI-RADS-3, LI-RADS-4, and LI-RADS-5 and include arterial-phase hyperenhancement, tumor diameter, washout appearance, capsule appearance and threshold growth. Ancillary are features that can be used to modify the LI-RADS classification. Ancillary features supporting malignancy (diffusion restriction, moderate T2 hyperintensity, T1 hypointensity on hapatospecifc phase) can be used to upgrade category by one or more categories, but not beyond LI-RADS-4. Our purpose is reporting an overview and update of major and ancillary MR imaging features in assessment of HCC.

Critical analysis of the major and ancillary imaging features of LI-RADS on 127 proven HCCs evaluated with functional and morphological MRI: Lights and shadows

PURPOSE

To report a critical analysis of major and ancillary MR imaging features in assessment of HCC.

METHODS

Retrospectively we evaluated 70 cirrhotic patients with 173 nodules, which were subjected to MR study at 0 time (MR0), after 3 (MR3) and 6 months (MR6) using two different contrast media. EOB-GD-DTPA was injected at MR0 and MR6, while Gd-BT-DO3A at MR3. Three expert hepatic radiologists reviewed all images, recording, according to LI-RADS, the size, the presence and quality of arterial-phase hyperenhancement, washout and capsule appearance, threshold growth. Additionally, we recorded signal intensity (SI) on T2-W images, on DWI, on apparent diffusion coefficient (ADC) maps and SI on T1-W images of EOB-GD-BPTA hepatospecific phase. Median value of ADC and of Intravoxel incoherent motion related parameters were assessed.

RESULTS

127 HCCs and 24 dysplastic nodules were assessed. Hypervascular on arterial phase was found in 84 HCCs, washout appearance in 124, capsule appearance in 111, hypointensity on hepatospecific phase in 127, hyperintensity on T2-W sequences and restricted diffusion in 107. Hyper vascular on arterial phase was found in 17 dysplastic nodules, wash-out appearance in 2, hypointensity on hepatospecific phase in 7 while no dysplastic nodules showed capsule appearance, hyperintensity on T2-W and restricted diffusion. Highest accuracy was obtained by washout appearance and hypointense signal on hepatospecific phase (97% and 95%).

CONCLUSIONS

Hypointensity on hepatospecific phase and washout appearance are the most relevant diagnostic sign for differentiating low-risk from high-risk HCC nodules. The capsule appearance, T2-W hyperintensity and restricted diffusion have high positive predictive value.

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).

Diagnosis of Hepatocellular Carcinoma with Gadoxetic Acid-Enhanced MRI: 2016 Consensus Recommendations of the Korean Society of Abdominal Radiology

Diagnosis of hepatocellular carcinoma (HCC) with gadoxetic acid-enhanced liver magnetic resonance imaging (MRI) poses certain unique challenges beyond the scope of current guidelines. The regional heterogeneity of HCC in demographic characteristics, prevalence, surveillance, and socioeconomic status necessitates different treatment approaches, leading to variations in survival outcomes. Considering the medical practices in Korea, the Korean Society of Abdominal Radiology (KSAR) study group for liver diseases has developed expert consensus recommendations for diagnosis of HCC by gadoxetic acid-enhanced MRI with updated perspectives, using a modified Delphi method. During the 39th Scientific Assembly and Annual Meeting of KSAR (2016), consensus was reached on 12 of 16 statements. These recommendations might serve to ensure a more standardized diagnosis of HCC by gadoxetic acid-enhanced MRI.

Magnetic resonance imaging of the cirrhotic liver: diagnosis of hepatocellular carcinoma and evaluation of response to treatment - Part 2

In the second part of this review, we will describe the ancillary imaging features of hepatocellular carcinoma (HCC) that can be seen on standard magnetic resonance imaging (MRI) protocol, and on novel and emerging protocols such as diffusion weighted imaging and utilization of hepatocyte-specific/hepatobiliary contrast agent. We will also describe the morphologic sub-types of HCC, and give a simplified non-invasive diagnostic algorithm for HCC, followed by a brief description of the liver imaging reporting and data system (LI-RADS), and MRI assessment of tumor response following locoregional therapy.

Imaging of hepatocellular carcinoma and image guided therapies - how we do it

Treatment options for hepatocellular carcinoma have evolved over recent years. Interventional radiologists and surgeons can offer curative treatments for early stage tumours, and locoregional therapies can be provided resulting in longer survival times. Early diagnosis with screening ultrasound is the key. CT and MRI are used to characterize lesions and determine the extent of tumour burden. Imaging techniques are discussed in this article as the correct imaging protocols are essential to optimise successful detection and characterisation. After treatment it is important to establish regular imaging follow up with CT or MRI as local residual disease can be easily treated, and recurrence elsewhere in the liver is common.

Hepatocellular carcinoma detection: diagnostic performance of a simulated abbreviated MRI protocol combining diffusion-weighted and T1-weighted imaging at the delayed phase post gadoxetic acid

PURPOSE

The purpose of this study was to evaluate the diagnostic performance of a "simulated" abbreviated MRI (AMRI) protocol using diffusion-weighted imaging (DWI) and T1-weighted (T1w) imaging obtained at the hepatobiliary phase (HBP) post gadoxetic acid injection alone and in combination, compared to dynamic contrast-enhanced (CE)-T1w imaging for the detection of hepatocellular carcinoma (HCC).

METHODS

This was an IRB approved HIPAA compliant retrospective single institution study including patients with liver disease who underwent gadoxetic acid-enhanced MRI for HCC diagnosis. Three independent observers assessed 2 sets of images (full CE-set and AMRI including DWI+T1w-HBP). Diagnostic performance of T1w-HBP and DWI alone and in combination was compared to that of CE-set. All imaging sets included unenhanced T1w and T2w sequences. A preliminary analysis was performed to assess cost savings of AMRI protocol compared to a full MRI study.

RESULTS

174 patients including 62 with 80 HCCs were assessed. Equivalent per-patient sensitivity and negative predictive value (NPV) were observed for DWI (85.5% and 92.2%, pooled data) and T1w-HBP (89.8% and 94.2%) (P = 0.1-0.7), while these were significantly lower for the full AMRI protocol (DWI+T1w-HBP, 80.6% and 80%, P = 0.02) when compared to CE-set (90.3% and 94.9%). Higher specificity and positive predictive value were observed for CE-set vs. AMRI (P = 0.02). The estimated cost reduction of AMRI versus full MRI ranged between 30.7 and 49.0%.

CONCLUSION

AMRI using DWI and T1w-HBP has a clinically acceptable sensitivity and NPV for HCC detection. This could serve as the basis for a future study assessing AMRI for HCC screening and surveillance.

Role of Diffusion Weighted Imaging (DWI) for Hepatocellular Carcinoma (HCC) Detection and its Grading on 3T MRI: A Prospective Study

BACKGROUND

Limited studies have evaluated the role of diffusion weighted imaging (DWI) and apparent diffusion coefficient (ADC) for histologically grading the hepatocellular carcinoma (HCC).

OBJECTIVE

To compare the efficacy of DWI with dynamic contrast enhanced magnetic resonance (DCEMR) in detection of HCC in cirrhosis, and to evaluate whether DWI can be used instead of DCEMR.

METHODS

20 patients of either sex with cirrhosis and suspected of having HCC on screening USG were included in this prospective study approved by the Institutional Ethics Committee. All patients underwent DCEMR of the abdomen on 3T scanner and fine needle aspiration of the lesions. MR protocol included T1WI, T2WI, DWI, and dynamic CEMR. The results of diffusion weighted imaging were compared with DCEMR to find the efficacy of DWI vis-à-vis CEMR.

RESULTS

DWI had a sensitivity and specificity of 100%, for diagnosis of lesions in cases having single lesion on CEMR, and sensitivity of 75% and specificity of 100% for diagnosis of lesions in cases having multiple lesions. There was a decreasing trend of ADC values with increasing grade of the tumor; however, the decreasing trend was not statistically significant. A cut-off ADC value of 0.8705 resulted in a sensitivity of 75% and specificity of 50% for differentiating between well-differentiated and other grades of HCC.

CONCLUSION

DWI can be used as an alternative for the detection and characterization of HCC, especially in patients with impaired renal function or contrast allergies precluding the use of contrast. In addition, DWI with ADC measurement may be helpful for non-invasive and preoperative prediction of the degree of differentiation of HCC.

Could ADC values be a promising diagnostic criterion for differentiating malignant and benign hepatic lesions in Asian populations: A meta-analysis

BACKGROUND

Liver cancer exhibits geographic and ethnic differences in its prevalence and biology, which implies that it is impractical to develop universal guidelines for all patients. Thus, a meta-analysis was conducted to identify the accuracy of apparent diffusion coefficients (ADCs) for discriminating malignant from benign liver lesions in Asians.

METHODS

Eligible studies published in PubMed, Ovid, and Embase/Medline were updated onto October 2014. STATA 12.0 and Meta-Disc 1.4 were used to perform this meta-analysis.

RESULTS

Eight studies comprising 661 benign liver lesions and 598 malignant liver lesions fulfilled all the inclusion criteria. The pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio were 0.88 (95% confidence interval [CI] 0.75-0.95), 0.93 (95% CI 0.86-0.97), 12.42 (95% CI 6.09-25.31), 0.13 (95% CI 0.06-0.29), and 95.58 (95% CI 35.29-258.89), respectively. Overall, the area under the summary receiver-operating characteristic curve was 0.96 (95% CI 0.94-0.98). Heterogeneity was found to originate potentially from the type of benign lesion. A subgroup analysis showed that differentiating between hemangiomas, cysts, and malignant liver lesions produced a significantly higher diagnostic accuracy than that of solid liver lesions.

CONCLUSION

Our meta-analysis indicated that ADC could be promising for characterizing liver lesions among Asians, indicating that the ADC value is a promising diagnostic criterion candidate. Meanwhile, the use of dual b values could be sufficient for liver lesion characterization. However, large-scale, high-quality trials should be conducted to identify specific standards, including cut-off values for further development of diffusion-weighted imaging as a routine clinical application among Asian populations.

Diffusion-weighted magnetic resonance imaging predicts malignant potential in small hepatocellular carcinoma

BACKGROUND

Poor differentiation and microvascular invasion are indicators of poor outcome after hepatectomy for patients with small hepatocellular carcinoma (HCC).

AIMS

We investigated whether gadoxetic acid-enhanced and diffusion-weighted magnetic resonance imaging (MRI) could predict these factors before hepatectomy.

METHODS

Between July 2008 and April 2012, 75 patients who underwent hepatectomy for small HCCs (diameter: ≤3cm, tumor number: ≤3) were consecutively enrolled. In gadoxetic acid-enhanced MRI, the signal intensity in the tumor was corrected to that in the paraspinous muscles, and the relative enhancement was calculated. In diffusion-weighted imaging, we measured the apparent diffusion coefficient (ADC). We then investigated the correlations between relative enhancement or ADC and histological grade, microvascular invasion and recurrence-free survival.

RESULTS

Poorly differentiated HCCs showed significantly lower ADC than well-differentiated and moderately differentiated HCCs. There was no significant difference in the hepatobiliary phase. Only ADC was an independent predictor of microvascular invasion, and the best cut-off point of its prediction was 1.175×10(-3)mm(2)/s. Additionally, the recurrence-free survival was significantly shorter in low-ADC group than in high-ADC group.

CONCLUSION

ADC is useful for predicting poorly differentiated HCCs and microvascular invasion, and low ADC is associated with increased recurrence risk for small HCCs after hepatectomy.

Hepatocellular Carcinoma and Diffusion-Weighted MRI: Detection and Evaluation of Treatment Response

Differentiating between cancerous tissue and healthy liver parenchyma could represent a challenge with the only conventional Magnetic Resonance (MR) imaging. Diffusion weighted imaging (DWI) exploits different tissue characteristics to conventional Magnetic Resonance Imaging (MRI) sequences that enhance hepatocellular carcinoma (HCC) detection, characterization, and post-treatment evaluation. Detection of HCC is improved by DWI, infact this technology increases conspicuity of lesions that might otherwise not be identified due to obscuration by adjacent vessels or due to low contrast between the lesion and background liver. It is important to remember that DWI combined with contrast-enhanced MRI has higher sensitivity than DWI alone, and that some patients are not eligible for use of contrast on CT and MRI; in these patients DWI has a prominent role. MRI has advanced beyond structural anatomic imaging to now showing pathophysiologic processes. DWI is a promising way to characterize lesions utilizing the inherent contrast within the liver and has the benefit of not requiring contrast injection. DWI improves detection and characterization of HCC. Proposed clinical uses for DWI include: assessing prognosis, predicting response, monitoring response to therapy, and distinguishing tumor recurrence from treatment effect. Ideally, DWI will help risk stratify patients and will participate in prognostic modeling.

Diffusion-Weighted MRI of Malignant versus Benign Portal Vein Thrombosis

Objective

To validate the diffusion-weighted MRI (DWI) for differentiation of benign from malignant portal vein thrombosis.

Materials and Methods

The Institutional Review Board approved this retrospective study and waived informed consent. A total of 59 consecutive patients (52 men and 7 women, aged 40–85 years) with grossly defined portal vein thrombus (PVT) on hepatic MRI were retrospectively analyzed. Among them, liver cirrhosis was found in 45 patients, and hepatocellular carcinoma in 47 patients. DWI was performed using b values of 50 and 800 sec/mm² at 1.5-T unit. A thrombus was considered malignant if it enhanced on dynamic CT or MRI; otherwise, it was considered bland. There were 18 bland thrombi and 49 malignant thrombi in 59 patients, including 8 patients with simultaneous benign and malignant PVT. Mean apparent diffusion coefficients (ADCs) of benign and malignant PVTs were compared by using Mann-Whitney U test. Diagnostic accuracy was evaluated using receiver operating characteristic (ROC) curve analysis.

Results

The mean ADC ± standard deviation of bland and malignant PVT were 1.00 ± 0.39 × 10^-3 mm²/sec and 0.92 ± 0.25 × 10^-3 mm²/sec, respectively; without significant difference (p = 0.799). The area under ROC curve for ADC was 0.520. An ADC value of > 1.35 × 10^-3 mm²/sec predicted bland PVT with a specificity of 94.6% (95% confidence interval [CI]: 84.9–98.9%) and a sensitivity of 22.2% (95% CI: 6.4–47.6%), respectively.

Conclusion

Due to the wide range and considerable overlap of the ADCs, DWI cannot differentiate the benign from malignant thrombi efficiently.

Comparison of diffusion-weighted imaging and T2-weighted single shot fast spin-echo: Implications for LI-RADS characterization of hepatocellular carcinoma

PURPOSE

To evaluate the performance of diffusion-weighted imaging (DWI) and T2-weighted single shot fast spin-echo (SSFSE) imaging of the liver in the detection of hepatocellular carcinoma (HCC) in reference to the LI-RADS classification system.

METHODS

MR images of 40 patients with 68 LI-RADS grade 3-5 lesions were analyzed. Two readers independently reviewed sequences and characterized lesion signal intensity, followed by consensus evaluation. CE-MRI served as reference standard. Sensitivities were compared across sequences. Lesion-to-liver contrast-to-noise ratios (CNRs) and apparent diffusion coefficients (ADCs) were measured and compared using the Wilcoxon signed-rank test across sequences and the Mann-Whitney U or Kruskal-Wallis test between LI-RADS categories. Inter-reader variability was assessed using Cohen's kappa statistic.

RESULTS

Consensus sensitivities of LI-RADS 3-5 lesions using SSFSE images versus DWI were similar (0.53-0.63, p=0.089), however, the sensitivity with DWI b=700 was higher (0.63) than DWI b=0 (0.53, p=0.039). Lesion-to-liver CNRs were larger for all DWI sequences compared to SSFSE images (p<0.001 for all). ADCs of large (>2cm) LIRADS 3-5 lesions were lower than those of small lesions (1.09±0.33 vs. 1.31±0.26, p=0.02), however lesion ADCs were not different from those of adjacent hepatic parenchyma for any LI-RADS lesion.

CONCLUSIONS

DWI has a similar sensitivity compared to SSFSE, but intensity on DWI likely represents intrinsic T2 signal hyper-intensity rather than restricted diffusion as the ADC values were not lower than adjacent parenchyma. Therefore it may not be appropriate to consider hyper-intensity on high b-value as a separate ancillary criteria to T2 hyper-intensity in LI-RADS.

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.

Noninvasive Diagnosis of Hepatocellular Carcinoma: Elaboration on Korean Liver Cancer Study Group-National Cancer Center Korea Practice Guidelines Compared with Other Guidelines and Remaining Issues

Hepatocellular carcinoma (HCC) can be diagnosed based on characteristic findings of arterial-phase enhancement and portal/delayed "washout" in cirrhotic patients. Several countries and major academic societies have proposed varying specific diagnostic criteria for HCC, largely reflecting the variable HCC prevalence in different regions and ethnic groups, as well as different practice patterns. In 2014, a new version of Korean practice guidelines for management of HCC was released by the Korean Liver Cancer Study Group (KLCSG) and the National Cancer Center (NCC). According to the KLCSG-NCC Korea practice guidelines, if the typical hallmark of HCC (i.e., hypervascularity in the arterial phase with washout in the portal or 3 min-delayed phases) is identified in a nodule ≥ 1 cm in diameter on either dynamic CT, dynamic MRI, or MRI using hepatocyte-specific contrast agent in high-risk groups, a diagnosis of HCC is established. In addition, the KLCSG-NCC Korea practice guidelines provide criteria to diagnose HCC for subcentimeter hepatic nodules according to imaging findings and tumor marker, which has not been addressed in other guidelines such as Association for the Study of Liver Diseases and European Association for the Study of the Liver. In this review, we briefly review the new HCC diagnostic criteria endorsed by the 2014 KLCSG-NCC Korea practice guidelines, in comparison with other recent guidelines; we furthermore address several remaining issues in noninvasive diagnosis of HCC, including prerequisite of sonographic demonstration of nodules, discrepancy between transitional phase and delayed phase, and implementation of ancillary features for HCC diagnosis.

Hypovascular hypointense nodules on hepatobiliary phase without T2 hyperintensity on gadoxetic acid-enhanced MR images in patients with chronic liver disease: long-term outcomes and risk factors for hypervascular transformation

PURPOSE

To evaluate the long-term outcomes and imaging features associated with hypervascularization of hypovascular nodules that show T2 iso-/hypointensity and hypointensity on hepatobiliary phase (HBP) of gadoxetic acid-enhanced magnetic resonance (MR) images in patients with chronic liver disease.

MATERIALS AND METHODS

Sixty patients and 114 nodules, which were hypovascular and iso-/hypointense on T2-weighted images and hypointense on HBP of gadoxetic acid-enhanced MRI, were included. We evaluated the effect of baseline clinical features, baseline MR features and growth rate on subsequent hypervascularization.

RESULTS

Twenty-seven nodules in 21 patients transformed to hypervascular hepatocellular carcinoma (HCC). Using multivariate Cox analysis, T1 hyperintensity (hazard ratio [HR] = 2.69, P = 0.021), previous history of HCC (HR = 2.64, P = 0.021), and initial nodule size (HR = 1.09, P = 0.046) were identified to be associated with hypervascularization. The growth rate of nodules was a more powerful determinant of subsequent hypervascularization than baseline clinical and MR features. At long-term follow-up after >3 years, only one nodule with T1 isointensity showed hypervascularization.

CONCLUSION

Careful follow-up or diagnostic procedures, such as biopsy, should be considered for up to 3 years after detection of hypointense nodules on HBP with T1 hyperintensity or a higher growth rate.

KEY POINTS

• T1 hyperintensity is a baseline MR predictive factor for subsequent hypervascularization. • A higher growth rate is a more powerful determinant of subsequent hypervascularization. • Management of patients with these predictive factors requires more attention.

Combined Application of Gadoxetic Acid Disodium-Enhanced Magnetic Resonance Imaging (MRI) and Diffusion-Weighted Imaging (DWI) in the Diagnosis of Chronic Liver Disease-Induced Hepatocellular Carcinoma: A Meta-Analysis

Objective

Gadoxetic acid disodium (Gd-EOB-DTPA) is a magnetic resonance imaging (MRI) contrast agent to target the liver cells with normal function. In clinical practice, the Gd-EOB-DTPA produces high quality hepatocyte specific image 20 minutes after intravenous injection, so DWI sequence is often performed after the conventional dynamic scanning. However, there are still some disputes about whether DWI sequence will provide more effective diagnostic information in clinical practice. This study aimed to explore the diagnostic value of combining Gd-EOB-DTPA-enhanced MRI and DWI in the detection of hepatocellular carcinoma (HCC) in patients with chronic liver disease.

Methods

A systematic literature search was performed in the PubMed and Cochrane library database up to March 2015. The quality assessment of diagnostic accuracy studies (QUADAS) was used to evaluate the quality of studies. Heterogeneous test on the included literature was performed by using the software Review Manager 5.3. The MetaDiSc 1.4 software was used to calculate the pooled sensitivity, specificity, positive likelihood ratio and negative likelihood ratio; meanwhile the summary receiver operating characteristics (SROC) curve was drawn to compare the diagnostic performance.

Results

A total of 13 literatures were included in this study. In 8 literatures regarding HCC diagnosis based on Gd-EOB-DTPA-enhanced MRI, the pooled sensitivity: 0.90 (95% confidence interval (CI): 0.88–0.93); specificity: 0.89 (95% CI: 0.85–0.92); positive likelihood ratio: 8.60 (95% CI: 6.20–11.92); negative likelihood ratio: 0.10 (95% CI: 0.08–0.14) were obtained. The area under curve (AUC) and Q values were 0.96 and 0.90, respectively. In 5 literatures relating to HCC diagnosis by combination of Gd-EOB-DTPA-enhanced MRI and DWI sequence, the pooled sensitivity: 0.88 (95% CI: 0.85–0.91), specificity: 0.96 (0.94–0.97), positive likelihood ratio: 19.63 (12.77–30.16), negative likelihood ratio: 0.10 (0.07–0.14) were obtained. The AUC value was 0.9833 and Q value was 0.9436. The AUC value of comprehensive evaluation method was significantly higher than that of Gd-EOB-DTPA-enhanced MRI alone(P<0.05).

Conclusion

Combination of Gd-EOB-DTPA-enhanced MRI and DWI sequence significantly improves in both the diagnostic accuracy and specificity of chronic liver disease-associated HCC.

Histological grade of hepatocellular carcinoma correlates with arterial enhancement on gadoxetic acid-enhanced and diffusion-weighted MR images

PURPOSE

To retrospectively determine the correlation between heptic tumor signal intensity on gadoxetic acid-enhanced and diffusion-weighted MR images and histopathological grading of hepatocellular carcinoma (HCC).

METHODS

We retrospectively reviewed the MR images of 79 patients with 141 surgically resected HCCs. The signal intensity and its relationship with histopathological grade were assessed. We measured the apparent diffusion correlation (ADC) values and calculated arterial enhancement ratios, washout ratios, and relative intensity ratios of HCCs relative to the surrounding liver parenchyma in gadoxetic-enhanced MR images in order to determine their relationship to the histological grade.

RESULTS

Morphological evaluation showed that larger tumor size and extrahepatic extension were associated with higher histologic grade (p < 0.01). Multivariate logistic regression showed that low ADC value and low relative intensity ratio in the arterial phase (RIRa) predict high histological grade. ADC value (cut-off 1.7 × 10(-3) mm(2)/s, sensitivity 82.4%, specificity 83.2%) was the best predictor of well-differentiated HCC, and RIRa (cut-off 0.93, sensitivity 81.4%, specificity 93.9%) was superior to ADC for predicting poorly differentiated HCC.

CONCLUSION

Relative low arterial enhancement on gadoxetic acid-enhanced MR images and low ADC are predictive of worse histological grades of HCC.

Gd-EOB-DTPA-enhanced and diffusion-weighted magnetic resonance findings in hepatic epithelioid angiomyolipoma: A case report

The present study reports a case of histologically proven hepatic epithelioid angiomyolipoma that was evaluated with gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging and diffusion-weighted imaging. A 23-year-old female was admitted to the Northern Jiangsu People's Hospital (Yangzhou, Jiangsu, China) due to a 5.6-cm mass in the liver, and a right partial hepatectomy was performed. Magnetic resonance imaging (MRI) revealed a hypointense mass on T1-weighted imaging, and a hyperintense mass on T2-weighted and diffusion-weighted imaging, with a higher apparent diffusion coefficient value compared with normal liver parenchyma. On the dynamic Gd-EOB-DTPA-enhanced MRI scan, the lesion manifested as hypervascular with multiple filiform vessels and a pseudocapsule image, and in the hepatobiliary phase the lesion demonstrated a lack of contrast retention, thus appearing hypointense compared with the background liver. Pre-operatively, EMAL was diagnosed on the basis of these findings in the tumor. The optimum treatment is complete surgical excision and subsequent follow-up. The patient was healthy and free from recurrence at 6 months and 1 year post-surgery. Therefore, knowledge of EAML specific features on dynamic Gd-EOB-DTPA-enhanced and DWI scans may improve the diagnostic accuracy of hypervascular hepatic tumors and may facilitate treatment selection.

[Rational imaging of hepatocellular carcinoma. The challenge of multimodal diagnostic criteria]

CLINICAL/METHODICAL ISSUE

Both computed tomography (CT) and magnetic resonance imaging (MRI) constitute the gold standard in radiological imaging of hepatocellular carcinoma (HCC). In cases of typical contrast behavior each modality as a single dynamic technique allows the diagnosis of HCC. There is still a challenge in detection of small HCCs < 2 cm, in differentiating HCC and high-grade dysplasia from other benign liver lesions as well as the evaluation of hypovascular liver lesions in the cirrhotic liver.

PERFORMANCE

Nowadays, both modalities achieve high detection rates of 90-100 % for lesions > 2 cm. Regarding lesions between 1 and 2 cm there is a higher sensitivity for MRI ranging between 80 and 90 % compared to 60-75 % with CT. Besides the multimodal diagnostic criteria, MRI provides significant benefits with the use of hepatobiliary contrast. Especially in combination with diffusion- weighted imaging (DWI) increased sensitivity and diagnostic accuracy compared to CT has been described for lesions sized < 2 cm. Regarding the differentiation from other hepatic nodules in the cirrhotic liver there is strong evidence that the coexistence of arterial enhancement and hypointensity on hepatobiliary imaging is specific for HCC. Moreover, hypointensity on hepatobiliary imaging is associated with a high positive predictive value (PPV) of up to 100 % for the presence of high-grade dysplasia and HCC.

ACHIEVEMENTS

The use of MRI including hepatobiliary imaging and DWI has to be regarded as the best non-invasive imaging modality for the detection of HCC and for the characterization of nodules in patients with liver cirrhosis. In comparison to CT there are benefits regarding detection of small lesions < 2 cm and evaluation of hypovascular liver lesions in the context of the hepatocarcinogenesis including prognostic values of premalignant lesions.

PRACTICAL RECOMMENDATIONS

Both MRI and CT provide a high diagnostic performance in evaluation of HCC in liver cirrhosis. With MRI there are considerable advantages regarding the detection rate and specificity. For daily clinical routine, CT offers a fast, reliable and easy available modality with benefits for patients in reduced general state of health and restricted compliance.

Role of diffusion-weighted imaging, apparent diffusion coefficient and correlation with hepatobiliary phase findings in the differentiation of hepatocellular carcinoma from dysplastic nodules in cirrhotic liver

OBJECTIVES

To investigate the utility of diffusion-weighted imaging (DWI), apparent diffusion coefficient (ADC) and the correlation with hepatobiliary phase (delayed phase imaging, DPI) findings in the differentiation of cirrhotic hepatocellular nodules.

METHODS

Forty-three patients with 53 pathology-proven nodules (29 hepatocellular carcinomas (HCCs), 13 high-grade (HGDNs) and 11 low-grade dysplastic nodules (LGDNs); mean size 2.17 cm, range 1-4 cm), who underwent liver MRI with DWI and DPI sequences, were retrospectively reviewed. Lesions were classified as hypointense, isointense, or hyperintense relative to the adjacent liver parenchyma. ADC of each nodule, of the surrounding parenchyma, and lesion-to-liver ratio were calculated.

RESULTS

Hyperintensity versus iso/hypointensity on DWI, hypointensity versus iso/hyperintensity on DPI, and the mean lesion-to-liver ratio showed a statistically significant difference both between HCCs versus DNs and between "HCCs + HGDNs" versus LGDNs (p < 0.05); sensitivity, specificity, and accuracy for the diagnosis of "HCCs + HGDNs" were 96.8 %, 100 %, 97.4 % respectively when combining hyperintensity on DWI and hypointensity on DPI, and 90.9 %, 81.0 %, 83.6 % respectively when lesion-to-liver ratio was <0.95.

CONCLUSIONS

Hyperintensity on DWI, especially in association with hypointensity on DPI, and low lesion-to-liver ratios should raise the suspicion of HCC, or at least of HGDN, thus helping the characterization of atypically enhancing lesions.

KEY POINTS

• Usefulness of DWI and ADC is shown in differential diagnosis of cirrhotic nodules. • Correlation of DWI with DPI improves differential diagnosis of cirrhotic nodules. • Characterization of atypically enhancing lesions becomes more confident.

Magnetic resonance imaging of the cirrhotic liver: An update

Noninvasive imaging has become the standard for hepatocellular carcinoma (HCC) diagnosis in cirrhotic livers. In this review paper, we go over the basics of MR imaging in cirrhotic livers and describe the imaging appearance of a spectrum of hepatic nodules marking the progression from regenerative nodules to low- and high-grade dysplastic nodules, and ultimately to HCCs. We detail and illustrate the typical imaging appearances of different types of HCC including focal, multi-focal, massive, diffuse/infiltrative, and intra-hepatic metastases; with emphasis on the diagnostic value of MR in imaging these lesions. We also shed some light on liver imaging reporting and data system, and the role of different magnetic resonance imaging (MRI) contrast agents and future MRI techniques including the use of advanced MR pulse sequences and utilization of hepatocyte-specific MRI contrast agents, and how they might contribute to improving the diagnostic performance of MRI in early stage HCC diagnosis.

New imaging techniques for liver diseases

Newly developed or advanced methods of ultrasonography and MR imaging provide combined anatomical and quantitative functional information about diffuse and focal liver diseases. Ultrasound elastography has a central role for staging liver fibrosis and an increasing role in grading portal hypertension; dynamic contrast-enhanced ultrasonography may improve tumor characterization. In clinical practice, MR imaging examinations currently include diffusion-weighted and dynamic MR imaging, enhanced with extracellular or hepatobiliary contrast agents. Moreover, quantitative parameters obtained with diffusion-weighted MR imaging, dynamic contrast-enhanced MR imaging and MR elastography have the potential to characterize further diffuse and focal liver diseases, by adding information about tissue cellularity, perfusion, hepatocyte transport function and visco-elasticity. The multiparametric capability of ultrasonography and more markedly of MR imaging gives the opportunity for high diagnostic performance by combining imaging biomarkers. However, image acquisition and post-processing methods should be further standardized and validated in multicenter trials.

Nonhypervascular Hypointense Nodules at Gadoxetic Acid-enhanced MR Imaging in Chronic Liver Disease: Diffusion-weighted Imaging for Characterization

PURPOSE

To compare the diagnostic performance of magnetic resonance (MR) imaging features, including those on diffusion-weighted (DW) and T2-weighted images, in differentiating between hypovascular hepatocellular carcinoma (HCC) and dysplastic nodules seen as hypointense nodules at hepatobiliary phase gadoxetic acid-enhanced MR imaging.

MATERIALS AND METHODS

The institutional review board approved this retrospective study and waived the need to obtain informed patient consent. There were 53 patients (39 men and 14 women; age range, 32-75 years) with histologically proven hypovascular HCCs (n = 25) and/or dysplastic nodules (n = 31) who underwent gadoxetic acid-enhanced MR imaging at 3.0-T between March 2011 and January 2014. Images of 25 HCCs and 31 dysplastic nodules were analyzed for nodule size; signal intensity on T1- and T2-weighted, portal venous phase, and DW (b value = 800 sec/mm(2)) images; and intralesional fat. Correlations between the hyperintensity grade of lesions and the liver-to-lesion signal intensity ratio at T2-weighted and DW imaging were determined by means of analysis with generalized estimating equations.

RESULTS

Hyperintensity at T2-weighted and DW imaging and hypointensity in the portal venous phase were significant features for differentiating hypovascular HCCs from dysplastic nodules (P < .05). The sensitivity of DW imaging tended to be higher than that of T2-weighted imaging (72.0% [18 of 25] vs 40.0% [10 of 25]; P = .008 for grade 2 and 3 hyperintensity). Use of the parameter of hyperintensity similar to or slightly lower than the signal intensity of the spleen on DW images (b value = 800 sec/mm(2)) yielded a specificity of 100% (31 of 31) for the diagnosis of hypovascular HCC by differentiating it from a dysplastic nodule.

CONCLUSION

Hyperintensity at DW imaging could be a useful MR imaging feature for differentiating hypovascular HCCs from dysplastic nodules seen as hypointense nodules at gadoxetic acid-enhanced MR imaging.

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.