Magnetic Resonance Imaging Of Hepatocellular Carcinoma Research Articles

MRI for hepatocellular carcinoma and the role of abbreviated MRI for surveillance of hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) constitutes the majority of liver cancers and significantly impacts global cancer mortality. While ultrasound (US) with or without alpha-fetoprotein is the mainstay for HCC surveillance, its limitations highlight the necessity for more effective surveillance tools. Therefore, this review explores evolving imaging modalities and abbreviated magnetic resonance imaging (MRI) (AMRI) protocols as promising alternatives, addressing challenges in HCC surveillance. This comprehensive review delves into the evaluation and challenges of HCC surveillance tools, focusing on non-contrast abbreviated MRI (NC-AMRI) and contrast-enhanced abbreviated MRI protocols. It covers the implementation of AMRI for HCC surveillance, patient preferences, adherence, and strategies for optimizing cost-effectiveness. Additionally, the article provides insights into prospects for HCC surveillance by summarizing meta-analyses, prospective studies, and ongoing clinical trials evaluating AMRI protocols. The opinions underscore the transformative impact of AMRI on HCC surveillance, especially in overcoming US limitations. Promising results from NC-AMRI protocols indicate its potential for high-risk patient surveillance, though prospective studies in true surveillance settings are essential for validation. Future research should prioritize risk-stratified AMRI protocols and address cost-effectiveness for broader clinical implementation, alongside comparative analyses with US for optimal surveillance strategies.

Prediction of Microvascular Invasion via Gadoxetic Acid-enhanced MRI in Hepatocellular Carcinoma: The Implication of Planning Extent of the Hepatectomy

Introduction: The purpose of this study was to identify predictive factors for microvascular invasion (MVI) in hepatocellular carcinoma (HCC) using clinical factors and imaging findings of magnetic resonance imaging (MRI), to divide the patients into a subgroup with similar prognosis and finally to evaluate whether the extent of hepatectomy can affect long-term outcomes in the subgroup.

Prediction of microvascular invasion via gadoxetic acid-enhanced MRI in hepatocellular carcinoma: The implication of planning extent of the hepatectomy

The purpose of this study was to identify predictive factors for microvascular invasion (MVI) in hepatocellular carcinoma (HCC) using clinical factors and imaging findings of magnetic resonance imaging (MRI), to divide the patients into a subgroup with similar prognosis and finally to evaluate whether the extent of hepatectomy can affect long-term outcomes in the subgroup. A total of 410 patients with surgically resected single HCC (≤ 5 cm) who underwent preoperative gadoxetic acid-enhanced MRI were included. Significant predictive factors for MVI were identified via univariate and multivariate analysis and used to divide the patients into low and high-risk groups. In the subgroup, long-term outcomes were analyzed after the minor versus major hepatectomy. Four variables were independently associated with MVI: alpha-fetoprotein ≥ 400 ng/mL (p = 0.021), tumor size ≥ 3 cm (p < 0.001), non-smooth tumor margin (p < 0.001) and arterial peritumoral enhancement (p = 0.001). Patients with a combination of three or more factors were classified as the high-risk group (n = 103), which showed worse prognosis than the low-risk group (n = 307) (p < 0.001). While the extent of hepatectomy was not associated with prognosis in the low-risk group, major hepatectomy significantly improved disease-free survival (p < 0.011) and decreased early intrahepatic recurrence (< 2 years) (p = 0.005) than minor hepatectomy in the high-risk patients. The patients who had a combination of three or more predictive factors for MVI showed worse prognosis after hepatectomy for HCC and major hepatectomy improved long-term outcomes in these high-risk patients.

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

To compare the presence of washout and the diagnostic performance of computed tomography (CT) and magnetic resonance imaging (MRI) for hepatocellular carcinoma (HCC) according to the presence of hepatic steatosis. This retrospective study included 566 patients with chronic liver disease who had undergone hepatic resection for hepatic tumors (482 HCCs and 84 non-HCCs) between January 2016 and June 2018 and had available multiphasic CT and MR images. Patients were allocated in the fatty liver (n = 141) or non-fatty liver (n = 425) group according to the presence of hepatic steatosis, defined as lipid droplets in at least 5% of hepatocytes on pathological examination. The presence of HCC washout and the diagnostic performance of CT and MRI for HCC were compared between the groups. HCC washout was less frequently seen in the fatty liver group than in the non-fatty liver group on CT (61.5% vs. 88.9%, p < 0.001), whereas it was similarly present on MRI in both groups (77.0% vs. 74.4%, p = 0.565). For diagnosis of HCC, the sensitivity (53.3% vs. 80.0%, p < 0.001) and accuracy (53.9% vs. 80.9%, p < 0.001) of CT were lower in the fatty liver group than in the non-fatty liver group. However, for MRI, these values were not significantly different between the groups (p > 0.05). Hepatic steatosis significantly decreased the performance of CT for the diagnosis of HCC, whereas it did not significantly alter the performance of MRI. • Unlike MRI, there is vanishing HCC washout on CT caused by the background hepatic steatosis. • The diagnostic performance of CT for the diagnosis of HCC was significantly altered by hepatic steatosis. • The optimal cutoff HU value of the liver parenchyma for the vanishing washout of HCC was < 50HU on unenhanced CT images.

Diagnostic performance of MRI for HCC according to contrast agent type: a systematic review and meta-analysis.

Conflicting results have been reported between the use of extracellular contrast agent (ECA) and hepatobiliary contrast agent (HBA) when magnetic resonance imaging (MRI) is used for the diagnosis of hepatocellular carcinoma (HCC). Therefore, we aimed to compare the diagnostic performance of MRI using ECA (ECA-MRI) and HBA (HBA-MRI). Original studies reporting the diagnostic performance of contrast-enhanced MRI for the diagnosis of HCC published between January 2010 and February 2020 were identified in a Pubmed, EMBASE, and Cochrane Library database search. The pooled sensitivity and specificity of ECA-MRI and HBA-MRI were calculated using a bivariate random effects model and compared using a joint-model bivariate meta-regression. Subgroup analyses were performed to compare the diagnostic performance of ECA-MRI and HBA-MRI according to study design, underlying liver disease, lesion size, reference standard, and imaging criteria. Of the 1760 screened articles, 31 studies were included: 15 studies included 2890 lesions imaged using ECA-MRI and 19 studies included 3893 lesions imaged using HBA-MRI. The pooled sensitivity and specificity were not significantly different between ECA-MRI (sensitivity, 72% [95% confidence interval 65-79%]; specificity 92% [89-95%]) and HBA-MRI (76% [68-83%]; 92% [87-95%], p = 0.72). Subgroup analyses did not find differences in diagnostic performance between ECA-MRI and HBA-MRI according to study design (p ≥ 0.11), underlying disease (p ≥ 0.09), lesion size (≤ 2cm, p = 0.97), reference standard (p = 0.70), or imaging criteria (p = 0.33). ECA-MRI showed similar performance to HBA-MRI in the diagnosis of HCC. The contrast agent might be selected with consideration of the advantages of each agent.

Atypical magnetic resonance imaging features and differential diagnosis of hepatocellular carcinoma

ObjectiveHepatocellular carcinoma (HCC) is the most common primary malignant tumor of the liver. We aimed to summarize and analyze the atypical magnetic resonance imaging (MRI) features of HCC to improve its diagnostic accuracy.MethodsWe retrospectively analyzed MRI data for 66 patients with HCC with atypical MRI features confirmed by operation and pathology.ResultsTwelve patients had high signals and 18 patients had significant decreases in opposed phase signals in T1WI plain scans. Nine patients had high signals and six patients had large cystic lesions in apparent diffusion coefficient images. Dynamic enhancement showed progressive enhancement in 15 patients, ring enhancement in three, irregular patchy enhancement in three, ‘nodule-in-nodule’ enhancement in six, delayed central patchy enhancement in six, delayed central ‘star-like aristate scars’ (T2WI revealed high signal intensity) in 21, and poor blood supply in three patients.ConclusionsMRI can make a clear diagnosis of typical HCC, and atypical cases can also be distinguished from other tumors or tumor-like lesions by MRI. The analysis of atypical signs may improve the diagnostic accuracy of MRI for HCC.

Gadoxetic acid-based hepatobiliary MRI in hepatocellular carcinoma.

Background & AimsSORAMIC is a prospective phase II randomised controlled trial in hepatocellular carcinoma (HCC). It consists of 3 parts: a diagnostic study and 2 therapeutic studies with either curative ablation or palliative Yttrium-90 radioembolisation combined with sorafenib. We report the diagnostic cohort study aimed to determine the accuracy of gadoxetic acid-enhanced magnetic resonance imaging (MRI), including hepatobiliary phase (HBP) imaging features compared with contrast-enhanced computed tomography (CT). The primary objective was the accuracy of treatment decisions stratifying patients for curative or palliative (non-ablation) treatment.MethodsPatients with clinically suspected HCC underwent gadoxetic acid-enhanced MRI (HBP MRI, including dynamic MRI) and contrast-enhanced CT. Blinded read of the image data was performed by 2 reader groups (radiologists, R1 and R2). A truth panel with access to all clinical data and follow-up imaging served as reference. Imaging criteria for curative ablation were defined as up to 4 lesions <5 cm and absence of macrovascular invasion. The primary endpoint was non-inferiority of HBP MRI vs. CT in a first step and superiority in a second step.ResultsThe intent-to-treat population comprised 538 patients. Treatment decisions matched the truth panel assessment in 83.3% and 81.2% for HBP MRI (R1 and R2), and 73.4% and 70.8% for CT. Non-inferiority and superiority (second step) of HBP MRI vs. CT were demonstrated (odds ratio 1.14 [1.09–1.19]). HBP MRI identified patients with >4 lesions significantly more frequently than CT.ConclusionsIn HCC, HBP MRI provided a more accurate decision than CT for a curative vs. palliative treatment strategy.Lay summaryPatients with hepatocellular carcinoma are allocated to curative or palliative treatment according to the stage of their disease. Hepatobiliary imaging using gadoxetic acid-enhanced MRI is more accurate than CT for treatment decision-making.

Integrin α6-Targeted Magnetic Resonance Imaging of Hepatocellular Carcinoma in Mice.

Magnetic resonance imaging (MRI) has a high spatial resolution for detecting hepatocellular carcinoma (HCC). Integrin α6 has emerged as a diagnostic and prognostic biomarker of HCC. Here, we developed the MR contrast agent RWY-dL-(Gd-DOTA)4 based on the integrin α6-targeted RWY peptide that we previously identified to detect HCC. Contrast-enhanced MRI was carried out to evaluate the use of RWY-dL-(Gd-DOTA)4 to detect HCC lesions in subcutaneous and diethylnitrosamine (DEN)-induced HCC mouse models. Enhancement MR signals were observed in HCC-LM3 subcutaneous liver tumors in the first 5min post-injection of RWY-dL-(Gd-DOTA)4 at a low dose of 0.03mmol Gd/kg. Moreover, RWY-dL-(Gd-DOTA)4 generated superior contrast enhancement for liver tumors in chemical-induced HCC mice. Importantly, RWY-dL-(Gd-DOTA)4 provided complementary enhancement MR signals to the clinical available hepatobiliary MR contrast agent gadoxetate disodium Gd-EOB-DTPA. Additionally, RWY-dL-(Gd-DOTA)4 showed minimal gadolinium retention in normal tissues and organs at 48h post-injection. These findings potentiate the use of RWY-dL-(Gd-DOTA)4 for the MRI of HCC to improve the diagnosis of HCC.

A scientometric analysis on hepatocellular carcinoma magnetic resonance imaging research from 2008 to 2017.

With the development of new magnetic resonance imaging (MRI) techniques, an increasing number of articles have been published regarding hepatocellular carcinoma magnetic resonance imaging (HCCMRI) in the past decade. However, few studies have statistically analyzed these published articles. In this study, we aim to systematically evaluate the scientific outcomes of HCCMRI research and explore the research hotspots from 2008 to 2017. The included articles regarding HCCMRI research from 2008 to 2017 were downloaded from the Web of Science Core Collection and verified by two experienced radiologists. Excel 2016 was used to analyze the literature data, including the publication years and journals. CiteSpace V was used to perform co-occurrence analyses for authors, countries/regions and institutions and to generate the related collaboration network maps. Reference co-citation analysis (RCA) and burst keyword detection were also performed using CiteSpace V to explore the research hotspots in the past decade. A total of 835 HCCMRI articles published from 2008 to 2017 were identified. Journal of Magnetic Resonance Imaging published the most articles (79 publications, 9.46%). Extensive cooperating relationship were observed among countries/regions and among authors. South Korea had the most publications (199 publications, 21.82%), followed by the United States of America (USA) (190 publications, 20.83%), Japan (162 publications, 17.76%), and the People's Republic of China (148 publications, 16.23%). Among the top 10 co-cited authors, Bruix J (398 citations) was ranked first, followed by Llovet JM (235 citations), Kim YK (170 citations) and Forner A (152 citations). According to the RCA, ten major clusters were explored over the last decade; "LI-RADS data system" and "microvascular invasion" (MVI) were the two most recent clusters. Forty-seven burst keywords with the highest citation strength were detected over time. Of these keywords, "microvascular invasion" had the highest strength in the last 3 years. The LI-RADS has been constantly updated with the latest edition released in July 2018. However, the LI-RADS still has limitations in identifying certain categories of lesions by conceptual and non-quantitative probabilistic methods. Plenty of questions still need to be further answered such as the difference of diagnostic efficiency of each major/ancillary imaging features. Preoperative prediction of MVI of HCC is very important to therapeutic decision-making. Some parameters of Gd-EOB-DTPA-enhanced MRI were found to be useful in prediction of MVI, however, with a high specificity but a very low sensitivity. Comprehensive predictive model incorporating both imaging and clinical variables may be the more preferable in prediction of MVI of HCC. HCCMRI-related publications displayed a gradually increasing trend from 2008 to 2017. The USA has a central position in collaboration with other countries/regions, while South Korea contributed the most in the number of publications. Of the ten major clusters identified in the RCA, the two most recent clusters were "LI-RADS data system" and "microvascular invasion", indicative of the current HCCMRI research hotspots.

Magnetic Endoglin Aptamer Nanoprobe for Targeted Diagnosis of Solid Tumor.

Based on molecular targeting, magnetic resonance imaging (MRI) is an ideal noninvasive approach for tumor diagnosis. Construction of targeting probes to enhance the MRI efficacy has become a research hotspot recently. In this study, magnetic endoglin aptamer (mEND) imaging nanoprobes based on mEND-modified magnetic carboxymethyl chitosan (CMCS) nanoparticles (denoted mEND-Fe₃O₄@CMCS) were developed. The mEND-Fe₃O₄@CMCS naoprobe was prepared using mEND as the recognition molecule and Fe₃O₄@CMCS as the carrier to enhance the MRI efficacy of hepatocellular carcinoma (HCC). On the one hand, the CMCS self-assembled on the surface of Fe₃O₄ improved the biocompatibility and nontoxicity of magnetic nanoparticles. On the other hand, chemical groups provided by CMCS contributed to the modification of more aptamers. More importantly, the assembled aptamers significantly improved the probe targeting ability, thus enhancing the diagnosis efficacy of MRI of HCC. As a result, the average diameter and zeta potential of the nanoprobe was 87.15±1.66 nm and -31.9±0.5 mV, respectively. The MRI imaging result indicated that this probe effectively targeted neovascularization of mouse HCC and improved the imaging contrast of subcutaneous tumor in mice. Cytotoxicity and histological tests confirmed that the constructed probe possessed low toxicity. In conclusion, the mEND-Fe₃O₄@CMCS nanoprobe showed high targeting affinity, enhanced MRI effect and good biocompatibility. This study provides new MRI probes to target CD105 positive cells and is a promising candidate for HCC early diagnosis.

Extracellular contrast agent-enhanced MRI: 15-min delayed phase may improve the diagnostic performance for hepatocellular carcinoma in patients with chronic liver disease.

To determine the value of a 15-min delayed phase in extracellular contrast agent (ECA)-enhanced magnetic resonance imaging (MRI) for evaluation of hepatocellular carcinoma (HCC) in patients with chronic liver disease. Between 2014 and 2015, 103 patients with chronic liver disease underwent ECA-enhanced MRI; 133 lesions consisting of 107 HCCs, 23 benign lesions and three non-HCC malignancies were identified with pathological or clinical diagnosis. MRI images were reviewed by two abdominal radiologists independently using the European Association for the Study of the Liver (EASL) and Liver Imaging Reporting and Data System (LI-RADS) criteria. Imaging features observed in the 15-min delayed phase were recorded. Of 107 HCCs, three or four additional HCCs were diagnosed according to the EASL criteria by adding the 15-min delayed phase, increasing sensitivity (Reviewer 1, from 69.2-72.0 % [P = 0.072]; Reviewer 2, from 75.7-79.4 % [P = 0.041]). Reviewers 1 and 2 upgraded one and four HCCs from LR-4 to LR-5 based on the LI-RADS, respectively. Among 23 benign lesions, no additional findings were observed in the 15-min delayed phase. Including the 15-min delayed phase in ECA-enhanced MRI may improve the diagnostic performance for HCC in patients with chronic liver disease. • Additional acquisition of 15-min delayed phase (FDP) requires approximately 20 s. • About 5 % of HCCs show washout or capsule appearance only in FDP. • Including FDP improves the sensitivity of extracellular contrast agent-enhanced MRI for HCC. • These results are applicable only to patients with chronic liver disease.

Gadoxetic acid-enhanced magnetic resonance imaging reflects co-activation of β-catenin and hepatocyte nuclear factor 4α in hepatocellular carcinoma.

The aim of this study is to clarify the correlation of the co-activation of β-catenin and hepatocyte nuclear factor (HNF)4α with the findings of gadoxetic acid-enhanced magnetic resonance imaging (MRI), organic anion transporting polypeptide (OATP)1B3 expression, and histological findings in hepatocellular carcinoma (HCC). One hundred and ninety-six HCCs surgically resected from 174 patients were enrolled in this study. The HCCs were classified into four groups by immunohistochemical expression of β-catenin, glutamine synthetase (GS), and HNF4α: (i) β-catenin/GS (positive [+]) HNF4α (+); (ii) β-catenin/GS (+) HNF4α (negative [-]); (iii) β-catenin/GS (-) HNF4α (+); and (iv) β-catenin/GS (-) HNF4α (-). We compared the four groups in terms of the enhancement ratio on the hepatobiliary phase of gadoxetic acid-enhanced MRI, immunohistochemical organic anion transporter polypeptide (OATP)1B3 (a main uptake transporter of gadoxetic acid) expression and histological features, overall survival, and no recurrence survival. The Kruskal-Wallis test, Steel-Dwass multiple comparisons test, Fisher's exact test, and log-rank (Mantel-Cox) test were used for statistical analyses. Enhancement ratio on gadoxetic acid-enhanced MRI in HCC with β-catenin/GS (+) HNF4α (+) was significantly higher than those of the other three groups (P < 0.001). The OATP1B3 grade was also significantly higher in HCC with β-catenin/GS (+) HNF4α (+) (P < 0.001). Hepatocellular carcinoma with β-catenin/GS (+) HNF4α (+) showed the highest differentiation grade as compared to the other groups (P < 0.004). There were no significant differences in portal vein invasion, macroscopic growth pattern, or prognosis analyses between the four groups. Co-activation of β-catenin and HNF4α would promote OATP1B3 expression, and consequently higher enhancement ratio on gadoxetic acid-enhanced MRI and higher differentiation grade in HCC.

Magnetic Resonance Imaging in Diagnosis and Monitoring of Hepatocellular Carcinoma in Liver Transplantation: A Comprehensive Review.

Hepatocellular carcinoma (HCC) is the most common primary liver cancer. One of the most important risk factors of HCC is cirrhosis. The optimal treatment of HCC is liver transplantation, since it treats both the underlying cirrhosis and the cancer. Patients that have risk factors should be included in surveillance programs since HCC can be cured only during the early stages. Surveillance can be performed by ultrasonography (US), which is an inexpensive, non-invasive, and widely available technique, but it is considered to have a low sensitivity. If a suspicious lesion is detected on US exam, computerized tomography (CT) or magnetic resonance imaging (MRI) can be used to further evaluate this lesion. MRI is considered to be superior to CT because it has greater contrast resolution and tissue characterization. In this article, we present a review of MRI for HCC in liver transplantation (LT) with a focus on characteristic MR features of this tumor and current guidelines.

Imaging Techniques for the Diagnosis of Hepatocellular Carcinoma: A Systematic Review and Meta-analysis.

Several imaging modalities are available for diagnosis of hepatocellular carcinoma (HCC). To evaluate the test performance of imaging modalities for HCC. MEDLINE (1998 to December 2014), the Cochrane Library Database, Scopus, and reference lists. Studies on test performance of ultrasonography, computed tomography (CT), or magnetic resonance imaging (MRI). One investigator abstracted data, and a second investigator confirmed them; 2 investigators independently assessed study quality and strength of evidence. Few studies have evaluated imaging for HCC in surveillance settings. In nonsurveillance settings, sensitivity for detection of HCC lesions was lower for ultrasonography without contrast than for CT or MRI (pooled difference based on direct comparisons, 0.11 to 0.22), and MRI was associated with higher sensitivity than CT (pooled difference, 0.09 [95% CI, 0.07 to 12]). For evaluation of focal liver lesions, there were no clear differences in sensitivity among ultrasonography with contrast, CT, and MRI. Specificity was generally 0.85 or higher across imaging modalities, but this item was not reported in many studies. Factors associated with lower sensitivity included use of an explanted liver reference standard, and smaller or more well-differentiated HCC lesions. For MRI, sensitivity was slightly higher for hepatic-specific than nonspecific contrast agents. Only English-language articles were included, there was statistical heterogeneity in pooled analyses, and costs were not assessed. Most studies were conducted in Asia and had methodological limitations. CT and MRI are associated with higher sensitivity than ultrasonography without contrast for detection of HCC; sensitivity was higher for MRI than CT. For evaluation of focal liver lesions, the sensitivities of ultrasonography with contrast, CT, and MRI for HCC are similar. Agency for Healthcare Research and Quality. ( CRD42014007016).

Hepatocellular carcinoma: diagnostic performance of multidetector CT and MR imaging-a systematic review and meta-analysis.

To perform a systematic review and meta-analysis of the diagnostic performance of computed tomography (CT) and magnetic resonance (MR) imaging as noninvasive modalities for evaluating hepatocellular carcinoma (HCC) in patients with chronic liver disease. A search of the MEDLINE, EMBASE, and Cochrane Library databases was performed to identify studies providing per-patient or per-lesion diagnostic accuracies of multidetector CT and MR imaging for HCCs in patients with chronic liver disease. Studies published from January 2000 to December 2012 that used a reference standard based on histopathologic findings and/or findings at follow-up were included. Summary estimates of diagnostic accuracy were obtained by using a random-effects model with further exploration with meta-regression and subgroup analyses. Forty studies (six on multidetector CT, 22 on MR imaging, and 12 on both CT and MR imaging) were included. The studies evaluated a total of 1135 patients with multidetector CT and 2489 patients with MR imaging. The overall per-patient sensitivity of MR imaging was 88% (95% confidence interval [CI]: 83%, 92%), with a specificity of 94% (95% CI: 85%, 98%). The overall per-lesion sensitivity of MR imaging was higher than that of multidetector CT when the paired data of the 11 available studies were pooled (80% vs 68%, P = .0023). Gadoxetic acid-enhanced MR imaging showed significantly higher per-lesion sensitivity than MR imaging performed with other contrast agents (87% vs 74%, P = .03). Per-lesion sensitivity was significantly lower for HCCs smaller than 1 cm than that for HCCs 1 cm or larger (P < .001 for CT, P = .02 for MR imaging) and for those in explanted livers (P = .04 for CT, P < .001 for MR imaging). MR imaging showed higher per-lesion sensitivity than multidetector CT and should be the preferred imaging modality for the diagnosis of HCCs in patients with chronic liver disease.

MRI of hepatocellular carcinoma: an update of current practices.

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide, and liver transplantation is the optimal treatment for selected patients with HCC and chronic liver disease (CLD). Accurate selection of patients for transplantation is essential to maximize patient outcomes and ensure optimized allocation of donor organs. Magnetic resonance imaging (MRI) is a powerful tool for the detection, characterization, and staging of HCC. In patients with CLD, the MRI findings of an arterial-enhancing mass with subsequent washout and enhancing capsule on delayed interstitial phase images are diagnostic for HCC. Major organizations with oversight for organ donor distribution, such as The Organ Procurement and Transplantation Network (OPTN), accept an imaging diagnosis of HCC, no longer requiring tissue biopsy. In patients that are awaiting transplantation, or are not candidates for liver transplantation, localized therapies such as transarterial chemoembolization and radiofrequency ablation may be offered. MRI can be used to monitor treatment response. The purpose of this review article is to describe the role of imaging methods in the diagnosis, staging, and follow-up of HCC, with particular emphasis on established and evolving MRI techniques employing nonspecific gadolinium chelates, hepatobiliary contrast agents, and diffusion weighted imaging. We also briefly review the recently developed Liver Imaging Reporting and Data System (LI-RADS) formulating a standardized terminology and reporting structure for evaluation of lesions detected in patients with CLD.

Recent advances in visualization, imaging, and navigation in hepatobiliary and pancreatic sciences

Recent introduction of multi-detector CT (MDCT) and high-speed magnetic resonance (MR) imaging have dramatically advanced visualization and imaging technology in diagnostic and therapeutic strategy in hepatobiliary pancreatic disease. However, image diagnostics have progressed with a background of the essence of anatomy, pathology, and physiology. It is important to object the reflection of the patient's condition and pathology of each disease and remove pattern recognition in what they were depicted as an image. Visualization plays another important role in various medical diagnostics. Trends in scientific visualization will depend on advancements in molecular technology and computer hardware as well as trends in engineering disciplines. In this special issue, the recent advances in visualization and imaging in the field of hepatobiliary and pancreatic sciences are featured including application of advanced visualization techniques, data management, data compression, feature extraction. We discuss the potential benefits of new technologies and procedures in hepatobiliary and pancreatic areas, that are circulating tumor cells, MR imaging for hepatocellular carcinoma, indocyanine green using fluorescence under infrared light observation, carbon dioxide enhanced MDCT virtual cholangiopancreatography, endoscopic ultrasonography-guided biliary drainage, natural orifice translumenal endoscopic surgery, MR-laparoscopy, and image overlay navigation surgery by OsiriX. Some of the recent trends are discussed in terms of visualization and imaging in hepatobiliary and pancreatic sciences. The goal in using visualization is to assist existing scientific procedures by providing new insight through visual representation.

MR Imaging of Hepatocellular Carcinoma in the Cirrhotic Liver: Challenges and Controversies

The incidence of hepatocellular carcinoma (HCC) is expected to increase in the next 2 decades, largely due to hepatitis C infection and secondary cirrhosis. HCC is being detected at an earlier stage owing to the implementation of screening programs. Biopsy is no longer required prior to treatment, and diagnosis of HCC is heavily dependent on imaging characteristics. The most recent recommendations by the American Association for the Study of Liver Diseases (AASLD) state that a diagnosis of HCC can be made if a mass larger than 2 cm shows typical features of HCC (hypervascularity in the arterial phase and washout in the venous phase) at contrast material-enhanced computed tomography or magnetic resonance (MR) imaging or if a mass measuring 1-2 cm shows these features at both modalities. There is an ever-increasing demand on radiologists to detect smaller tumors, when curative therapies are most effective. However, the major difficulty in imaging cirrhosis is the characterization of hypervascular nodules smaller than 2 cm, which often have nonspecific imaging characteristics. The authors present a review of the MR imaging and pathologic features of regenerative nodules and dysplastic nodules and focus on HCC in the cirrhotic liver, with particular reference to small tumors and lesions that may mimic HCC. The authors also review the sensitivity of MR imaging for the detection of these tumors and discuss the staging of HCC and the treatment options in the context of the guidelines of the AASLD and the imaging criteria required by the United Network for Organ Sharing for transplantation. MR findings following ablation and chemoembolization are also reviewed.

High-resolution dynamic MR imaging of hepatocellular carcinoma with a phased-array body coil.

High spatial resolution dynamic magnetic resonance (MR) imaging performed with a phased-array body coil is a useful tool for evaluating hepatocellular carcinoma. The examination consists of fast spin-echo T1- and T2-weighted images obtained in a single breath hold; multisection, dynamic, fast gradient-echo images obtained in a single breath hold; and contrast material-enhanced images obtained in the arterial-dominant and delayed phases. Hepatocellular carcinoma, with its predominantly arterial blood supply, usually appears hyperintense on arterial-dominant phase images and isointense or hypointense relative to liver parenchyma on delayed-phase images. Hepatocellular carcinomas, especially those larger than 1.5 cm, contain a fibrous capsule or an inner septum, which allows them to be differentiated from other tumors. These characteristics are particularly important in the diagnosis of hypovascular hepatocellular carcinomas, which do not have an arterial blood supply and thus do not enhance. Extracapsular invasion, a relatively common finding in advanced cases, is seen as a nodular enhancing area that projects into the surrounding liver parenchyma adjacent to the main tumor on arterial-dominant phase images and as an iso- or hypointense area on delayed-phase images. Portal vein invasion appears as an obstruction of the vein, and portal vein tumor thrombi appear as intermediate-signal-intensity masses. The technique can also be helpful in the follow-up of treatment.

Plain and gadolinium-DTPA-enhanced MR imaging of hepatocellular carcinoma treated with transarterial chemoembolization

To assess unenhanced and gadolinium-enhanced magnetic resonance (MR) imaging patterns of hepatocellular carcinoma (HCC) treated with transarterial chemoembolization (TACE). Thirty-two patients with 48 HCC lesions underwent MR imaging before and 15 days after TACE. Fifteen lesions were then surgically resected. The remaining 33 lesions were not removed and were followed up with MR imaging at 3, 6, 12, and 18 months after treatment. Spin echo (SE) T1- and T2-weighted and gadolinium-enhanced SE T1-weighted sequences were employed. Qualitative evaluation of signal intensity pattern of the treated lesions was performed in all cases. Histological evaluation and selective hepatic arteriography were considered the gold standard of the study for the 15 resected lesions and the 33 unresected lesions, respectively. On follow-up enhanced T1-weighted images of the 15 resected lesions, seven showed no area of enhancement corresponding to complete necrosis at histologic examination. The remaining eight resected lesions showed areas of enhancement; in six of these cases, viable tumor tissue was found at histology; in the other two lesions, histologic examination revealed the presence of complete tumor necrosis. In the group of resected lesions, T2-weighted images showed no pattern characteristic of necrosis. In 24 of 33 unresected lesions, loss of enhancement on follow-up enhanced T1-weighted images was a characteristic finding, which correlated to devascularization at arteriography. Of these 24 lesions, 17 were completely hypointense on follow-up T2-weighted images; the remaining seven showed small foci of hyperintensity. The other nine unresected lesions showed enhanced portions on follow-up enhanced T1-weighted images, which corresponded to hyperintense areas on T2-weighted images. These findings correlated to persistence of hypervascular areas at arteriography. Gadolinium-enhanced T1-weighted MR imaging is a reliable method for evaluating the outcome of TACE treatment and is more accurate than unenhanced T2-weighted MR imaging.